Silurian Rugose Corals of 

the Klamath Mountains 

Region, California

GEOLOGICAL SURVEY PROFESSIONAL PAPER 738
Silurian Rugose Corals of 

the Klamath Mountains 

Region, California

By CHARLES W. MERRIAM

GEOLOGICAL SURVEY PROFESSIONAL PAPER 738

A descriptive, taxonomic, and stratigraphic study 

of Klamath Mountains Silurian Rugosa

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1972
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress catalog-card No. 72-600033

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.C. 20402 - Price $1 (paper cover)

Stock Number 2401-2077
CONTENTS

Abstract. _ --_-_--_----_--_______-__________________

Introduction. ______________________________________

Objectives and scope. ___________________________

History of investigation. ________________________

Methods of study______ _________________________

Acknowledgments. __ _ ___________________________

Distribution of Paleozoic rocks in the Klamath Mountains region. _____________________________________

Paleozoic strata of the northeastern Klamath subregion_ 

Gazelle Formation of Silurian age, Willow Creek

Bonnet Rock section- _--___-___-_-___-______

Chastain Ridge section- _____________________

Mallethead Ridge section. ___________________

Gazelle Formation at Parker Rock____ ____________

Silurian or Early Devonian limestones of the Gregg 

Ranch area_ _________________________________

Silurian or Early Devonian strata of the Grouse 

Creek area. __________________________________

Early Silurian and Ordovician(?) deposits of the 

Horseshoe Gulch area. ________________________

Rugose corals and associated fossils of the northeastern 

Klamath subregion__ _ _____________________________

Atrypella fauna of the Willow Creek area_ _________

Fossils of unit 1 of the Gazelle Formation, 

Willow Creek area_ ___---__----___________

Silurian fossils of unit 3 of the Gazelle Formation, Willow Creek area_ __________________

Silurian rugose corals and associated fossils of the 

Parker Rock area__ ___-------_-______-________

Faunas of the Gregg Ranch area_ ________________

Rugose corals and associated fossils of the Grouse 

Creek area. __________________________________

Rugose corals and associated fossils of the Horseshoe Gulch area_ ________-__---__-_____-______

Geologic correlation of the northeastern Klamath subregion Paleozoic rocks_ _______________________ i____

Correlation with Silurian rocks of the Douglas City 

area___ _________ _____________________________

Correlation with older Paleozoic rocks of the Taylorsville area, California. ______________________

Correlation with southeastern Alaska Silurian and 

Early Devonian sequences- ____________________

Heceta-Tuxekan Island area__ ________ ________

Kuiu Island. _______________________________

Kasaan Bay area, Alaska_ ___________________

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Geologic correlation, etc. Continued page

Correlation with Silurian rocks in the Great Basin __ 20 

Correlation with eastern North America, Europe,

and Australia._________----__________--___-__ 20

Eastern North America____________________ 20

Europe ____________________________________ 21

Australia-___----------------_----------__ 22

Geologic age of Paleozoic rocks in the northeastern Klamath subregion___--______________________________ 22

Depositional environment and origin of the northeastern

Klamath subregion coral-bearing deposits.___________ 24

Coral-bearing limestone conglomerate.____________ 25

Origin of coralline limestones in the Gazelle Formation- -_-_--_-_________-____-___------_____ 26

Classification of Klamath Mountains Silurian Rugosa___ 26

Systematic and descriptive paleontology-----_________ 27

Family Laccophyllidae__________________________ 27

Syringaxon-- __ ____________________________ 27

Family Streptelasmatidae___-____________--_-_-__ 28

Dalmanophyllum,- ___________________________ 28

Family Stauriidae--___-__------_-__---_---_---_- 28

Palaeophyllum. _____________________________ 29

Wintunast raea______________________________ 29

Family Pycnostylidae___________________________ 30

Pycnostylid sp. H_________________________ 31

Family Tryplasmatidae_-__----__--_-------_---_- 31

Zelophyllum- _______________________________ 31

Family Kodonophyllidae_____--------------.__-_- 32

Subfamily Kodonophyllinae._________________ 32

Kodonophyllum,- ________________________ 32

Subfamily Mycophyllinae____________________ 32

Mucophyllum_ __________________________ 32

Family Lykophyllidae __--____-__------------__- 33

Cyathactis- ___________--_-___---_-------_-__ 33

Family Cystiphyllidae_________________________ 35

Cystiphyllum,- ______________________________ 35

Family Kyphophyllidae._________-__------_----_ 36

Kyphophyllum. ___________-____--_----_--__- 36

Petrozium- ___________________---__---___-__ 37

Shastaphyllum. _____________________________ 38

Family Endophyllidae___________--_-_-------___- 39

Klamathastraea. ___-__-______-_---_---_----- 40

Locality register.________________-__--___-_---_-_--- 41

References cited-_____-________-_--_--_--__-_---_-i- 42

Index._________---_---------_---_-----_----------- 47

ni
IV CONTENTS

ILLUSTRATIONS

[Plates follow index]

PLATE 1. Zelophyllum, pycnostylid, Dalmanophyllum, and Cystiphyllum.

2. Shastaphyllum, pycnostylid, and Palaeophyllumt

3. Wintunastraea, Shastaphyllum, and Cystiphyllum.

4. Australophyllum, Wintunastraea, Shastaphyllum, fOrthophyllum, Syringaxon, Kodonophyllum, and coralline rubbly limestone of the Gazelle Formation.

5. Klamathastraea and Australophyllum.

6. Cyathactis and Mucophyllum.

7. Petrozium and Kyphophyllum.

8. Kyphophyllum.

Page

FIGURE 1. Map of Klamath Mountains region, California, showing rock belts and locations of fossiliferous exposures-... __ 5

2. Map of the northeastern Klamath subregion, showing the five separate areas wherein coral-bearing Paleozoic

rocks occur._______-.-______________--_-_--_-_-_-__-_------_-____________________________________ 7

3. Geologic map and section of the type area of the Gazelle Formation.______________________________________ 9

4. Photograph of Bonnet Rock and Chastain Ridge, showing bold outcrops of the caprock limestone of Gazelle

unit 3____________---__-_-_---_-_--___--------_---_-----------__________________________________ 10

5. Photograph of argillaceous limestone breccia-conglomerate of Gazelle unit 2_________________________________ 11

6. Photograph of Chastain Ridge, showing limestone caprock of Gazelle unit 3 in fault contact with unit 1______ 12

TABLES

Page 

TABLE 1. Fauna of the Atrypella zone, Gazelle Formation, Willow Creek area.__-_-_--__-___-___-_-_-_-_-_________-_- 14

2. Silurian fossils from the Gazelle Formation, Parker Rock area____-----_-___---_-_-_-_-___-______________ 15

3. Identification of fossils in the Gazelle Formation by previous workers______________________________________ 23
SILURIAN RUGOSE CORALS OF THE KLAMATH 

MOUNTAINS REGION, CALIFORNIA

By CHARLES W. MERRIAM

ABSTRACT

The graywacke-iargillite sequence of the northeastern Klamath 

subregion, Siskiyou County, Calif., includes limestone and limestone conglomerate containing distinctive Silurian rugose corals 

associated with Atrypella, Gonchidium, and Encrinurus.

Part of this sequence has been designated the Gazelle Formation; the type section is on Willow Creek near Gazelle, where 

it comprises lithologic units 1 through 3 in ascending order. Most 

of the corals come from unit 2, an argillaceous limestone conglomerate underlying the massive limestone of unit 3. To the 

west in the Scott River drainage, different coral-brachiopodmolluscan faunas occur in lenticular limestones of the graywacke belt; Halysites, absent from the type area of the Gazelle, 

occurs in the more westerly Silurian facies.

The graywacke-argillite sequence with its localized coralline 

limestone lenses was deposited in the Pacific Border graywacke 

belt, which includes the Silurian strata of southeastern Alaska. 

In Alaska this succession includes volcanic rocks, some of which 

are pillow lavas. No diagenetic dolomite is known in the Pacific 

Border Silurian, in sharp contrast to the Great Basin shelf sea 

strata of this system.

Of 33 rugose coral families identified in the Great Basin 

Silurian, 10 occur also in the northeastern Klamath faunas. 

Wintunastraea, Shastaphyllum, and Klamathastraea are new 

genera of colonial Rugosa, thus far known only in the Gazelle 

Formation. Most of the Klamath Mountains genera and species 

of Rugosa differ from those of the Great Basin.

The Klamath Mountains beds share the following rugose coral 

families: Streptelasmatidae, Kodonophyllidae, Tryplasmatidae, 

Lykophyllidae, Stauriidae, Kyphophyllidae, and Endophyllidae 

with the Swedish Gotland beds (Silurian standard) of western 

Europe. A majority of the families and genera that are present 

in both the Gotland and Klamath deposits seem to peak earlier 

in the Silurian at Gotland than in the Silurian at Klamath.

On the basis of correlation with the Atrypella-ConcMdium 

beds of southeastern Alaska and of comparison with coral assemblages of the Great Basin, Gotland, Czechoslovakia, and 

Australia, the Gazelle coralline beds of unit 2 are considered to 

be of Late Silurian (Ludlovlan) age. Older and probably 

younger coral-bearing strata occur in the Scott River drainage. 

No coral or brachiopod faunas of Devonian (Kennett Formation) age were recognized in the northeastern Klamath 

subregion.

The Rugosa of the northeastern Klamath subregion are described, classified, and illustrated.

INTRODUCTION

Coral-bearing limestones of Silurian age form a geomorphically conspicuous but otherwise minor part of 

structurally and stratigraphically complex rock sequences in the northeastern part of the Klamath Mountains region. Pre-Silurian strata, doubtless present here, 

remain to be identified paleontologically with assurance. 

Devonian beds have not been conclusively dated; all 

rocks in this vicinity previously assigned to the Devonian System on tenuous fossil evidence are now believed to be older. The Devonian is much better known 

in the southeastern part of the Klamath Mountains 

region (fig. 1).

In the northwestern states generally, Paleozoic history is obscured by deformation, metamorphism, and 

cover of younger rocks, especially volcanic rocks. To 

this the northeastern Klamath subregion is no exception, situated as it is adjacent to the Cascade belt. Here, 

as on the east side of the Cascades scattered f ossilif erous 

exposures suggest that earlier in geologic history the 

Paleozoic systems were possibly continuous and fairly 

complete beneath terrane now occupied by the volcanic 

chain. Although igneous intrusion and metamorphism 

are Avidespread in the Klamath Mountains province, 

fairly large areas in the eastern half escaped the total 

ravages of alteration and yield well-preserved fossils.

The rugose corals of these little-known Silurian beds 

were selected for detailed study because of their taxonomic diversity and good state of preservation, and 

because they fitted into a long-term research program 

on western North American middle Paleozoic Kugosa 

as guides to age determination, correlation, and historical geology. In this connection, associated fossils, 

particularly tabulate corals and brachiopods, have also 

been evaluated, in order that the stratigraphic and age 

conclusions not be based solely on the study of a single 

fossil group.

1
SILURIAN RUGOSE CORALS OP THE KLAMATH MOUNTAINS REGION, CALIFORNIA

OBJECTIVES AND SCOPE

Primary objectives of this investigation are the description, classification, and illustration of Silurian 

rugose corals from the Gazelle Formation. Dealt with 

also are Rugosa of strata not included in the Gazelle 

as that division is restricted in this region; part of these 

rocks are Early Silurian in age and part may bridge the. 

gap between Upper Silurian and Devonian.

In connection with the descriptive paleontology, the 

areal distribution and stratigraphy of the fossil-bearing 

rocks were discussed with the ultimate objective of establishing an integrated Paleozoic sequence and a true 

stratigraphic order of the several faunas. At present too 

little is known of the geology and paleontology of this 

region to make this objective possible; more detailed 

geologic mapping in conjunction with stratigraphic 

paleontology is required.

Understanding of the rugose corals and associated 

fossils of the Gazelle Formation and other units of this 

region is at present inadequate for more than provisional age determination and geologic correlation with 

other areas; more positive conclusions await detailed 

study of associated fossil groups, among which are 

brachiopods, trilobites, and calcareous algae.

Study of the Klamath Rugosa has been carried out 

concurrently with research upon Silurian rugose corals 

of the Great Basin and the Alexander Archipelago of 

southeastern Alaska. The Silurian rocks of the Klamath 

Mountains are quite similar to those of southeastern 

Alaska; both regions lie within the Pacific Border 

province in which graywacke and volcanic rocks are 

conspicuous. In the summers of 1961 and 1963 Alaska 

field parties of the U.S. Geological Survey were visited 

briefly for the purpose of comparing Silurian marine 

sections with those of the Klamath Mountains and of 

enlarging collections of comparative fossil material.

HISTORY OF INVESTIGATION

During the summer of 1884, J. S. Diller of the U.S 

Geological Survey was engaged in a pioneering geologic 

study of Mount Shasta and adjacent mountain ranges in 

Siskiyou County (Diller, 1886). At a base camp on the 

lower slope of this great volcanic peak, his explorer's 

curiosity was aroused by early morning sunlight illuminating light-colored crags to the northwest across 

Shasta Valley. Local residents informed Diller of the 

fossiliferous nature of the craggy limestones so clearly 

visible in the foothills of the Scott Mountains. Arrangement was made for a geologic reconnaissance later that 

year. Diller's brief examination of the limestone area 

on Willow Creek 3 miles southwest of Gazelle (Edson's 

Ranch) resulted in a neatly executed geologic structure 

section and sketch map recorded in his 1884 field notes;

his section and map delineate quite accurately the essential stratigraphic relations as they are presently 

understood. Some of the Silurian rugose corals collected 

by Diller at that time are described herein.

A preliminary report by Diller in 1886 on the geology 

of northern California directed attention to newly discovered Paleozoic rocks, including those now known as 

the Gazelle Formation. These strata were at that time 

assigned to the Carboniferous, together with upper 

Paleozoic rocks of the Redding area previously dated 

correctly by Meek (1864) in a report of the first California State Geological Survey. Initial error in age determination of the Gazelle probably resulted from the 

exterior resemblance of KlamatJiastraea to a lonsdaleioid coral, the problems of homoeomorphy among 

Rugosa not then being understood.

In 1893 the Diller party collected additional Gazelle 

fossils at Willow Creek, and a study of all Klamath 

Mountains Paleozoic fossils was undertaken by Charles 

Schuchert. In 1894 the results of this paleontologic investigation were published by Diller and Schuchert as 

a contribution announcing discovery of Devonian strata 

in northern California. Schuchert recognized the previous error of Carboniferous age assignment and reassigned the Gazelle to the Devonian System, together 

with the formation in the Redding area now called the 

Kennett Formation. Surficial resemblances of certain 

Gazelle brachiopods to Late Devonian species of the 

Great Basin and continental interior explain the 

Devonian assignment.

Diller's (1903) northern California field studies were 

extended in subsequent years to the south-central and 

western Klamath Mountains. Fossilif erous exposures, in 

mostly carbonate rocks, were discovered in association 

with metamorphic rocks at numerous localities. Although the fossils are for the most part rather scrappy 

and inadequate for positive identification, these collections from partly altered rocks made possible 

qualified determinations of age ranging from Devonian 

to latest Paleozoic.

Diller's most noteworthy achievement was the Redding Folio of 1906, an outstanding contribution describing the geology of a key area in the far west and elucidating its Paleozoic stratigraphy and historical geology. 

In this work the broader outlines of geologic structure 

and stratigraphy were convincingly set forth. Although 

no beds older than the Devonian Kennett Formation 

were dated by fossils, the pre-Kennett volcanic rocks 

were correctly identified, and there have been no subsequent major changes in the stratigraphic column of 

the southeastern Klamath subregion.

In 1930 Stauffer reviewed Schuchert's paleontologic 

conclusions when he compared the Devonian faunas
INTRODUCTION

and stratigraphy of northern California with those of 

the Inyo Mountains; his findings supported those of 

previous investigators that the Gazelle and the Kennett are of Devonian age, together with limestones of 

the northern Inyo Mountains now considered mainly 

Silurian and designated the Vaughn Gulch Limestone.

The writer's association with problems of northern 

California middle Paleozoic dates from 1932. In that 

year his attention was called to the Gazelle fossil occurrences by the late F. M. Anderson, who had observed the 

abundantly fossiliferous nature of these rocks while 

examining properties for the Southern Pacific Kailroad. 

From 1932 to 1935 several collecting trips to the Gazelle 

Formation in the Chastain Ranch area were made by 

the writer in the company of R. A. Bramkamp, F. E. 

Turner, and other graduate students at the University 

of California in Berkeley. The fossil material then obtained was found to include several species in the Diller 

collections. With the cooperation and guidance of G. A. 

Cooper of the Smithsonian Institution the Chastain 

Ranch material was identified as Silurian (Merriam, 

1940, p. 47^t8).

About 1946, economic interest in Siskiyou County 

limestone resources led to geologic mapping by Heyl 

and Walker (1949) of an area which included the type 

section of the Gazelle Formation. Like most Silurian 

limestones of the Pacific Border province, those of the 

Gazelle are fairly pure and nondolomitic. They have 

have been quarried for commercial purposes.

During the years from 1946 to 1960, student interest 

in rocks and fossils of the northeastern Klamath subregion led to recognition of the westerly continuation 

of the Silurian beds from Shasta Valley near Gazelle to 

Scott Valley. Among those whose fossil collections and 

geologic conclusions have come to the attention of the 

writer are B. J. Westman (1947), J. R. Mclntyre (unpub. data), and Michael Churkin, Jr. (1961,1965). Important fossil discoveries in these rocks at Scott Valley 

were made by Rodney Gregg of Gregg Ranch.

Following World War II, detailed geologic mapping 

of the copper districts north of Redding called for a 

review of the fossil evidence and stratigraphy of the 

Paleozoic rocks in the southeastern Klamath subregion 

(Kinkel and others, 1956). These investigations disclosed no strata carrying Silurian fossils beneath 

Devonian limestones of the Kennett Formation. Concurrent studies in the northeastern Klamath subregion 

failed to reveal the presence of Devonian strata with 

Kennett faunas in the Gazelle area.

During the 1950's reconnaissance geologic mapping 

was conducted by F. G. Wells within the northeastern 

Klamath subregion under the chromite program of the 

U.S. Geological Survey. In September of 1951 several

days were devoted to field study of fossil-bearing exposures by the writer in the company of F. G. Wells, J. 

R. Mclntyre, and W. C. Smith.

A geologic reconnaissance of little-known parts of the 

Klamath Mountains by W. P. Irwin and D. B. Tatlock 

led to the discovery of other Paleozoic rock exposures 

(Irwin, 1960) ; this discovery provided further incentive to restudy the Klamath Mountains Paleozoic geology. Of special interest was the finding of a Silurian 

fauna with Rhizophyllum (Helen Duncan and W. A. 

Oliver, Jr., written commun., 1961; Oliver, 1964, p. 150) 

in the Weaverville area of the central metamorphic belt 

(Irwin, 1963).

Discovery of Monograptm by Churkin (1965) in the 

Gazelle Formation on Willow Creek supported a Silurian age for these deposits. Fossil collecting by Maitland 

Stanley at Willow Creek in the summer of 1967 led to 

the finding of new rugose corals, including the new 

genus W intunastraea.

METHODS OF STUDY

Stratigraphic paleontology of the complex Paleozoic 

rocks in the northeastern Klamath Mountains calls 

for detailed geologic mapping as a basis for section discrimination and ultimate fossil zoning. Mapping thus 

far in this vicinity is of a most general nature except 

for small areas; one of these is the type area of the 

Gazelle Formation (fig. 3A) on Willow Creek, which 

was mapped by Heyl and Walker (1949). Some of the 

fossils are loose float material which was collected from 

the slopes of Chastain Ridge and Bonnet Rock; other 

fossils are traceable to weathered exposures of Gazelle 

unit 2. Other float of this kind undoubtedly comes from 

small, poorly exposed lower limestone lenses and cobbles 

of undetermined horizon in the thick Gazelle unit 1 

graywacke. Here and at Parker Rock detailed geologic 

study will eventually provide a better stratigraphic 

sequence. Only broad generalizations of the stratigraphy, structure, and depositional history of these interesting marine deposits are now possible. Field observations, fossil collecting, and sediment sampling in 

connection-with this study are inadequate for sedimentation analysis or biof acies appraisal.

Concurrent research upon southeastern Alaskan and 

Great Basin Silurian faunas by the writer has provided 

the advantage of direct comparison of corals, brachiopods, and other fossils with those of the Klamath Mountains region. Comparison of the Rugosa of the Klamath 

Mountains with related corals in the important Gotland 

and Czechoslovakian reference columns has not been 

satisfactory because of lack of comparative fossil material. Furthermore, most rugose corals of both European
SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

regions are in need of complete restudy using modern 

thin section techniques.

Preservation of Gazelle rugose corals ranges from 

excellent to poor, although little fossil silicification has 

taken place in these nondolomitic rocks. Difficulty was 

experienced in obtaining good photographs of the delicate internal structures, as for example with Cyathactis 

gazellensis and Petrozium staufferi. Staining the 

smoothed surfaces by the alizarine technique aided in 

differentiating the coral structure from the cloudy 

matrix, but the stain applied to thin sections did not 

improve photographic results.

ACKNOWLEDGMENTS

The writer is indebted to the University of California 

(Berkeley), Department of Paleontology, for use of 

fossil collections made in the years 1945 to 1949 by J. R. 

Mclntyre at Parker Rock, Grouse Creek, and Gregg 

Ranch. Use of excellent Gazelle corals collected by 

Maitland Stanley on Willow Creek in 1967 is greatly 

appreciated. Thanks are due also to Rodney Gregg of 

Gregg Ranch for guidance to the collecting sites in that 

vicinity.

Comparison of the Silurian strata from the Klamath 

Mountains and Alaska was greatly facilitated by visits 

to the better sections on Heceta, Tuxekan and Kuiu Islands under the guidance of G. D. Eberlein and 

L. J. P. Muffler of the U.S. Geological Survey during 

the summers of 1961 and 1963.

P. E. Hotz, W. P. Irwin, and G. W. Walker of the 

U.S. Geological Survey read the sections of this paper 

which deal with stratigraphic geology and made 

numerous constructive suggestions. The paleontologic 

section was critically reviewed by W. A. Oliver, Jr., 

of the U.S. Geological Survey, whose suggestions regarding matters of rugose coral taxonomy and description have been most helpful.

All fossil photographs are the work of Kenji Sakamoto, of the U.S. Geological Survey.

DISTRIBUTION OF PALEOZOIC ROCKS IN THE 

KLAMATH MOUNTAINS REGION

Paleozoic and pre-Cretaceous Mesozoic strata of the 

Klamath Mountains region are distributed in northtrending belts of differing rock character, age range, 

and metamorphism. As delineated by Irwin (1960, fig. 

3), an arcuate central belt of prevailingly metamorphic

rocks extends north through Weaverville to Yreka, in 

a sense dividing the Klamath region into western and 

eastern parts. Paleozoic rocks treated in this report lie 

east of the central belt of metamorphic rocks, in what 

is termed the "eastern Paleozoic belt" of Irwin. The 

Paleozoic rocks of this eastern belt may be further subdivided areally, on the basis of petrologic character, 

stratigraphy, and paleontology, into the northeastern 

Klamath subregion and the southeastern Klamath subregion (fig. 1).

Paleozoic rocks of the northeastern Klamath 

subregion abut on the west against the central belt of 

metamorphic rocks; those of the southeastern Klamath 

subregion are separated from the same metamorphic 

belt by a wide band comprising ultramafic rocks and 

granitic plutons, blanketed in part by Cenozoic volcanic rocks of the Mount Shasta vicinity and areas to 

the south. Little is known of Paleozoic bedrock within 

this intermediate band. The southeastern Klamath subregion, including the Redding and Shasta copper districts, is the more completely mapped and studied geologically ; in this subregion, Paleozoic strata ranging in 

age from Middle Devonian to Permian are dated paleontologically with confidence. Except for the Douglas 

City area, Silurian rocks have been identified with assurance only in the northeastern Klamath subregion 

with which this report is primarily concerned.

In rugged, forested areas of the central metamorphic 

belt and to the west are many scattered, little-known 

exposures of fossil-bearing limestone, marble, and argillite, some Paleozoic, others of Mesozoic or probable 

Mesozoic age. Many of these rocks are crinoidal; others 

contain tabulate corals, stromatoporoids, Chaetetes-like 

remains, and calcareous algae of uncertain affinity. 

Carbonate rocks with fossils occur along the Trinity 

River South Fork, in the southernmost Salmon Mountains, and sporadically in a very large area between 

Chanchelulla Peak and the South Fork Mountains. Several of these southern and southwestern Klamath exposures yield fusulinids and other late Paleozoic fossils; 

some, like the Whiterock occurrence northwest of North 

Yolla Bolly Mountain, once believed to be entirely 

Devonian, are actually of Triassic age in part (N. J. 

Silberling, written commun., 1958). Conclusively dated 

strata of Silurian and Devonian ages are, with one exception in the Douglas City area near Weaverville, all 

situated east of the central metamorphic belt.
DISTRIBUTION OF PALEOZOIC ROCKS IN THE KLAMATH MOUNTAINS REGION

CALIFORNIA

.. \ /Approximate boundary of 

; /Klamath Mountains region

lie /

Approximate

boundary of

Klamath

Mountains

region

EXPLANATION

Fossil-bearing rocks, 

mainly Paleozoic

Limestones and marbles of uncertain age, 

probably Paleozoic or Mesozoic

Rocks of Triassic age

D 

Rocks of Devonian age

SD 

Rocks of Silurian or Devonian age

Rocks of Silurian age

FOSSIL LOCALITIES

1 Gazelle Formation, Willow Creek area

2 Gazelle Formation, Parker Rock area

3 Silurian or Devonian, Grouse Creek area

4 Early Silurian, Horseshoe Gulch area

5 Silurian, Douglas City area

6 Limestone cobble with? Shastaphyllum

7 Silurian or Devonian on Knownothing Creek

8 Montgomery Limestone of Silurian age

9 Whiterock fossil area

10 Rocks of probable Permian age

11 Rocks of probable Permian age

12-15 Kennett Formation, Middle Devonian

FIGURE 1. The Klamath Mountains region, California, showing rock belts and locations of fossiliferous exposures. Adapted from

Irwin (1960, fig. 3).

454-393 O - 72 - 2
6

SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

PALEOZOIC STRATA OF THE NORTHEASTERN 

KLAMATH SUBREGION

The northeastern Klamath subregion (figs. 1, 2) occupies some 800 square miles between Shasta Valley 

on the east and Scott Valley on the west, extending 

from the Callahan vicinity north to Yreka. The only 

Paleozoic strata of firmly established age in this subregion are Silurian (Merriam, 1961) ; however, Upper 

Ordovician rocks are reported, and structurally isolated 

exposures of uncertain stratigraphic position contain 

faunas of probable Early Devonian age. There is little 

stratigraphic continuity here because of the complex 

geologic structure, patchy metamorphism, and intrusion by peridotite and granitoid bodies. Few sections 

lend themselves to bed-by-bed measurement and systematic fossil collecting for more than a few hundreds 

of feet.

The more conspicuous outcrops of this subregion are 

massive light-gray craggy limestones forming geomorphic features like Parker Kock, Mallethead Kock, and 

Bonnet Rock. Bold isolated limestone masses of this 

kind give an initial impression of having been formed 

as marine reefs, which were later entombed by clastic 

sediments. Although in considerable part of organic 

origin, these carbonate bodies lack true reef structure. 

Most of the Silurian corals and other fossils here dealt 

with come not from these prominent craggy limestone 

masses, but from partly argillaceous beds which underlie them.

Much more extensive areally than the craggy limestones are clastic siliceous sedimentary rocks, chert, 

phyllite or schist, and the plutonic rocks. Most abundant 

among the clastic rocks are graywacke, argillite, and 

conglomerate.

In this subregion, phyllite and schist, to which the 

name Duzel Formation has been applied (Wells and 

others, 1959), are of unknown age. There seems to be no 

convincing stratigraphic evidence to indicate that they 

are older than the Silurian rocks. In the Horseshoe 

Gulch area, these metamorphic rocks include thin unfossiliferous limestone beds. On Willow Creek they are 

believed to be faulted against the Gazelle Formation 

and are possibly the upper plate of a thrust in that area 

(Churkin and Langenheim, 1960, fig. 1).

Systematic fossil collecting has been done in five different areas of the northeastern Klamath subregion 

(fig. 2). Between most of these areas there is little

similarity in faunas and details of stratigraphy, and 

they are (as presently understood) not paleontologically correlative. To what extent this lack of agreement 

is a matter of facies change and how much is due to 

difference of stratigraphic position remains unestablished. At present these faunas have not been arranged 

in sequential order with confidence. Faunas and stratigraphy of the five separate areas are dealt with separately 

in the hope that an integrated column may eventually 

be set up. The five areas are as follows: (1) Willow 

Creek area (type area of the Silurian Gazelle Formation), (2) Parker Rock area, (3) Horseshoe Gulch area, 

(4) Grouse Creek area, and (5) Gregg Ranch area. 

Fossil localities in each area are described in a locality 

register at the end of this paper.

With some assurance it may be said that the oldest 

Paleozoic strata of this subregion are in the west at 

Horseshoe Gulch. Ordovician fossils have been reported 

in that vicinity, possibly below the Early Silurian fauna 

here dealt with. The highest beds of the Gazelle Formation at the east edge of the subregion are Late 

Silurian. In the south at Gregg Ranch and Grouse 

Creek, the youngest strata recognized thus far are those 

of possible Early Devonian age.

Detailed geologic mapping, in conjunction with 

stratigraphic paleontology and studies of metamorphism, still has to be done in this structurally complex 

terrane before a composite stratigraphic column can 

be proposed.

GAZELLE FORMATION OF SILURIAN AGE, WILLOW 

CREEK AREA

The Willow Creek drainage southwest of Gazelle 

includes the sections at Bonnet Rock, Chastain Ridge, 

and Mallethead Ridge within the type area of the 

Gazelle Formation. The geology of this vicinity was 

first described by Diller in unpublished notes of 1884. 

