Jurassic (Bathonian and Gallovian) Ammonites 

in Eastern Oregon and Western Idaho

GIOXOOICAL JSURVIY PROFESSIONAL PAPER

Jurassic (Bathonian and Callovian) Ammonites 

in Eastern Oregon and Western Idaho

By RALPH W. IMLAY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 1142

The late Bathonian to middle Callovian 

ammonite succession in eastern Oregon is 

remarkably similar to that in southern Alaska

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1981
UNITED STATES DEPARTMENT OF THE INTERIOR 

CECIL D. ANDRUS, Secretary

GEOLOGICAL SURVEY

H. William Menard, Director

Library of Congress Cataloging in Publication Data

Imlay, Ralph Willard, 1908-

Jurassic (Bathonian and Callovian) ammonites in eastern Oregon and western Idaho.

(Geological Survey professional paper; 1142)

Bibliography: p.

Includes index.

1. Ammonoidea. 2. Paleontology-Jurassic. 3. Paleontology-Oregon. 4. Paleontology-Idaho. I. Title. II. Series: United States.

Geological Survey. Professional paper; 1142.

QE807.A5159 564'.53 79-13537.

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

Washington, D.C. 20402
CONTENTS

	Page

Abstract ________________________________________________ 1

Introduction ______________________________________________ 1

Biologic analysis ___________________________________________ 2

Stratigraphic summary _______________________________________ 3

East-central Oregon _______________________________________ 3

Snake River Canyon area in Idaho and Oregon ________________________ 7

Ages and correlations ________________________________________ 7

Snowshoe Formation in east-central Oregon _________________________ 7

Trowbridge Shale in east-central Oregon ___________________________ 11

Lonesome Formation in east-central Oregon _________________________ 11

Jurassic beds near Mineral, western Idaho __________________________ 12

Jurassic beds near Pittsburg Landing in northeast Oregon _________________ 12

Ammonite faunal setting _______________________________________ 12

Geographic distribution ________________________________________ 13

Systematic descriptions _______________________________________ 17

References cited _________________________________________ 21

Index _________________________________________________ 23

ILLUSTRATIONS

[Plates follow index]

PLATE 1. Parapatoceras, Bullatimorphites, Xenocephalites, Iniskinites, and Lilloettia.

2. Kepplerites, Pseudocadoceras, and Choffatial

3. Torricelliceras.

4. Iniskinites.

5. Cobbanites and Grossouvria.

Page

FIGURES 1-4. Index maps showing:

1. General areas in which Bathonian and (or) Callovian ammonites occur in eastern Oregon and westernmost Idaho __ 2

2. Bathonian and Callovian ammonite areas in the Suplee-Izee-Seneca region, east-central Oregon ____________ 3

3. Bathonian and Callovian USGS Mesozoic localities from which ammonites were collected in the Izee area, east-central

Oregon ____________________________________________________________ 4

4. Bathonian (?) and Callovian ammonite localities near Mineral (abandoned), western Idaho ________________ 5

5. Correlation of some Middle Jurassic (Bathonian and Callovian) formations and faunas in eastern Oregon and southern

Alaska ________________________________________________________________ 6

6. Stratigraphic ranges of late Bathonian to middle Callovian ammonites in the Suplee-Izee-Seneca region, east-central

Oregon _______________________________________________________________ 8

TABLES

Page

TABLE 1. Ammonite genera of Bathonian and Callovian Age in eastern Oregon and western Idaho ___________________ 2

2. Thicknesses of the Trowbridge Shale in east-central Oregon ____________________________________ 5

3. Stratigraphic positions of Bathonian ammonites in the upper part of the upper member of the Snowshoe Formation,

Izee area, Grant County, east-central Oregon __________________________________________ 9

4. Geographic distribution of Bathonian ammonites in the Izee area, Grant County, east-central Oregon ____________ 9

5. Geographic distribution of Callovian or possible Callovian ammonites in eastern Oregon and western Idaho _________ 12

6. Description of Bathonian and Callovian ammonite localities in east-central Oregon and westernmost Idaho _________ 13

in
CONVERSION FACTORS

Metric unit Inch-Pound equivalent

Length

millimeter (mm) 

meter ( m ) 

kilometer (km)

= 0.031937 inch (in) 

= 3.28 feet (ft) 

= .62 mile (mi)

Area

square meter (m-) 

square kilometer (km2 ) 

hectare (ha)

= 10.76 square feet (ft2 ) 

= .386 square mile (mi2 ) 

= 2.47 acres

Volume

cubic centimeter (cm3 ) 

liter (L) 

cubic meter (m3 ) 

cubic meter 

cubic hectometer (hm3 ) 

liter 

liter 

liter 

cubic meter

cubic meter

= 0.061 cubic inch (in3 ) 

= 61.03 cubic inches 

= 35.31 cubic feet (ft3 ) 

= .00081 acre-foot (acre-ft) 

= 810.7 acre-feet 

= 2.113 pints (pt) 

= 1.06 quarts (qt) 

= .26 gallon (gal) 

= .00026 million gallons (Mgal or 

10" gal) 

= 6.290 barrels (bnl) (1 bbl = 42 gal)

Weight

gram (g) 

gram 

metric tons (t) 

metric tons

= 0.035 ounce, avoirdupois (oz avdp) 

= .0022 pound, avoirdupois <lb avdp) 