In later years the area was partly mapped geologically 

(fig. 3) by Heyl and Walker (1949) and by Churkin 

(Churkin and Langenheim, 1960). Two sedimentary 

rock formations are present the little-altered Gazelle 

Formation consisting of limestone, shale and argillite, 

graywacke, sandstone, conglomerate, and chert, and a 

schist and phyllite unit of unknown age which is in 

fault contact with the Gazelle. Locally these metamorphic rocks appear to rest against the Gazelle in a possible thrust fault relationship.
PALEOZOIC STRATA OF THE NORTHEASTERN KLAMATH SUBREGION

41 R 8 W 122°45 R 6 W 30' R 4 W 122°15' R 3 W

I ^Q^<: A I

\ \ jy

SISKIYOUy COUNTY x ^ /^

Base from U.S. Geological Survey 

1:250,000, Weed, 1958. Revised 1963

i i i 1_

10 MILES

_J

FIGURE 2. The northeastern Klamath subregion, showing the five separate areas wherein coral-bearing Paleozoic rocks occur: 

I. Willow Creek area, II. Parker Rock area, III. Gregg Ranch area, IV. Grouse Creek area, V. Horseshoe Gulch area.
S^VHOO jIO 3HJ, SLVWVTa SNIVUSinOM NOID3H f
3000 '-

-3500'

3000'

B

FIGUKE 3. Geologic map and section of the type area of the Gazelle Formation. A, Silurian fossil localities and relationships of stratigraphic units in the Lime Gulch 

area on Willow Creek. Modified from Heyl and Walker (1949, pi. 26). B, Section along line A-A' between North Peak and Bonnet Rock shows relations of the 

stratigraphic units.

CO
10 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

BONNET ROCK SECTION

The type section of the Gazelle Formation lies on 

the southwest side of Bonnet Rock, where it comprises 

three units as follows:

Type section of Gazelle Formation, southwest side Bonnet Rock

Top of section 

Gazelle Formation: Feet

Unit 3. Limestone, fairly uniform fine texture, 

craggy and cliffy, thick, evenly bedded; weathers 

medium- to light-gray. Includes contemporaneous 

limestone breccia-conglomerate lenses; chert 

pebbles in basal part. Abundantly fossiliferous 

to bioclastic in pockets_______________ 175±

Gradational boundary locally

Unit 2. Coarse limestone conglomerate and nodular 

argillaceous limestone with cobbles and subangular clasts of highly fossiliferous medium- to 

light-gray limestone in a matrix of tan-weathering argillite. Associated argillaceous pockets contain contemporaneous or unreworked fossils_ 0-25

Possibly disconformable contact

Unit 1. Predominant shale, dark-gray, weathers 

tan to maroon, and argillite with graywacke and 

coarse gritty sandstone. Subordinate beds of 

siliceous conglomerate and gray chert. Limestone lenses scattered, light-gray, fossiliferous- 1, 000±

1,200± 

Base unexposed

Bonnet Rock occupies the east limb of a north-trending asymmetric anticline in which ridge-capping limestone of unit 3 dips east at a low angle (fig. 4). Less 

competent beds of underlying unit 1 and unit 2 are 

more deformed and locally show indications of differential movement near the unit 3 boundary. No major 

shift related to possible thrust displacement of the massive unit 3 was recognized.

Unit 1, having a thickness estimated to be at least 

1,000 feet, occupies the axial part of the anticline between Bonnet Rock and Chastain Ridge (fig. SB). Its 

base is not exposed. This unit is predominantly dark 

gray and greenish-gray, tan-weathering shale and 

argillite, which is red or maroon in places. With the 

argillaceous beds are much graywacke and gritty sandstone; these are probably tuffaceous in considerable 

part. Subordinate are siliceous conglomerate and darkgray bedded chert. These highly variable lithologic 

types are discontinuous laterally. On the west side of 

Bonnet Rock in the upper 25 feet of unit 1 are lenses 

of tan and dark-gray argillite, sandstone, and graywacke which change laterally and below to siliceous 

conglomerate. A 15-foot conglomerate lens in this interval contains rounded to subangular cobbles as much 

as 10 inches long in a partly laminated argillite matrix; 

in places this f acies is a sort of puddingstone with scattered cobbles. The cobbles include hornfels, chert, 

porphyritic igneous rocks, graywacke, and limestone. 

The limestone cobbles are less than 2 percent of the 

total and have the general appearance of the limestone 

in unit 3. These cobbles were probably derived from 

the lower limestone lenses in unit 1 at Mallethead 

Ridge.

Unit 2, ranging in thickness from a few feet to about 

25 feet, is composed of rubbly-weathering nodular limestone and limestone conglomerate with tan to palegreen argillaceous matter as matrix between cobbles 

or nodules (fig. 5; pi. 4, fig. 13). In small fossil-rich 

lenses some of the cobbles and nodules are in fact 

corals and brachiopods which, when they weather free, 

may be coated by the tan or green argillaceous matter. 

Scattered lenses of the argillaceous material contain 

abundant small fossils.

ii.

FIGURE 4. View northwest toward Bonnet Rock and Chastain Ridge, showing bold outcrops of the cap-rock limestone of unit 3 in 

the type section of the Gazelle Formation. Lower slopes of Bonnet Rock underlain by argiliite and graywacke of unit 1. Photograph from Heyl and Walker (1949, fig. 2).
PALEOZOIC STRATA OF THE NORTHEASTERN KLAMATH SUBREGION 11

Occurring at the base of the massive limestone of 

unit 3, these argillaceous-limestone conglomerate beds, 

being less competent than the beds of units 1 and 3, 

have been deformed by differential movement and are 

therefore unsatisfactory for stratigraphic interpretation 

at their boundaries (fig. 5). However, it is probable 

that unit 2 has pockety distribution upon an uneven 

surface of disconformity because here and there the massive limestone of unit 3 rests directly upon unit 1. For 

example, on the west side of Bonnet Rock a sharp 

uneven contact with considerable relief locally separates 

the massive gray limestone of gray unit 3 from the 

graywacke of unit 1. At other exposures the nodularconglomeratic limestone of unit 2 appears to grade upward into the normal thick-bedded limestone of unit 3. 

The lack of lithologic uniformity within unit 2 is further 

discussed in connection with the exposures at Chastain 

Ridge.

Several of the better fossil collections from the 

Gazelle came from unit 2 at Bonnet Rock, where small

FIGURE 5. Argillaceous limestone breccia-conglomerate of unit 2, 

Gazelle Formation. Large boulder in middle foreground is 

about 15 inches wide, left to right. West side of Bonnet Rock.

lenses contain abundant tabulate corals, rugose corals, 

and brachiopods. Fossils occur in the argillaceous matrix as well as in limestone clasts and nodules.

Unit 3, the massive crag-forming upper limestone, is 

estimated to range in thickness from 75 feet to about 

150 feet at Bonnet Rock (fig. 4). It is thickly but evenly 

bedded, of fairly uniform fine texture, and is bluishgray when fresh and light gray when weathered. Unit 

3 includes scattered lenses of limestone conglomerate, 

chert conglomerate, and gray bedded chert. Corals and 

brachiopods are numerous in pockets. The limestone of 

unit 3, which has a very low magnesium content, is 

fairly pure chemically. (See Heyl and Walker, 1949, 

p. 519-520 and table 1.)

No rocks younger than unit 3 are known in this area. 

The relationship of unit 3 to underlying unit 2 is locally 

gradational, but where unit 2 was not found, it appears 

to rest disconformabry upon unit 1.

CHASTAIN RIDGE SECTION

The thick-bedded limestone of unit 3 is well exposed 

in Chastain Ridge, which is oriented north-south, and 

is 0.7 mile southwest of Bonnet Rock. Along the east 

side of this ridge, no exposures of unit 2 were found, 

and the contact between unit 3 and unit 1 is mapped 

as a fault. Fossils which weather out along this fault 

(fig. 6) appear to have come from unexposed beds of 

unit 2 or from the upper argillaceous beds of unit 1.

Shales and argillites occur in the upper beds of unit 

1 along the lower slopes east of the craggy limestones 

of unit 3 in this ridge; the shales weather in places from 

tan to green or maroon. On the southwest side of 

Chastain Ridge, the lower 30 feet of the massive limestone of unit 3 includes chert pebble lenses. Below unit 

3 are chert cobble conglomerates and grayish-green 

hornfelsic argillite, which are underlain by more chert 

cobble conglomerate and similar argillite members with 

graywacke and gritty sandstones. The distinctive fossilrich rubbly limestone conglomerate of unit 2 at Bonnet 

Rock was not found here, possibly being absent locally 

because of a disconf ormity below unit 3, but faulting is 

the explanation for some exposures. Heyl and Walker 

(1949, p. 517) observed siliceous conglomerate grading 

upward into limestone conglomerate at the base of unit 

3, with progressive increase of carbonate cement and 

limestone clasts.

The largest fossil collections from the Gazelle came 

from the south end of Chastain Ridge on the east side 

(loc. M78). Here the fossils weather out of argillaceous 

beds along the fault contact with the massive limestone 

of unit 3. Silurian graptolites reported by Churkin 

(1965) were collected from unit 1 about a mile westsouthwest of locality M78.
12 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

MALLETHEAD RIDGE SECTION

The prominent craggy limestone of unit 3 has been 

mapped south from Chastain Ridge into the western 

part of Mallethead Ridge, which extends eastward from 

Mallethead Rock to The Point (fig. 3A). Disconnected 

limestone exposures in the eastern part of this ridge 

have the lithologic appearance of unit 3, but they were 

not identified as such by fossils. On the south slope of 

Mallethead Ridge where outcrops are poor, the strata 

appear to be Gazelle Formation unit 1; the strata consist of argillite, graywacke, gray bedded chert, siliceous 

conglomerate, and subordinate gray limestone with 

abundant crinoidal debris and f avositid corals. Vertical 

stratigraphic order could not be determined within this 

sequence; it is several hundreds of feet thick, and 

scattered fossiliferous limestone bodies are seemingly 

distributed throughout its extent. Gray limestone cobbles in the upper part of unit 1 at Bonnet Rock could 

readily have been derived from the limestone in some 

of these lower lenses.

Diagnostic Silurian rugose corals of the genus Mucophyllum were collected from a limestone lens at the 

foot of Mallethead Ridge on the south side, 21/2 miles 

southwest of The Point. Near this limestone exposure 

a significant trilobite assemblage was collected from 

shales by Churkin (1961).

GAZELLE FORMATION AT PARKER ROCK

Parker Rock, an important collecting locality of 

Silurian corals, brachiopods, and mollusks, lies on the 

east fork of Scott River 6 miles northeast of Callahan 

near the old Parker Ranch site (fig. 2). Like Bonnet 

Rock on Willow Creek, Parker Rock is capped by lowdipping massive limestone of the Gazelle Formation. 

This limestone caprock, probably the equivalent of unit 

3 in the Willow Creek area, is underlain by weaker rocks 

which include deformed argillaceous siltstone and rubbly weathering breccia-conglomerate limestone (pi. 4, 

fig. 13) corresponding to beds of the unit 2 and topmost 

unit 1 interval at Bonnet Rock. In places at Parker 

Rock, tongues of the conglomeratic limestone with argillaceous matrix like unit 2 pass upward into the thickbedded equivalent of unit 3. These tongues suggest possible marginal reef talus features and are discussed 

elsewhere in this regard. Halysites and other corals are 

common in the lower beds of the massive caprock, but 

most of the coral and brachiopod material was collected 

from underlying conglomeratic and argillaceous limestone from which they weather free, as they do in unit 

2 at Bonnet Rock.

Collections of well-preserved fossils made by J. R. 

Mclntyre from the Parker Rock vicinity appear to have 

come mainly from strata below the upper massive limestone and probably represent the interval equivalent to 

unit 2 and the higher beds of unit 1.

FIGURE 6. View northwest toward Chastain Ridge, which is underlain by the Gazelle Formation. Limestone caprock of unit 3 

is in fault contact with unit 1 on east. Collecting locality M78 in middleground left.
RUGOSE CORALS AND ASSOCIATED FOSSILS OF THE NORTHEASTERN KLAMATH SUBREGION 13

SILURIAN OR EARLY DEVONIAN LIMESTONES OF THE 

GREGG RANCH AREA

The Gregg Ranch area lies on the east fork of Scott 

River northeast of Parker Rock between Rail Creek 

and Houston Creek (fig. 2). Fossil-rich Paleozoic limestone outcrops in this vicinity appear to be lenses scattered in a predominantly argillite-graywacke sequence 

lithologically similar to unit 1 of the Gazelle Formation 

in the Willow Creek area. The exposures are, however, 

poor, and the absence of continuous outcrop precludes 

the determination of stratigraphic sequence. Fossil evidence reviewed elsewhere suggests that some of the 

Gregg Ranch limestones are younger than those in 

Gazelle unit 3; it is possible that the strata here include 

a higher continuation of that succession, thus ranging 

upward from Silurian into the Devonian System. In 

general, the faunas of the Gregg Ranch area differ 

from those of neighboring Parker Rock. How much of 

the difference is related to depositional and f aunal f acies 

and how much reflects differences of stratigraphic horizon has not been established.

Greenstones with limestone lenses on the east side of 

the Gregg Ranch area (Wells and others, 1959, p. 648) 

have previously been considered to be of possible 

Devonian age.

SILURIAN OR EARLY DEVONIAN STRATA OF THE 

GROUSE CREEK AREA

The Grouse Creek area lies on Grouse Creek west of 

Cooper Meadow, 6y2 miles east of Callahan (fig. 2). 

Well-preserved brachiopods, corals, and Mollusca 

occur here in dark-gray calcareous siltstone and silty 

limestones in an isolated belt of very poor exposures in 

forested terrain where the sedimentary rocks were extensively penetrated by peridotite and other basic 

intrusives.

Lithologically these fossil-rich Paleozoic rocks do not 

resemble those in other parts of the northeastern 

Klamath subregion and no stratigraphic sequence has 

been observed. Corals from the Grouse Creek area have 

their nearest analogs in the Gregg Ranch area, but in 

general the Grouse Creek faunas are quite different 

from other assemblages of this subregion.

EARLY SILURIAN AND ORDOVICIAN(?) DEPOSITS OF 

THE HORSESHOE GULCH AREA

Paleontologic evidence strongly suggests that older 

strata of the northeastern Klamath subregion lie to the 

west in the Horseshoe Gulch area (fig. 2), within the 

westernmost outcrop belt of the Duzel Formation 

(Wells and others, 1959, pi. 1). Poorly exposed rocks of 

Horseshoe Gulch, an east branch of McConnahue 

Gulch, consists of deformed graywacke, phyllite, limestone, and marble within which no stratigraphic order 

has been determined. Fossils collected here have previously been dated provisionally as Ordovician (?), 

Early Silurian, and more doubtfully as Devonian. 

These fossils have come from isolated, relatively little 

altered, but fractured, variably iron-rich limestone 

quite unlike the thick-bedded light-gray limestone of 

Gazelle unit 3 at Willow Creek. Structural and 

stratigraphic relationships of these fossil-bearing limestones to the much more extensively exposed Duzel 

phyllites have not been established. Duzel phyllites of 

this vicinity include thin unfossiliferous limestone or 

marble layers.

That Duzel phyllite and associated rocks of Horseshoe Gulch are actually equivalent to the phyllite and 

schist faulted against the Gazelle Formation on Willow 

Creek remains to be demonstrated. At Bonnet Rock 

these metamorphic rocks differ in appearance and are 

not known to have limestone intercalations like the 

Duzel phyllite of Horseshoe Gulch. Fossils and age of 

the Horseshoe Gulch beds are discussed below.

RUGOSE CORALS AND ASSOCIATED FOSSILS OF 

THE NORTHEASTERN KLAMATH SUBREGION

Rugose corals of the five areas within this subregion 

(fig. 2) are associated with other fossils, nearly all of 

which are undescribed. Some were previously referred 

to Devonian species to which they are unrelated. Because these associated fossils are important in establishing age and correlation, they are listed here, mostly 

as genera unless otherwise known to resemble previously described species, as for example certain 

Alaskan brachiopods of Silurian age.

Only in the Willow Creek area is the stratigraphy 

sufficiently well known to make possible a treatment of 

the faunas in terms of stratigraphic position. Here, 

however, most of the material comes from a 50-foot 

interval bracketing Gazelle unit 2, the topmost beds of 

unit 1, and the basal beds of unit 3. Fossils from this 

interval are considered together as the Atrypella fauna. 

The type section for the Gazelle Formation on the 

southwest side of Bonnet Rock has yielded a good representation of the fauna from this interval, and it was 

probably here that most of Diller's collections were 

made. Most of the material collected by the writer and 

his associates in later years came from localities along 

the southeast edge of Chastain Ridge, from what is 

regarded as the same 50-foot interval. Here the fossils 

weather free along the fault contact of Gazelle unit 3 

and unit 1, the unit 2 limestone conglomerate not being 

exposed (fig. 6). At Parker Rock the Silurian section is 

similar to that of the Willow Creek area, but detailed

454-393 O - 72 - 3
14 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

mapping is needed to elucidate the stratigraphic 

sequence.

ATRYPELLA FAUNA OF THE WILLOW CREEK AREA

The Atrypella fauna is so named because of the 

abundance of this smooth spiriferoid so characteristic 

of the higher Silurian of the circumboreal belt from 

Alaska to Greenland. In the Willow Creek area this 

fauna characterizes unit 2 of the Gazelle Formation, 

extending up into basal beds of unit 3 and occurring 

in the topmost beds of unit 1. Table 1 shows rugose 

corals and associated fossils collected from this interval at Bonnet Rock and Chastain Ridge.

As noted below, the Silurian beds of Parker Rock 

include some species of the Atrypella fauna, but the 

coral, molluscan, and trilobite facies differ.

TABLE 1. Fauna of the Atrypella zone, Gazelle Formation, 

Willow Creek area

Species

Bonnet Rock Chastain Ridge

M191

US OS 586 

M1132 M190 M78 M1135

Rugose corals:

? Orthophyllum sp__--. -

Syrmgaxon sp.---------------

tPalaeophyllum sp. G- --------

Wintunastraea stanleyi n. 

gen., n. sp..-..-------------

Zelophyllum sp. G_-----------

Cyathactis gazellensis n. sp_ - 

Cystiphyllum sp. c.----------

tKyphophyllum...............

Petrozium staufferi n. sp- - - -

Shastaphyttum schucherti n. 

gen., n. sp- -- -

Klamathastrea dilleri n. gen.,

n. sp 

Tabulate c

Heliolit

Plasma

Favosit 

Stromatopi 

Brachiopods:

tlsorthis

Conchidi

Gypidula

Ban an '

Atrypa

Atrype'

Plectat

Alaska,

IStrick

strophi 

Trilobites:

Bumastus..

Encrinurus

:orals:

ds:

:i». ...................

I

eodont. .-._.-_.---_..

X -----

... X 

... X -----

... X -----

X ------

X V

x

X

X

--XX

 --- --- X X

y v

._-_--._...--- X _-_.-.--

x

X

FOSSILS OF UNIT 1 OF THE GAZELLE FORMATION, 

WILLOW CREEK AREA

Topmost beds of unit 1 contain the Atrypella fauna, 

but most of this thick unit has yielded no significant 

fossil evidence from beds of known stratigraphic position. Limestone float with tabulate corals is fairly common within the outcrop area of unit 1, but it cannot be 

determined with certainty that this material was not 

derived from Gazelle unit 3.

Monograptus, collected by Churkin (1965) in upper 

Lime Gulch (loc. M1280), probably occurs in the upper 

part of unit 1 below the Atrypella zone. Possibly much

lower in unit 1 are the trilobite and coral occurrences 

(loc. M87) on the south side of Mallethead Ridge. 

Along this slope from the top of the ridge south to the 

middle fork of Willow Creek, coral-bearing limestone 

float probably came from lenses within unit 1. At 

locality M87 the horizon of the limestone bed containing the diagnostic rugose coral, MucopJiyllum 

mcintyrei, is possibly close to that of the shale which 

yielded a trilobite assemblage (Churkin, 1961). This 

fauna, identified by Churkin, is listed below: 

Trilobites:

Lconaspis (AcantJialomina) minuta (Barrande)

Dicranopeltis sp., cf. D. decipiens (Weller)

Trochurus sp. indet.

Scutellwni sp. indet.

Proetus sp. indet.

Cheirurus cf. C. insignis Beyrich

Encrinurus (Cromus) ~beaumonti (Barrande) 

Brachiopods:

Leptaena rhomboid alls Wilckens?

Atrypa reticularis Linnaeus var. orUcularis Sowerby?

Atrypella scheii (Holtedahl) ?

Gypidula sp.

SILURIAN FOSSILS OF UNIT 3 OF THE GAZELLE 

FORMATION, WILLOW CREEK AREA

The massive light-gray, ridge-capping limestones of 

unit 3 are quite fossiliferous or biogenic in places, but 

thus far have yielded few well-preserved fossils because of the difficulty of extraction. Silicified material 

is uncommon, perhaps because dolomitization, which 

often accompanies fossil silicification, did not take place 

here. Other than debris of crinoids, tabulate corals, 

and algae, the only forms generically identified are 

small Atrypella-like brachiopods and the rugose corals 

Kodonophyllum and Zelophyllum.

Calcareous algae, probably important limestone 

builders of unit 3, have been listed and figured by 

Johnson and Konishi (1959, p. 136) from the type area 

of the Gazelle ("Graystone area"). Among these are 

the following:

Parachaetetes sp.

Vermiporella cf. ~borealis H0eg

Girvanella pro~blematica Nicholson and Btheridge

Dasyporella norvegica H0eg

It is likely these algae were collected from the massive 

limestones of unit 3. Because of the resemblance of 

the algae from the type Gazelle to those from the Early 

Silurian of Horseshoe Gulch, the former were also considered Llandoverian by Johnson and Konishi (1959, 

p. 158, table 3).

SILURIAN RUGOSE CORALS AND ASSOCIATED FOSSILS 

OF THE PARKER ROCK AREA

Table 2 lists fossils collected by the writer in 1951 and 

1956 and by J. R. Mclntyre during the years 1945 to
RUGOSE CORALS AND ASSOCIATED FOSSILS OF THE NORTHEASTERN KLAMATH SUBREGION 15

1949. In the main, the Parker Rock material is believed 

to represent the Gazelle Formation and the interval 

of the Atrypella fauna, although Atrypella is itself 

poorly represented.

The distinctive colonial Rugosa of the Gazelle at 

Willow Creek were not found at Parker Rock. However, Cyathactis gazellensis is present, as are the brachiopods Conchidium, Plectatrypa, and small spiriferoids provisionally assigned to Alaskospira. Also abundant are the tabulates Heliolites, Favosites, and Halysites. A significant facies difference is absence of Halysites at Willow Creek. Absence of the Gazelle colonial 

Rugosa at Parker Rock is also ascribed to facies difference. In other regions coralline biofacies of the Silurian 

not uncommonly lack Hafysites where other tabulates 

may be abundant.

The biofacies at Parker Rock favored the gastropods 

to a greater extent than the biofacies at Willow Creek,

T

TABLE 2. Silurian fossils from the Gazelle Formation, Parke

Rock area

Species M1028 M1029 M1030 M81 M83 M84 M85 M86 M90

X ?

Rugose corals:

?pycnostylid------ -.---.-.--------- X _-__.__.-.__.

Mucophyllum cf. M. 

meintyrei n. sp..- ._ ____ . X _---_ 

Cyathactis gazellensis n. 

sp----------------.--------- X ._.__._._.._-

Tabulate corals:

Favosites (massive)_____-- X X X X ____.-__-______ -__.__

Heliolites................................... X .....--.-....-..--

Halysites (Catenipora)..-..-.......... X X ___ ..-__ __ _.-__

Syringopora................................. X _ __ 

Brachiopods:

Hesperorthis-....................................................... X

Dalmanella................................................... X -----

?Skenidioides............................................ X ----------

stropheodont -- __ __ __ _ X

Camarotoechia cf. C. 

reesidei Kirk and Amsden...-.- --.-..-.-.._--_-----______- ------ X

X

Atrypa. ... .................................................... X X

1 Plectatrypa . ................................................. X .._...

1 Atrypella .................................. X ...-...-.-.-....... -..

tAlaskospira cf. A. dunbari Kirk and Amsden _ -. -- ____ ._ - X X

TTrematospira. ..... ................................................. X

Howellella. ................................................... X ._.__

Conchidium sp. ............................. X .______..-_-._-._._-_-_

Conchidium cf. C. biloculare (Linneaus). _-_.--._..._.__.__.____. X ............ X X

tPentamerus..-.- ......... X ..........................................

Amphineurans:

Gryphochitonid plates ........................... X ..-..---..-..--..

Gastropods:

Platyceras ........................................................ X

bellerophontid (large) __ ..-..-.-..-.-..-.....-.-.....-..--.. X .....

Holopea.. .......................................................... X

Prosolarium or Pseudophorus ... ................................. X .........-.-.-....--.-.

Rotellomphalus cf. R. 

tardus Perner. . -_..._._..._._._.._...____.._._.. X .................

Hormotoma. ................................ X .......................

Ruedemannia cf. R. 

lirata Ulrich and 

Scofleld. ------------------------ X .......................

Raphispira cf, R. plena 

Perner __ _ -- -- __- X .................

Eunema cf. E. strigilZotMwi Salter--------------- ------------- -.- X X -----------

Mesocoelia cf . M. janus 

(Perner)-.-.--- --------------------------- X __.-__.._-_.--___.---.-

Stylonema .............................................. X _--_._._._.

Murchisonia. ... ............................. X .......................

Pelecypods:

Nuculites or Palaeoneilo .... ....................... X -----------------

Conocardium (small)---.------.------------------- X --_._-_-__-_.-.-.

Ostracods:

Leperditia .... ........................................... X -----------

Trilobites:

Calymene.. ........ ......................... X .......................

Pseudocheirurus .... ................................................. X

cheiruridpygidia---. _.__-_-_--_-_------_-_-_----------- X X .-._-

to judge from the number of genera represented. Attention is called to the amphineuran plates; these are 

the only known occurrence of such fossils in western 

North America of Silurian age.

FAUNAS OF THE GREGG RANCH AREA

The Gregg Ranch faunas include few rugose corals 

Kyphophyllwm greggi being the only representative. 

More numerous are the tabulates, with Favosites and 

Cladopora. A list of fossils from the Gregg Ranch area 

follows:

Favosites sp.

Cladopora sp.

Kyphophyllum greggi n. sp.

Hesperorthis sp.

Skenidioides sp.

Howellella n. sp., cf. H. smithi Waite

Eunema OY Lophospira cf. L. Mcincta (Hall) Lindstrom

Progalerus or Cyrtospira sp.

Hurchisonial sp.

Loxonema 1 sp.

Holopea cf. H. synmietrica Hall

Beraun-ia cf. B. bifrons Perner

Hercynella cf. H. bohemica Barrande

The gastropod Beraunia and the peculiar helmet-shaped 

Hercynella are associated with Kyphophyllwn greggi 

at locality M82. At locality M89 rugose corals provisionally assigned to Kyphophyllum greggi are associated with Favosites, Cladopora, and the small spiriferoid brachiopod, HoweUella. The Hoiuelletta resembles, 

but is not conspecific with H. smithi Waite of the Lone 

Mountain Dolomite of Late Silurian age in the Great 

Basin (Merriam, unpub. data) ; Howellella is abundantly represented by other distinctive species in the 

Lone Mountain and in the Rabbit Hill Limestone of 

Early Devonian age in that province.

At locality M80 the brachiopods, Hesperorthis and 

Skenidioides, occur in a gastropod association lacking 

corals. The abundant gastropods are medium- to highspired forms of small and medium size resembling some 

of those in gastropod assemblages from Parker Rock 

and Grouse Creek. Conchidium and Atrypella, which 

establish a Silurian age at Parker Rock and Willow 

Creek, are conspicuously absent at the Gregg Ranch 

localities.

RUGOSE CORALS AND ASSOCIATED FOSSILS OF THE 

GROUSE CREEK AREA

Rugose corals are uncommon in the facies at Grouse 

Creek (fig. 2) where the fossils were collected. Most 

numerous here are the gastropods and brachiopods. A 

list of fossils from locality M1134 follows:

Favosites sp. (massive) 

Gladopora sp. (slender) 

Kyphophyllum cf. K. greggi n. sp.
16 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

Zelophyllum'i sp. (solitary?)

Lingulasp. (large form)

Pholidops sp.

Schizophoriat cf. 8. Msinuata Weller

Stropheodonta (Brachyprion) cf. B. seretensis Kozlowski

Camarotoechia"! sp.

Oyrtina sp. (coarse ribbing)

Ambocoelia! sp. (ventral valves only)

Glassia"? sp.

Nucleospira cf. N. ventricosa Hall

Whitfieldella'i sp.

Conocardium sp. (small)

Murchisonia cf. M. Mlineata (Dechen)

Stylonema cf. 8. potens (Perner)

Gyclonema carinatum Sowerby

Cyclonema cf. G. 'bilex (Conrad)

Proetus sp.

stromatoporoids

tentaculitids

The abundant brachiopods are Stropheodonta and 

the Schizophoria-like form. Compared with Weller's 

"Schizophoria bisinuata" the latter presents a superficial resemblance to Isorthis of the Silurian but differs 

by possessing a broad ventral valve sulcus anteriorly 

and lacks the brachial valve sulcus of the genus Isorthis. 

Small gastropods placed in Cyclonema resemble Silurian species from Gotland that were described by Lindstrb'm (1884). Except for the corals and some of the 

gastropods, this fauna shows no close resemblance to 

others in the northeastern Klamath subregion.

RUGOSE CORALS AND ASSOCIATED FOSSILS OF THE 

HORSESHOE GULCH AREA

Three fossil collections from Horseshoe Gulch, made 

in 1950 by F. G. Wells and G. W. Walker, give evidence 

of possible range in age from Late Ordovician to 

Devonian (J. M. Berdan, written commun., 1957). Of 

these collections, two (GWW-9A-50, GWW-12-50) include branching Favosites, which are almost certainly 

younger than Ordovician. Collection GWW-10-50 is 

reported upon by Miss Berdan as follows:

Gatenipora sp., horn coral, undetermined tubular organisms, 

undetermined immature brachiopods. Catenipora ranges from 

Ordovician to the end of the Silurian. The horn coral is very 

close to Crrewingtcia, which is an Upper Ordovician genus, but 

as it is coarsely silicified and as similar forms occur in the 

Silurian, it is not possible to make a precise identification. The 

age of this collection may be, therefore, either Upper Ordovician 

or Silurian.

Collection GWW-10-50 with Catenipora and a 

Crrewingkia-like rugose coral was the basis for the 

subsequent Late Ordovician (?) age assignment of the 

entire Duzel Formation (Wells and others, 1959).

Calcerous algae collected in Horseshoe Gulch by L. K. 

Laudon were identified by Johnson and Konishi (1959, 

p. 135-158); their findings are considered below under 

correlation and age. The algae are as follows:

ParacJiaetetes sp. 

Vermiporella cf. borealis H0eg 

Vermiporella h0egi Johnson and Konishi 

CKrvanella problematica Nicholson and Etheridge 

Dasyporella norvegica H0eg

Most of the algae from Horseshoe Gulch are reported 

also by Johnson and Konishi from Gazelle beds on 

Willow Creek. Because these Gazelle beds are believed 

to be considerably younger than the Horseshoe Gulch 

beds, it seems possible that the calcareous algae in question are better indicators of environment than of precise 

geologic age.

A Silurian type of colonial pycnostylid rugose coral 

(pi. 1, figs. 8-10) was collected from light-gray limestone in Horseshoe Gulch by A. J. Boucot in 1964.

Silicified corals and brachiopods, collected by 

Merriam in 1951 and 1956, came from a small isolated 

exposure of fractured, mildly altered, irony limestone 

near a reservoir in upper Horseshoe Gulch (loc. Ml 131). 

The identifiable fossils follow:

Holy sites (Catenipora) sp. 

Plasmopora cf. P. follis Edwards and Haime 

Strlatoporal cf. S. gwenensis Amsden 

Syringopora or Romingeria sp.

Dalmanophyllum sp. h, cf. dalmani (Edwards and Haime) 

Palaeophyllum sp. 

Zelophyllum'i sp. (solitary form) 

Hesperorthisl sp.

Schizoramma sp. cf. 8. nisis (Hall and Whitfield) 

?calcareous sponges of the Heterocoelia type, with seivelike 

partitions

It is possible that the collection from the Wells and 

Walker locality, GWW-10-50, with Gatenipora, 

G-rewingkial, and undetermined tubular organisms, 

may have come from the same horizon as the Merriam 

collection at locality M1131. Catenipora is present in 

both assemblages, and the streptelasmid coral, GrewingJkia, possesses generic features in common with the 

related Dalmanophyllum.

Nothing is known of the relative stratigraphic horizons of the several fossil collections made thus far in 

the Horseshoe Gulch area; it is possible that these 

collections may represent a considerable timestratigraphic range. With little doubt, however, the 

faunules containing Catenipora and the small solitary 

streptelasmid corals are the oldest found thus far in the 

northeastern Klamath subregion but have little in common with Gazelle fossil assemblages from Willow Creek 

and Parker Rock.

The question of possible Late Ordovician age of the 

GWW-10-50 f aunule of Horseshoe Gulch cannot be resolved on the basis of existing fossil collections. As 

noted below, the paleontologic evidence from locality 

M1131, possibly the same horizon as GWW-10-50, seems 

to favor somewhat an Early Silurian assignment for 

the strata at that locality.
GEOLOGIC CORRELATION OF THE NORTHEASTERN KLAMATH SUBREGION PALEOZOIC ROCKS 17

GEOLOGIC CORRELATION OF THE NORTHEASTERN KLAMATH SUBREGION PALEOZOIC 

ROCKS

Within the graywacke province on the Pacific Border 

of North America, few other areas of Silurian and 

Devonian rocks have been sufficiently studied paleontologically to make possible definitive correlation. A 

Silurian fauna comparable to that of Gazelle unit 2 

has been collected in the Douglas City area near 

Weaverville; the fauna of the Montgomery Limestone 

from Taylorsville, Calif., may be compared to one of 

the f aunules from Horseshoe Gulch. Otherwise the most 

meaningful comparisons at present are with the Silurian 

and Devonian strata of southeastern Alaska.

Although there is no direct paleontologic support, it 

appears not unlikely that some part of the northeastern 

Klamath subregion Paleozoic section is equivalent to 

volcanic rocks called Copley Greenstone and Balaklala 

Ehyolite, which underlie the southeastern Klamath subregion Devonian strata (Albers and Eobertson, 1961, 

p. 10).

Correlations which serve to establish the age and 

stratigraphic position of the Paleozoic rocks from the 

northeastern Klamath subregion are based to a considerable extent upon paleontologic comparison with 

distant sections, including those of the Great Basin, 

Gotland, England, eastern Europe, and Australia.

CORRELATION WITH SILURIAN ROCKS OF THE 

DOUGLAS CITY AREA

Silurian fossils collected by W. P. Irwin of the U.S. 

Geological Survey on the Trinity Eiver west of Douglas 

City came from limestone blocks seemingly derived from 

a conglomerate interpreted as part of the Mississippian 

Bragdon Formation (Irwin, 1963). Irwin (written 

commun., 1969) regards the Bragdon of this exposure 

as an outlier upon rocks of the central metamorphic belt. 

Among the fossils are Spongophylloidesl, Zelophylluml, Tryplasmal, heliolitids, and Rhizophyllum sp. C 

(Helen Duncan and W. A. Oliver, Jr., written commun., 

1961). The Rhizophyllum (Oliver, 1964) supports a 

Silurian age, which may be the same age as that of 

Rhizophyllum-bå beds of southeastern Alaska. In 

southeastern Alaska Rhizophyllum occurs in the Atrypella-Conchidium zone, which is believed to be approximately correlative with the Atrypella zone of the 

Gazelle Formation.

If the limestone blocks yielding the Silurian fossils 

are associated with the Bragdon, they are reworked; if 

not, the Mississippian Bragdon may rest unconformably 

upon older Paleozoic beds within the outlier. As noted 

above, fossiliferous limestone conglomerate like that of 

Gazelle unit 2 is characteristic of the Silurian marine

column in the Pacific Boarder province. It is not unlikely, therefore, that the conglomerate with Silurian 

fossils near Douglas City may have been derived from 

thus far undiscovered strata equivalent to the Gazelle 

Formation and possibly equivalent to some part of the 

Copley volcanic sequence in areas east of Douglas City 

and Weaverville.

CORRELATION WITH OLDER PALEOZOIC ROCKS OF 

THE TAYLORSVILLE AREA, CALIFORNIA

Diller (1908, p. 13-19), describing the important Taylorsville Paleozoic section (fig. 1), applied the name 

Montgomery Limestone to a 30-foot-thick fossiliferous 

gray limestone within a thick siliceous clastic sequence 

consisting of shale or slate, quartzite, and minor conglomerate. Silurian fossils are common in the Montgomery, but none of diagnostic value were found in the 

clastic rocks below it or above. By inference, the shale, 

quartzite, and conglomerate between the Montgomery 

and higher beds considered Carboniferous were questionably assigned to the Devonian by Diller.

Stratigraphic investigations by V. E. McMath (written commun., 1959) cast doubt upon the continuity of 

the succession, but his Montgomery fossil collections 

bear out the initial Silurian assignment. As a generalization, it may be said that predominance of siliceous elastics and possible equivalence of the Montgomery and 

the Early Silurian limestone of Horseshoe Gulch suggest that these beds at Taylorsville were also deposited 

in the Pacific Border province as an outlying part of 

the graywacke suite, rather than within the intermediate 

limestone belt of the Great Basin province to the east.

The fauna of the Montgomery Limestone may be 

compared to fossil assemblages from Horseshoe Gulch 

in the northeastern Klamath subregion. Present in the 

Montgomery and comparable to forms occurring at 

Horseshoe Gulch locality M1131 are Holy sites (Catenipora) sp., Plasmopora sp., Ddlmanophylkim? sp., Palaeophyllum sp., and brachiopods assigned to Hesperothis 

and Schizoramma. Also in both assemblages are the 

problematic nodose-tubular organisms resembling the 

calcareous sponge Heterocoelia. The Montgomery Limestone contains the brachiopods Dicaelosia and Skenidioides not found at Horseshoe Gulch. Grewingkia-likv 

streptelasmid corals in the Montgomery may be compared to those of Horseshoe Gulch locality GWW10-50, which may be the same horizon as the fauna at 

locality M1131. As noted below, the DalmanophyllwnPalaeocyclus beds of coral zone A (Early Silurian) 

from the Great Basin are believed to be correlative with 

the Montgomery and with limestones of Horseshoe 

Gulch.

454-393 O - 72 - 4
18 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

CORRELATION WITH SOUTHEASTERN ALASKA 

SILURIAN AND EARLY DEVONIAN SEQUENCES

Silurian marine rocks of southeastern Alaska, some 

20,000 feet thick, provide the best reference sections for 

the North American Pacific Border province. These 

strata have been described by Kindle (1907), Wright 

(1915), Burchard (1920), and in more comprehensive 

terms, by Buddington and Chapin (1929). In recent 

years Silurian beds of this region have been mapped and 

studied in greater detail by geologists of the U.S. Geological Survey, among whom are Michael Churkin, Jr., 

W. H. Condon, G. D. Eberlein, L. J. P. Muffler, and 

A. T. Ovenshine. Fossil studies by Kindle (1907) and 

Kirk and Amsden (1952) establish provisional age and 

correlation of some units.

Silurian beds of the northeastern Klamath subregion 

have their nearest analogs petrologically and faunally 

in the southeastern Alaska column. For example, the 

brachiopod genera Atrypella and Alaskospira indicate 

a fairly specific correlation of Gazelle unit 2 with an 

horizon in the upper-middle part of the HecetaTuxekan Island sequence.

G. D. Eberlein's mapping and stratigraphic investigations of the Alexander Archipelago (written 

commun., 1963) and those of Eberlein and Churkin 

(1970) show that the Heceta-Tuxekan marine rocks of 

Silurian age are over 20,000 feet thick in places. 

Gray wacke-type elastics are especially well represented 

in the lower and upper divisions of this column; the 

largest limestone bodies lie in the upper-middle part, accompanied by thick lenses of limestone breccia, conglomerate, and sandstone. The lower graywackes, according to Eberlein, consist mainly of volcanic detritus 

in a marine sequence which includes andesitic and basaltic flows; some have pillow structure.

Like the pure massive limestones of the Gazelle Formation, those of the Heceta-Tuxekan section are nondolomitic, having at most a very low magnesium content. 

Many of these Silurian limestones from Alaska are relatively pure and of commercial quality. No bedding 

structures indicating reef origin have been recognized, 

as in the more southerly Gazelle. Eugose corals and 

calcareous algae seem to be numerically less important 

in the Alaskan carbonate deposits although the tabulate 

corals are abundant. The brachiopod biofacies are perhaps better developed than in the Klamath Mountains.

The Silurian graywackes of the Klamath Mountains 

do not disclose interbedded lavas like those of southeastern Alaska; however, the petrologic similarity of 

the Gazelle graywackes to those of Alaska, and the occurrence of interbedded chert leave no doubt of the 

volcanic environment. As in Alaska also, the abundance of fairly coarse siliceous conglomerate in the

Klamath seaway supports a theory of contemporaneous 

deformation in concert with vulcanism.

Study of Silurian Rugosa and associated fossils of 

the Heceta-Tuxekan Island area, including the south 

shore of Kosciusko Island together with those of Kuiu 

Island (Muffler, 1967) sheds light upon the correlation 

and age of the Klamath Silurian beds. Somewhat 

younger deposits at Kasaan Bay on the east side of 

Prince of Wales Island are of interest in connection 

with age determination of the Gregg Ranch beds 

wherein the fossil evidence is more suggestive of an interval bracketing the Silurian-Devonian boundary.

HECETA-TUXEKAN ISLAND AREA

Silurian limestone and calcareous shale of northernmost Heceta Island and the south shore of neighboring Kosciusko Island contain abundant brachiopods 

(Kirk and Amsden, 1952) and tabulate corals. Conditions were evidently not especially favorable for the 

Rugosa because Zelophyllum is the only genus abundantly represented. Among other Rugosa in the collections are Try plasma, SalairophyUuml., Cystiphyllum, 

and an undescribed Entelophyllum-\\k& genus with a 

very narrow dissepimentarium having several columns 

of unusually small dissepiments. Rhizophyll/u,m sp. A 

(Oliver, 1964) occurs in these beds on Kosciusko Island. 

None of the distinctive colonial Rugosa of the Gazelle 

were found in the Heceta-Tuxekan beds. Rhizophyllum 

has not been found in the Gazelle; Zelophyllum and 

Cystiphyllum are the two genera common to both regions. Of these, Zelophyllum sp. G of the Gazelle is 

similar to the species well represented in the HecetaTuxekan brachiopod facies. Brachiopod genera common to the Gazelle and to the southeast Alaskan beds 

are Atrypella, Atrypa, Alaskospira, Howellella, Isorthis, and Conchidium. The Gazelle Conchidium does 

not belong in the same taxonomic subgroup with 

ConcMdium alaskense, the most distinctive fossil of 

the Atrypella-Conchidium beds from the HecetaTuxekan. Conchidium alaskense is closer to C. knighti 

of the British Ludlovian (Aymmestry). Of the remaining distinctive Alaskan pentamerids (Brooksina, 

Harpidium, and Cymbidium], none *were identified 

with assurance in the Gazelle although an incomplete 

coarse-ribbed ventral pentamerid valve has heavy ornamentation suggesting that it belonged to either Cymoidium or Stricklandinia.

The Atrypella-Conchidium beds of the HecetaTuxekan section with which Gazelle unit 2 is correlated 

represent an interval in the upper middle part of the 

very thick Silurian column. These beds are considered 

Ludlovian mainly on the basis of the similarity of Conchidium alaskense to the British Conchidium knighti. 

The possibility of higher Wenlockian being represented
GEOLOGIC CORRELATION OF THE NORTHEASTERN KLAMATH SUBREGION PALEOZOIC ROCKS 19

in this interval is not eliminated (Kirk and Amsden, 

1952).

For most of the Heceta-Tuxekan beds of the Silurian 

below the Atrypella-Conchidium zone, there is as yet 

no basis for meaningful paleontologic comparison with 

the older Gazelle beds of unit 1 or with the Lower 

Silurian rocks of Horseshoe Gulch. The middle and 

lower parts of the Alaskan sequence have yielded little 

fossil evidence other than a few graptolites in the lower 

graywacke.

KUIU ISLAND

The Kuiu Limestone of Late Silurian age (Muffler, 

1967, p. 11) contains somewhat more diverse coral 

faunas than the approximately correlative beds of the 

Heceta-Tuxekan area to the south. The compound 

Rugosa, Petrozium and Entelophyllum, were collected 

here in addition to Zelophyllum, SalairophyllMml, 

Cystiphyllum, Microplasma and lykophyllids of the 

Phaulactis type. The stratigraphic position of the Kuiu 

coral beds was not determined because of faulting and 

other factors which obscure these relations. Conchidium, 

alaskense and Zelophyllum indicate probable equivalence to the fauna from the northern part of Heceta 

Island that has this large pentamerid and Atrypella. 

A distinctive columellate, Petrozium from Kuiu (pi. Y, 

figs. Y, 8), is specifically different from the Gazelle 

Petrozium; the resemblance is perhaps closer to P. 

dewari of the British Early Silurian. It seems likely the 

Kuiu faunas may include species of Wenlock as well 

as Ludlow age.

KASAAN BAY AREA, ALASKA

The faunas from Long Island, Kasaan Bay, assigned 

by Kindle (190Y) to the Devonian, are significant for 

the dating of the Gregg Ranch strata which bear Hercynella. Kindle's material came from massive limestones 

which he subdivided into lower and upper divisions 

(Wright, 1915, p. YO-Y2; Buddington and Chapin, 1929, 

p. 99-101). Large specimens of Hercynella, found only 

in the lower division, were assigned by Kindle to the 

European species H. ~bohemica and H. nobilis. The 

Gregg Ranch Hercynella, associated with Kyphophyllum, resembles H. bohemica of the Czechoslovakian 

Early Devonian. Kyphophyllum was not found in the 

Long Island Hercynella beds.

The genus Hercynella has a reported range from 

mid-Silurian to mid-Devonian in the Old World 

(Perner, 1911; Gill, 1950; Termier and Termier, 1950) ; 

it peaks in Early Devonian at about the stage of 

H. bohemica. In eastern North America other species of 

Hercynella occur in the Bertie Limestone of Late 

Silurian age (Grabau, 1910, p. 195; O'Connell, 1914,

p. 96). Confirming evidence of Devonian age from fossils other than Hercynella was not obtained from 

Kindle's lower limestone of the Long Island section.

Kindle's upper limestone unit at Long Island yielded 

a large fauna in which Devonian elements appear to be 

associated with others which might almost be interpreted individually as Silurian. Oliver (1964, p. 150) 

has restudied Kindle's coral material, identifying the 

rugose forms as E ddastraeal, Rhizophyllum sp. B, 

Pseudamplexus sp. cf. P. princeps Etheridge, and 

stauriid Rugosa. Other fossils listed by Oliver are 

Amphipora, Aulocystis, Favosites, and TTiamnopora. 

Eddastraeat, Thamnopora, and Amphipora would 

seem at first to favor a Middle or Late Devonian age, 

judging from ranges of Amphipora and Thamnopora 

in the Great Basin. Although Rhizophyllum has survivors in the Devonian of eastern Europe and Australia, 

its great evolutionary burst worldwide is in the Silurian. Pseudamplexus-like corals range from Middle 

Silurian to Late Devonian; the stauriids range upward 

from Ordovician to Late Paleozoic. In the late Middle 

and Late Devonian of the Cordilleran belt, Amphipora 

is a limestone-builder. However, the reliability of this 

branching stromatoporoid as a Devonian indicator in 

southeastern Alaska is questionable. G. D. Eberlein and 

C. W. Merriam in 1961 found Amphipora abundantly 

represented at the north end of Heceta Island, where 

it occurs in beds which appear on the map to be continuous with those containing Conchidium alaskense. 

Amphipora from this locality (M115Y) is structurally 

quite typical of the genus, possessing the characteristic 

axial canal.1 At locality M115Y Amphipora is directly 

associated with Microplasma and corals of the Zelophyllum type. Russian reports of Amphipora in Silurian rocks, of which there are several, have not been 

evaluated in the available literature (Khodalevich, 

1939). In Japan digitate stromatoporoids of the Silurian assigned by Sugiyama (1940, p. 114, pis. 14,16,19) 

to Amphipora do not show the axial canal convincingly 

and, as pointed out by Oliver (written commun., 1968), 

are somewhat more suggestive of the genus 

Olavidictyon.

It is not possible at present to evaluate fully the age 

significance of these Alaskan fossils; further collecting 

and field stratigraphic observation are necessary in the 

Long Island section. Weighing available fossil evidence 

from the massive Long Island limestone beds yielding 

Hercynella, Rhizophyllum, and Amphipora, it may be 

said that the presence of possible Silurian elements 

somewhat weakens, but does not eliminate, a Devonian 

assignment for the entire unit. These Alaskan strata

1 W. A. Oliver, Jr., has confirmed the generic identification (written 

commun., July 11, 1963).
20 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

and the possibly equivalent Gregg Ranch beds containing Hercynella and KyphopJiyllum are viewed provisionally as falling within an indefinite zone which 

brackets the Late Silurian and Early Devonian.

CORRELATION WITH SILURIAN ROCKS IN THE GREAT

BASIN

Coral-bearing strata of Silurian age in the Great Basin 

are distributed in two major marine rock belts of contrasting lithof acies: the intermediate limestone belt and 

the eastern dolomite belt. In describing the Silurian 

rugose corals of the Great Basin province 2 five Silurian 

coral zones have been proposed, lettered A through E 

in ascending stratigraphic order. Coral zone A is of 

Llandovery age, B and C are considered Wenlockian; 

D and E are Ludlovian.

The oldest Silurian fauna of the northeastern 

Klamath subregion, that of Horseshoe Gulch, includes 

Dalmanophyllum, Catenipora, and Plasmopora; this 

assemblage is correlated with coral zone A of the Great 

Basin which contains Dcdmanophyllum, Pcdaeocyclus, 

and ArachnophyTbum as well as the common tabulate 

corals of the Early Silurian. In the Great Basin, beds 

carrying the coral zone A assemblage rest conformably 

upon Late Ordovician strata containing a Richmondian 

fauna; coral zone A has been recognized in both the 

intermediate limestone belt and the eastern dolomite 

belt.

Equivalents of coral zones B and C of the Great Basin 

have not been identified in the northeastern Klamath 

subregion although the two rugose coral groups present 

in Gazelle unit 2 are present also in coral zone B of the 

Great Basin. These are solitary lykophyllids of the 

Cyathactis-Ryderophyllum group and the phaceloid 

Petrozium, Different species are found in the two regions. Overall fossil evidence in Gazelle unit 2, particularly the brachiopod correlations with Alaska, favor a 

Ludlovian age and correlation with coral zone E of 

the Great Basin. In the Panamint Mountains, where 

coral zone B is best shown, zone B is low in the Silurian 

column and is considered early Wenlockian.

Coral zone E of the Great Basin is known only in 

the intermediate limestone belt. None of the Rugosa 

from unit 2 is conspecific with a form from coral zone 

E of the Great Basin. The closest ties are the Endophyllidae, represented in unit 2 by Klamathastraea dilleri, 

and an evolutionary parallel classified in a new subgenus of Australophyllum from coral zone E. The rugose 

coral genus KyphopJiyllum (pi. 8, fig. 6) is present in 

Great Basin coral zone E and in the Gregg Ranch 

beds, herein designated as Silurian or Early Devonian. 

Gazelle unit 2 has yielded a questionable Kyphophyl2 Merriam, C. W. ( unpublished data.

lum. The massive coralline limestones of Gazelle unit 3 

contain Kodonophyllum, which resemble those from 

coral zone E.

MucophyUum mcintyrei of Gazelle unit 1 differs 

specifically from an undescribed MucopJiyUum from 

coral zone E in the Great Basin.

Rugose corals are greatly affected by their environment. The rugose corals in higher beds of the Great 

Basin eastern dolomite belt differ from those of Silurian 

coral zones D and E of the intermediate limestone belt 

to such an extent that they can not at present be correlated paleontologically. The Ludlovian beds of the 

eastern dolomite belt carry an EntelopJiyllum fauna 

which also includes an abundance of the small spiriferiod Hoioellella. These eastern dolomites represent the 

upper Laketown-Lone Mountain biof acies. Atrypella, a 

genus characteristic of the Late Silurian in the Pacific 

Border province, has been recognized also in the eastern 

dolomite belt of the Great Basin (Johnson and Reso, 

1964).

Among associated brachiopods, comparable species of 

Plectatrypa occur in coral zone E of the Great Basin 

Silurian and in unit 2 of the Gazelle. The large ConcJiidium of Gazelle unit 2 externally resembles brachiopods of this Silurian genus in beds which range upward from coral zone B to coral zone E.

Whereas calcareous algae are well represented in the 

Gazelle Formation and older Silurian beds of the 

Klamath Mountains (Johnson and Konishi, 1959), it is 

worthy of note that the large and distinctive dasycladacean Verticillopora, so abundant locally in the 

Silurian of the Great Basin, has not been recognized in 

the Klamath region.

CORRELATION WITH EASTERN NORTH AMERICA, 

EUROPE, AND AUSTRALIA

EASTERN NORTH AMERICA

Meaningful correlation of the Silurian and Early 

Devonian beds of the Klamath Mountains with the 

eastern standards by means of Rugosa and associated 

fossils is not yet feasible. The more complex colonial 

rugose genera of the Gazelle Formation and younger 

beds are thus far unknown in the East, where their ecologic niches may be occupied by species of Entelophyllum, a genus not recognized in the Klamath Mountains 

region. Solitary forms of the rugose families occurring 

both in the Klamath deposits and in the eastern Silurian deposits are Streptelasmatidae, Kodonophyllidae, 

Lykophyllidae, Tryplasmatidae, and Cystiphyllidae. 

Of these, the first three are the more significant.

Dalmanophyllum of the Streptelasmatidae, present 

in Early Silurian beds of Horseshoe Gulch and low in 

the Gotland column, ranges upward into the Louisville
GEOLOGIC CORRELATION OF THE NORTHEASTERN KLAMATH SUBREGION PALEOZOIC ROCKS 21

Limestone of Kentucky (Stumm, 1964, p. 17) which is 

Wenlockian or Ludlovian.

Lykophyllids comparable to but not conspecific with 

Cyathactis gazellensis of Gazelle unit 2 are represented 

in the Brownsport Formation of Kentucky (Amsden, 

1949) by Cyathophyllum pegramense (Foerste) and in 

the Henryhouse Limestone of Oklahoma (Sutherland, 

1965 by Micula^ catilla. These formations are considered Wenlockian and therefore are probably older than 

Gazelle unit 2, which is regarded as Ludlovian. Similar 

lykophyllids assigned to Phaulactis occur in the Mont 

Wissick Formation of Quebec (Oliver, 1962a, p. 12) 

which is of Wenlock or Ludlow age. Phaulactis is also 

reported by Stumm (1962, p. 2) in the Cranbourne 

Limestone of Quebec, which probably has about the 

same age range as the Mont Wissick Formation.

Kodonophyllidae of the Gazelle Formation are Kodonophyllum and Mucophyllum. In the East, a colonial 

Kodonophyllwn was described by Oliver (1962b, p. 23) 

from beds in Quebec of Wenlock or Ludlow age. The 

Klamath Kodonophyllum is in Gazelle unit 3 of probable Ludlow age. This genus is present also in the Louisville Limestone of Kentucky (Stumm, 1964, p. 26).

Mucophyllum, although not itself recorded from the 

East, has a related and parallel genus, Schlotheimophyllum, in the Louisville Limestone (Stumm, 1964, p. 

25). The Gazelle species, M. mcintyrei, comes from Gazelle unit 1 in beds of probable Wenlock age and perhaps roughly equivalent to the Louisville of Kentucky.

Of the higher strata in the northeastern Klamath 

subregion, the Gregg Ranch and Grouse Creek beds of 

Silurian or Early Devonian age contain the rugose coral 

genus Kyphophyllum, which is thus far unreported in 

the eastern Silurian or Early Devonian. Abundant in 

these Grouse Creek beds is a small orthoid brachiopod 

resembling (?) Schizophoria bisinuata Weller, a species 

characterizing the Coeymans Formation of New Jersey 

of Early Devonian age.

EUROPE

The coral-rich Silurian strata of Gotland, Sweden, 

provide a satisfactory carbonate facies reference column for western Europe. Kugosa occur in nearly all the 

13 major map divisions spanning this geologic system 

(Hede, 1921; Regnell and Hede, 1960). The rugose coral 

families identified both in Gotland and in the Klamath 

Mountains of Silurian and Early Devonian age are: 

Streptelasmatidae, Kodonophyllidae, Tryplasmatidae, 

Lykophyllidae, Stauriidae, Kyphophyllidae, and 

Endophyllidae.

Of the Streptelasmatidae, Dalmanophyllum of Early 

Silurian age from the Horseshoe Gulch beds, coral zone 

A, of the Great Basin, and the Montgomery Limestone

of Taylorsville, Calif, is matched by Dalmanophyllum 

dalmani of the Gotland Hogklint Group (earliest 

Wenlockian).

In Gotland, Kodonophyllum ranges through the 

Wenlockian into Ludlovian, but it is known only in 

Gazelle unit 3 (Ludlovian) of the Klamath region. The 

Mucophyllum group of this family has a more restricted range in Gotland, where it is represented by 

Schlotheimophyllum patellatum in the upper Visby 

Marl (early Wenlockian). Mucophyllum occurs in Gazelle unit 1 probably higher in the Wenlockian.

Among the Tryplasmatidae, Zelophyllum is Wenlockian in Gotland. This genus is present in Gazelle 

unit 2 and in more or less equivalent Ludlovian strata of 

southeastern Alaska.

Beginning with late Llandovery Phaulactis, the 

Lykophyllidae from Gotland range through most of 

the Silurian; they are especially numerous in lower to 

middle Wenlock. In the Great Basin this family is well 

represented in coral zone B (early Wenlock); in the 

Klamath region Cyathactis of the Lykophyllidae is Late 

Silurian (Ludlovian), occurring in Gazelle unit 2.

Regarding the Stauriidae, Stauria favosa, the common Gotland species, is an occupant of the Slite Group 

of the later Wenlockian. There are few records of 

Stauriidae in the American Silurian. Wintunastraea 

of this family comes from beds either at the top of 

Gazelle unit 1 or in unit 2. This genus is perhaps 

slightly younger than Stauria of the Slite Group.

The Gotland species of Kyphophyllum are from 

beds of early and middle Wenlockian age, but in the 

Klamath region this genus occurs in higher beds of 

Late Silurian or Early Devonian age at Gregg Ranch. 

In the Great Basin Kyphophyllum is in coral zone E 

which is Late Silurian.

Silurian Endophyllidae are generally Ludlovian, for 

example, Klamathastraea dilleri of Gazelle unit 2 

(Ludlovian) and the undescribed complex Australophypllum subgenus of coral zone E in the Great 

Basin. In Gotland ?Australophyllum rectiseptatum 

(Dybowski) of probable Ludlovian age seemingly belongs in this family.

In summary, of the rugose coral families and genera 

here considered, a majority seemingly peak in the Gotland Silurian at stratigraphic horizons geologically 

older than their peak in the Klamath region. This is 

especially true of lykophyllids, kyphophyllids, and 

kodonophyllids. Agreeing more or less in stage or range 

are representatives of the poorly known endophyllids, 

the stauriids, and the streptelasmatids.

Hede (1942) has correlated the standard Silurian 

column of Britain with that of Gotland by means of 

graptolites. Several of the rugose genera from Gotland
22 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

are reported in the British section, among which 

Phaulactis of the Lykophyllidae is of special interest 

here. Phaulactis in the Valentian (Llandovery) of 

Shropshire agrees with the early appearance of this 

genus in Gotland, but differs from the later occurrence 

of lykophyllids in Gazelle unit 2. Petrozium dewari 

Smith (1930, p. 307), the type of this genus, comes from 

Valentian (Llandovery) Early Silurian beds of Shropshire, thus being older than Petrozium staufferi of 

Gazelle unit 2, which is considered to be Ludlovian.