= 1.102 tons, short (2,000 Ib) 

= 0.9842 ton, long (2,240 Ib)

Specific combinations

kilogram per square 

centimeter (kg/cm2 ) 

kilogram per square 

centimeter 

cubic meter per second 

( m;>/s >

_ 0.96 atmosphere (atm)

= 33.3 cubic feet per second (ft3 /s)

Metric unit

Specific

liter per second (L/s) 

cubic meter per second 

per square kilometer 

[(m3/s)/km2 ] 

meter per day (m/d)

meter per kilometer 

(m/km) 

kilometer per hour 

(km/h) 

meter per second (m/s) 

meter squared per day 

(mVd) 

cubic meter per second 

(mVs) 

cubic meter per minute 

(ni3/min) 

liter per second (L/s) 

liter per second per 

meter [<L/s)/m] 

kilometer per hour 

(km/h) 

meter per second (m/s) 

gram per cubic 

centimeter (g/cm3 ) 

gram per square 

centimeter (g/cm2 ) 

gram per square 

centimeter

Inch-Pound equivalent

combinations Continued

= .0353 cubic foot per second 

= 91.47 cubic feet per second per 

square mile [ (ft3/s)/mi2 ]

= 3.28 feet per day (hydraulic 

conductivity) (ft/d) 

= 5.28 feet per mile (ft/mi)

 .9113 foot per second (ft/s)

 3.28 feet per second

= 10.764 feet squared per day (ft2/d) 

( transmissivity ) 

= 22.826 million gallons per day 

(Mgal/d) 

= 264.2 gallons per minute (gal/min)

= 15.85 gallons per minute 

= 4.83 gallons per minute per foot 

[(gal/min) /ft] 

 .62 mile per hour (mi/h)

= 62.43 pounds per cubic foot (lb/ft3 ) 

= 2.048 pounds per square foot (lb/ft2 ) 

= .0142 pound per square inch (lb/in2 )

Temperature

degree Celsius (°C) 

degrees Celsius 

(temperature)

= 1.8 degrees Fahrenheit (°F) 

= rU.SX°C)+32] degrees Fahrenheit
JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES 

IN EASTERN OREGON AND WESTERN IDAHO

By RALPH W. IMLAY

ABSTRACT

Jurassic ammonites of late Bathonian to middle Callovian Age have 

been found in 12,000-13,000 feet (3,660-3,960 m) of strata exposed in 

the area near and south of Izee and Seneca in east-central Oregon. Ammonites of early Callovian Age and possibly also late Bathonian Age 

occur in several hundred feet of black shale exposed along Dennett 

Creek near Mineral, Idaho. Early Callovian ammonites also occur in 

similar black shale exposed on the Oregon side of Snake River Canyon 

about 32 miles (52 km) south of the northeast corner of Oregon.

The late Bathonian near Izee, Oreg., is represented in the upper 700 

feet (213 m) of the Snowshoe Formation by an association of the ammonites Bullatimorphites, Xenocephalites, Kepplerites, Torricelliceras, Iniskinites, Parareineckeia, Cobbanites, and Choffatia. 

Such as association also occurs west of Cook Inlet, Alaska, in the upper 

few hundred feet of the Bowser Formation; this upper part is dated as 

late Bathonian by one occurrence of the Bathonian genus Cobbanites 

only 100 feet (30 m) below an occurrence of Kepplerites, a genus not 

known below the upper Bathonian. The late Bathonian is also possibly 

represented near Mineral, Idaho, by an immature ammonite assigned 

to Cobbanites.

The early Callovian near Izee, Oreg., is represented from 1,000 to 

1,500 feet (305 to 458 m) above the base of the Trowbridge Shale by an 

association of the ammonites Xenocephalites vicarius Imlay, Lilloettia 

buckmani (Crickmay), L. stantoni Imlay, and Kepplerites. It is 

represented in the Mineral area of Idaho by the same genera and most 

of the same species, and it is represented on the Oregon side of Snake 

River Canyon area near Pittsburg Landing by the same species of 

Xenocephalites and Lilloettia and by Grossouvria. Such an assemblage 

occurs west of Cook Inlet, Alaska, in the lower part of the Chinitna 

Formation, associated with and overlying the highest occurrences of 

Iniskinites.

No faunal evidence has been found concerning the age of the lower 

1,000 feet (305 m) of the Trowbridge Shale in the Izee area. 

Nonetheless, the conformable position of this lower part of the 

Trowbridge below the fossiliferous middle part, its unconformable 

position above the Snowshoe Formation, and the southwestward 

overlap of the lower and middle parts of the Trowbridge far beyond the 

upper member of the Snowshoe Formation are similar to those aspects 

of the Iniskinites-bearing beds in the basal part of the Chinitna Formation in southern Alaska. The Iniskinites-being beds, formerly considered to be either of latest Bathonian or earliest Callovian Age, are 

now assigned to the latest Bathonian on the basis of recent discoveries 

in Canada.

Likewise, no faunal evidence is available concerning the age of the 1 

upper part of the Trowbridge Shale in the Izee area, but its 

stratigraphic position shows that it is of early Callovian age.