The inadequately known rugose coral faunas from 

Czechoslovakia of Late Silurian and Early Devonian 

age (Pocta,1902) include the common Gotland chonophyllid, Ketophyllum, and possible Lykophyllidae. In 

general these rugose assemblages from eastern Europe 

seem less diverse taxonomically than those of Gotland. 

The endophyllid, Australophyllum fritschi (Novak) of 

Czechoslovakia (Late Silurian "Kozel e2"), is of 

special interest because it parallels Klamathastraea 

dUleri of Gazelle unit 2. CyathopTiyllum prosperum 

Barrande of "Tachlowitz e2" and presumably also Late 

Silurian is probably a lykophyllid because it shows internal features similar to Cyathactis gazeUensis of 

Gazelle unit 2.

AUSTRALIA

In Australia the Silurian Kugosa of the YcssBowning area (Hill, 1940, 1954, 1958) include at least 

three forms resembling Gazelle genera, but none are 

conspecific. Klamathastraea dilleri of Gazelle unit 2 

shares some features with both Australophyllum 

spongophylloides (Foerste) and Yassia enormis 

(Etheridge) ; the lykophyllid Hercophyllum shears- 

~byi only remotely resembles Cyathactis gazeUensis. Of 

the Kodonophyllidae, Muchophyllum crateroides 

(Etheridge) is quite similar to M. mcintyrei of Gazelle 

unit 1. The Yass-Bowning coral beds are probably 

about equivalent to the upper part of Gazelle unit 1 

and to unit 2. According to Hill (1940, p. 388), these 

Australian strata are probably of later Wenlockian to 

early Ludlovian age.

GEOLOGIC AGE OF PALEOZOIC ROCKS IN THE 

NORTHEASTERN KLAMATH SUBREGION

Comparison of fossils in the Gazelle Formation with 

the nearest described species of the central Great Basin 

(Diller and Schuchert, 1894) led inevitably to Devonian 

assignment of the beds on Willow Creek; these were 

earlier identified erroneously as Carboniferous (Diller, 

1886, p. 21). When Schuchert's paleontologic examination was made in 1894 (table 3), little progress had been 

made in the description and illustration of fossils from 

the western middle Paleozoic. The figures and descriptions of the few species from the Eureka mining district, Nevada, and White Pine mining district, Nevada, 

that were available in the literature provided scant 

opportunity for meaningful paleontologic comparison 

and evaluation. Later researchers have demonstrated 

that the suggestive similarities of Gypidula-like, 

brachiopods of the Gazelle to Late Devonian pentamerids of the White Pine district are surficial only. 

The Gazelle colonial rugose corals in question are not 

congeneric with Late Devonian forms described by 

Meek (1877) from White Pine to which they were referred by Schuchert on the basis of external appearance. 

Although Schuchert did not evaluate the Gazelle corals 

in accordance with modern thin-section, standards, he 

recognized the endophyllid affinity of a large cerioid 

coral herein named Klamathastraea by external examination alone; it had earlier been confused with Carboniferous Lithostrotion. The presence of Endophyllum, as 

this family of corals was construed in 1894, favored 

Devonian age.

Other than the doubtful Conchidium in Schuchert's 

faunal list, fossils which would be accepted today as 

unequivocal Silurian indicators were presumably absent 

from the original Diller party collections or, as is more 

likely, had not been generically differentiated at the 

time of the Diller-Schuchert report. Among these are 

the spiriferoid brachiopods Atrypella and Alaskospira, 

the rugose coral Zelophyllum, Silurian coral genera 

herein proposed, and the diagnostic trilobite Encrinurm. Schuchert's "terebratuloid cf. Newberria" (table 

3) is possibly a variant of Atrypella. Later collections 

from Willow Creek have contained better Conchidium 

material. The diagnostic Halysites, which supports a 

pre-Devonian age, was discovered, not on Willow Creek, 

but in correlative beds at Parker Rock.

Schuchert's homologizing of Gazelle fossils with the 

Upper Devonian species from the central Great Basin 

led Diller and Schuchert to the erroneous conclusion 

that the Gazelle was younger, not older, than the more 

firmly dated Middle Devonian strata of the Redding 

district. Today the Gazelle is believed to predate the 

Kennett Formation of the Redding district in the southeastern Klamath Paleozoic subregion.

Stauffer's findings (1930, p. 98), after more collecting 

and reappraisal of all paleontologic data, were 

essentially in accord with Schuchert's Devonian 

assignment.

Table 3 presents the writer's evaluation of Gazelle 

fossil identifications by previous workers.

Gazelle fossils which were collected by University of 

California field parties during the 1930's were identified 

by the writer in collaboration with G. A. Cooper of the 

U.S. National Museum (Merriam, 1940, p. 48). Conchidium, Atrypella, Encrinurus, and illaenid trilofites
GEOLOGIC AGE OF PALEOZOIC ROCKS IN THE NORTHEASTERN KLAMATH SUBREGION 23

indicated probable Silurian, rather than Devonian age. 

Further support of Silurian age came with the discovery 

of Monograptus by Churkin (1965) and with the current results of coral investigations.

TABLE 3. Identification of fossils in the Gazelle Formation by 

previous workers

Diller and Schuchert, 1894 Stauffer, 1930 Merriam, this report

A

2

3

4

5

6

7

8

9

10

11 

12

13

14

15

16

17

18

19

20

21

22

23

£ UVVSUKS, t species

Diphyphyllum fasciculum Meek.

Acervular ia pentagona

(Goldfuss) Meek.

Endophyllum n. sp _ -..

Oypidula cfr. comis

Owen.

Oypidula lotis Walcott

Conchidium'! (small,

strongly plicated) .

terebratuloid cf.

Newberria.

Loxonema cf. delphicola

Hall.

Murchisonia .... --_. ....

Bellerophon cf. septentrionalis Tschernyschew.

Mytilarca sp ............

Orthoceras --------------

crinoid columnals

(large).

Favosites basalticust Goldfuss.

Favosites polymorphal

Goldfuss.

Favosites turbinata Billings.

Favosites sp-.---.-. -.-.-.-

Cladoporalabiosa Billings 

Alveolites multilamellal

Meek.

Diphyphyllum fasciculuml

Meek.

Tabulophyllum sp. ------ 

Stromatoporasp---.- ..- -

Cranaenal sp _ -----------

. Murchisonia sp. ...........

crinoid stems . ...........

. lavusiuus ^iiitissi v vj . 

Do.

Do.

Do.

Do.

Cladopora sp. 

Alveolites sp.

Petrozium staufferi n. sp.

Shastaphyllum schucherti

n. gen., n. sp.

Klamathastraea dilleri n.

gen., n. sp.

Zelophyllum or Cyathactisl 

stromatoporoids.

Oypidula or Barrandella

n. sp.

Oypidula n. sp.

Conchidium n. sp.

1 Atrypella cf. A. tenuis

Kirk and Amsden.

lAtrypella.

ILoxonema sp.

Murchisonia sp.

bellerophontid.

IMytilarca sp.

Orthoceras.

crinoid columnals (large) .

Most of the Gazelle fossils come from a position high 

in the formation, a 50-foot stratigraphic interval bracketing Gazelle unit 2, the topmost beds of unit 1, and the 

basal beds of unit 3. This interval is characterized by 

the Atrypella fauna, so designated because of the abundance of this smooth spiriferoid brachiopod.

A review and analysis of age ranges of the various 

faunal elements in the Atrypella assemblage suggest 

that it is probably no older than late Wenlockian and 

is more likely Ludlovian. Among the more significant 

fossils in this regard are Atrypella, Alaskospira, 

Conchidium, and the endophyllid coral Klamathastraea. 

It should at this point be mentioned, however, that in 

this fauna occur rugose coral genera to be expected 

lower in the Silurian System. Among these are the colonial Petrozium and lykophyllid Rugosa such as Cyathactis. Both belong to taxonomic groups which became established in Europe by late Early Silurian time; 

in Gotland the lykophyllids differentiated early to 

reach a peak in the Wenlockian. Petrozium and the 

lykophyllids are thus far known only in the early Wenlockian coral zone B of the Great Basin.

The genera Atrypella, Alaskospira, and Zelophyllum 

link paleontologically the Atrypella fauna of the upper 

Gazelle with that of the Atrypella-Conchidium beds of 

Heceta Island, Alaska. These southeastern Alaskan

strata are probably no older than late Wenlockian. Because of the similarity of the large ornate Conchidium 

alaskense to Conchidium knighti from the British 

Aymmestry (Ludlovian), these Alaskan AtrypellaConchidium beds are here considered to be late Silurian.

Conclusive paleontologic evidence of Silurian age is 

provided by study of the Parker Rock section, where the 

higher beds correspond lithologically to combined unit 

3, unit 2, and the upper beds of unit 1 of the Gazelle. As 

at Bonnet Rock on Willow Creek, the Atrypella fauna 

of Parker Rock occurs beneath a massive, craggy caprock limestone like unit 3. Halysites, unrecognized in 

the Willow Creek area, is abundant in the basal part of 

the unit 3 equivalent. Corals of the Parker Rock Atrypella fauna include Cyathactis gazellensis and 

Mucophyllum.

A large general collection of fossils from Parker 

Rock which probably represents the Atrypella interval 

was made in the years 1945 to 1949 by J. R. Mclntyre, 

while he was a graduate student at the University of 

California. This material includes brachiopods and trilobites not found elsewhere in the Gazelle. Among these 

are Camarotoechia cf. C. reesidei, Hesperorthis sp., 

\Glassia sp., Trematospira sp., and two species of Conchidium. One Conchidium resembles C. ~biloculare of 

the Gotland Klinteberg Group. Among the Silurian trilobites are Pseudocheirurus sp. and other cheirurid genera. Like corresponding fossil assemblages at Willow 

Creek, these assemblages also probably are of Ludlovian 

age.

The greater part of the type area of the Gazelle section on Willow Creek is undated paleontologically. Except for the topmost beds of unit 1, no fossils have been 

collected from an established stratigraphic position in 

the 1,000 feet or more of structurally deformed argillite, 

graywacke, conglomerate, and chert which make up 

most of this division. Exposures on the south side of 

Mallethead Ridge which yielded Mucophyllum mcintyrei and a Silurian trilobite assemblage (Churkin, 

1961) are believed to occupy horizons well below the 

top of unit 1. Although these fossils have been dated 

no more precisely than Wenlock or Ludlow, it is reasonable to assume that the greater part of unit 1 of the 

Gazelle Formation is Wenlockian, and that the formation as a whole ranges in age from Middle through 

Late Silurian.

Limestones at Horseshoe Gulch locality M1131 are 

dated provisionally as Early Silurian (Llandoverian) 

mainly on the basis of the small solitary rugose coral 

Dalmanophyllum sp. h cf. D. dalmani. associated Plasmopora, and Catenipora. Moreover, the fossils of this 

locality agree in general with those of the Silurian 

Montgomery Limestone at Taylorsville, Calif. Except 

possibly for calcareous algae described by Johnson and
24 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

Konishi (1959), there is no paleontologic evidence linking the limestones of Horseshoe Gulch with other beds 

of the northeastern Klamath subregion.

Faunas containing possible Devonian as well as Silurian elements and accordingly interpreted at present as 

Late Silurian or Early Devonian are those from the 

Gregg Ranch and Grouse Creek areas. The Gregg Ranch 

assemblages include Kyphopliyllum, which resembles 

those of coral zone E of the Great Basin (Late Silurian), in association with the large helmet-shaped 

gastropod Hercynella, which is comparable to Early 

Devonian Hercynella bohemica of eastern Europe. The 

small spiriferoid, HoweTlella, of Gregg Ranch is somewhat more suggestive of H. smithi Waite from the 

Late Silurian upper beds of the Great Basin Lone 

Mountain Dolomite than of a subspecies of H. cycloptera which characterizes the Early Devonian Rabbit 

Hill Limestone of that province.

The Grouse Creek fauna differs in overall content 

from those of Gregg Ranch, but it includes a similar 

KyphopTiyUum (pi. 8, fig. 7) and a possible Zelophyllum. The most distinctive fossils are an abundant 

small Schizophoria-like orthoid brachiopod resembling 

IScliizophoria ~bisinuata Weller of the Early Devonian 

Coeymans Formation of New Jersey, a small coarseribbed Cyrtina, and the trilobite Proetus. Further study 

of the numerous brachiopod and molluscan species in 

this well-preserved assemblage may show it to be entirely Devonian.

Calcareous algae from the Horseshoe Gulch vicinity 

reported upon by Johnson and Konishi (1959, p. 15Y158) were dated by them as Lower Silurian (Llandoverian) although the flora gave evidence of Upper 

Ordovician affinity. That these algae have greater value 

as facies indicators than evidences of age is suggested 

by the fact that Johnson and Konishi list some of the 

same and comparable forms in the type Gazelle ("Graystone area"), where the limestones which yielded them 

are no older than Middle Silurian (Wenlockian) and 

are probably for the most part Ludlovian.

DEPOSITIONAL ENVIRONMENT AND ORIGIN OF 

THE NORTHEASTERN KLAMATH SUBREGION 

CORAL-BEARING DEPOSITS

Limestone and limestone conglomerate are the principal coral-bearing Silurian and possible Early Devonian rocks of the northeastern Klamath subregion. In 

these sections carbonate deposits are volumetrically subordinate to the poorly sorted siliceous elastics, which 

consist of graywacke and gritty sandstone, argillite, and 

conglomerate. Occurring with these are considerable 

amounts of gray bedded chert. Rock associations of this 

kind characterize the Pacific Border province from

California to Alaska, where the Silurian record is one 

of recurrent volcanic activity and crustal unrest. Andesites and basalts appear to have been the sources from 

which much of the graywacke was derived. Moreover, 

it is not improbable that the bedded cherts are also 

related in origin to vulcanism.

The Pacific Border graywacke suite is limited on the 

east by a belt of coralline limestones unaccompanied by 

graywacke and volcanic rocks. This belt crosses the 

western Great Basin in a northeasterly direction between the graywacke and the very extensive Silurian 

dolomite belt occupying the central and eastern Great 

Basin. Thus the Silurian marine rocks in the southwestern part of the Cordilleran geosyncline are distributed in three contrasting lithologic belts as follows:

(1) western graywacke belt of the Pacific Border;

(2) intermediate limestone belt; and

(3) eastern dolomite belt.

In these belts or subprovinces, rugose coral faunas of 

about the same age show biof acies differences seemingly 

related in part to change of depositional environment, 

as well as to the vagaries of faunal dispersal and 

paleogeography.

Clastic sediments of the Gazelle Silurian seaway, 

which are on the whole poorly sorted and of prevailingly coarse texture, suggest rapid deposition and highenergy agencies of transport. In spite of somewhat 

inharmonious factors, the entombed limestone bodies are 

largely fine-textured, quite pure carbonate and are exclusively nondolomitic. These limestone bodies appear 

to have been deposited in relatively quiet water.

As noted elsewhere, the Silurian rocks of the Pacific 

Border province of southeastern Alaska are some 20,000 

feet thick (G. D. Eberlein, written comniun., 1963) and 

are on the whole similar lithologically and f aunally to 

those of the northeastern Klamath subregion. Absence 

of diagenetic dolomite is likewise a feature of these 

Alaskan strata. It is premature to generalize, but present data support the conclusion that extensive dolomitization did not take place in the Silurian of the American 

Pacific Border.

Limestone bodies of the Gazelle Formation range 

from small lenses a foot thick within the siliceous elastics to heavy bedded masses over a hundred feet thick 

having lateral extent of several thousands of feet. The 

largest of these limestones, like unit 3, is situated near 

the top of the formation; smaller bodies appear to be 

distributed sporadically throughout this predominantly 

clastic formation.

Reef origin has long been suspected for the isolated 

craggy limestone bodies in the Gazelle. Thus far, however, a search for reef al bedding structures has remained 

unrewarded. Much of the coarser textured carbonate
ENVIRONMENT AND ORIGIN OF THE NORTHEASTERN KLAMATH SUBREGION CORAL-BEARING DEPOSITS 25

within this formation is obviously biogenic, like that of 

the Niagaran patch reefs and bioherms of the continental interior and the well-known Gotland reefs; as in 

many of the described Silurian reef complexes, a large 

percentage of the Gazelle calcareous detritus is 

crinoidal; lesser amounts of detritus were contributed 

by stromatoporoids, calcareous algae, corals, brachiopods, and mollusks and are listed in decreasing order of 

magnitude. Origin of the wholly fine-textured pure 

limestone facies, whether chemical or mechanical, is 

unexplained.

Virtual absence of fossils in the noncalcareous or 

sparingly calcareous graywacke suggests that the sea 

bottom where this kind of rapid sedimentation was in 

progress may have been inhospitable to benthonic 

species.

The Niagaran reefs (Lowenstam, 1948, 1949, 1950) 

and those of the Gotland Silurian (Hadding, 1941, 

1950; Jux, 1957) reveal complex bedding characteristics 

unrecognized thus far in the Gazelle limestones and in 

those of southeastern Alaska. Among those features are 

massive unstratified core rock as distinguished from that 

of inclined flank beds and well-stratified interreef rock. 

Evidently the reefs exhibited bottom relief. Typical 

Gotland patch reefs or bioherms have cores of inverted 

cone shape; the massive core rock intertongues 

marginally with reef detritus and thence merges laterally with interreef marlstone. Bioherm and patch reef 

complexes of the Great Lakes Niagaran are shallow sea 

features distinguished by unstratified, somewhat altered 

cores surrounded by inclined flank beds suggesting initial relief. Lowenstam's detailed researches (1948,1950) 

point up the major role of frame-building and sediment-binding organisms in their construction. Calcareous algae and stromatoporoids probably functioned 

in the strengthening processes, but the biologic affiliation 

of some of the cementing organisms which made rigid 

wave-resistant structures possible has not been 

ascertained.

Diversity of the Gazelle coral faunas and the great 

abundance of other lime-secreting organisms including 

algae suggest that the essential biota for reef building 

existed. As in tropical regions today, the warm, shallow 

sea evidently favored rapid proliferation and evolutionary differentiation of corals and other invertebrate 

groups. The Gazelle rugose corals appear to be more 

numerous and generically diverse than are those known 

in the southeastern Alaska Silurian; it is inferred these 

taxonomic differences may be of a latitude-zonal nature. 

Frame-building and cementing organisms like stromatoporoids and calcareous algae, which are abundant 

in the Gazelle, provided agents for sediment binding,

essential to continued in situ upbuilding in a shallow 

marine zone of strong wave action.

Factors unfavorable to growth of reef or bioherm 

complexes in the Gazelle sequence are the widespread 

barren graywacke environment and the tectonic instability of the shallow sea bottoms and neighboring land 

areas. Sites for limestone deposition were less numerous 

and extensive than in shelf sea areas where clastic deposition was reduced. Scattered reefs are nonetheless to 

be expected in the tectonically active Pacific Border 

province, especially during quiescent intervals when 

vulcanism ceased.

The shelf seas of the Great Lakes Silurian (Lowenstam, 1948, 1950) provide an interesting contrast with 

their extensive reef-complex building. However, shelf 

sea conditions and tectonic stability do not provide the 

entire explanation, for the coexisting shelf sea dolomites 

of the central and eastern Great Basin were seemingly 

not amenable to the growth of patch reefs of the Great 

Lakes or Gotland types.

The significance of primary or diagenetic dolomitization in relation to Silurian reefs calls for detailed investigation. At one extreme we have the dolomite-free 

limestones of the tectonically active Pacific Border, at 

the other the eastern Great Basin shelf sea carbonates 

in which dolomitization is essentially complete. Intermediate in character are the dolomite-prone Great 

Lakes Niagaran reefs and the Gotland reef complex 

deposits with little or no dolomite.

In the Gotland region, where reef building conditions were optimum and dolomitization unimportant, 

the general environment was more like that of a stable 

shelf. There is, however, indirect evidence of rather 

active crustal unrest in the not distant hinterland, possibly to the north. As described by Hede (1921), Hadding (1941), and more recently by Jux (1957), lateral 

facies change is great in the Gotland reef complex intervals, thus complicating mapping and stratigraphic interpretation. In part this facies fluctuation is related 

to repeated influx of argillaceous debris in large 

amounts, a possible result of landward crustal 

disturbance.

CORAL-BEARING LIMESTONE CONGLOMERATE

The limestone breccia-conglomerate, which is described as Gazelle unit 2 (text fig. 5; pi. 4, fig. 13), has 

yielded more corals and other fossils than any other 

part of this formation. Conglomerates of underlying 

unit 1 are mainly of the siliceous variety, whereas those 

of unit 2 are composed of angular to subrounded gray 

limestone blocks and cobbles cemented by argillite matrix. Corals and other fossils are abundant in limestone 

cobbles as well as in the argillite matrix. The partly

454-393 O - 72 - 5
26 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

angular shape of some blocks makes it unlikely that 

the material was transported far from the site of initial 

deposition and partial lithification. In some places the 

limestone conglomerate passes gradationally into overlying thick-bedded pure limestone of Gazelle unit 3 

and the admixed argillaceous matter disappears. The 

genetic relationship of the coral-rich limestone brecciaconglomerate is considered in connection with origin 

of the massive limestones.

ORIGIN OF CORALLINE LIMESTONES IN THE GAZELLE 

FORMATION

Explanation of the origin of the coral-bearing limestone bodies in the Gazelle Formation is at present 

highly speculative; these limestone bodies invite comparison with the classic coral-rich Niagaran carbonate 

rocks and with those of Gotland. For the present, however, field observations of even bedding in the Gazelle 

limestones largely rule out the existence here of features 

analogous to bioherms or patch reef complexes. These 

rather pure limestones are believed to have accumulated 

as mixtures of in situ bioclastic material and fine lime 

mud partly of mechanical origin but perhaps also partly 

of chemical origin. A good deal of this material was 

undergoing wave attack and redistribution after initial 

deposition, as evidenced by patches of limestone conglomerate within Gazelle unit 3. The limestone bodies 

are viewed as shallow sea banks accumulating in protected embayments where, in somewhat quieter waters, 

they were bypassed by currents transporting the coarse 

material which formed graywacke and siliceous conglomerate on neighboring sea bottoms. Later changes 

such as renewal of vulcanism and crustal disturbance, 

brought about burial of these limestone bodies to form 

lenses in the clastic graywacke sequence.

The coral-bearing limestone conglomerate of Gazelle 

unit 2 largely represents reworked material from more 

or less lithified coralline limestone. Several explanations are possible. For example, uplift of the sea bottom 

or marine withdrawal may have resulted in accelerated 

wave erosion and undermining of consolidated coralline 

lime mud banks, or this material may represent submarine talus debris torn from the margins of reefs. 

However, the field observations do not support a theory 

that these blocks occupy inclined reef flank beds dipping away from a reef core. Burial of the conglomerate 

blocks by laterally introduced argillaceous material is 

perhaps significant in this connection (pi. 4, fig. 13). 

At Parker Eock the basal part of the limestone cap 

rock corresponding to Gazelle unit 3 shows inclined 

tongues of limestone breccia-conglomerate. These 

tongues are the nearest thing to reef flank features recognized in the northeastern Klamath subregion.

At one locality the lowest beds of massive limestone 

of Gazelle unit 3 include abundant chert pebbles in a 

30-foot-thick transitional zone from a siliceous conglomerate which at that point occupies the position of 

the limestone conglomerate of Gazelle unit 2. Here is 

shown the upward change from conditions of highenergy coarse debris transport to a presumably more 

tranquil environment of lime mud accumulation and 

coral proliferation.

Eeefs and reef flank structures have not been observed 

in the Silurian beds of Alaska on the Pacific Border or 

in coral-rich beds of the eastern dolomite belt of the 

Great Basin. Coral-rich limestone breccia-conglomerate 

occurs in the uppermost Silurian of the intermediate 

limestone belt of the Great Basin. In the northern Simpson Park Mountains of west-central Nevada coarse 

limestone breccias have yielded a large Silurian rugose 

coral fauna; although no supporting structural evidence 

of reefs was found here, these limestone breccias suggest that marginal reef talus material was deposited 

here in a high-energy wave environment (Winterer and 

Murphy, 1960).

CLASSIFICATION OF KLAMATH MOUNTAINS 

SILURIAN RUGOSA

Taxonomic evaluation of certain rugose coral families and genera is encouraged by current research upon 

Silurian and Devonian corals of this coelenterate order 

throughout the Cordilleran Belt. The classification 

which has evolved as a result of these efforts differs 

in some details from existing arrangements. Family assignment of particular genera as well as family or subfamily status of some groups departs from the recent 

classification of Hill (1956), the most comprehensive 

and adequate thus far published. Availability in the 

literature of existing family designations eliminates the 

necessity far more than a very few new family names. 

Among the proposed additions and emendations are 

the elevation of subgenera to generic status or the reverse and the proposal of new genera and subgenera. 

The family Pycnostylidae is restored.

Gross morphologic characters (Hill 1935, 1956) are 

relied upon in these descriptive and taxonomic studies. 

Whereas attention was given to details of microstructure and fine structure use of these minute features as 

aids in rugose coral systematics is thus far attended by 

limited success (Wang, 1950; Kato, 1963) as compared, 

for example, with highly effective use of wall structure 

in fusulinid classification. It is nonetheless recognized 

that fine structure will eventually aid in recognition of 

some rugose coral families, such as Tryplasmatidae and 

Phillipasastraeidae. Because of poor preservation, techniques of this kind are futile in connection with study
SYSTEMATIC AND DESCRIPTIVE PALEONTOLOGY 27

of many of the western Paleozoic corals, especially as 

applied to those from dolomitic rocks where complete 

fossil silicification is to expected.

Of 13 rugose coral families recognized in the Great 

Basin Silurian,3 10 occur in the northeastern Klamath 

subregion. Silurian rugose coral families not found thus 

far in this subregion are: Arachnophyllidae, Goniophyllidae, Chonophyllidae, and Acervulariidae.

Order RUGrOSA Edwards and Haime, 1850

I. Family Laccophyllidae Grabau, 1928

1. Genus Syringaxon Lindstrom, 1882 

Syringaxon sp. c

II. Family Streptelasmatidae Nicholson, 1889 4 (as

Streptelasmidae)

a. Subfamily Streptelasmatinae Nicholson, 1889 4 

1. Genus Dalmanophyllum Lang and Smith,

1939 

Dalmanophyllum sp. h

III. Family Stauriidae Edwards and Haime, 1850

1. Genus Palaeophyttum Billings, 1858 

Palaeophyllum^ sp. G

2. Genus Wintunastraea new genus

Wintunastraea stanleyi n. gen., n. 

sp.

IV. Family Pycnostylidae Stumm, 1953 

1. pycnostylid sp. H

V. Family Tryplasmatidae Etheridge, 1907

1. Genus Zelophyllum Wedekind, 1927 

Zelophyllum sp. G

VI. Family Kodonophyllidae Wedekind, 1927 

a. Subfamily Kodonophyllinae

1. Genus KodonophyUum Wedekind, 1927

Kodonophyilum sp. g 

b. Subfamily Mycophyllinae

1. Genus Mucophyllum Etheridge, 1894 

Mucophyllum mcintyrei n. sp.

VII. Family Lykopliyllidae Wedekind, 1927 

1. Genus Cyathactis Soshkina, 1955 

Cyathactis gazellensis n. sp.

VIII. Family Cystiphyllidae Edwards and Haime, 1850 

1. Genus Cystiphyllum Lonsdale, 5 1839

Cystiphyllum sp. c 

IX. Family Kyphophyllidae Wedekind, 1927

1. Genus Kyphophyllum Wedekind, 1927 

Kyphophyttum greggi n. sp.

2. Genus Petrozivm Smith, 1930 

Petrozium staufferi n. sp.

a Merriam, C. W., unpublished data.

* In Nicholson and Lydekker, 1889.

8 Pages 675-699 and 5 plates in Murchison, 1839.

3. Genus Shastaphyllum new genus

Shastaphyllum schucherti n. gen.,

n. sp.

'{Shastaphyllum sp. c 

X. Family Endophyllidae Torley, 1933

1. Genus Klamathastraea new genus

Klamathastraea dilleri n. gen. 3 n. 

sp.

SYSTEMATIC AND DESCRIPTIVE 

PALEONTOLOGY

Family LACCOPHYLLIDAE Grabau, 1928

Reference form. Syringaxon siluriensis (McCoy) 

1850.

Diagnosis. Small solitary turbinate to subcylindrical 

rugose corals with narrow peripheral stereozone. Septa 

smooth, lamellar, dilated periaxially within a tubular 

stereoplasmic aulos. No dissepiments. Tabulae uparched 

strongly, complete or nearly so; axial parts horizontal 

within aulos, lateral segments steeply inclined to outer 

wall.

Remarks. Corals of this family characterize the 

higher Silurian and Lower Devonian rocks with the 

genera Syringaxon Lindstrom and Barrandeopliyllum 

Pocta. Late Paleozoic genera provisionally classified 

here include Trochophyllum Edwards and Haime, 

Permia Stuckenberg, and Amplexocarinia Soshkina.

Genus SYEINGAXON" Lindstrom, 1882

1882. Syringaxon Lindstrom, p. 20.

1900. Laccopliyllum Simpson, p. 201.

1902. Niclwlsonia Pocta, p. 184.

1928. Lacoophyllum Simpson. Grabau, p. 82.

1928. Alleynia Pocta (Nicholsonia Pocta). Grabau, p. 82.

1935. Syringaxon Lindstrom. Butler, p. 117.

1938. Syringaxon Lindstrom (in part). Prantl, p. 21.

1949. Syringaxon Lindstrom. Stumm, p. 10.

1962. Syringaxon Lindstrom (in part). Fliigel and Free, p. 224.

Type species. Oyathaxonia siluriensis McCoy 1850 

(Butler, 1935); by monotypy. Silurian; Upper Ludlow, 

England.

Diagnosis. Laccophyllid corals with deep calice and 

strongly developed aulos (Fliigel and Free, 1962). 

Uparched tabulae either continue wall to wall through 

aulos, terminate in aulos, or abut as tabellae on contiguous tabulae. Quadrants in neanic growth stages 

defined by narrow fossulae.

Remarks. Laccophyllum Simpson 1900 is a synonym 

(Grabau, 1928). Syringaxon occurs in the western 

American Silurian but is most abundant in Early De-
28 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

vonian Rabbit Hill strata of the Great Basin, where it 

characterizes the Syringaxon coral f acies. Although uncommon in the west above the Rabbit Hill Limestone, 

this genus ranges into the Middle Devonian. Late Paleozoic analogs may be homeomorphic.