The late early to middle Callovian in east-central Oregon is 

represented in the Lonesome Formation by the presence of (1) 

Xenocephalites throughout the lower 7,000 feet (2,134 m) of the formation; (2) Lilloettia at one locality about 1,250 feet (381 m) above the 

base of the formation; (3) Pseudocadoceras grevringki (Pompeckj) 

throughout the upper half of the formation; and (4) Pseudocadoceras 

cf. P. grewingki throughout nearly all the formation. In comparison 

with beds containing the ammonite sequence in southern Alaska, the 

beds in the Lonesome Formation that contain Xenocephalites and 

Lilloettia cannot be younger than the middle part of the Paveloff 

Siltstone Member of the Chinitna Formation, which part is of early 

middle Callovian Age. The beds containing Pseudocadoceras, however, 

could represent any part of the Callovian above the basal zone of 

Macrocephalites macrocephalus. Consideration of both stratigraphic 

and faunal evidence shows that the Lonesome Formation is approximately equivalent to the Paveloff Siltstone Member and is mostly of 

middle Callovian Age, but its basal part must be of late early Callovian 

Age and is probably equivalent to the highest part of the Tonnie 

Siltstone Member of the Chinitna Formation.

INTRODUCTION

Some of the ammonites described herein as of late 

Bathonian to middle Callovian Age were described by 

the writer in 1964 as entirely of early Callovian Age. 

After the publication of the 1964 report, many ammonites were collected by H. J. Buddenhagen in 1967; 

by H. C. Brooks, Gabriel Paris, and T. L. Vallier in 1968; 

by Tom Hendrickson in 1972; by D. W. Taylor in 1973; 

by Paul Smith in 1975; and by R. W. Imlay and W. 0. 

Ross in 1965, 1966, 1969, 1973, and 1975. The ammonites collected by H. C. Brooks and T. L. Vallier are 

from the Oregon side of Snake River Canyon near Pittsburg Landing; those collected by Gabriel Paris and Tom 

Hendrickson are from the vicinity of Mineral in western 

Idaho; those collected by H. J. Buddenhagen are mostly 

from the West Myrtle Butte, Delintment Lake, and 

Sawtooth Creek Quadrangles, east-central Oregon; 

thosexollected by D. W. Taylor and Paul Smith are from 

the upper member of the Snowshoe Formation in the 

Izee Quadrangle, east-central Oregon; and those collected by Imlay and W. 0. Ross are from all listed areas 

in east-central Oregon.

These collections show that certain parts of the formations of Bathonian and Callovian Age are highly 

fossiliferous, whereas other parts are poorly 

fossiliferous. Most of the well-preserved ammonites are
JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES, EASTERN OREGON, WESTERN IDAHO

in concretions. Most of the crushed and fragmentary 

ammonites are on the bedding planes of soft shale and 

are found mainly in roadcuts. Such occurrences suggest 

that trenching of shale units whose ages are in doubt 

should yield identifiable ammonites of age value. 

Many thanks are due the geologists listed, particularly 

H. J. Buddenhagen, for information concerning the 

stratigraphic occurrences of the fossil collections and 

the characteristics of the formations of Bathonian and 

Callovian Age.

BIOLOGIC ANALYSIS

The Bathonian and Callovian ammonites from Oregon 

and Idaho that are described or discussed herein number 

371 specimens. Their distribution by genus, subfamily, 

and family is shown on table 1. Among the nine families 

represented, the Macrocephalitidae constitute 45 percent, the Cardioceratidae, 42 percent, and the 

Perisphinctidae, 8 percent of the total specimens.

TABLE 1. -Ammonite genera of Bathonian and Callovian Age in 

eastern Oregon and western Idaho

Family

Phylloceratidae

Do

Lytoceratidae

Spiroceratidae

Tulitidae

Macrocephalitidae

Do

Kosmoceratidae

Do

Cardioceratidae ___ 

Do

Do

Reineckeiidae?

Perisphinctidae

Do

Do

Do

Do

Subfamily

Phylloceratinae

Calliphylloceratinae

Cadoceratinae ____ 

do

do

Leptosphinctinae _ 

do

Pseudoperisphinctinae 

do

do

Genus

Phylloceras

Cauiphylloceras

Kepplerites

Torricelliceras

Pseudocadoceras _ 

Pseudocadocerasl _ 

Iniskinites

Parareineckeia

Cobbanites

Choffatial

Grossouvria

Number 

of 

specimens

3 

1 

1 

1 

2 

104 

63 

9 

3 

120 

1 

33 

1 

19 

3 

4

1 

2

124° 120°

John Day /oMineral

Suplee^ o Seneca 

~lzee

1-20 / 

i

FIGURE 1.-Index map showing general areas in which Bathonian and (or) Callovian ammonites occur in eastern Oregon and westernmost

Idaho. Numbered ammonite areas are listed in tables 4 and 5.
STRATIGRAPHIC SUMMARY

R. 25 E. R. 26 E. 119°30' R. 27 E. R. 30 E. ;119°00' R. 31 E.

T.16S

T. 20 S

FIGURE 2. - Index map showing Bathonian and Callovian ammonite areas (numbers 1-20) in the Suplee-Izee-Seneca region, east-central

Oregon.

STRATIGRAPHIC SUMMARY 

EAST-CENTRAL OREGON

In the area near and south of Suplee, Izee, and 

Seneca, in east-central Oregon (figs. 1-4), the Bathonian 

and Callovian sequence consists from bottom to top of 

about half the upper member of the Snowshoe Formation and the entire overlying Trowbridge Shale and 

Lonesome Formation (fig. 5). The upper member of the 

Snowshoe Formation, as described by Dickinson and 

Vigrass (1965, p. 45-47), is about 1,250 feet (381 m) 

thick along the South Fork of the John Day River near 

Izee but thickens northeastward to about 2,000 feet (610 

m) and thins southwestward to a featheredge. It consists of poorly exposed volcanic gray to black laminated

mudstone and siltstone that is interbedded with thick 

beds of gray limy volcanic sandstone. The upper 

member of the Snowshoe rests conformably on the middle member in most of the Izee area or on the 

volcaniclastic Silvies Member near the head of Lewis 

Creek. Its contact with the overlying Trowbridge Shale 

is sharp, is marked by a change from laminated 

mudstone and sandstone to massive black or green 

mudstone, and is an unconformity, as is shown by 

gradual but complete southwestward overlap of the 

Trowbridge Shale onto the middle member of the 

Snowshoe Formation (Dickinson, 1962a, p. 252; 1962b, 

p. 483). No faunal evidence for the existence of the upper member of the Snowshoe Formation has been found 

in the Sawtooth Creek, West Myrtle Butte, and Delintment Lake Quadrangles.
JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES, EASTERN OREGON, WESTERN IDAHO

R. 28 E.

FIGURE 3. -Index map showing Bathonian and Callovian USGS Mesozoic localities from which ammonites were collected in the

Izee area, east-central Oregon.

The Trowbridge Shale exposed in the Izee Quadrangle 

thickens northeastward from 2,250 feet (686 m) on Flat 

Creek to 3,250 feet (991 m) on Lewis Creek (table 2) and 

consists mostly of black to green mudstone and shale 

characterized by marble-sized black concretions. It is 

divisible into three members on the basis of the presence 

of some interbedded volcaniclastic beds (middle 

member) that thicken northeastward from 100 feet (30.5 

m) on Flat Creek to 500 feet (152 m) on Lewis Creek 

(Dickinson and Vigrass, 1965, p. 60-64, 96; Dickinson, 

1962a, p. 252) and that overlie 400-500 feet (122-152 m) 

of black to green mudstone (lower member) in the type 

area near Izee.

Southward from the Izee Quadrangle, similar changes 

in the Trowbridge Shale take place from east to west, 

according to studies made by H. J. Buddenhagen (written communs., 1967, 1969, 1977, 1978). Thus, in the 

northwestern part of the Delintment Lake Quadrangle, 

the formation is about 1,000 feet (305 m) or less in 

thickness and consists mostly of black mudstone and

shale. About 10 miles (16 km) to the east near Alder 

Creek, the Trowbridge Shale is at least 1,600 feet (488 

m) thick. Another 10 miles (16 km) farther east near 

Bear Creek, the Trowbridge contains some thin units of 

fine-grained sandstone and tuff in its upper part and is 

at least 2,000 feet (610 m) thick. Another 13 miles (21 

km) east-northeast of the Bear Creek area, near Jack 

Andy Creek, the Trowbridge is at least 3,800 feet (1,159 

m) thick and consists partly of interbedded shale and tuffaceous siltstone and partly of black laminated shale; it 

also contains many thin to thick beds of sandstone, of 

which some are tuffaceous. These data show that the 

Trowbridge Shale becomes much thicker and sandier 

eastward over a distance of about 33 miles (53 km).

The Trowbridge Shale near Izee rests unconformably 

on beds of different ages (Dickinson and Vigrass, 1965, 

p. 84). Near Izee, its lower member rests on the upper 

member of the Snowshoe Formation, which is herein 

dated as of latest Bathonian Age. Six miles to the 

southwest, at Big Flat, the middle member of the
STRATIGRAPHIC SUMMARY

R.45E. 117°10' R. 46 E. 117°05' R. 6W.

44°35'

R. 7 W.

FIGURE 4.-Index map showing Bathonian (?) and Callovian ammonite areas (numbers 22-25) near Mineral (abandoned), western Idaho.

TABLE 2.-Thicknesses of the Trowbridge Shale in east-central Oregon

Area Approximate thickness Section, township, and range Quadrangle County

Flat Creek__________________

South Fork of John Day River_____

Lewis Creek____________________

Headwaters of Warm Spring, Grindstone, and Twelvemile Creeks.

Alder Creek____________________

Blue Creek_____________________

Bear Creek_____________________

Jack Andy Creek________________

2,250 ft (686 m)____. 

2,750 ft (838 m)____. 

3,250 ft (991 m)_____ 

1,000 ft (305 m) or less.

1,600-1,700 ft (488-518 m)_

2,800 ft (853 m)_________. 

2,000 ft (610 m), incomplete__. 

3,800-4,000 ft (1,100-1,220 m), 

incomplete.

Sec. 15, T. 18 S., R. 27 E______ Izee ____ Grant 

Sec. 28, T. 17 S., R. 28 E______ __ do __ Do. 

Sees. 18 and 19. T. 17 S. R. 28 E__ __ do __ Do. 

NEV4NEV4 sec. 6, T. 19 S., R. 26 E. Delintment Harney

andNWV4sec. 2, T. 19 S., R. 25 E. Lake. 

SV2 sec. 26, T. 20 S., R. 27 E____ Sawtooth Grant

Creek.

SWV4 sec. 27, T. 20 S., R. 28 E___ __ do __ Harney 

Sees. 5 and 6, T. 19 S., R. 29 E___ __ do __ Do. 