Syringaxon sp. c 

Plate 4, figure 10

Small trochoid to ceratoid solitary corals, 8 mm or less 

in length fairly common in the Gazelle Formation. Of 

these, a single individual herein figured reveals a septal 

pattern like that of Syringaxon, with 20 smooth even 

straight septa coalescing laterally short of the axis to 

produce a partial aulos. No minor septa. Inside the thin 

epitheca the septa thicken peripherally in a well-defined 

septal stereozone.

Another individual of the same size (pi. 4, fig. 9) has 

short septa of about the same number, but it lacks the 

aulos. Perhaps it is more appropriately assigned to 

lOrthophyllum sp.

Syringaxon sp. c has fewer septa than the species 

characterizing the Syringaxon f acies of the Great Basin 

Rabbit Hill Limestone (Kelderbergian). The Rabbit 

Hill species has minor septa and a very deep calice.

Occurrence. In tan-\veathering shales of either unit 

2 or the top beds of unit 1, Gazelle Formation at south 

end of Chastain Ridge, loc. Ml 135.

Family STKEPTELASMATIDAE Nicholson, 1889 6 

(as STKEPTELASMIDAE)

Reference form. Streptelasma corniculum Hall 

1847; Trenton Group, Middle Ordovican

Diagnosis. Solitary rugose corals with wedge-tapering lamellar major septa, short to very short minor 

septa, and a well-developed septal stereozone. Septa 

thickened ontogenetically to later neanic growth stage 

and laterally in contact, thereafter thinning progressively from axis toward periphery. Tabulae and tabellae irregularly arched, obscured by stereoplasmic 

thickenings. No dissepiments. Fossula weak or lacking.

Remarks. Streptelasmatidae with long septa tend to 

produce either loose or rodlike axial structures; these 

are twisted combinations of stereoplasmically swollen 

axial tips of septa involved with uparched median tabular segments.

In some western Late Ordovician stratigraphic sections, Streptelasmatidae are the earliest solitary Rugosa 

and have already evolved specialized genera like Bighornia (Duncan, 1957) Avith columella and externally 

angulate cross section. The western Silurian Streptelasmatidae are subdivided into two subfamilies: Streptelasmatinae and Siphonophrentinae.

6 In Nicholson and Lydekker, 1889.

Subfamily STREPTELASMATINAE Nicholson, 1889 7 

Genus DALMANOPHYLLUM Lang and Smith, 1939

1933. Tyria Scheffen, p. 33, pi. V, figs. 2-3.

1939. Dalmanophyllum Lang and Smith, p. 153.

1940. Dalmanophyllum. Lang, Smith, and Thomas, p. 49. 

1961. Dalmanophyllum Lang and Smith. Minato, p. 81-86, text 

figs. 20, 21, 22, 23 ; pi. XI, pi. XIX, figs. 2-5.

Type species. Cyathaxonia dalmani Edwards and 

Haime 1851; by original designation (Lang and Smith, 

1939, p. 153). Silurian (early Wenlockian) ; Hogklint 

group, Gotland, Sweden.

Diagnosis. Trochoid Streptelasmatinae with solid 

bladelike axial structure occupying center of inverted 

bell-shaped calice; transverse outline of calice rim 

broadly ovoid, nonangulate. Weak fossula in line with 

median plane of axial rod. Major septa dilated, extend 

to columella in early adult and younger growth stages; 

minor septa short. Septal stereozone narrow to moderately wide. Tabulae largely suppressed by stereoplasmic 

thickening.

Occurrence. Late Llandovery and early Wenlock.

Dalmanophyllum sp. h 

Plate 1, figures 11-14

Incomplete solitary ceratoid corals from Horseshoe 

Gulch have the axial structure and wide septal stereozone of Dalmanophyllum. Major septa number about 

36; some are incorporated axially in the rodlike columellar structure. Minor septa mostly less than half the 

length of major septa; some do not extend far beyond 

the stereozone. Irregular tabulae distally arched; no 

dissepiments. In longitudinal thin section, the axial 

structure appears as a distinct rod, reinforced by stereoplasm, projects upward in a deep calice.

Remarks. Similar DalmanophyHum with narrow 

stereozone occurs in the Montgomery Limestone of the 

Taylorsville area, California. A larger streptelasmid 

in the Montgomery has a wider, more open axial structure and is more suggestive of the genus G-rewingkio. 

Trochoid Dalmanophyllum occurs also in Great Basin 

coral zone A of Early Silurian age in the Vaughn 

Gulch Limestone and Hidden Valley Dolomite of the 

northern Inyo and Panamint Mountains.

Occurrence. Horseshoe Gulch area, loc. M1131; associated with a fauna considered to be Early Silurian.

Family STAUKIIDAE Edwards and Haime, 1850

Reference form. Stauria astreiformis Edwards and 

Haime. Silurian; Gotland, Sweden.

As here interpreted the Stauriidae comprise primitive 

bushy and cerioid Rugosa with slender elongate corallites, narrow peripheral stereozone, complete tabulae, 

and thin lamellar septa. Major septa are very long or

7 In Nicholson and Lydekker, 1889.
SYSTEMATIC AND DESCRIPTIVE PALEONTOLOGY 29

of medium length, never stubby as in Pycnostylidae or 

stubby-spiny as in the Tryplasmidae. In the more primitive species, dissepiments are absent. In other species, 

dissepiments develop sporadically in local groups of 

one to three columns; some corallites lack dissepiments.

Stauriidae comprise the more abundant compound 

Kugosa of Late Ordovician rocks; these seemingly have 

no morphologic or genetic connection with the contemporary members of the solitary Streptelasma group. 

Origin of the Stauriidae is perhaps to be sought among 

the Tabulata. Ordovician Stauriidae are Favistella 

Dana (or Favistina Flower), Cyathophylloides Dybowski, and Palaeophyllum Billings. These are succeeded in 

the Silurian by advanced species of Palaeophyllum and 

Oyathophylloides as well as by Stauria and Wintunastraea. The Silurian Circophyllum may also belong in 

this family.

In the Devonian System, Stauriidae continue on as 

Dendrostella Glinski, Columnaria Goldfuss, and possibly also Synaptophyllum Simpson (as revised by 

McLaren, 1959).

A stauriid known only from float material near the 

Ordovician-Silurian boundary in the Koberts Mountains, Nev., has the overall characterization of Cyathophylloides but possesses a single column of large peripheral dissepiments.

In the Gazelle Formation, Silurian corals referable to 

the Stauriidae are the species questionably placed in 

Palaeophyllum and the new stauriid genus Wintunastraea.

Genus PALAEOPHYLLUM Billings, 1858

1858. Palaeophyllum Billings, p. 168.

1956. Palaeophyllum. Duncan, pi- 25, figs. la-b.

1959. Palaeophyllum Billings. Hill, p. 4.

1961. Palaeophyllum Billings. Flower, p. 88.

1963. Palaeophyllum Billings. Oliver, p. 4.

Type species. Palaeophyllum rugosum Billings. 

Ordovician; Black River or Trenton Group, Quebec, 

Canada.

Diagnosis. Phaceloid Stauriidae with narrow peripheral stereozone; no dissepiments. Major lamellar 

septa long and simple, minor septa short; tabulae complete, commonly arched with axial depression. Forms 

large colonies by lateral increase.

Remarks. This genus is probably related to the cerioid Favistella or Favistina and to Oyathophylloides 

common in the Late Ordovician. Palaeophyllum and 

Cyathophylloides are present in the Silurian strata of 

the Cordilleran Belt where they occur with nondissepimented corals of similar growth habit but have 

acanthine septa and are therefore assigned to the tryplasmids. The morphology and taxonomy of Palaeophyllum have recently been dealt with by Flower (1961) 

and by Oliver (1963).

Palaeophyllum? sp. G 

Plate 2, figures 9, 10

These nondissepimented phaceloid Rugosa provisionally assigned to Palaeophyllum have complete straight 

tabulae, only slightly thickened lamellar septa, and little peripheral stereoplasm. In transverse thin section 

Palaeophyllum^. sp. G shows about 44 mostly rather 

short but not stubby septa which alternate long and 

short in places, the longer extend to about half the 

corallite radius. In longitudinal thin section the straight 

tabulae are fairly closely spaced. Where peripheral 

stereoplasm is present the trabeculae are nearly 

horizontal.

Zelophyllum sp. G from the same beds differs from 

Palaeophyllum^ sp. G. in possessing thick and very 

short undifferentiated septa in a fairly uniform septal 

stereozone. Unlike PalaeophyHuml sp. G. the Zelophyllum in question is not known to be colonial.

Occurrence. Willow Creek area, Chastain Ridge 

locality MT8. Weathered fossils along fault zone in Gazelle Formation, probably from topmost unit 1 or unexposed unit 2. Corals quite similar to Palaeophyllum^. sp. 

G occur in the lower part of the Vaughn Gulch Limestone, northern Inyo Mountains, Calif.

Genus WINTTTNASTEAEA, new genus

Type species. Wintunastraea stanleyi n. gen., n. sp. 

(here designated); Silurian; Gazelle Formation, northeast Klamath Mountains, Siskiyou County, Calif.

Diagnosis. Cerioid stauriid having sporadic groups 

of small and large lonsdaleioid dissepiments but lacking 

a continuous dissepimentarium. Tabulae closely spaced, 

nearly flat peripherally, very strongly arched axially. 

Septal stereozone with scattered nearly horizontal trabeculae.

Remarks. Major septa of Wintunastraea are numerous, long, smooth or slightly wavy; minor septa are 

short. Some corallites reveal no dissepiments. Stauria 

may be either fasciculate or cerioid; the new genus 

Wintunastraea is known only with cerioid growth habit. 

Wintunastraea also differs from Stauria in having markedly arched tabulae and isolated groups of lonsdaleioid dissepiments in one to three columns. Columnaria 

has scattered smaller dissepiments which are less distinctly lonsdaleioid, has shorter septa, and lacks the 

arched tabulae of Wintunastraea. Cyathophylloides 

lacks the longsdaleioid dissepiments and has fewer septa 

and less arched tabulae.

Wintunastraea is monotypic, known thus far only in 

the Silurian Gazelle Formation.
30 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

Wintunastraea stanleyi, new genus, new species 

Plate 3, figures 1-3 ; plate 4, figures 4-5.

Type, Holotype, USNM 159464, Gazelle Formation; locality M1135, Willow Creek area. The holotype 

colony is the only specimen of this coral discovered so 

far.

Diagnosis. Wintunastraea has 24 to 30 long major 

septa. Septal tips very slightly dilated or coalesce with 

those of adjacent septa. Strongly uparched tabulae with 

an axial depression.

Transverse thin sections. Some major septa extend 

to the axis and range in number from 24 to 30; others 

merge at tips with contigous septa. Those septa with 

free axial tips may be slightly dilated. Minor septa short 

but not stubby; about one-fourth the length of major 

septa. Septa fairly smooth to slightly undulant, without 

major thickening beyond stereozone, which is of narrow to medium width. Lonsdaleioid dissepiments mostly 

rather large; groups of these most common at outer wall 

angulations. Stereozone usually on the inside of dissepiment groups. Outer wall sharply set off from stereozone 

by textural differences.

Longitudinal thin sections. Dissepiments absent in 

parts of. corallities. Tabulae close spaced, characterized 

by an outer and an axial series. Outer series nearly horizontal; axial series occupies about one-half the corallite diameter and rises abruptly in bulbous fashion with 

medium sag. Some individual tabulae traceable from 

the peripheral flat zone through the axial sag, but entire 

or complete tabulae uncommon; most of the flat 

peripheral parts terminate inward against bulbous 

tabellae of the axial arch. Some tabulae traceable 

peripherally through the stereozone to the outer wall. 

Nearly horizontal trabeculae visible between tabulae, 

locally these project spinosely beyond the stereozone.

Elongate lonsdaleioid dissepiments in localized 

groups, in single columns or as many as three columns 

commonly thickened by stereome on their axial surfaces.

Reproductive offsets. Small interstitial offsets lacking dissepiments and stereozone probably developed 

from outermost edge of a parent calice.

Fine structure. The thin outer wall or epitheca between corallites is minutely three layered and has a 

median clear lamina with outer and inner dark laminae 

of dusty carbonaceous calcite. The outer wall sharply 

contrasted with the lighter gray laminar stereozone.

Occurrence. The excellently preserved material of 

this new genus was collected by Maitland Stanley at 

the south end of Chastain Ridge (loc. M1135), where 

it was associated with Shastaphyllum schucherti. These 

fossils were embedded in tan argillaceous matrix, evidently having weathered from deformed beds near the 

contact between massive limestones of Gazelle unit 3

and the graywacke-argillite sequence of unit 1. It is 

possible the beds yielding this coral fauna are the limestone breccia-conglomerate of Gazelle unit 2 which is 

not exposed at locality M1135, but is exposed at Bonnet 

Rock where it yields the latest Gazelle fauna in this 

area. Study material consists of the single corallum 

which is the holotype.

Family PYCNOSTYLIDAE Stumm, 1953

Reference form. Pycnostylus guelphensis Whiteaves 1884. Silurian; Guelph Dolomite, Ontario, 

Canada.

Fasciculate rugose corals with subcylindrical mature 

corallites; septa low, continuous longitudinal ridges 

arising from narrow stereozone without acanthine 

spines. Tabulae complete, straight, unarched; no dissepiments. Reproduction by internal wall offsets from 

calice periphery. Trumpet-shaped flaring calices characteristic. 

Genera included in the Pycnostylidae are:

Pycnostylus Whiteaves, 1884 

Fletcheria Edwards and Haime, 1851 

(l)Fletcherina Lang, Smith, and Thomas, 1955 

(?) Cyathopaedium Schliiter, 1889

The Pycnostylidae are characteristic of the American 

Silurian. In the Great Basin they are represented by an 

undescribed genus with abundant lateral connecting 

processes, trumpet-shaped calice, and numerous offsets; 

Pycnostylus is reported to have but four such offsets, 

whereas the Great Basin genus has as many as eleven.

The Stauriidae differ in having long lamellar septa 

and uparched tabulae. Fasciculate Iryphasmatidae are 

externally similar but may be distinguished by their 

acanthine septa and lack of multiple calice offsets. The 

problematic Zelophyllum group of Tryplasmatidae is 

also homeomorphic but is not known to have multiple 

calice buds or markedly flaring calices; this group reveals discontinuous patches of acanthine septa (see pi. 1, 

figs. 3-5).

Fletcheria is poorly understood. This Gotland Silurian genus has some cystose tabulae and a rather thick 

wall, with structure like that of Syringopora (Duncan, 

1956, pi. 25, figs. 6a-b). According to Duncan, Fletcheria lacks septa. On the basis of Duncan's evaluation 

and the original figure of Edwards and Haime (1851, 

pi. 14, fig. 5), it seems doubtful that the type species of 

Fletcheria is congeneric with Pycnostylus as implied 

by Lang, Smith, and Thomas (1940, p. 112).

The Klamath Mountains pycnostylids are too incomplete to characterize generically, but they can be distinguished from ZelopTiyllwn by bushy growth habit 

and multiple calice offsets. It is possible that some 

straight-shaped Zelophyllum from Klamath and southeastern Alaska may be solitary corals.
SYSTEMATIC AND DESCRIPTIVE PALEONTOLOGY 31

Pycnostylid sp. H 

Plate 1, figures 8-10

Loosely fasciculate species from the Silurian beds 

at Horseshoe Gulch with calice offsets numbering from 

three to five and a fairly wide stereozone which is about 

one-quarter of the radius. Uiidifferentiated septa number about 46, some with and some without short internal 

projections. Trabeculae nearly horizontal; do not project inward significantly as acanthine spines. Tabulae 

straight, thickened, and widely spaced.

Occurrence, Horseshoe Gulch area, loc. M1130; collected by A. J. Boucot. This form was not found in 

association with the Early Silurian fauna of loc. M1131. 

Similar pycnostylids were collected by Boucot li/£ miles 

south of Mountain House, China Mountain quadrangle.

Comparable pycnostylids occur at Parker Eock, loc. 

M1030 (pi. 2, figs. 7, 8), but these have more closely 

spaced tabulae and narrower stereozone.

Family TRYPLASMATIDAE Etheridge, 1907

Reference form. Tryplasma aequabile (Lonsdale) 8 

1845. Silurian; Ural Mountains, Eussia.

Solitary and colonial rugose corals with acanthine 

septa (Hill, 1936) comprising columns of trabecular 

spines protruding from a peripheral stereozone. Tabulae complete or partial, unarched. No dissepiments.

In some Tryplasmatidae the trabecular spines are 

mostly buried in stereoplasm with only inner tips exposed; in others they project obliquely inward and upward as long free spines (Schouppe, 1950).

Genera of Tryplasmatidae in the Great Basin Silurian are: Tryplasma Lonsdale 8 1845, Palaeocyclus Edwards and Haime 1849, Rliabdocyclus Lang and Smith 

1939, and Zelophyllum Wedekind 1927. Of these, Tryplasma may be further subdivided on the basis of external form and growth habit (Stumm, 1952). Only Zelophyllum has been found in the northeastern Klamath 

Mountains.

Genus ZELOPHYLLUM Wedekind, 1927

1927. Zelophyllum Wedekind, p. 34-35, pi. 5, figs. 1-5, pi. 6,

figs. 11-13. 

1937. Zelophyllum Wedekind. Soshkina, p. 46-49, pi. vii, figs.

5-8, pi. viii, figs. 3-6.

1940. Zelophyllum Wedekind. Lang, Smith, and Thomas, p. 142. 

1956. Zelophyllum Wedekind. Hill, p. F312, fig. 213:7. 

1956. Zelophyllum. Duncan, pi. 23 (expl., figs. 2a-d).

Type species. Zelophyllum intermedium Wedekind, 

1927; by original designation. Silurian; Hogklint, Gotland, Sweden.

Diagnosis. Corallites of medium size, very elongate, 

subcylindrical, with medium to narrow septal stereo8 Appendix A, p. 591-634 of Murchison, de Verneuil, and Von Keyserling, 1845.

zone, short, partly acanthine septa, and complete, rather 

closely spaced tabulae. No dissepiments.

Remarks. Zelophyllum appears to have been correctly assigned to the Tryp] asmatidae by Hill (1956, 

p. F310-F312). Alaskan specimens show especially 

well the discontinuous acanthine features (pi. 1, figs. 

3-5) which cannot be observed in Wedekind's black 

and white illustrations of the type species. In transverse section the wide septal bases which comprise the 

stereozone are sutured laterally along a vague dark 

boundary (pi. 1, fig. 2). The axis of the septum is 

a more pronounced but shadowy dark line passing inward to the sharp blade (or spine) of the septal edge. 

In longitudinal section nearly horizontal trabeculae 

are visible within the stereozone; in places where the 

stereozone is thinnest, these project as long, fairly 

uniform spines like those of Tryplasma. Until Wedekind's Gotland type species is restudied in thin section, the true taxonomic status of Zelophyllum will 

remain uncertain.

Doubts exist regarding the colonial nature of Zelophyllum. Compact or fasciculate colonies are unknown 

among the Alaskan or Klamath species. Separate corallites as collected do not reveal lateral attachment processes or evidences of contact with adjacent corallites; 

hence these may have lived in solitary habit.

Pycnostylid Eugosa, which resemble Zelophyllum 

and are the most likely to be confused, have the fasciculate growth habit. Some Pycnostylidae develop numerous rodlike or tubular lateral connections. Members 

of this Silurian family lack acanthine septa and produce multiple internal calice offsets not known in 

Zelophyllum.

Phaceloid Stauriidae may be distinguished from 

Zelophyllum by their longer lamellar (not acanthine) 

septa. Some genera may have a few dissepiments.

Pseudamplexus differs in being, usually, a large and 

heavy coral with much wider septal stereozone and 

without true acanthine septal spines.

Occurrence. Zelophyllum is known only in strata of 

Silurian age.

Zelophyllum sp. G 

Plate 1, figures 6, 7

Incomplete subcylindrical Zelophyllum of medium 

size from the Gazelle Formation; probably of solitary 

growth habit. Resembles a species abundant in the 

Atrypella-Conchidium zone of southeastern Alaska 

(pi. 1, fig. 1-5).

The stereozone, approximately one-sixth of the radius, includes 56 short septa which are not well differentiated as major and minor. Inner septal blades may 

extend about one-half the stereozone width. Stereozone 

calcite is minutely laminar. The epitheca is very thin;
32 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

longitudinal (septal) grooves are weakly defined. External rugae are few and widely spaced.

Tabulae are close-set, fairly straight, unarched, and 

mostly complete. Most stereozone trabeculae are nearly 

horizontal; no well-defined acanthine spines were 

recognized.

Occurrence. Gazelle Formation, Chastain Ridge, 

loc. MT8. The figured specimen was partly encrusted 

by a stromatoporoid and is coated by a brown argillite 

matrix with crinoidal debris.

A similar Zelophyllum occurs in the massive lightgray limestone of Gazelle unit 3 at Bonnet Rock.

Family KODONOPHYLLLDAE Wedekind, 1927

Reference form. Kodonophyllum milne-edwardsi 

(Dybowski). Silurian; Gotland, Sweden.

Solitary and colonial rugose corals have long septa, 

a very wide stereozone, no dissepiments, and a tabularium of flat tabulae or arched tabellae; in one subfamily these tabellae combine with septal ends to produce an axial structure.

Two subfamilies are recognized: Kodonophyllinae 

and Mycophyllinae.

Subfamily KODONOPHYLLINAE Wedekind, 1927

Fasciculate colonial and platelike solitary Kodonophyllidae with arched tabellae and tabulae which 

combine with septal ends to produce an axial structure. Described genera are Kodonophyllum Wedekind 

and Schlotheimophyllum Smith. Only Kodonophyllum 

is known in the Klamath Mountains Silurian.

Kodonophyllum sp. g 

Plate 4, figures 11, 12

Fragmentary specimens of Kodonophyllum have 

been found only in the massive limestone unit 3 in the 

Gazelle Formation at Bonnet Rock.

In transverse section, species g shows a wide stereozone with 30 major septa which meet axially to form a 

twisted vortex. Minor septa, somewhat less than onehalf the radius, extend to the stereozone edge. Major 

septa thickened, with scattered small lateral bumps and 

swellings.

The longitudinal section reveals an axial boss in the 

center of a deep calice. Trabeculae are peripherally inclined a.t a low angle in the wide stereozone.

Kodonophyllum sp. g. resembles an undescribed 

species in Great Basin Silurian coral zone E at Coal 

Canyon, Simpson Park Mountains, Nev.9 The Great 

Basin species has more septa and is less twisted axially 

than the Klamath Mountains form. Kodonophyllum 

truncatum (Linnaeus) of the Gotland Silurian (Smith

9 Merriam, C. W., unpub. data.

and Tremberth, 1929, pi. VIII, figs. 5-7) has less 

twisted septal ends in the axial structure than the 

Klamath Mountains form. K. truncatum is a colonial 

form.

Occurrence. Willow Creek area, south side of Bonnet Rock east of locality M191 in massive limestone cap 

rock of unit 3, Gazelle Formation.

Subfamily MYCOPHYLLINAE Hill, 1940

Large solitary platelike and subcylindrical Kodonophyllidae with straight, usually unarched and complete 

tabulae. No axial structure. Genera included in this 

subfamily are. Mucophyllum Etheridge, 1894, Clamydophyllum Pocta, 1902, Pseudamplexus Weissermel, 

1897, and possibly Briantia Barrois, 1889. Only Mucophyllum is known in the Klamath Mountains Silurian.

Genus MUCOPHYLLUM Etheridge, 1894

1894. Mucophyllum Etheridge, p. 11-18, pis. iii, iv.

1926. Mucophyllum. Lang, p. 431, 433, pi. xxx figs. 7, 8.

1940. Mycophyllum. Lang, Smith, and Thomas, p. 87.

1940. Mycophyllum crateroides Etheridge. Hill, p. 399^00,

pi. xii, figs. 1, 2. 

1940. not Mycophyllum liliiforme (Etheridge). Hill, p. 401,

pi. xi. figs. 18, 10, pi. xii, figs. 3-6.

1945. Mucophyllum crateroides Etheridge. Smith, p. 19. 

1949. Mucophyllum Etheridge. Stumm, p. 49, pi. 23, figs. 9, 10. 

1956. Mucophyllum Etheridge. Hill, p. F277, fig. 189: 3a.

Type species. Mucophyllum crateroides Etheridge, 

1894, by monotypy. Silurian; Hatton's Corner, Yass 

River, New South Wales, Australia.

Diagnosis. Large discoid, or patellate to turbinate, 

usually solitary rugose corals with broad calice platform, reflexed margin, and flat-bottomed central pit. 

Septa numerous, thick, laterally in contact to form a 

wide stereozone; some longer septa reach the axis. Tabulae medium wide or narrow, complete, straight to undulant. No dissepiments. Longitudinal section shows fine, 

near-horizontal incremental layering of thick stereozone which is transected by near-vertical trabecular pillars. Radial grooves of calice platform overlie sutures 

between thickened septa.

Remarks. A distinctive feature of Mucophyllum is 

the thick layered stereoplasmic disc occupying the position of a dissepimentarium but lacking dissepiment 

structure. /Schlotheimophyllum has a less dense stereozone (Stumm, 1964) and a more complex axial structure 

like that of Kodonophyllum. Naos Lang, 1926 (possibly 

a synonym of Craterophyllum Foerste, 1909) has welldefined naotic dissepiments and zigzag septa which 

break up pheripherally in naotic fashion. Chonophyllum Edwards and Haime, 1850, as here interpreted, is a 

distinct genus unrelated to the above-mentioned genera 

with which it has been confused. The involved taxonomy 

of these genera has been treated in detail by Lang (1926,
SYSTEMATIC AND DESCRIPTIVE PALEONTOLOGY 33

p. 428-434), Smith (1945, p. 18-20), Stumm (1949, p. 

48-49), and Hill (1956, p. F271, F276-277, F300).

Mushroom-shaped and trumpet-shaped calices are 

characteristic of several perhaps unrelated Silurian 

rugose coral genera. These rugose genera, like Mucophyllum and Schlotheimophyllum, have complete 

straight tabulae, but others have elongate, stemlike 

cylindrical corallites without a greatly thickened 

stereoplasmic disc. Among these genera is Tryplasma 

liliiforme Etheridge, which is evidently not a Tryplasma ; Hill (1940, p. 401) placed it in Mucophyllum. Other 

elongate forms with flaring calice were assigned to 

Pseudomphyma by Wedekind (1927, pis. 6, 7, 8). In the 

Great Basin Silurian are generically unnamed corals resembling Tryplasma liliiforme with flaring calice. Some 

of these have sporadic acanthine septa and probably belong in Zelophyllum; others with very short septa are 

related to Pycnostylus Whiteaves.

Corals with generic features of Mucophyllum may 

have major septa extending to the axis as, for example, 

the specimens from the Silurian Roberts Mountains 

Formation in the Great Basin. These specimens, however, possess nearly horizontal tabulae, unlike the 

uparched tabulae of typical SchlotheimophyllMm, and 

lack the complex axial structure of that genus. As noted 

by Hill (1940, p. 400), individuals of the type species 

of Mucophyllum (M. crateroides Etheridge) may have 

long major septa which are amplexoid extended axially only on the upper surfaces of tabulae.

Geologic occurrence. Mucophyllum is known only 

in rocks of Silurian age. All known occurrences seem to 

be Wenlock or Ludlow.

Mucophyllum mcintyrei, new species 

Plate 6, figures 9, 10

Type. HolotypeUSNM 159453.

Diagnosis. Thick patellate Mucophyllum; markedly 

convex calice platform slopes abruptly inward to steepsided calice pit, and slopes more gently outward toward 

reflexed rim. Tabulae straight, thick, and closely spaced 

beneath flat-bottomed pit. Longer septa terminate at 

edge of tabularium. Stereozone vertically thickest below 

convex inflection of calice platform, thins peripherally 

to sharp rim.

Transverse section. No transverse thin section of a 

surface beneath the calice platform is available. The 

weathered undersurface (pi. 6, fig. 9) reveals about 66 

stereoplasmically thickened septa laterally in contact, 

except at tabularium margin where all taper to abrupt 

free terminations. Join lines of septa make prominent 

radial features on the weathered surface, each lying in 

a radial depression. No clearly denned concentric features suggesting residual or stereoplasmically suppressed dissepiments were observed.

Longitudinal section. Thick and rather close-set, 

somewhat undulant tabulae lack thickenings at septal 

intersection of other Mucophyllum species. Incremental 

stereoplasmic banding rather thick near the axis, thins 

appreciably toward the periphery (pi. 6, fig. 10). Halfway between the periphery and the calice platform inflection, the layers or bands number 22; light bands 

alternate with dark. Light, more transparent, bands 

thinner than dark. Abundant vertical trabecular rods 

clearly visible near periphery, become shadowy and 

vague toward axis.

Comparison loith related forms. The greatest depth 

(vertical thickness) of the stereozone of Mucophyllum 

mcintyrei is greater than that of M. crateroides 

Etheridge. An undescribed species from the Roberts 

Mountains Formation (Silurian) of Nevada has more 

numerous and more uniformly thin incremental layering of the stereozone and more irregular thickening 

and undulation of the tabulae due to septal intersections.

Occurrence. Unit 1, Gazelle Formation. South side 

of Mallethead Ridge on main fork of Willow Creek, 

China Mountain quadrangle, loc. M87. Study material 

of this new species consists of the single corallum collected at loc. M87 by J. R. Mclntyre, and fragmentary 

material, possibly representing the same form, collected 

at Parker Rock loc. M1030.

Family LYKOPHYLLIDAE Wedekind, 1927

Reference form. Phaulactis cyathopJiylloides Ryder, 

1926. Wenlock, Silurian, Slite Group, Gotland, Sweden.

Solitary rugose corals with multiple columns of small 

to medium dissepiments; tabularium fairly wide, usually not abruptly differentiated at margin from dissepimentarium. Septa thickened and laterally in contact into or beyond neanic growth stage. No well-defined 

f ossula in mature calice.

These profusely dissepimented Rugosa are the earliest 

of this kind in the geologic record. Devonian Halliidae 

and Bethanyphyllidae, though similar, have a mature 

fossula but do not have the persistent septal thickening 

in the neanic stages as do typical lykophyllids.