Sees. 20, 21, and 29, T. 18 S., R. West Myrtle Grant

31 E. Butte.

Trowbridge Shale rests on the middle member of the 

Snowshoe Formation of late middle Bajocian Age (Imlay, 1973, p. 10). About 20 miles southwest of Izee, in the 

northwestern part of the Delintment Creek Quadrangle, 

the Trowbridge Shale, probably represented only by its 

upper member as exposed near Izee, rests unconformably on the Basey Member of the Snowshoe Formation 

of late middle Bajocian Age (H. J. Buddenhagen, written commun., 1969). East of the Delintment Lake 

Quadrangle, the upper part of the Snowshoe Formation 

directly underlying the Trowbridge Shale contains ammonites of late middle Bajocian Age at Emigrant Creek 

(Imlay, 1973, p. 30) in the south-central part of the 

Sawtooth Quadrangle and at Bear Creek in the northeastern part of the same quadrangle. Evidently the 

Trowbridge Shale transgressed both westward and 

southward from the Izee area.

The unconformity at the base of the Trowbridge Shale 

apparently formed at the same time as that at the base 

of the Chinitna and Shelikof Formations in southern 

Alaska. Thus, the Chinitna Formation in the Talkeetna 

Mountains rests on beds ranging in age from late Bathonian to Early Jurassic (Imlay and Detterman, 1973, p. 

14,15; Imlay, 1975, p. 8, 9,14). West of Cook Inlet, between Tuxedni Bay and Iniskin Bay, the Chinitna Formation rests unconformably on the Bowser Formation 

(Bathonian), whose upper part is truncated northward 

(Detterman and Hartsock, 1966, p. 42; Imlay and Det-
Stage

Talkeetna

Mountains,

Alaska

Iniskin Bay to 

Tuxedni Bay west 

of Cook Inlet, Alaska

Izee-Seneca areas 

of eastern Oregon

Characteristic fossils 

in eastern Oregon

Characteris

in southern 

O

Chinitna 

Formation

Chinitna 

Formation

—7- -?-

0} 

O. 

O.

D

o>

TJ 

T3

Paveloff 

Siltstone 

Member

Pseudocadoceras grewingki

Lonesome 

Formation Lilloettia cf. 

L stantoni

Tonnie

Siltstone

Member

Trowbridge Shale

Lilloettia bucklandi 

and Kepplerites

No fossils found

Parareineckeia, Cobbanites, 

Kepplerites, and Iniskinites

iu

Xenocephalites

Bowser 

Formation

J 

,

Unnamed 

beds

Upper member of 

Snowshoe Formation

Age of basal beds is 

late Bajocian

No fossils found

Cadoceras (Stenoc

stenoloboide, Ps

grewingki and L

stantoni

Cadoceras catostom

Lilloettia buckmani

Iniskinites 

intermedius

Iniskinites cf . /. 

intermedius

Arctocephalites 

cf. A. elegans

Cranocephalites 

cf. C. ignekensis

Cranocephalites cos

7

FIGURE 5.-Correlation of some Middle Jurassic (Bathonian and Callovian) formations and faunas in eastern Oregon and southern Alask
AGES AND CORRELATIONS

terman, 1973, p. 14, 15; Imlay, 1975, p. 14). On the 

Alaska Peninsula, the Shelikof Formation rests unconformably on beds of early middle Bajocian Age (Imlay 

and Detterman, 1973, p. 15; 1977, p. 610). These 

remarkable similarities in areas now far apart (fig. 5) 

could be explained if the areas were once much closer 

together or if the sea level over great distances in the 

Pacific Coast region became somewhat lower during formation of the unconformity and then appreciably higher 

during deposition of the Chinitna and Shelikof Formations and Trowbridge Shale. The fact that Cadoceras is 

absent in the Callovian beds of eastern Oregon but is 

abundant in those beds in Alaska suggests that the two 

areas were fairly far apart during Callovian time.

The Lonesome Formation crops out in the 

southeastern part of the Izee Quadrangle in Grant County, in the northern and eastern parts of the Sawtooth 

Creek Quadrangle in Grant and Harney Counties, and in 

the northern part of the West Myrtle Butte Quadrangle 

in the same two counties. Its type section along the 

South Fork of the John Day River in the Izee quadrangle 

is well exposed, is at least 10,000 feet (3,150 m) thick, 

rests conformably on the Trowbridge Shale, and consists of thin to thick units of hard, massive volcanic gray 

to green graywacke that are characterized by graded 

bedding and sole markings and that alternate with thin 

to thick units of massive dark-gray to black siltstone, 

claystone, and mudstone (Dickinson and Vigrass, 1965, 

p. 64-67; Dickinson, 1962b, p. 483). The Lonesome Formation exposed in the Sawtooth Creek and West Myrtle 

Butte Quadrangles is similar lithologically and in 

thickness to the type section but differs by being less 

well exposed and more folded. Megafossils are rather 

sparse throughout all sections. The Lonesome Formation is overlain by Tertiary volcanic rocks.