Genera classified in the Lykophyllidae are: Phaulactis Ryder, 1926, Pycnactis Ryder, 1926, Holophragma 

Lindstrom, 1896, Desmophyllum Wedekind, 1927, Cyathactis Soshkina, 1955, and Ryderophyllum Tcherepnina, 1965. This family is represented in the northeastern 

Klamath Mountains by Cyathactis.

Genus CYATHACTIS Soshkina, 1955

1955. Cyathactis Soshkina, p. 122, pi. 11, figs. 1, 2.

1963. Cyathactis Soshkina. Ivanovsky, p. 75.

1965. Miculal catilla Sutherland, p. 28, pi. 17.

Type species. Cyathactis typus Soshkina, by author 

designation. Silurian; Russia.
34 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

Diagnosis. Small to medium-sized trochoid and ceratoid Lykophyllidae. Septa numerous, long, thin, smooth, 

fairly straight at maturity; a wide dissepimentarium 

of small and medium globose dissepiments. Tabularium 

medium wide with closely spaced, mostly incomplete, 

axially flattened tabulae and marginal tabellae. No 

septal stereozone. Crowded dissepiments with anguloconcentric chevron pattern in transverse section.

Remarks. Corals here assigned to Cyathactis resemble Phaulactis Ryder in advanced growth stages; the 

more significant differences are developmental. In the 

neanic stage, Phaulactis has thickened septa laterally in 

contact, followed by mature septal thinning (Minato, 

1961, p. 46-68). Material showing earliest development 

of Cyathactis is not available, but late neanic transverse 

sections of C. gazellensis, 8 mm in diameter, reveal 

thinned septa. Comparable transverse sections of Phaulactis cyathophylloides show all septa in lateral contact. 

Phaulactis is described as passing through an early 

Pycnactis phase (Ryder, 1926, p. 385-390; pi. IX). By 

definition, Pycnactis retains thickened septa throughout mature growth, whereas Phaulactis commonly loses 

the thickening more or less completely in advanced 

stages. Individuals of Phaulactis may retain some initial dilation in cardinal quadrants well into mature 

growth, as is well illustrated by Minato's researches.

Corals which probably belong either in Cyathactis or 

Phaulactis have previously been assigned to Cyathophyllum, Entelophyllum, and Xylodes. Of these, 

Xylodes Lang and Smith, 1927 is an homonym as well 

as a synonym of Entelophyllum Wedekind. Entelophyllum is usually colonial, having narrower tabulae and 

cylindrical corallites with numerous lateral connecting 

processes. Some species assigned in the past to Entelophyllum have abundant zigzag carinae, not features of 

Cyathactis.

The genus Micula Sytova (1952, p. 133) has thickened 

septa within the dissepimentarium of mature coralla. It 

possesses a wider tabularium than Cyathactis with its 

tabulae less flattened axially and also a narrow septal 

stereozone not present in Cyathactis.

Many described and well-illustrated corals may be 

compared generically in detail with Cyathactis gazellensis n. sp. It is probable that ' ' Micula ? catitta" Sutherland (1965, p. 28, pi. 17, figs. 1-2; pi. 18, fig. 5) is congeneric. CyathophyttumprosperumTS&rrsinde (inPocta, 

1902, p. 105, pi. 103, figs. 6-8; Prantl, 1940, p. 12-21, 

text figs. 1-3, pi. II, figs. 5-7) has similar features in 

longitudinal section. Cyathophyllum pegramense 

(Foerste) is perhaps the closest American form (Amsden, 1949, p. 110, pi. XXXIV, figs. 5-7,11,12), but if it 

has initial septal thickening, it would be classified as 

Phaulactis. Further comparisons are made below under

the description of Cyathactis gazellensis. Ryderophyllum Tcherepnina, 1965 is possibly a synonym of

Cyathactis.

Cyathactis gazellensis, new species 

Plate 6, figures 1-8

Type. Holotype USNM 159448; paratypes USNM 

159451, 159452,

Diagnosis. Cyathactis with numerous uniform, 

smooth, slightly wavy septa which are very thin in the 

tabularium and thin or very slightly thickened in the 

dissepimentarium. Some tabulae nearly complete with 

axial flattening and peripheral sag. Dissepiments in 

multiple columns, external ones flattened-elongate, inclined axially at low angle. Chevron pattern of close-set 

dissepiment traces shown in transverse section.

External features. Small curved-trochoid individuals characteristic, larger ones become ceratoid distally. 

Some individuals with prominent rugae or rejuvenescence flanges.

Mature transverse sections. Major septa about 34, 

some of which reach the axis; minor septa exceed onehalf the length of major septa. Chevron dissepiment 

traces most numerous in middle of dissepimentarium, 

become wider spaced and less regular near wall. Wall 

thin; stereozone absent. Symmetry entirely radial, without trace of f ossula.

Neanic transverse sections. A neanic section 8 mm in 

diameter with uniformly thin septa numbering about 

48, of which the longer major septa approach the axis. 

No stereoplasmic thickenings. No fossula.

Longitudinal sections. Tabularium slightly more 

than one-half corallite diameter and not sharply set off 

from the dissepimentarium. Most tabulae incomplete, 

slightly arched, with axial flatness or slight sag; marginal tabellae border the peripheral sag. Tabulae closely 

spaced. Wide dissepimentarium comprising as many 

as 16 columns on each side. Many peripheral dissepiments fairly large, elongate, or flattened; near the wall 

are inclined axially at a low angle.

Reproductive offsets. No offsets were found in this 

solitary species. An individual of Cyathactis catitta as 

figured by Sutherland (1965, pi. 17, fig. 3b) shows four 

offsets at the calice periphery.

Microstructure Septa reveal no trace of trabecular 

structure.

Comparison with related forms. Cyathactis catilla 

(Sutherland) of the Silurian Henryhouse Limestone 

possesses a similar longitudinal section; in transverse 

section the concentrated chevron pattern of dissepiment 

traces is not developed as in gazellensis. However, catilla appears more closely related morphologically to 

Cyathactis than to Micula or to Phaulactis. Sytova's 

Micula antiqua (Sytova, 1952, p. 134, pi. 1, figs. 1-11)
SYSTEMATIC AND DESCRIPTIVE PALEONTOLOGY 35

has a more nearly cylindrical shape, a wider tabularium, thickened septa, and a thicker wall.

Cyathophyllum pegramense (Foerste) is similar in 

gross characteristics (Amsden, 1949, p. 110, pi. XXXIV, 

figs. 5-7,11,12), but it has a wider tabularium and the 

transverse chevron pattern is less developed. Illustrations of the neanic stage in transverse sections are not 

available, but Amsden's longitudinal section suggests 

that pegramense has thickened septa at this stage and, 

therefore, may belong in Phaulactis.

A lykophyllid species in Silurian coral zone B of the 

Great Basin Hidden Valley Dolomite has a less concentrated chevron pattern than Cyathactis gazellensis 

and a wider tabularium; the neanic development is unknown. This form is provisionally assigned to 

Ryderophyllum.

Among well-illustrated foreign species of true Phaulactis, there are rather close resemblances in mature 

transverse section to P. irregularis (Wedekind) and P. 

cyathophylloides Ryder (Minato, 1961, pi. V, figs. 14- 

15; pi. VII, figs. 10-20; pi. II, fig. 23). However, these 

Gotland species lack the concentrated chevron pattern 

of Cyathactis gazellensis.

Cyathophyllum prosperum Barrande of the Bohemian Late Silurian (Tachlowitz, e2) shows a similar 

tabularium, but many more of the dissepiments are 

nearly horizontal and the corallum is subcylindrical. In 

transverse section the Bohemian species reveals thickened septa and a more complex pattern of dissepiment 

traces (Prantl, 1940, text figs. 6, 7, pi. II, fig. 5). The 

genus name Xylodes, applied to this foreign species, is 

an homonym and also a possible synonym of Entelophyllum Wedekind; the latter term seems inappropriate 

for the Gazelle fossil on morphologic grounds.

Occurrence. Unit 2, Gazelle Formation at Bonnet 

Rock, loc. M191. Parker Rock, loc. M1030. Study material from Bonnet Rock includes 16 coralla.

Family CYSTIPHYLLIDAE Edwards and Haime, 1850

Reference form. Cystiphyllum siluriense Lonsdale,10 1839. Silurian, Wenlock Limestone, Dudley, 

England.

Silurian Cystiphyllum, one of several genera characterized by mature internal structure mainly of cystose 

dissepimental tissue, is distinguished by trabecular septal spines like those of the Tryplasmatidae. Weak 

radiating spiny septal ridges on the calice floor are the 

nearest approach to continuous septa (Edwards and 

Haime, 1850-54, p. 298, pi. 72, fig. la; Pocta, 1902, pis. 

36^iO). There is a considerable difference among 

species in the size and number of septal spines; in fact, 

some of the western Silurian cystiphyllids reveal none

1 Pages 675-699 and 5 plates in Murchison, 1839.

and cannot, therefore, be placed in the genus with complete certainty.

Cystiphylloids of the Devonian include homeomorphic genera not known to be related genetically to Silurian Cystiphyllum. These do not have the trabecular 

septal spines and are classified in other families such as 

Cystiphylloididae and Digonophyllidae; the latter has 

strong septal crests and discrete, but usually discontinuous, septa.

Forms assigned to the family Cystiphyllidae are: 

Cystiphyllum Lonsdale,10 1839. Hedstromophyllum 

Wedekind, 1927, Holmophyllum Wedekind, 1927, and 

possibly Microplasma Dybowski, 1873. The group of 

Cystiphyllum? henryhousense Sutherland (1965), may 

constitute another potential genus or subgenus in this 

largely Silurian family.

Genus CYSTIPHYLLUM Lonsdale, 1839

1839. Cystiphyllum siluriense Lonsdale. In Murchison, 1839,

p. 691, pi. xvi bis, fig. 1 (not fig. 2).

1850-54. Cystiphyllum Lonsdale. Edwards and Haime, p. Ixxii. 

Cystiphyllum siluriense Lonsdale. Edwards and 

Haime, p. 298, pi. LXXII, figs. 1, la. 

1927. ( "i) Cystiphyllum siluriense Lonsdale. Wedekind, p. 65,

pi. 19, figs. 3-5.

1940. Cystiphyllum Lonsdale. Lang, Smith, and Thomas, p. 48. 

1949. (?) Cystiphyllum lineatum! Davis. Amsden, p. 112, pi.

XXIX, figs. 6-11.

1956. (?) Cystiphyllum Lonsdale. Hill, p. F312, fig. 214: la-b. 

1965. Cystiphyllum Lonsdale. Sutherland, p. 23-24.

Type species. Cystiphyllum siluriense Lonsdale, 

1839; by subsequent designation Edwards and Haime 

(1850-54, pi. Ixxii). Edwards and Haime cite Lonsdale 

(in Murchison, 1839, pi. xvi bis, fig. 1); they note that 

only fig. 1 represents the type species; thus they exclude 

fig. 2. Wenlock Silurian; Dudley, Worcestershire, 

England.

Diagnosis. Trochoid, turbinate, and ceratoid rugose 

corals with shallow to moderately deep conical calice. 

Internal tissue predominantly dissepimental; septa, if 

present, represented by radially alined, slender, mostly 

short trabecular spines extending inward and upward 

from convex distal surfaces of dissepiments and tabulae. 

Tabularium commonly not sharply differentiated from 

dissepimentarium; wide near-horizontal tabulae absent 

in mature growth stages.

Remarks. There is clearly much homoeomorphy 

among cystiphylloid corals. The Silurian Cystiphyllumlike corals are numerous and diverse but not sufficiently 

well understood at present to make possible a meaningful classification. Among them are possible new 

generic and subgeneric groupings based on such criteria 

as growth habit, width and discreteness of tabularium 

and size, abundance or absence of the trabecular septal
36 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

spines. In addition to the supposedly slender-spined 

type species siluriense, possibly new and distinct genera 

are embodied in such forms as Cystiphyllum^. henryhousense Sutherland (1965, p. 24, pis. 13-16). Variation studies like that made by Sutherland are needed for 

all other cystiphylloid genera. A wide discrete tabularium and elongate subcylindrical growth habit distinguish the unit of henry housense, which, as noted by 

Sutherland (1965, p. 23), should probably be viewed as 

generically distinct from Cystiphyllum proper.

New cystiphylloid genera with wide discrete tabularia have recently been described from the Siberian 

Platform by Ivanovsky (1963, p. 103-110, pis. XXIXXXXIII). The variation range of these Siberian Rugosa requires elucidation in comparison with henryhousense and other species.

To judge from study of western North American 

Silurian cystiphylloids, trabecular septal spines are the 

exception rather than the rule. Alaskan Silurian forms 

from Kuiu Island reveal no spines; these have a welldifferentiated tabularium and an outermost narrow zone 

of small compact dissepiments. The few specimens of 

cystiphylloids collected from the Gazelle Formation do 

not show trabecular septal spines.

Distinguishing Silurian cystiphylloids from some of 

those of the Devonian is difficult. Devonian species are 

generally considered to lack trabecular spines. Many 

of the larger Devonian forms are homoeomorphic and 

wholly distinct genetically. Some are classified with the 

Digonophyllidae; these have all degrees of septal development, from none whatever to sporadic septal crests to 

radially continuous lamellar septa. Theoretically the 

septal crests of Devonian cystiphylloids are distinguishable from the trabecular septal spines of Silurian true 

Cystiphyllum. Devonian species usually lack wide nearhorizontal tabulae like henry'housense.

Cystiphyllum sp. c 

Plate 1, figures 15,16; plate 3, figures 5, 6

The Gazelle corals classified as Cystiphyllum sp. c 

are medium to large size for this genus, external configuration trochoid to ceratoid. Conical calice deep, 

above a poorly differentiated tabularium; wide dissepimentarium reveals as many as 11 columns of large, 

elongate dissepiments on each side. Nonuniform tabularium formed of one or two large semiglobose axial 

tabellae with flat bases, or less commonly, a single wide 

continuous sagging tabula which terminates like an 

axially inclined dissepiment. No trabecular spines on 

most individuals. In longitudinal thin section most dissepiments have steeply inclined bases. In transverse section the pattern is of fairly uniform large, peripherally 

concave or lonsdaleioid dissepiments with a few scattered smaller ones. Trabecular spines, although uncommon, in the peripheral zone and near the wall of this 

species.

Cystiphyllum sp. c has relatively larger axial tabellae 

than the form figured by Edwards and Haime (1850-54, 

pi. 72, figs. 1, la) as C. siluriense Lonsdale, the type 

species. Wedekind's figures (1927, pi. 19, figs. 3-5) of 

siluriense from Gotland show numerous trabecular 

spines not present in Cystiphylfawi sp. c. Cystiphyllum? henryhousense Sutherland has an elongate subcylindrical growth habit, a well-differentiated and very 

wide tabularium, and scattered trabecular spines internally all features which distinguish it from Cystiphyllum sp. c.

Occurrence. Unit 2, Gazelle Formation, Willow 

Creek area. Chastain Ridge, loc. M1135; Bonnet Rock, 

loc. M191.

Family KYPHOPHYLLIDAE Wedekind, 1927

Named for the Gotland Silurian Kyphophyllum lindstromi Wedekind, this family, as presently interpreted, 

comprises cerioid and fasciculate species with elongate 

subcylindrical corallites having long lamellar septa and 

one to several dissepiment columns of which the outermost in some forms are lonsdaleioid. Tabulae in most 

are rather wide and uparched. An axial structure is 

developed in species of Petrozium.

Genera provisionally included in the Kyphophyllidae 

are: Kyphophyllum Wedekind 1927, Strombodes 

Schweigger, 1819, Petrozium Smith, 1930, Entelophyllum Wedekind, 1927, Entelophylloides Rukhin, 1938, 

Neomphyma Soshkina, 1937, and the new genus Shastaphyllum. Of these Kyphophyllum, Petrozium, and 

Shastaphyllum have been found in the beds of the 

northeastern Klamath subregion that are Silurian to 

possible Early Devonian.

Genus KYPHOPHYLLUM Wedekind, 1927

1927. Kyphophyllum Wedekind, p. 18-22, pi. 2, figs. 7-10; pi.

27, figs. 13-16. 

1937. Kyphophyllum Wedekind, Soshkina, p. 90-91, pi. Ill, figs.

1-5.

1940. Gyphophyllum Lang, Smith, and Thomas, p. 47. 

1952. Kyphophyllum Wedekind; Sytova, p. 144-150, text figs.

2, 15, 16, 17, 18, 19, 20; pi. V, figs. 1-7, pi. VI, figs. 1-6.

Type species. Kyphophyllum lindstromi Wedekind, 

1927 (by original designation). Silurian; Gotland, 

Sweden.

Diagnosis. Solitary and compound phaceloid rugose corals with a narrow to moderately wide septal 

stereozone, a nonunif orm peripheral zone partly of lonsdaleioid dissepiments, long thin septa (some of which 

extend to the axis), and a medium to wide tabularium 

with complete and incomplete tabulae.
SYSTEMATIC AND DESCRIPTIVE PALEONTOLOGY 37

Remarks. Species assigned to this genus also resemble phaceloid Pilophyllum* but differ by having a 

somewhat narrower septal stereozone and a decidely 

narrower tabularium. The tabulae of Pilophyllum are 

very wide, closely spaced, and largely incomplete. Neomphyma Soshkina 19,37 differs from Kyphophyllum by 

having a very narrow tabularium with large and irregular lonsdaleioid dissepiments.

Kyphophyllum greggi, new species 

Plate 8, figures 1-5, 8.

Type. Holotype, USNM 159461; paratypes, USNM 

159462,159463.

Diagnosis. Kyphophyllum with medium septal stereozone, medium-wide to wide, closely spaced, partly 

complete tabulae with axial sag. Peripheral zone with 

septal crests.

External appearance. Bushy heads, medium-sized, 

with small corallites; fairly compact to loose with matrix-filled interstices. No lateral connections observed. 

Longitudinal (septal) grooves well defined.

Transverse sections. Major septa number about 22, 

some extend to the axis; minor septa commonly more 

than one-half the length of major septa. Septa straight 

or slightly wavy; generally thin except for peripheral 

stereozone. Though some slightly thicken at axis, no 

axial structure is formed. Mature stages have groups 

of larger lonsdaleioid dissepiments in localized patches.

Longitudinal sections. Dissepiments in two to four 

columns on each side, mostly elongate; outer as well as 

inner dissepiments commonly inclined steeply. Tabulae 

usually sag rather than uparch as in the type species.

Reproductive offsets. Numerous small interstitial 

corallites represent offsets from mature calice rims.

Fine structure. Septal stereozone with fine lamellar 

structure in stereoplasm, but no distinctive trabecular 

features observed.

Comparison with related forms. Kyphophyllum 

greggi resembles a form in the Ural Mountains assigned 

by Sytova (1952, p. 145) to K. lindstromi Wedekind, a 

Gotland species. The new species, greggi, does not, however, have uparched tabulae, which seem to be a feature 

of the Ural species. Typical lindstromi (Wedekind, 

1927, pi. 2, figs. 7-10) differs by having more widely 

spaced, uparched tabulae, fewer elongate dissepiments, 

and a larger septal count. Closely related forms occur 

in the Late Silurian (coral zone E) of the Toquima 

Range of central Nevada (p. 8, fig. 6).

Occurrence. Coral-rich limestone of Silurian or 

Early Devonian age at Gregg Ranch, loc. Ml 133. Study 

material consists of parts of four large coralla, each 

with numerous corallites (pi. 7, figs. 11-14; pi. 8, fig. 7).

Genus PETROZIUM Smith, 1930

Type species. Petrosium dewari Smith (by original 

designation). Silurian (Valentian); Build was, Shropshire, England.

Diagnosis. Smith's original diagnosis is as follows:

Dendroid rugose corals with long cylindrical corallites, which 

are reproduced non-parricidally by marginal gemmation; thin 

carinate septa of which the major reach or nearly reach the 

axis; small, distally arched tabulae; and small well-developed 

dissepiments.

Remarks. Smith's figures are not sufficiently enlarged to show the details of carinate septa. Of the three 

American species referred to this genus and here discussed, only one has suggestions of zigzag carinae; the 

other two have smooth septa. The axial structure may 

be well developed as a rod reinforced by stereome, as in 

the Alaskan Petrosium from Kuiu Island, or it may be 

incipient or undeveloped as in the other two species and 

in Dewari, the type species. The arching tabulae of the 

tabularium, well illustrated by Smith (1930, pi. xxvi, 

fig. 28), seem to be characteristic of the genus; globose 

or strongly arched axial tabulae (or tabellae) are 

bordered periaxially by smaller tabellae of a depressed 

zone. The axial tabellae may be combined with septal 

ends in an axial structure. The globose dissepiments are 

in two or three columns; the outer column is commonly 

almost horizontal.

The stratigraphic range of Petrosium is unknown, 

but the type species is Valentian or Lower Silurian; the 

Hidden Valley form occurs in Silurian coral zone B of 

the Great Basin, which is probably Wenlockian and 

possibly well down in that stage.

Petrosium differs from Devonian Disphyllum which 

lacks the uparched tabular features of Petrosium and 

does not have an incipient or well-developed axial 

structure.

Petrozium staufferi, new species

Plate 7, figures 1-6

1894. Diphyphyllum fasciculum Meek. Schuchert, p. 422 (in

Diller and Schuchert). 

1930. Diphyphyllum fasciculum Meek. Stauffer, p. 98.

Type. Holotype, USNM 159458.

Diagnosis. Petrosium with fairly compact phaceloid growth habit, forms heads more than one foot in 

diameter. Corallites slender. Septa non-carinate; longer 

septa extend to axis where some join but do not form a 

discrete axial structure. Wall thin, without continuous 

stereozone. Dissepimentarium narrow, commonly in two 

columns; peripheral dissepiments nearly horizontal. 

Some of the wide strongly uparched tabulae nearly 

complete.

External features. Large colonies of this species 

fairly compact to more open phaceloid; always with
38 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

considerable amounts of argillaceous matrix between 

the roughly parallel cylindrical corallites. Outer surfaces of corallities with epitheca which is covered by 

fine incremental transverse raised rings, but otherwise 

devoid of prominent rugae. No transverse connections 

observed between corallites.

Transverse sections rSlender corallites with about 18 

major septa. Major septa tend to become more irregular 

toward the axis; some merge laterally; others radially. 

Minor septa usually more than half the length of major 

septa. Septa smooth, slightly thickened. No uniform 

septal stereozone. Irregular patches of stereoplasmic infilling. In corallites where most major septa meet 

axially, no discrete rod or axial structure. Axial union 

of a pair of major septa in some corallites suggests a 

cardinal fossula.

Longitudinal sections. Width of tabularium exceeds half the corallite diameter. Tabulae strongly uparched, with periaxial depression; some tabulae nearly 

complete. Dissepiments usually in two columns, less 

commonly three or even four; outer dissepiments nearly 

horizontal, inner dissepiments more nearly vertical.

Reproductive offsets. None observed. Probably develop as several offsets from outer edge of calice.

Comparison with related forms. Petrozium staufferi 

differs from the type species P. dewari Smith by lacking carinae, but it is otherwise quite similar. An undescribed species from the Silurian and Early Devonian 

Hidden Valley Dolomite of the Panamint Mountains, 

Calif., has thicker septa peripherally, with a few zigzag 

carinae; its dissepiments are relatively smaller and 

form more numerous vertical columns. The Alaskan 

Petrozium from the Silurian of Kuiu Island has an 

even wider dissepimentarium and an axial column 

reenforced by stereoplasm to form a discrete rod (pi. 7, 

figs. 7,8).

Occurrence. Unit 2, Gazelle Formation; Bonnet 

Rock, loc. M191. This species seems to be the more 

abundant colonial rugose coral in unit 2, where it is 

associated with Cyathactis gasellensis. Study material 

of this form consists of parts of at least four large 

coralla comprising several hundreds of corallites.

Genus SHASTAPHYLLTTM, new genus

Type species. Shastaphyllum sch-ucherti n. sp., here 

designated. Silurian, Gazelle Formation; northeastern 

Klamath Mountains, Calif.

Diagnosis. Cerioid rugose corals with elongate, slender, thin-walled corallites. Septa numerous, thin and 

noncarinate; some major septa extend to axis. Tabularium narrow; tabulae straight, complete, and closely 

spaced. Dissepiments relatively large, steeply inclined, 

some elongate or lonsdaleioid peripherally, and 

arranged in three or four columns.

Remarks. Some corallites may lack lonsdaleioid 

features. Shastaphyllum differs from Spongophyllum, 

as represented by its type species, S. sedgwicki Edwards 

and Haime, by having a much thinner wall, more numerous septa, more dissepiment columns, and a 

narrower tabularium.

Unrelated cerioid and phaceloid Eugosa with nonuniform scattered lonsdaleioid dissepiments like /Shastaphyllum have, from time to time, been placed by authors 

in Spongophyllum. (See Birenheide, 1962.) It is proposed that only those resembling sedgwicki (with thickwalled slender corallites, few dissepiment columns and 

sporadic lonsdaleioid features) be included. Those having a more uniform, wide and continuous lonsdaleioid 

band and lacking an axial structure are here classified 

as Endophyllidae including Klamathastraea n. gen. and 

Australophyllum. Australophyllu/m, as here employed, 

includes species previously assigned by authors to 

Spongophyllum.

ShastaphyUum differs from Evenkiella Soshkina, 

1955, as represented by E. helenae Soshkina (Ivanovsky, 

1963, p. 88; pi. XXIV, figs. 2a-b), by having a much 

wider tabularium. Tenuiphyllum Soshkina, 1937 differs 

by having wider uparched tabulae and a suggestion of 

an inner wall in some mature corrallites.

Shastaphyllum schucherti, new genus, new species 

Plate 2, figures 1-6 ; plate 3, figure 4; plate 4, figure 8

1894. Acervularia sp. undet. Schuchert, p. 422 (in Diller and

Schuchert). 

1930. Acervularia, sp. Stauffer, p. 98.

Type. Holotype, USNM 159457 loc. M1132; paratype, USMN 159465, Loc. M1135; Chastain Ridge, Willow Creek area, northeastern Klamath Mountains, Calif. 

Ludlovian, Late Silurian.

Diagnosis. Shastaphyllum with about 60 uniformly 

thin septa, slender corallites and delicate internal structure. Scattered irregular lonsdaleioid dissepiments in 

peripheral zone; very narrow tabularium in some 

corallites.

Transverse sections. Major septa average about 29, 

thin, noncarinate, fairly straight, even, or minutely 

wavy; many septa reach the axis where the tips may 

be dilated. No continuous stereozone, but thin septa 

wedge out abruptly toward wall. Minor septa range 

from very short peripheral wedges to those more than 

one-third the length of major septa. Septa discontinuous 

peripherally in patches of lonsdaleioid dissepiments

Longitudinal sections. Tabularium narrow, usually 

less than one-fourth the width of corallite, less commonly widening to one-third the width. Tabulae very 

thin, straight, unarched, complete, and closely spaced. 

Dissepiments retatively large, partly elongate, and
SYSTEMATIC AND DESCRIPTIVE PALEONTOLOGY 39

steeply inclined, in three or four columns on each side. 

Tabulae vague or unrecognizable in some corallites.

Reproductive offsets. Transverse sections show offsets from calice rim and probably also within calice. 

Some immature corallites with slight septal thickening 

toward axis; septal thickening produces an incipient 

aulos.

Comparison ^uith other forms. This coral differs 

greatly from Spongophyllum sedgwicki, the type species of Spongophyllum, which has a thick wall, fewer 

septa, and fewer dissepiment columns. Spongophyllum 

inficetum Pocta (1902, pi. 102, fig. 1; Prantl, 1952, p. 

13, pi. 1, fig. 2) of the Bohemian Late Silurian possesses 

more numerous and regular lonsdaleioid dissepiments. 

Spongophyllum shearsbyi Chapman of the Yass, Australia, Silurian (Hill, 1940, p. 408, pi. XII, figs. 1, 2) 

has a thicker wall, more fully developed lonsdaleioid 

dissepiments, and a wider tabularium.

Spongophyllum saumaensis Shurygina (1968, p. 134, 

pi. 59, figs. 4a-b) which is from the eastern slope of the 

Ural Mountains, appears to be congeneric with the Gazelle form, but it differs specifically by having a thicker 

wall, fewer septa, and more numerous lonsdaleioid dissepiments. Both species have the narrow tabularium of 

Shastaphyllum and are quite similar in longitudinal 

section. Although regarded by Shurygina (1968, p. 123) 

as Early Devonian, the associated rugose coral assemblage is quite suggestive of faunas from the Cordilleran 

belt of North America, here interpreted as Late Silurian (Ludlovian).

In transverse section Shastaphyllum schucherti resembles Tenuiphyllum ornatum Soshkina (1937) of the 

Ural Mountains Silurian; this Eussian form differs in 

its wider arched tabulae and greater number of dissepiment columns. Tenuiphyllum ornatum has a suggestion 

of an inner wall in some mature corallites, a feature observed only in immature corallites of Shastaphyllum.

Occurrence. Gazelle Formation, Willow Creek area; 

Chastain Eidge; at fault contact of unit 1 and unit 3, 

loc. M1135. Holotype from Diller collection, loc. M1132.

Similar corals occur in the upper middle part of the 

Silurian and Devonian(?) Vaughn Gulch Limestone 

of Owens Valley, Inyo County, Calif.

Stu,dy material of Shastaphyllum schucherti consists 

of five coralla and fragments of other coralla.

Shastaphyllum? sp. c 

Plate 4, figures 6, 7

An unusually well preserved partial corallum from 

the Hayfork vicinity, Trinity County, Calif., is provisionally assigned to the new cerioid genus 

Shastaphyllum.

Shastaphyllum^ sp. c has about 40 thin, fairly 

straight, noncarinate septa; some of the major septa

reach the axis. Minor septa may exceed half the length 

of major septa. No stereozone; the fairly even septa do 

not wedge out approaching the thin wall. Lonsdaleioid 

dissepiments, if present, inconspicuous. Tabularium onefourth to one-third the corallite width; some tabulae 

complete, fairly straight. Dissepiments, three or four 

columns, medium to large, axially inclined at low angles 

for this genus.