SNAKE RIVER CANYON AREA IN IDAHO AND OREGON

Unnamed Jurassic beds exposed near Mineral (abandoned), Idaho (fig. 4), consist, from the base upward, of 

(1) about 300 feet (91 m) of a coarse conglomerate; (2) 

about 100 feet (30 m) of dark-gray thin-to thick-bedded 

sandy tuff; and (3) several hundred feet of dark-gray 

calcareous concretionary shale. The upper part of the 

tuff contains Gryphaea culebra Imlay, which has been 

found in eastern Oregon northwest of Brogan in association with such early Bajocian ammonites as 

Eudmetoceras, Erycitoides, and Tmetoceras (USGS 

Mesozoic loc. 30142). Concretions in the upper unit of 

dark shale contain ammonites that are identical with 

those of Callovian Age in the Trowbridge Shale in the 

Izee area of east-central Oregon.

Unnamed Jurassic rocks occur on the Oregon side of 

Snake River Canyon about 32 miles (52 km) south of the 

northeast corner of Oregon near Pittsburg Landing (fig.

1). These rocks consist of black shale and brown 

graywacke, are tightly folded, are at least several hundred feet thick, and rest unconformably on Upper 

Triassic rocks (Vallier, 1968, p. 247). The fossils present 

consist mostly of ammonites identical with those in 

similar shaly beds near Mineral, Idaho, and in the 

Trowbridge Shale of east-central Oregon. Other fossils 

include a fish scale, a large tooth, and belemnite 

fragments.

AGES AND CORRELATIONS

SNOWSHOE FORMATION IN EAST-CENTRAL OREGON

The lower and middle members of the Snowshoe Formation in the Izee area are dated by ammonites as late 

Toarcian to late middle Bajocian, as discussed elsewhere 

(Imlay, 1968, p. C14, C16, C44-C46; 1973, p. 25-30). 

The basal part of the upper member is dated as early late 

Bajocian by the presence of Leptosphinctes (Imlay, 1973, 

p. 15, 25, 91, pi. 47, fig. 24). Above is 800-900 feet 

(244-274 m) of beds that have not furnished any ammonites but that, on the basis of stratigraphic position, 

should represent the latest Bajocian and most of the 

Bathonian. In contrast, the upper 700 feet (213 m) of the 

upper member has provided many ammonites that were 

once considered to be of late Bathonian or early Callovian Age, or both (Imlay, 1964, p. D8, D9). The ammonites are now definitely assigned to the late Bathonian (figs. 5 and 6) on the basis of a comparison with 

recently studied Callovian and Bathonian ammonites 

from southern Alaska (Imlay, 1975; 1979).

The ammonite genera of age significance in the upper 

part of the upper member of the Snowshoe Formation 

include Bullatimorphites, Xenocephalites, Kepplerites, 

Torricelliceres, Iniskinites, Parareineckeia, Cobbanites, 

and Choffatia (tables 3 and 4). They do not include 

Lilloettia, whose former identification (Imlay, 1964, p. 

D7) was based on immature specimens of Iniskinites. 

Most genera of age significance are all associated at one 

locality (USGS Mesozoic loc. 26778) about 150 feet (46 

m) below the top of the member; some are associated at 

two or three localities (table 4) that are lower 

stratigraphically. In addition, the lowest occurrences of 

Xenocephalites, Kepplerites, Torricelliceras, Iniskinites, 

and Cobbanites are 550-700 feet (168-214m) 

stratigraphically below the top of the upper member 

(table 3). These data compared with those for the ranges 

of the same ammonite genera in southern Alaska, as 

discussed herein, make possible a definite late Bathonian Age assignment for the uppermost part of the 

Snowshoe Formation.
JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES, EASTERN OREGON, WESTERN IDAHO

Stage

Bathonian

Lower Upper

Callovian

Lower Middle

Unit

Genus and species

Snowshoe Formation 

(upper member)

Trowbridge 

Shale

Lonesome 

Formation

Phylloceras sp —————————————————

Calliphylloceras sp ———————————————

Lytoceras sp —————————————————————————

Bullatimorphites sp————————————————

Lilloettia buckmani (Crickmay)______________ 

L. stantoni Imlay———>•——————————————————— 

L. cf. L. stantoni Imlay ——————————————————— 

L. cf. L. mertonyarivoodi (Crickmay)———————————

.L/. sp ~ ——————————————————

Xenocephalites vicarius Imlay————————————

X. cf. X. vicarius Imlay——————————————

X. ? Sp.-.———————————————————————

Kepplerites cf. K. plenus (McLearn) —————————

K. cf. K. torrense (McLearn) —————————————

K. sp —————————————————————_______-

Torricelliceras izeeensis Imlay, n. sp ————————

T. cf. I", spinosus (Imlay) ———————————————

Iniskinites acuticostatus Imlay, n. sp -—————————

/. cf. 7. acuticostatus Imlay, n. sp ——————————

7. cf. 7. intermedius (Imlay)—————————————

/. martini (Imlay) —————————————————

I. sp—————————————————————

Pseudocadoceras grewingki (Pompeckj; ——————————

P. cf. P. grewingki (Pompeckj) ———————————

Parareineckeia cf. P. hickersonensis Imlay ——————

Cobbanites ochocoensis Imlay, n. sp-——————————— 

r< O. ? 

. op ari ._________________________________ ——

Choffatia cf. C. cerealis Arkell ——————————————— 

(7. ? Sp _____________________________

FIGURE 6. - Stratigraphic ranges of late Bathonian to middle Callovian ammonites in the Suplee-Izee-Seneca region, east-central Oregon. 