Shastaphyllum 9. sp. c differs from S. schucherti n. 

gen., n. sp., of the Silurian Gazelle by having larger 

corallites and a much lower septal count, by lacking 

well-defined lonsdaleioid features, and by the flatness 

of its dissepiments. Shastaphyllum^ sp. c bears some 

resemblance to an undescribed Entelophylloides in the 

Silurian Eoberts Mountains Formation (Great Basin 

Silurian coral zone C) of central Nevada. The Nevada 

coral has more numerous columns of small dissepiments, 

a higher septal count, and somewhat arched tabulae.

Occurrence. Hayfork area, southern part of the 

Hayfork quadrangle, Trinity County, Calif., loc. M1281. 

Collected by W. P. Irwin of the U.S. Geological Survey, 1968. This coral was not found in place, and the 

strata from which it oame are unknown. Other identified 

Paleozoic fossils from this general vicinity are of late 

Paleozoic age.

Family ENDOPHYLLIDAE Torley, 1933

Reference forms. Endophyllum bowerbanki Edwards and Haime, and E. abditum Edwards and Haime, 

1851. Devonian, Torquay, England.

Cerioid and aphroid rugose corals with wide to very 

wide corallites. A broad marginarium with some large 

lonsdaleioid dissepiments. Tabularium, narrow to very 

wide, with closely spaced tabulae. No axial structure.

Genera provisionally assigned to the Endophyllidae 

are as follows:

Endophyllum Edwards and Haime, 1851 

Yassia Jones 1930 

Australophyllum Stumm, 1949

An undescribed Great Basin Silurian subgenus of Australophyllum 

Klamathastraea n. gen.

Pilophyllum Wedekind of the Gotland Silurian, a solitary or phaceloid genus, may likewise belong in this 

family, but it differs from the others by 'having a wider 

septal stereozone and a noncompact subcylindrical 

growth habit.

Some corals here assigned to the Endophyllidae have 

previously been placed by authors in Spongophyllum. 

True Spongophyllum, as typified by S. sedgwicki Edwards and Haime, is excluded from the Endophyllidae, 

as here redefined, by reason of its slender corallites, 

rather narrow tabularium, and narrower, simpler, and 

possibly only sparingly lonsdaleioid dissepimentarium.
40 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

It is proposed that the generic name Spongophyllum 

be reserved for species agreeing in general structure and 

proportions witlh the Devonian S. sedgwicki, as originally illustrated by Edwards and Haime (1853, pi. 56, 

figs. 2, 2a-c, and 2e). These figures reveal a thickened 

wall and little suggestion of lonsdaleioid features in four 

of the five transverse views; only figure 2d of Edwards 

and Haime's plate 56 shows a lonsdaleioid pattern. 

There is no assurance that the form so illustrated (fig. 

2d) is conspecific. (See also Stumm, 1949, p. 31, pi. 14, 

figs. 10, 11; Birenheide, 1962, p. 68-74, pi. 9, fig. 8, pi. 

10, fig. 10.)

Lonsdaleioid dissepiments recur in several rugose 

coral families and by themselves are not regarded as indicative of direct genetic relationship. Among the Silurian Rugosa, dissepiment patterns of this kind characterize the Endophyllidae as well as other families to 

which belong the following genera: Ketophyllum, 

Spongophylloides, Strombodes, Kyphophyllum, and 

Pilophyllum. Of the various Devonian rugose coral 

groups with lonsdaleioid features, several of cerioid 

habit have, from time to time, rather indiscriminately 

been classified as Spongophyllum. Some of these may 

more appropriately be assigned to Australophyllum; 

others are perhaps allied to Hexagonaria. Late Paleozoic columellate corals like Lonsdaleia, which has a marginarium of this pattern, are well known.

Abbreviation or loss of mature septa is a tendency 

manifested by the later Silurian Endophyllidae. Among 

these are Yassia, without mature septa; a subgenus of 

Australophyllum (see Australophyllum sp. E, pi. 4, 

figs. 1-3), with septa reduced or lost in some corallites; 

and the new genus Klamathastraea, with similarly 

reduced or obsolete septa.

Genus KLAMATHASTRAEA, mew genus

Type species. Klamathastraea dilleri n. sp.; here 

designated. Silurian Gazelle Formation, Siskiyou 

County, Calif.

Diagnosis. Cerioid endophyllid corals with wide, 

straight, flat and mostly complete tabulae. Septa usually 

short, confined to outer part of tabularium. Lonsdaleioid dissepimentarium wide, outer dissepiments flat. 

Septal crests absent. Wall thin.

Remarks. Tabulae commonly have a well-defined 

peripheral depression. Endophyllum is distinguished by 

its wider tabulae, more persistent peripheral depression 

and much longer septa which may reach the axis and 

extend laterally to break up as septal crests. Moreover 

the British Devonian Endophyllum includes aphroid 

forms lacking an outer wall as well as cerioid forms with 

a much thicker wall than Klamathastraea. (See Jones 

1929, p. 84-87, pi. X, figs. 1-4.)

Australophyllum differs from Klamathastraea by 

laving a narrower tabularium with overall proximal 

sag and lacking a peripheral depression. Also its long 

septa may reach the axis and extend laterally as septal 

rests. Yassia Jones of the Australian Silurian has narrower tabulae and is without septa, but it otherwise resembles Klamathastraea.

Klamathastraea dilleri, new genus, new species 

Plate 5, figures 1-5

1894. Endophyllum n. sp. Schuchert (in Diller and Schuchert),

p. 420-422. 

1930. Endophyllum sp. Stauffer, p. 98.

Type. USNM 159456; Silurian; Gazelle formation, 

Siskiyou County, Calif. Loc. M1132.

Diagnosis. Klamathastraea with short septa distinguishable as major and minor; no conspicuous overall 

tapering or waviness. Peripheral depression of tabulae 

well developed to absent in some corallites.

External features. Holotype a large flattened lenticular head about 10 inches in greatest diameter. Weathered upper surface resembles that of Lonsdaleia or 

LitJiostrotionella without axial structures. Corallites 

mostly large; small interstitial corallites and calice offsets unknown.

Transverse sections. Septa about 38, short, simple, 

unthickened, without overall axial taper, commonly alternate short and very short. Dissepimentarium without 

septal crests; thin wall lacks wall crests. Some larger 

dissepiments unevenly concave outward.

Longitudinal sections. Dissepimentarium sharply 

set off from tabularium. Lonsdaleioid dissepiments 

mostly large and elongate, in three to six columns in 

mature stages; flattened and horizontal near periphery, 

axially becoming near vertical. Wide tabulae closely 

spaced, with peripheral sag lacking1 in parts of some 

corallites.

Fine structure. Eecrystallization has destroyed trabecular structure in the very narrow stereozone. A 

median dark threadlike wall band paralleled by narrow, discontinuous hyaline strands on one or both sides. 

Reproductive offsets. Unknown. 

Comparison with other forms. Klamathastraea dilleri n. sp. resembles undescribed Silurian species of Australophyllum, especially a subgenus occurring in the 

higher Silurian limestone (Great Basin Silurian coral 

zone E) of the central Great Basin (pi. 4, figs. 1-3); 

however, these species lack the peripheral depression of 

the tabulae, which are narrower, and they normally 

have long septa with septal crests. Australophyllum 

fritschi (Novak) from beds of possible Late Silurian 

age in Czechoslovakia (p. 5, figs. 6-8) has a thicker wall 

with wall crests, less even tabulae with no peripheral
SYSTEMATIC AND DESCRIPTIVE PALEONTOLOGY 41

sag, and corallites with long septa; other sporadic 

corallites have reduced septa like K. dilleri.

Remarks. The holotype of Klamathastraea dilleri, 

here described, is believed to be the specimen referred to 

in Diller's field notes of October 20,1884, as having come 

from the limestone at Bonnet Rock. Mistakenly identified as "Lithostrotion" (Walcott, 1886), this coral was 

probably the basis for an initial Carboniferous age assignment of the Gazelle Formation.

Occurrence. Unit 2, Gazelle Formation, west side 

of Bonnet Rock, Willow Creek area. Greenish-gray 

shale attached to the base of this coral agrees lithologically with the argillaceous matrix of the rubbly 

conglomeratic limestone from which most of the 

well-preserved Gazelle fossils in that area have come.

LOCALITY REGISTER

(See figs. 1, 2, and 84) 

Northeastern Klamath subregion

Willow Creek area

Locality M191. Yreka quadrangle, Calif. (1954) ; Bonnet 

Rock, southwest side, SE% sec. 6, T. 42 N., R. 6 W., altitude 

4,000 feet. Nodular argillaceous limestone of unit 2, Gazelle 

Formation.

Locality M1132. Yreka quadrangle, Calif. (1954) ; Bonnet 

Rock, west side, sec. 6, T. 42 N, R. 6 W. Old USGS number 

586. Heads of rugose corals from this locality are labeled 

as collected by "Storrs," Nov. 1, 1893. However, Diller's field 

notes of 1884 refer to similar corals collected at that time, 

probably from unit 2 of the Gazelle Formation.

Locality M18. Yreka quadrangle, Calif. (1954) ; Chastain 

Ridge, south end, NW% sec. 7, T. 42 N., R. 6 W., about onethird of a mile northnortheast of old Chastain Ranch house 

(now Pay ton Ranch). Collections made at east edge of massive limestone outcrop and 700 feet east of a limestone 

quarry. Loose fossils weather from shale near a fault, probably having come from unexposed unit 2 or topmost beds of 

unit 1 in the Gazelle Formation. Original collections of 1933 

made by R. A. Bramkamp, F. E. Turner, and C. W. Merriam.

Locality M190 Yreka quadrangle, Calif. (1954) ; Chastain 

Ridge, south end, NW% sec. 7, T. 42 N., R. 6 W., 1,800 feet 

north of Lime Gulch road, on east side of ridge, altitude 

3,600 feet. Lower part of thick-bedded limestone of unit 3, 

Gazelle Formation.

Locality M81. China Mountain quadrangle, Calif. (1955) ; 

south side of Mallethead Ridge on main fork of Willow 

Creek, NW% sec. 19, T. 42 N., R. 6 W.; 1,000 feet north of 

creek, 500 feet east of section line; altitude 3,500 feet. Limestone lenses with rugose corals.

Locality M230. Yreka quadrangle, Calif. (1954) ; Chastain 

Ridge, south end. Field loc. S26, Aug. 31, 1951; same general 

locality as M78.

Locality M1135. Yreka quadrangle, Calif. (1954) ; Chastain 

Ridge, south end, east side, SW% sec. 6, T. 42 N., R. 6 W., 

500 feet north of section line, altitude 3,600 feet. Near contact of unit 3 massive limestone and unit 1, Gazelle 

Formation.

Locality M1280. Yreka quadrangle, Calif. (1954) 4 ; upper part 

of Lime Gulch, 1 mile east of Payton Ranch house, 

NE^NW^SW^ see. 12, T. 42 N., R. 7 W. Gazelle Formation; Monoffraptus locality of Michael Churkin, Jr. (1965).

Parker Rock (Lovers Leap) area

Locality M81. Etna quadrangle, Calif. (1934) ; at Rail 

Creek-Kangaroo Creek divide on Rail Creek side, SE1^ sec. 

29, T. 41 N., R. 7 W. Small limestone outcrop.

Locality M83. Etna quadrangle, Calif. (1934) ; northwest 

side of Parker Rock, altitude 4,700 feet; SW% sec. 29, T. 41 

N., R. 7 W. Limestone cobbles with silicified fossils in 

conglomerate associated with Halysites-bearing limestone.

Locality M84. Etna quadrangle, Calif. (1934) ; northwest 

side of Parker Rock, altitude 4,700 feet; SW1^ see. 29, T. 41 

N., R. 7 W. Other fossil-rich cobbles from same conglomerate 

as M83 but containing a different fauna.

Locality M85. Etna quadrangle, Calif. (1934) ; southeast side 

of Parker Rock, altitude 4,600 feet; NW% sec. 32, T. 41 N., 

R. 7 W. Fossiliferous limestone cobbles in brecciaconglomerate.

Locality M86. Etna quadrangle, Calif. (1934) ; south side of 

Lovers Leap at west end Parker Rock, altitude 4,800 feet; 

NE^ sec. 31, T. 41 N., R. 7 W. Thinly bedded gray limestone 

beneath massive limestone caprock of Parker Rock.

Locality M90. Etna quadrangle, Calif. (1934) ; on top of ridge 

at Parker Rock; SW% sec. 29, T. 41 N., R. 7 W., altitude 

5,000 feet. Massive Haly sites-bearing limestone on ridge line 

near boundary between sections 29 and 32.

Locality M10Z8. China Mountain quadrangle, Calif. (1955>; 

east side of Parker Rock near top; SE% see. 29, T. 41 N., 

R. 7 W., altitude 5,000 feet. Fossil-bearing conglomeratic 

limestone below massive limestone caprock of Parker Rock, 

1 mile south of Gregg Ranch house.

Locality M1029. China Mountain quadrangle, Calif. (1955) ; 

south side of Parker Rock; NE% sec. 32, T. 41 N., R. 7 W., 

altitude 4,800 feet. Rubbly conglomeratic limestone beneath 

massive gray limestone eaprock of Parker Rock.

Locality M1030. China Mountain quadrangle, Calif. (1955) ; 

southeast side of Parker Rock, NE1^ sec. 32, T. 41 N., R. 7 W., 

altitude 4,700 feet near boundary of sections 32 and 33. Near 

base of massive limestone caprock of Parker Rock.

Gregg Ranch area

Locality M80. China Mountain quadrangle, Calif. (1955) ; 

southwest of Gregg Ranch house on east fork Scott River 

("Plowmans Valley"), south of Callahan road; SE%NEi4 

see. 20, T. 41 N., R. 7 W. Fossiliferous limestone cobbles 

from conglomerate.

Locality M82. China Mountain quadrangle, Calif. (1955) ; 

east fork of Scott River three-fourths of a mile northeast 

of Gregg Ranch house; SE% sec. 16, T. 41 N., R. 7 W., 

altitude 4,150 feet. Small limestone outcrop with corals on 

south side of stream.

Locality M89 Etna quadrangle, Calif. (1934) ; three-fourths 

of a mile southeast of Gregg Ranch house; middle of line 

separating NE*4 from SW}4 see. 21, T. 41 N., R. 7 W. Silicified fossils in limestone lenses.

Locality MUSS. China Mountain quadrangle, Calif. (1955) ; 

seven-tenths of a mile southeast of Gregg Ranch house, 

altitude 4,200 feet; SE1^ sec. 21, T. 41 N., R. 7 W.; coralbearing limestone.
42 SILURIAN RUGOSE CORALS OF THE KLAMATH MOUNTAINS REGION, CALIFORNIA

Grouse Creek area

Locality M1134. China Mountain quadrangle, Calif. (1955) ; 

south fork of Grouse Creek on "Red Tag trail", altitude 

4,600 feet; SE1^ sec. 21, T. 40 N, R. 7 W. Dark-gray silty 

limestone with well-preserved fossils.

Horseshoe Gulch area

Locality M1130. FAna quadrangle, Calif. (1955) ; Horseshoe

Gulch, an east branch of McConnahue or "McConaughy"

Gulch; in sec. 3 or sec. 4, T. 41 N., R. 8 W. Float limestone

cobbles with corals. 

Locality M1131. Etna quadrange, Calif. (1955) ; Horseshoe

Gulch; near line between sees. 3 and 4, T. 41 N., R. 8 W.

Limestone with silicifled fossils near small earth dam, on

north side of gulch.

Central ~belt of metamorpJiic rocks

Weaverville area

Locality Ml318. Weaverville quadrangle, Calif. (1950) ; 

northwest of Douglas City on Trinity River, near middle of 

sec. 2, T. 32 N., R. 10 W. Limestone cobbles from conglomerate. Rhizophyllum.

Western belt of Paleozoic and Triassic rocks

Hayfork area

Locality M1281. Hayfork quadrangle, Calif. (1951) ; 4 miles 

southeast of Hayfork, 1,000 feet south of the Mueller mine, 

altitude 3,650 feet, middle branch of Kingsbury Gulch. 

Float coral material.

REFERENCES CITED

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INDEX

[Italic page numbers indicate both major references and descriptions]

Page 

abditum, Endophyllum........................ 39

(Acanthalomina) minuta, Leonaspis........... 14

Acervularia pentagona.... _ _____ __ __. _ "23

sp........................................ 38

Acervulariidae _ __--- ____ _. _

Acknowledgments. -.------.--.-..............

aequabtte, Try plasma..........................

Age, Atrypella-Conchidium beds__........

Atrypella-Conchidium beds, Heceta-Tuxekan section.......................

AtrypeUa fauna of Parker Rock...........

Duzel Formation.........................

Gazelle Formation..--.--. . ..........

unit 1................................

unit 2................................

Gregg Ranch fauna.................... 18,

Grouse Creek fauna......................

Heceta-Tuxekan Island sequence.........

Horseshoe Gulch area....................

Horseshoe Gulch limestones.__..._.....--

Long Island limestone beds... ... 

Louisville Limestone_...__.__ _ _._

Montgomery Limestone..................

Mont Wissick Formation.................

northeastern Klamath subregion..--....-.

rugose corals_...........................

Yass-Bowning coral beds.-.--.........-..

Alaska, Silurian faunas.__--____......_._.....

alaskense, Conchidium...................... 18,

Alaskospira. _........................... 15,18,

dunbari. ......_____ ___ _ _ .._

Alexander Archipelago.......................

Algae, faciesindicators..-..----..-...........

Gazelle Formation.......................

units...._.........................

Alleynia......................................

Alveolites multilamella.........................

27

4

31

23

18

23

16

23

20,23

20,21

19,24

24 

18 

16 

23

19,20 

21 

17 

21 

4,6 

13 

22 

3

19,23 

22,23 

14,15 

2,18 

16,24 

20 

14 

27 

23 

23 

Ambocoelia sp__............................. 16

Amphineuran plates_....................... 15

Amphipora................................... 19

Amplexocarinia--.-........................... 27

Anderson, F. M., cited._-.___.-..-.......-. 3

antigua, Micula............................... 34

Arachnophyllidae............................ 27

Arachnophyttum.............................. 20

astreiformis, Stauria...,....................... 28

Atrypa.................................... 14,15,18

reticularis orbicularis...................... 14

Atrypella...................... 14,15,18,19,20,22,23

fauna............................... 13,14,15,23

Willow Creek area.................... 14

scheii..................................... 14

tennis..................................... 14,23

zone......................_.......__.. 17

Atrypella-Conchidium beds, Heceta-Tuxekan

Island area..--------............. 18

zone............................. 17,18,19,23,31

Aulocystis.................................... 19

Australia.__._..............__...... 17,19,**

Australophyllum. _._._._................ 20,38,39,40

fritschi ............................ 22,40, pi. 5

rectiseptatum...........................__. 21

spongophylloides __.--..................... 22

sp. E._.__......--.. . ---.. -....- 40, pi. 4

sp.

Page 

Barrandella................................... 14

sp -- - 23

Balaklala Rhyolite.__........................ 17

Barrande ophyllum............................ 27

basalticus, Favosites........................... 23

beaumonti, Encrinurus (Cromus).............. 14

Bellerophon septentrionalis.................... 23

Bellerophontid............................... 15,23

Beraunia..................................... 15

bifrons.................................... 15

Berdaii, J. M., quoted...-.----.......-....--. 16

Bertie Limestone.-........................... 19

Bethanyphyllidae..----_---._--_-_._- 33

bicincta, Lophospira...------------------------ 15

bifrons, Beraunia............................. 15

Bighornia..................................... 28

bilex, Cydonema.............................. 16

bilineata, Murchisonia......................... 16

biloculare, Conchidium........................ 15,23

bisinuata, Schizophoria..................... 16,21,24

Black River Group..__......--..--.-....--- 29

bohemica, Hercynella....................... 15,19,24

Bonnet Rock........ 3,6,10,11,13,14,30,32,35,36,38

structure..--.--....--.-----..----.----.-- 10

borealis, Vermiporella......................... 14,16

Boucot, A. J., cited__...................... 16,31

bowerbanki, Endophyllum..................... 39

(Brachyprion) seretensis, Stropheodonta....... 16

Bragdoii Formation...............__....... 17

Briantia...................................... 32

Brooksina..................................... 18

Brownsport Formation.----..---------------- 21

Buildwas, Shropshire, England_........... 37

Bumastus..................................... 14

Calymene..................................... 15

Camarotoechia reesidei......................... 15,23

sp.--.--..-.-.----.-_--.-.-.--..--.-__.--- 16

carinatum, Cydonema......................... 16

Cascade belt_.......------.---...-.---..--- 1

Catenipora................................. 16,20,23

sp...--...---.--.----..-..-... -...--- 16 

(Catenipora), Halysites........................ 15

sp, Halysites.............................. 16,17

catilla, Cyathactis............................. 34

Micula................................. 21,33,34

Chaetetes..................................... 4

Chanchelulla Peak. ______________.._.._-_- 4

Chastain Ranch area----.-.------------------ 3

Chastain Ridge.....3,12,13,14, 28, 29,30,32,36,38,39

Cheirurid pygidia......._---------------_ 15

Cheirurus insignia............................ 14

Chonophyllidae. -. 27

Chonophyllum................................ 32

Churkin, Jr., Michael, cited....--------.-.--- 3,14

Circophyllum................................. 29

Cladopora.................................... 15

labiosa.................................... 23

sp.............. ... 15,23

Clamydophyllum.............................. 32

Clastic rocks, northeastern Klamath subregion.--------------------------- 6

southeastern Alaska...----------.---.---- 18

Clavidictyon................................... 19

Page

Coal Canyon_____ . . 32 

Coeymans Formation.--------------- -... 21,24

CoZwrnnorJo....------------------------------- 29

Conchidium................----.- 14,15,18,20,22,23

alaskense............................... 18,19,23

bttoculare................................. 15,23

knighti.................................... 18,23

sp...... - -- 15,23

Conocardium..............-..-.---.........

sp.

 15

___ 16

Cooper, G. A., cited..--. --- ------ 3,22

Copley Greenstone--.--.-.. - - 17 

Cordilleran Belt ........... 19,26,29,39

Cordilleran geosyncline, Silurian marine

rocks.__-.. ---.. -------- 24

corniculum, Streptelasma...................- 28

Cranaena sp_ ._------- 23

Cranbourne Limestone..-..- 21

crateroides, Mucophyllum................... 22,32,33

Craterophyllum............................... 32

Crinoids._....... _ - - 23

(Cromus) beaumonti, Encrinurus...........--. 14

Cyathactis--...--------.--------------- 21,23,27,33

catilla................ ..---. ------------- 34

gazellensis.... 4, 14, 15, 21, 22, 23, 27, 34,38, pi.6

typus.----.------.----...----------------- 33

Cyathactis-Ryderophyllum group............... 20

Cyathaxonia dalmani-.------------------------ 28

stturiensis. .. ---------------------------- 27

Cyathopaedium ------------------------------- 30

Cyathophylloides.----------------------------- 29

Phaulactis........ .........------- 33,34,35

Cyathophyllum ........-.-... ------------- 34

pegramense........ . -21,34,35

prosperum... ----------------------- 22,34,35

bilex.------------------------------------- 16

carinatum... ......-.--------- ---------- 16

cycloptera, HowellelU........----------------- 24

Cymbidium.. --------------------------------- 14,18

Cyphophyllum.. ------------------------------ 36

Cyrtina. -------------------------------- 24

sp - - -- - - I6

Cyrtospira sp.. ------------------------------- 15

Cystiphyllidae----------------------- 20,27,35

Cystiphylloididae- ------------------------- 35

Cystiphyllum. 18,19,27,35

henryhousense....- -------------------- 35,36

lineatum...- -- -------------------- 35

siluriense ......------------------------- 35,36

sp.c .. - 14, 27,36, p^. 1,3

Czechoslovakia, coral faunas __ ------- 22

related corals---------- ---------------- 3,40

D

dalmani, Cyathaxonia -------------------------

Dalmanophyllum .... ........ -..-.-----.---

Dalmanophyllum... ... ------ .-.. ----- 16,20,21

dalmani------ ----- ----------------------

-Palaeocyclus beds. ---------------

. fyj ao sp. h-----. ------------------ 27>^

Dasyporella norvegica .. 

decipiens, Dicranopeltis . 

delphicola, Loxonema ...

28

21,23 

27, 28 

21,23

17 

pi. 1

17 

14,16

14

23

47
48 INDEX

Page 

Dendrostella..... .-......................... 29

DesmophyUum-............................... 33

dewari, Petrozium.................. .. _ 19,22,37,38

Dicaelosia..................................... 17

DicranopeUis decipiens........................ 14

Digonophyllidae_ _.. 35,36

Diller, J. S., cited............................. 2

dilleri, Klamathastraea.... .___.._....__ 14,

20,21, 22,23,27, 40, 41, pl.5 

Diphyphyttumfasciculum..................... 23,37

Disphyllum.-. ................................ 37

Dolomite, diagenetic....._._.._....._.....-.. 24,25

Douglas City area.---...._--..-_-.---.....-._ 4

fauna__:............................... 17

Dudley, Worcestershire, England._........ 35

dunbari,Alaskospira-......................... 14,15

Duzel Formation.._.-._._._.__..--.-----_.- 6,13,16

phyllites- - 13

19,22 

SO

18

19

2

14,22

14

E 

Eastern Europe........................... 17,

Eastern North America----._.-._._-.-__.___.

Eberlein, G. D., cited........................

Eddastraea....................................

Edson's Ranch._-_-.._._..._..........._..._.

EncrinuTUs.-----------.......................

(Cromus) beaumonti ......................