(Most fossils were collected where the upper member of the Snowshoe Formation is about 1,500 ft (457 m) thick, the Trowbridge 

Shale about 2,250 ft (686 m) thick, and the Lonesome Formation about 10,000 ft (3,050 m) thick.)
AGES AND CORRELATIONS

TABLE 3-Stratigraphic positions of Bathonian ammonites in the 

upper part of the upper member of the Snowshoe Formation, Izee 

area, Grant County, east-central Oregon

Genera and species

Positions in feet (meters) 

below top of formations

Phulloceras sp ___________________

Calliphylloceras sp _______________

Bullatimorphites sp ______________

Lytoceras sp. juy. ________________

Xenocephalites vicarius Imlay ______

X. ef. X. vicarius Imlay ____________

XI sp _____________________

Kepplerites ef. K. plenus (McLearn) __ 

K. ef. K. tprrensi (McLean) _________

Torricelliceras cf. T. spinosus (Imlay) 

T. izeeensis Imlay, n. sp ___________

Iniskinites acuticostatus Imlay, n. sp. 

I. cf. I. acuticostatus Imlay, no. sp ___ 

I. cf. intermedius (Imlay) __________

I. sp ___________________________

L martini (Imlay)

580 (177)

150

450

310

46)

137)

95)

150-620 (46-189)

220

380

550

!67)

Parareineckeia cl. P. hickersonensis Imlay. 

Cobbanites ochocoensis Imlay, n. sp ______.

C. 1 sp _____________________.

Choffatia cf. C. cerealis Arkell __________

116)

168) 

85-150 (26-46) 

150 (46)

450-580 (137-177) 

110-600 (34-183) 

220 (67) 

600 (183) 

165-620 (50-189) 

640 (195) 

150 (46)

85-700 (26-213) 

380 (116) 

150 (46)

Of the genera listed (table 3), Bullatimorphites in 

Eurasia ranges through the Bathonian and most of the 

Callovian (Hahn, 1971, p. 96). The subgenus Bomburites 

ranges through the upper Bathonian into the middle 

Callovian but is most common in the basal Callovian 

(Hahn, 1971, p. 59, 106). The compressed species that 

Enay (1959, p. 253) assigned to Treptoceras are reported 

by him (1959, p. 255-258) to range through the upper 

Bathonian into the lowermost Callovian 

(Macrocephalites macrocephalus zone). Kepplerites 

ranges from upper Bathonian to upper lower or lower 

middle Callovian.

Xenocephalites in southern Alaska is fairly common 

throughout the Bowser Formation above the basal beds 

characterized by Cranocephalites costidensus Imlay (Imlay, 1979), is common in the lower part of the Tonnie 

Siltstone Member of the Chinitna Formation (Imlay, 

1975, p. 3, 6, 7), and is represented by a single specimen 

from near the middle of the Paveloff Siltstone Member 

of the Chinitna Formation (Imlay, 1953, p. 69, 78, pi. 29, 

figs. 6, 7; 1975, p. 7). Its occurrences in the Bowser Formation represent most of the Bathonian, and occurrences in the lower part of the Chinitna Formation 

represent both uppermost Bathonian and lowermost 

Callovian; its single occurrence in the Paveloff Siltstone 

Member represents lower middle Callovian. The species 

X. vicarius Imlay in Alaska has been found only in the 

lower part of the Chinitna Formation and in the uppermost part of the Bowser Formation.

Kepplerites in the Cook Inlet region of southern 

Alaska is rare in the upper few hundred feet of the 

Bowser Formation and is fairly common throughout the 

lower three-fourths of the Chinitna Formation. Its age 

range in Alaska is late Bathonian to early or early middle Callovian. In the Bowser Formation, it is 

stratigraphically near Iniskinites and Cobbanites. In the 

basal part of the Chinitna Formation, it is associated 

with Lilloettia, Iniskinites, Xenocephalites, and 

Cadoceras. In the uppermost part of its range, it is commonly associated with Cadoceras and Pseudocadoceras 

(Imlay, 1975), p. 6). Whether any occurrence is younger 

than early middle Callovian is doubtful.

Torricelliceras west of Cook Inlet is represented by T. 

spinosus (Imlay), which is found a little below the middle

TABLE 4.- Geographic distribution ofBathonian ammonites in the Izee area, Grant County, east-central Oregon

[Numbered areas 1-7 are shown in figs. 1 and 2]

Upper member of Snowshoe Formation

Genus and species

Phylloceras sp _______________________

Calliphylloceras sp ___________________

Lytoceras sp. juv. _____________________

Bullatimorphites sp ___________________

Xenocephalites vicarius Imlay __________

X. cf. X. vicarius Imlay ________________

X. 1 sp ____________________ _ 

Kepplerites cf. K. plenus (McLearn) ______

K. cf. K. torrensi (McLearn) ____________

Torricelliceras izeeensis Imlay, n. sp _____

T. cf. T. spinosus (Imlay) _______________

Iniskinites acuticostatus Imlay, n. sp _____

I. cf. I. acuticostatus Imlay, n. sup ______

I. cf. I. intermedius (Imlay) _____________

I. sp. _______________________________

I. martini (Imlay) _____________________

Parareineckeia cf. P. hickersonensis Imlay 

Cobbanites ochocoensis Imlay, n. sp. ______

C. ? sp ______________________________

Choffutia cf. C. cerealis Arkell __________

X

X

X X

X __ X ___ 

X __ __ X

X X X

X X __ X X X __.