Endophyllidae...................... 20,21,27,

Endophyllum.................................2,2, 39

abditum................................... 39

bowerbanki................................ 39

sp._..................................... 23,40

England....---.--.-.......................... 17,27

enormis, Yassia............................... 22

Entelophylloides............................... 36,39

Entelophyllum.................... 18,19,20,34,35,36

Eunema ..................................... 15

strigillatum............................... 15

Eureka mining district, Nev...__-_.-__..____- 22

Europe.. _. ___________________________________ HI

Evenkiella.................................... 38

helenae................................... 38

F

fasciculum, Diphyphyllum..................... 23,37

Fauna, Gazelle Formation_................ 23

Gazelle Formation, Atrypella zone........ 14

Great Basin, coral zone A...------------- 20

Gregg Ranch area.---.--..--............. 75,24

Grouse Creek area_.........._..._. 15,16,24

Heceta-Tuxekan Island area....---....-.. 18

Horseshoe Gulch area---....-.......-.-_. 16,20

Kuiu Limestone.----.._._._.__....-....-. 19

Long Island, Kasaan Bay....---_........ 19

Montgomery Limestone---.....--...--... 17

northeastern Klamath subregion.......... 1

Parker Rock a,re&......................... 15,23

Weaverville area.._---_......._...-....... 3

Willow Creekarea_-_-_-.-_..-_._-_--___._ 14 

Faunal areas, northeastern Klamath subregion --.--....-_.-_-.--_._._-.__. 6

Faunal range, HercyneUa..................... 19

Favistella.-................................... 29

Favistina ---.................._............... 29

favosa, Stauria................................ 21

Favosites............................. 14,15,16,19,23

basalticus................................. 23

polymorpha............................... 23

turbinata................................. 23

sp- .... -__.._..._.--_-_----_.-_-....... 15,22

Fletcheria..................................... 30

Fletcherina......... _............._._......._. 30

fottii, Plasmopora............................. 16

Fossil preservation...._.............._.._..._ 4

Fossils, Gazelle Formation........_.......... 3

Gazelle Formation, Chastain Ridge...... 12

unit 1, Willow Creek area..-.--...... 14

unit 2, Bonnet Rock.................. 11

Page 

fritschi, Australophyllum................. 22,40, pi. 5

Fusulinids__.-..--.--.-....----.-.---.--.-. 4

G 

Gazelle Formation.......................... 2,

3,17, 20, 21, 22, 28, 29, 30, 31, 32, 36, 38, 39

40,41 

age.-...-..........---...---.---------.--- 2

Bonnet Rock section..................... 10

Chastain Ridge section ................ 11

clastic sediments.-...-.------.-.-----.--- 24

depositional history -.-.-....... ..... 25

fauna-.----------.----------------------- 30

Gregg Ranch area, limestones--..-....--. 13

limestone bodies ..._........---- .... 24

limestones.-------..------...------------ 25

Mallethead Ridge section................ 12

origin of coralline limestones. ------------- tfi

origin of limestone bodies.----.---.------- 24,25

Parker Rock, limestone breccia-conglomerate .--..-.-.....-.------------- 26

Parker Rock area_...........-..-.. .-- IS

reef growths..---.------------------------ 25

type area..------------------------------ 3,6,23

type section--...-...-..------_-----_--- 3,10,13

unit 1-...........-..------... 3,10,12,20,21,33

fossils.. ------------------------- 14

lithology--- ....-..-. ... - 10

siliceous conglomerates...... .. ..- 25

unit 2.. ._...-_._-_._..-.-- --- - 3,

10,11,14,18,20,21,30,35,36,38,41

limestone breccia-conglomerate.... 25,26,30

lithology....--------------------- 10

unit 3..- .___...---- 11,12,13,20,21,26,32

fossils........ ----------------------- 14

limestone conglomerates. ......-.--- 26

lithology----.------------------------ 11

Willow Creek area.-------.----------- 3,6

phyllites. -------------------- 13

gazellensis, Cyathactis......................... 4,

14,15,21,22,23,27, 84, 38, pi. 6 

Oirvanella problematica........................ 14,16

Olassia....................................... 15

sp........................................ 16,23

Goniophyllidae_.....-.--.-..-...---------.. 27

Gotland, Sweden...............-.- ---- ... 16,

17,20,21,22,28,30,31,32,33,36,39 

Sweden, corals_.....-_..-......----...- 3,35

depositional history.---..........-..- 25

reef growths. __ - 25

Graptolites, Gazelle Formation, Chastain

Ridge.-.......-..-.--.--.--- 12

Heceta-Tuxekan beds. -_ - 19

Great Basin........_._-..-_. 2,15,17,22,28,30,31,33

coral zone A.-------------- 17,20,21,28

coral zone B---.-------.--~--- 20,21,23,35,37

coral zone C-.--.~~~- -------------- 20,39

coral zone D_.---------------------------- 20

coral zone E_.. . .-. - 20,21,24,32,37,40 

eastern dolomite belt....__. ._ . 20,26

intermediate limestone belt_--------.... 20,26

shelf sea dolomites ---------------------- 25

Silurian coral zones.---.----.------------- 20

Silurian faunas ------------------------- 3

Great Lakes, patch reefs.__~....~~~~~. 25

Silurian shelf seas___~~~--~~- ~. 25 

Gregg, Rodney, cited___..-.._._-.__-_--_-_ 3,4 

Gregg Ranch-.--.-------------------------- 6,37

Gregg Ranch area... - - - 6,41

facies problem... -.-...~~~~~ ~_ 13 

faunas_....... ....-...-... -.-... . 15, 24

greenstones..----------------------------- 13

Silurian or early Devonian Limestones- - - IS 

greggi, Kyphophyllum.............. 15,27,37,pis. 7,8

Orewingkia................................ 16,17,28

Grouse Creek.___............_~~...__ 6,13

faunas... -- ..............-.... -. . 13,24

	Page 

Grouse Creek area._.-.-......-....-- -.-.. 6,42

facies problem.- -. ................... 13

rugose corals and associated fossils........ 15

Silurian or early Devonian Strata.__... IS

Gryphochitonid plates.---. .. .- - 15

Guelph Dolomite.._........................ 30

guelphensis, Pycnostylus...................... 30

gwenensis, Striatopora......................... 16

Oypidula ................................... 14,22

comis.------------_---.-.....-- ---.- 23

lotis...................................... 23

sp.......................----- -_--- 14

Halliidae- ------- .- ---. 33

Halysites............................... 12,15,22,23

(Catenipora).............................. 15

sp-.-~-.~- -- -..-----...-.-- 16,17

Harpidium................................... 18

Ration's Corner, Yass River, New South

Wales, Australia . .- ..... 32

Hayfork, Trinity County, Calif.. ______ 39 

Hayfork area.______ - ___-..-.. 42

Heceta Island, Alaska....~.____-_.. 18,19,23

Heceta-Tuxekan Island area....____...... 18

Heceta-Tuxekan section, Alaska.------------- 18

Hedstromophyllum............................ 35

helenae, Evenkiella-............-...---..-.---- 38

HeliolUes..................................... 14,15

Heliolittds... - ... --------- 17

Henryhouse Limestone 21,34

henryhousense, Cystiphyllum.................. 35,36

Hercophyllum shearsbyi....................... 22

Hercynella.............................. 15,19,20,24

bohemica....----- -- . -.------- 15,19,24

nobilis-.-----------------...-------------- 19

Old World range .. - 19

Hesperorthis.................................. 15,17

sp-- .. . - - ---- 15,16,23

Heterocoelia...-------------------------------- 16,17

Hexagonaria-....-.--------------------------- 40

Hidden VaUey. ----------------------- 37

Hidden Valley Dolomite-...._ ,- --- 28,35,38

History of investigation---------- - *

htfegi, Vermiporella....... -------- 16

HBgklintgroup. -- 21,28,31 

Holmophyllum-......................-.-.-- . 35

Holopea.. ..-..............-..-. .. --.--- 15

symmetrica.... ..--.- -- -------------- 15

Holophragma ...-........-- _.__ ~~ 33

Ho rmotoma ----------------------------------- 15

Horseshoe Gulch... 6,14,16,20,23,28,31

Horseshoe Gulch area-------------------- 6,31,42

calcareous algae.. ------------------- 24

Early Silurian and Ordovician deposits. - - IS 

facies problem - -- - - 13 

rugose corals and associated fossils......-- 16

HoweZ^O-.----------------------- 15,18,20,24

cydoptera...------------------------------ 24

------------------------- 15,24

inficetum, Spongophyllum..............---...- 39

insignis, Cheirurus..-..... -... - - 14

intermedium, Zelophyllum-...-- - .. -__._- 31 

Introduction --.._ ------ 1

Inyo County, Calif -------------------- 39

Inyo Mountains.---..--- ----- -------- 3,28,29

irregularis, Phaulactis.-----..----------------- 35

Irwin, W. P., cited..-------------------- 3,39

Isorthis -. _... 14,16,18

Johnson, J. H., quoted.--...-------------- 16

Kasaan Bay..------------------------ ----- i8

Kasaan Bay area, Alaska - - - - - 19
INDEX 49

Page

Kennett Formation _._ ..__-_-.-.- 2,3,22 

Ketophyttum ............................... 22,40

Klamath Mountains. -. - 2,3,18,20,29,30,31,32,33,38 

Klamathastraea-................ 2,22,23,27,38,39,40

dilleri............. 14,20,21,22,23,27, 40, 41,pi. 5

Klinteberg Group............................ 23

knigMi, Conchidium........................... 18,23

Kodonophyllidae...------.--..-..._. 20,21,22,27,30

Kodonophyllinae............................. 27,Sg

KodonophyUum...................... 14,20,21,27,32

mUne-edwardsi............................ 32

truncatum................................ 32

sp.g.-------------..-.---.-------.- 27,SS.pl. 4

Konishi, Kenji, quoted....................... 16

Kosciusko Island............................. 18

Kuiu Island, Alaska................. 18, 19, 36,37,38

Kulu Limestone.. - _------ - - -- 19

Kyphophyllidae--------.--..------------- 21,27,36

Kyphophyttum-............ 14,19,20,21,24,27,36,40

greggi.......................... 15,27,37,pis. 7,8

Mmtofrdmi ------------------------------ 36,37

sp --------------------------- 37,pi. 8

labtosa, Cladopora............................. 23

Laccophyllidae.... -_. -..-... -..----.-.- n

Laccophyllum................................. 27

Laudon, L. R., cited.. ..................... 16

Leonaspis (Acanthalomina) minuta............ 14

LeperdUia.................................... 15

Leptaena rhomboidalis......................... 14

liliiforme,Mycophyttum....................... 32

Tryplasma................................ 33

Lime Gulch - - -_..................... 14

Limestone, Heceta-Tuxekan section.......... 18

Limestone conglomerate, coral-bearing_.... SB

Limestone facies, northeastern Klamath

subregion_..................... 6

origin...---_..--.-----.-.--_------------ 25

lindstromi, Kyphophyttum..................... 36,37

lineatum, Cystiphyllum........................ 35

Lingulasp.................................... 16

lirata, Ruedemannia........................... 15

Lithology, Gazelle Formation, Chastain

Ridge...--.....--------.------- 11

Gazelle Formation, type section. ____ 10 

Heceta-Tuxekan marine rocks._____ 18 

Montgomery Limestone____________ 17

northeastern Klamath subregion-.____ 6 

Lrthostrotion.................................. 22,41

Lithostrotionetta............................... 40

Locality register_.............__.......... 41

Lone Mountain Dolomite____............. 15,24

Long Island, Kasaan Bay._.._-_-_.._........ 19

Lonsdaleia.................................... 40

Lophospira bicincta. ___..........._...... 15

lotis, Oypidula................................ 23

Louisville Limestone...______________________ 20,21

Loxonema delphicola.......................... 23

sp................................ 15,23

Lykophyllidae...---- -____________ 20,21,22,27,33

M

McConnahue Gulch.......................... 13

Mclntyre, J. R., cited.._.___.___... 3,4,12,14,23,33 

mcint'jrei, Mucophyllum 14,15,20,21,22,23,27,33, pi. 6 

McMath.V. E., cited.-....................... 17

Mallethead Ridge...................... 12,14,23,33

Mallethead Rock__.--.-..-.-.............. 6

Mesocoelia janus.............................. 15

Methods of study...........................__ 3

Microplasma.................................. 19,35

Mieula........................................ 34

antiqua..................___.............. 34

catUla.................................. 21,33,34

mUne-edwardsi, Kodonophyttum............... 32

minuta, Leonaspis (Acanthalomina)........... 14

Monograptus................................ 3,14,23

Page 

Montgomery Limestone___._......_. 17,21,23,28

Mont Wissick Formation..._---------------- 21

Mountain House. ..__..______......... 31

Mount Shasta..---- -_.................. 2

Mucophyllum..................... 12,20,21,23,27,31!

crateroides............................. 22,32,33

mdntyrei........... .14,15,20,21,22,23,27,33,pi. 6

muttilamella,Alveolttes..--_-_................. 23

Murchisonia.................................. 15,23

bilineata.................................. 16

sp_ - -._-_._-..-.-.-.-. . 15,23 

Mycophyllinae....------......_........... 27,3s

Mycaphyllumlttiiforme-.-._.._................ 32

Mytilarca sp....------------------------------ 23

N

Naos.... .--................................. 32

Neomphyma.................................. 36,37

Newberria.................................... 22,23

Niagaranreef growths-.----. ..--..-----.--- 25

Nicholsonia................................... 27

nisis, Schizoramma............................ 16

nobilis,Hercynella............................ 19

North American Pacific Border province,

reference sections.-.-------------- 18

Northeastern Klamath subregion. ------------ l,

3,4,17,24,27,36 

correlated with eastern North America,

Europe, and Australia__._.__-_ 20 

correlated with older paleozoic rocks o.

Taylorsville area__------------ .7

correlated with Silurian rocks of Douglas

City area..-.-...-.-.-.---------- .7

correlated with Silurian rocks in the

Great Basis.-..---.-------------- SO

correlated with southeastern Alaska 

Silurian and early Devonian 

sequences_______.___........... 18

depositional environment and origin of

the coral-bearing deposits..-.----- 24

facies problem... .--_................... 6

geologic age of paleozoic rocks._ ......... 88

geologic correlation of paleozoic rocks..... 17

reef flank features__..._............... 26

rugose corals and assoicated fossils -..__... IS 

North Yolla Bolly Mountain_-------------- 4

norvegica, DasyporeUa......................... 14,16

Nucleospira ventricosa......................... 16

NucullUs............._..._____........... 15

O

Objectives and scope of investigation...__. . *

Ontario, Canada_ ._ -___...-...-. - 30

orbicularis, Atrypa reticularis.................. 14

ornatum, TenuiphyUum....................... 39

Orthoceras.................................... 23

OrthophyUum sp .... --.-- .....-.. 14,28, pi. 4

Owens Valley-..--__-.__-___... ...-.-.-.- 39

Pacific Border graywacke suite...............

Pacific Border province_......... _ 2,3,17,

southeastern Alaska, Silurian rocks.. 

Palaeocyclus..................................

Palaeoneilo...................................

Palaeophyttum...----------------------__.-.

nigotum..................................

sp. G. ....................... 14,27,59,

sp........................................

Paleozoic rocks in the Klamath Mountains 

region, distribution..... _......

subdivision___....-.....-....--.-.-..

Paleozoic strata, northeastern Klamath subregion....._..._._.-_-..

PanamintMountains.-_,.__.. ...... 20,

Parachaetetes sp___...__........____-.-

Parker Rock. .............. 6,12,13,14,22,31,

24 

24,25

24 

20,31

15 

27; 29

29

pi. 2 

16,17

4

4

28,38

14,16

Page 

Parker Rock area............................. 6,41

patellatum, Schlotheimophyttum................ 21

pegramense, Cyathophyllum................ 21,34,35

pentagona, Acervularia........................ 23

Pentamerus................................... 15

Permia....................................... 27

P_<roziwn---.--.-.---___-. 19,20,23,27,36,57,38 

dewari.............................. 19,22,37,38

staufferi...................4,14,22,23,27,37, pi. 7

sp-------------- - .-.------.-.-38, pi. 7

Pkaulactis.............................. 19,21,33,34

cyathophylloides- -.-_._............... 33,34,35

irregularis................................ 35

Phillipasastraeidae... _.......-.-.-.-.. . 26

PUophyttum............................... 37,39,40

Plasmopora................................ 14,20,23

fottis...................................... 16

sp--------------------------------- 17

Platyceraa---.-------------------------------- 15

PUctatrypa................................ 14,15,20

plena, Raphispira............................. 15

polymorpha, Favosites......................... 23

potens, Stylonema.. ......................... 16

Prince of Wales Island-..................._- 18

princeps, Pseudamplexus...................... 19

problematica, Girvanella....................... 14,16

Proetus--................................... 24

sp. .---. . . . --- - 14,16 

------------------------------ 15

Prosolarium.................................. 15

prosperum, Cyathophyllum...-......-.-.-.- 22,34,35

Pseudamplexus............................ 19,31,32

princeps..-------------------------------- 19

Pseudocheirurus.............................. 15

sp ..-- ------ - --- 23

Pseudomphyma............................... 33

Pseudophorus................................. 15

Pycnactis..................................... 33,34

Pycnostylid-..--_............ -. ...-... 15

sp. H--- ------------------------ 27,3.,pi. 1

sp. - - .------. -- 31,pi.2

Pycnostylidae................ -...-. 26,27,29,80

Pj/cnostj/Zws...------------------------------- 30,33

guelphensis.........................------ 30

Q

Quebec, Canada..------------------ ------ 29

R

Rabbit Hill Limestone-..------------- 15,24,28

Raphispira plena................-.----------- 15

rectiseptatum Australophyttum................. 21

Redding copper district..............--.-.--- 3,4

Redding Folio of J.S.Diller...----------- 2

reesidei, Camarotoechia.............. ------- 15,23

References cited.----------------------------- 4&

reticularis orbicularis, Atrypa.............. .- 14

Rhabdocyclus..............................---- 31

Rhizophyttum............................ 3,17,18,19

sp. A .. I8 

sp. B.._ ....... 19

sp. C_. .. 17

rhomboidalis, Leptaena........................ 14

Roberts Mountains Formation.... 33,39

Roberts Mountains, Nov.. 29 

Romingeria sp____- -__... ------- 16

Rotellomphalus tardus____.... -- 15

Ruedemannia lirata........................... 15

Rugosa.. --------- - ----- ----- #7

Rugose corals, facies indicators-. ... 20 

stratigraphic ranges -- 21 

Rugose corals and associated fossils, northeastern Klamath subregion IS 

rugosum, Palaeophyttum...................... 29

Russia.... --------------------- ------- 33

Ryderophyttum......................-.----- 33,34,35
50 INDEX

Salairophyllum..........._____..........

Salmon Mountains__--.--.._.-. ------

saumeaensis, Spongophyllum... ... . _.

scheii, Atrypella ..............................

Schizophoria..................................

bisinuata..... ____________._ 16, 

Schizoramma........____.___..._....

nisis......................................

Schlotheimophyllum. -.................... 21,

patellatum................................

Schuchert, Charles, cited..............._...

schucherti, Shastaphyllum.. 14, 23, 27,30, 38, pis, 

Scott Mountains__..........................

Scott River______________.__.......

Scott Valley----------------------------

Scutellumsp..................................

sedgwickl, Spongophyllum............. ..__. 38,

septentrionalis, Bellerophon....................

seretensis, Stropheodonta (Brachypriori). .......

Shasta copper district........................

Shastaphyllum............................. 27,

Shasta Valley____ __ __ _-...-

schucherti.............. 14,23,27,30, 38, pis.

sp.c..... ....................... 27,S<

shearsbyi, Hercophyllum.......................

Spongophyllum...........................

Shropshire, England___- .___. . _- _ 

Siberian Platform......._......__........__

Silurian fossils, Gazelle Formation, unit 3, 

Willow Creek area.--.-----._...

Silurian rugosa of Klamath Mountains, 

classification._.____...........

Silurian rugose corals, Parker Rock area......

siluriense, Cystiphyllum.......................

siluriensis, Cyathaxonia.......................

Syringaxon...............................

Simpson Park Mountains, Nev.--_---...-....

limestone breccias..--...-.-.-..-.........

Siphonophrentinae...........................

Siskiyou County, Calif__ .......-....- 2,3,

Skenidioides........................ ...........

Slite Group.----..-.-.-. -.-...-..._......

Smith, Stanley, quoted_.........-.-. -.-..

smtthi, Howellella.............................

South Fork Mountains-.-._..................

Southeastern Alaska, limestones. .............

Silurian marine rocks_...-....-.-..-....

Southeastern Klamathsubregion.............

Spongophylloides..............................

spongophylloides, Australophyllum.............

Spongophyllum............................ 38,

inficetum................................

sedgwicki. 

shearsbyi..

Page

18,19

4

39

14

16,24

,21,24

17

16

,32,33 

21 

2

. 2,3,4 

2 

13 

3 

14

, 39,40 

23 

16 

4

, 36, 38

2,3

2,3,4

', pl. 4

22

39

22

36

14

14

35,36

27

27

26,32

26

28

29,40

15,17

21,33

37

15,24

4

25

18

3,4

17,40

22

39,40

39

. 39

39,40

39

Page 

Stanley, Maitland.cited------.-..----....... 3,4,30

stanleyi, Wintunastraea......... 14,27,29, SO, pis. 3,4

staufferi, Petrozium........... 4,14,22,23,27, 37, pl. 7

Stauria....................................... 29

astreiformis.---------..................... 28

favosa.....-.....-..---.-..-..-......-..--. 21

Stauriidae.--..-_---_-------_-------- 21,27,28,30,31

Stratigraphy, Gazelle Formation, unit 2...... 11

Heceta-Tuxekan Island section........... 18

Horseshoe Gulch area--.__.. .._.... 16

Streptelasma.................................. 29

corniculum................................ 28

Streptelasmatidae------------------- 20,21,27,28

Streptelasmatinae.-----------------------_-.- 27,28

Streptelasmidae..... .. -. ....... 27,28

Striatopora gwenensis...---------------------- 16

SMcklandia...- ---------- ---------.. 14,18

strigillatum Eunema.--------................. 15

Stromatopora sp___-- -_ -- __.__ 23 

Strombodes ................................. 36,40

Stropheodont_ ...........

Stropheodonta...............

(Brachyprion) seretensis. 

Stylonema..................

symmetrica, Holopea........................

Synaptophyllum............................

Syringaxon----..--.........................

sdurienala..............................

sp. Q,................................. 27,28,pl.4

sp........................................ 14

Syringopora................................ 15,16,30

Systematic and descriptive paleontology___ 27

Tabulata____..... 

Tabulophyttum sp_.. 

tardus, Rotellomphalus. 

Tatlock, D.B., cited 

 .... . 29

.... 23

 . 15

 3

Taylorsville, Calif.-..-- ----- 17,21,23,28

Tenuiphyllum................................ 38

ornatum.................................. 39

tenuis, Atrypella.................... ....... 14,23

Thamnopora........................._-_ 19

The Point..... ...... - - --- 12

Toquima Range, Nev_______ ...._ 37

Torquay, England....- - - - 39

Trematospira................................. 15

sp. 23

Trenton Group.. - . 28,29

Trilobite assemblage, Mallethead Ridge...... 12

Trinity River...-.....-.----..-..--..-..... 17

South Fork.............--.---.-..--..-.. 4

Trochophyttum................................ 27

Trochurussp................................. 14

Page 

truncatum, Kodonophyllum.................... 32

Tryplasma................................. 17,18,31

aeguabile..... ........._.....____... 31

liliiforme.................................. 33

Tryplasmatidae............... 20,21, 26, 27,30, 31, 35

Tryplasmidae..________________ 29 

turbinata, Faeosites............................ 23

typus, Cyathactis.............................. 33

 28

U

Ural Mountains, Russia.._------_-__. 31,37,39

Vaughn Gulch Limestone.._.____ 3,28,29,39 

ventricosa, Nucleospira........................ 16

Vermiporellaborealis.......................... 14,16

htfegi.-................................... 16

Verticillopora....._........................... 20

Visby Marl.................................... 21

W

Walker, G. W., cited . . __ 16 

Weaverville, Calif.... .. ... 17

Weaverville area___..-.-.-_-.-.-_--... 42 

Wells, F. G.,eited. . ... 3,16

Wenlock Limestone___..... . .. 35

Westman, B. J., cited.. 3

White Pine mining district, Nev_...- . 22 

Whitfteldella sp................................ 16

Willow Creek - . - 2,3,6,13,22 

Willow Creek area..... 6,12,13,28,30,32,36,38,39,41

stratigraphy_._._...._...... 13 

Wintunastraea........................... 3,21,27,89

stanleyi ..___- .--.. 14,27,29, SO, pis. 3,4

X

Xylodes....................................... 34,35

Yass, Australia.-..._..._.__...._.-... 39

Yass-Bowning area.-.-----.-.__.___-... 22

Yassia. .................................... 39,40

enormis................................... 22

Zelophyttum. 14,17,18,19,21,22, 23, 24,27,29,30, 81, 33 

intermedium.............................. 31

sp. G.. . 14,18,27,29, 81, pl. 1

sp.___.- ..._________.__ 16, pl. 1
PLATES 1-8

[Contact photographs of the plates in this report are available, at cost, from U.S. Geological Survey Library, Federal Center, Denver, Colo. 8Uif23]
PLATE 1

FIGURES 1-4. Zeolphyllum n. sp. (p. 31).

1. Transverse thin section (X 4).

2. Transverse thin section (X 8).

3. Longitudinal thin section (X 4).

4. Longitudinal thin section (X 8).

Locality M1001, Cone Bay; northern Heceta Island, southeastern Alaska. Late Silurian Atrypella-Conchidium beds. 

5. Zelophyllum n. sp. (p. 31).

Longitudinal thin section (X 8). Northern Heceta Island, southeastern Alaska. Late Silurian Atrypella-Conchidium

beds. 

6, 7. Zelophyllum sp. G (p. 31).

Transverse and longitudinal thin sections (X 2); USNM 159454. Gazelle Formation, locality M78, Chastain Ridge. 

8-10. Pycnostylid sp. H (p. 31).

Transverse and longitudinal thin sections (X 2); USNM 159455. Silurian beds, locality M1130, Horseshoe Gulch. 

11-14. Dalmanophyllum sp. h (p. 28).

11. Calice view (X 2).

12. Lateral calice view showing median boss (X 2).

13. Longitudinal thin section (X 2) showing axial structure.

14. Transverse thin section (X 3). 

Early Silurian; locality M1131, Horseshoe Gulch. 

15, 16. Cystiphyllum sp. c (p. 36).

Longitudinal thin section (X 1^); transverse thin section (X 2). Unit 2, Gazelle Formation; locality M191, Bonnet 

Rock.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 738 PLATE 1

15 

ZELOPHYLLUM, PYCNOSTYLID, DALMANOPHYLLUM, AND CYSTIPHYLLUM
PLATE 2

FIGURES 1-6. Shastaphyllum schucherti n. gen., n. sp. (p. 38).

1, 2. Transverse thin sections (X 6) and (X 3) of holotype, USNM 159457. 

3-6. Longitudinal thin sections of holotype, USNM 159457, (X 3), (X 6), (X 6), (X 6). 

Silurian. Gazelle Formation; locality M1132. Bonnet Rock, 

7, 8. Pycnostylid sp. (p. 31).

Transverse and longitudinal sections (X 2). Silurian, Gazelle Formation; locality M1030 Parker Rock. 

9, 10. Palaeophyllum? sp. G. (p. 29).

Transverse and longitudinal sections (X 2). Silurian, Gazelle Formation; locality M78, Chastain Ridge.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 738 PLATE 2

9 10 8 

SHASTAPHYLLUM, PYCNOSTYLID, AND PALAEOPHYLLUM*!
PLATE 3

FIGURES 1-3. Wintunastraea stanleyin. gen., n. sp. (p. 30).

Transverse and longitudinal thin sections of holotype (X 5); USNM 159464. 

4. Shastaphyllum schucherti n. gen., n. sp. (p. 38).

Longitudinal thin section of paratype (X 5); USNM 159465. 

5, 6. Cystiphyllum sp. c (p. 36).

Longitudinal and transverse thin sections, slightly enlarged; USNM 159466. Silurian, Gazelle Formation; locality 

Ml 135, Chastain Ridge.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 738 PLATE 3

^f^^'Sfa^^ &a;-lMM^

WINTUNASTRAEA, SHASTAPHYLLUM, AND CYSTIPHYLLUM
PLATE 4

FIGURES 1-3. Australophyllum sp. E (p. 40).

1. Transverse thin section (X2), USNM 159420.

2. Longitudinal thin section (X2), USNM 159420.

3. Transverse thin section (X2), USNM 159420.

Late Silurian, coral zone E; locality Ml 114, Ikes Canyon, Toquima Range, Nev. 

4, 5. Wintunastraea stanleyi n. gen., n. sp. (p. 30).

Transverse and longitudinal thin sections of holotype (X l/^), USNM 159464. Late Silurian, Gazelle Formation;

locality M1135, Chastain Ridge, Willow Creek area. 

6, 7. Shastaphyllum? sp. c (p. 39).

Transverse and longitudinal thin sections(X l/^)- Locality M1281, southern part of Hayfork quadrangle, Trinity 

County, Calif.

8. Shastaphyllum schucherti n. gen., n. sp. (p. 38).

Weathered surface of corallum (X !) Late Silurian, Gazelle Formation; locality Ml 135, Chastain Ridge, Willow 

Creek area.

9. tOrthophyllum sp. (p. 28).

Transverse thin section (X 7). Late Silurian, Gazelle Formation; locality Ml 135, Chastain Ridge, Willow Creek 

area.

10. Syringaxon sp. c (p. 28).

Transverse thin section (X 15). Late Silurian, Gazelle Formation; locality M1135, Chastain Ridge, Willow Creek

area. 

11, 12. Kodonophyllum sp. g (p. 32).

Transverse and longitudinal thin sections (X 2). Late Silurian, Gazelle Formation, unit 3; Bonnet Rock, Willow

Creek area.

13. Spotted argillaceous rubbly limestone with corals (X 1%) of type common in unit 2 of the Gazelle Formation (p. 12). 

Locality M1029, Parker Rock, east fork of Scott River.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 738 PLATE 4

AUSTRALOPHYLLUM, WINTUNASTRAEA, SHASTAPHYLLUM, WRTHOPHYLLUM, SYRINGAXON, 

KODONOPHYLLUM,ANV CORALLINE RUBBLY LIMESTONE OF THE GAZELLE FORMATION
PLATE 5

FIGURES 1-5. Klamathastraea dilleri n. gen., n. sp. (p. 40).

1, 2. Transverse and longitudinal thin sections of holotype (X 2%); USNM 159456. 

3, 4. Transverse and longitudinal thin sections of holotype (X l^)j USNM 159456.

5. Weathered under surface of holotype (X %); USNM 159456. 

Silurian, Gazelle Formation; locality Ml 132, Bonnet Rock. 

6-8. Australophyllum fritschi (Novak). (p. 40).

Transverse and longitudinal thin sections (somewhat enlarged). Copies of figs. 6, 7, 8, pi. 102, Pocta (1902). Upper 

Silurian (Kozel, e2), Czechoslovakia.
PROFESSIONAL PAPER 738 PLATE 5

KLAMATHASTRAEA AND AUSTRALOPHYLLUM
PLATE 6

FIGURES 1-5, 7-8. Cyathactis gazellensis n. sp. (p. 34).

1, 2. Lateral views of two small corallites (XI); USNM 159446, 159447.

3, 4. Transverse thin section of holotype (X 2); USNM 159448 and enlargement of part of same (X 8). 

5. Longitudinal thin section of paratype (X 6); USNM 159449.

7, 8. Longitudinal thin sections of two paratypes: USNM 159451 (X 2), USNM 159452 (X 4). 

Silurian, Gazelle Formation, unit 2; locality M191, Bonnet Rock, Willow Creek area. 

6. Cyathactis gazellensis n. sp. (p. 34).

Transverse thin section (X 3); USNM 159450. Silurian, Gazelle Formation; locality M1030, Parker Rock. 

9, 10. Mucophyllum mcintyrei n. sp. (p. 33).

9. Weathered undersurface of holotype USNM 159453 (X 1).

10. Longitudinal thin section of holotype USNM 159453 (X 1^)-

Silurian, Gazelle Formation; locality M87, main fork of Willow Creek, China Mountain quadrangle, Calif.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 738 PLATE

CYATHACTIS AND MUCOPHYLLUM
PLATE 7

FIGURES 1, 3-6. Pelrozium staufferi n. sp. (p. 37). 

Holotype, USNM 159458. 

1. Transverse thin section (X 4). 

3. Longitudinal thin section of corallite (X 4). 

4-6. Longitudinal thin sections of three corallites (X 8).

Silurian, Gazelle Formation unit 2; locality M191, Bonnet Rock, Willow Creek area. 

2. Petrozium staufferi n. sp. (p. 37).

Oblique external view of part of large colony (X !) 

Silurian, Gazelle Formation unit 2; locality M191, Bonnet Rock, Willow Creek area. 

7, 8. Petrozium sp. (p. 38).

Transverse and longitudinal thin sections (X 4); shows discrete axial rod. Silurian; locality Ml 162 Kuiu Island,

southeastern Alaska. 

9, 10. Kyphophyllum greggi n. sp. (p. 37).

9. Transverse thin section (X 4); USNM 159459.

10. Longitudinal thin section (X 2); USNM 159460. 

Gazelle Formation, locality M1133, Gregg Ranch. 

11. Kyphophyllum cf. K. greggi n. sp. (p. 37).

Longitudinal thin section (X 4). Silurian or Early Devonian; locality M1134, Grouse Creek Etna quadrangle,

Calif. 

12-14. Kyphopyhllum cf. K. greggi n. sp. (p. 37).

Transverse and longitudinal thin section (X 4). Gazelle Formation, locality M82. Gregg Ranch.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 738 PLATE 7

PETROZIUM AND KYPHOPHYLLUM
PLATE 8

FIGUEES 1-5, 8. Kyphophyllum greggi n. sp. (p. 37).

1. Transverse thin section of holotype (X 4); USNM 159461.

2. 3. Transverse thin sections (X 4).

4. Transverse thin section of holotype (X 4); USNM 159461.

5. Longitudinal thin section of paratype (X 4); USNM 159462. 

8. Longitudinal thin section of paratype (X 4); USNM 159463. 

Silurian or Early Devonian. Locality Ml 133, Gregg Ranch.

6. Kyphophyllum sp. (p. 37).

Transverse thin section (X 4). Late Silurian; locality Ml 114, Ikes Canyon, Toquima Range, Nev.

7. Kyphophyllum cf. K. greggi n. sp. (p. 37).

Transverse thin section (X 4). Silurian or Early Devonian; locality M1134, Grouse Creek, Etna quadrangle, 

Calif.
GEOLOGICAL SURVEY PROFESSIONAL PAPEK 738 PLATE

KYPHOPHYLL UM