_ X 

_ X X X
10 JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES, EASTERN OREGON, WESTERN IDAHO

of the Tonnie Siltstone Member of the Chinitna Formation and just above the range of Iniskinites (Imlay, 1975, 

p. 6). It should be of early Callovian Age and a little 

younger than a specimen from eastern Oregon that has 

similar ornamentation.

Iniskinites west of Cook Inlet, in southern Alaska, occurs in the upper part of the Bowser Formation as well 

as in the basal part of the Chinitna Formation. It is 

associated in the lowest part of its range with the 

highest occurrences of Crcmocephalites and the lowest 

occurrence of Xenocephalites. Higher in the Bowser Formation it is associated with Kepplerites, Cobbanites, and 

Chinitnites. Those three genera and Iniskinites also are 

found in the lower two-fifths of the Tonnie Siltstone 

Member of the Chinitna Formation associated with 

Lilloettia, Xenocephalites, and Cadoceras. These 

associations indicated that Iniskinites in southern 

Alaska ranges in age from late middle Bathonian to at 

least late Bathonian. Furthermore, the highest occurrences in the basal part of the Chinitna Formation are 

herein dated as latest Bathonian Age. The fact that Iniskinites acuticostatus Imlay, n. sp., in the upper 

member of the Snowshoe Formation is not associated 

with Lilloettia or Cadoceras indicates that the member 

is not as young as the basal part of the Chinitna Formation, which contains those genera in association with /. 

intermedius (Imlay).

As both species of Iniskinites are useful in making 

fairly close age determinations, the Iniskinites intermedius subzone of Imlay (1975, p. 7) is herein raised 

to the rank of a zone, and the overlying Cadoceras 

catostoma zone in southern Alaska is restricted to occurrences of that species above the range of Iniskinites. 

The new zone of Iniskinites intermedius also includes 

occurrences of that species below the range of Lilloettia 

and Cadoceras, as in the uppermost part of the Bowser 

Formation in southern Alaska. Similarly, a new zone of 

Iniskinites acuticostatus is herein established for the 

f aunal sequence in the upper part of the Snowshoe Formation of eastern Oregon, as described herein.

Parareineckeia west of Cook Inlet is represented in 

the basal part of the Bowser Formation by P. hickersonensis Imlay in association with Cranocephalites 

costidensus Imlay. At Wide Bay on the Alaska Peninsula, it is represented in the lower part of the lower 

member of the Shelikof Formation by P. shelikofana 

(Imlay), which is at about the same stratigraphic position as the lowest occurrence of Lilloettia buekmani 

(Crickmay) but below all local occurrences of Iniskinites 

and Cadoceras (Imlay, 1975, p. 12). These occurrences 

show that Parareineckeia ranges throughout the entire 

Bathonian and that, because of its presence in the 

Shelikof Formation, it could also be of earliest Callovian 

Age. The close resemblance of the Oregon specimen

described as Parareineckeia cf. P. hickersonensis Imlay 

to the inner whorls of P. hickersonensis Imlay from 

southern Alaska definitely suggests a Bathonian Age 

for the upper part of the upper member of the Snowshoe 

Formation.

Cobbanites in southern Alaska occurs with 

Cranocephalites costidensus Imlay in the Wrangell and 

Talkeetna Mountains. West of Cook Inlet at Tuxedni 

Bay, Cobbanites was collected about 150 feet (46 m) 

below the top of the Bowser Formation within a sequence containing Iniskinites and Kepplerites and about 

140 feet (43 m) above Cranocephalites. These occurrences represent most of the Bathonian. Such an age for 

the upper part of the upper member of the Snowshoe 

Formation is favored, therefore, by the presence of Cobbanites at stratigraphic positions ranging from 85 to 700 

ft (26 to 213 m) below the top of that formation.

Chojfatia is represented west of Cook Inlet by one 

large specimen (Imlay, 1953, p. 102, pi. 54, figs. 1, 2; 

Arkell, 1956, p. 536) that is associated with Iniskinites 

intermedius (Imlay, 1953, p. 81; 1975, p. 4, 6) in the 

basal beds of the Chinitna Formation. This occurrence is 

herein dated as latest Bathonian in age. As Choffatia in 

Eurasia ranges in age from middle Bathonian to middle 

Callovian (Arkell and others, 1957, p. L317; Arkell, 

1958, p. 211), it is not useful in determining the exact 

age of the uppermost part of the Snowshoe Formation 

of eastern Oregon.

In summation, the upper part of the upper member of 

the Snowshoe Formation in east-central Oregon is dated 

as late Bathonian by a comparison of its ammonite 

assemblage with assemblages in the Bathonian and 

Callovian sequences of southern Alaska (fig. 5). Such a 

date is proved by the association of Kepplerites, Iniskinites, Parareineckeia, and Cobbanites throughout 

most of the upper 600-700 feet (183-213 m) of the 

Snowshoe Formation (see table 3 and fig. 6); by the fact 

that Kepplerites in southern Alaska and East Greenland 

has not been found below beds of late Bathonian Age; by 

the presence of Cobbanites in southern Alaska only in 

beds of Bathonian Age; by the absence in the Snowshoe 

Formation of Lilloettia and Cadoceras, which in 

southern Alaska do not occur below the Chinitna Formation; and by the close resemblance of an immature 

specimen of Parareineckeia in the Snowshoe Formation 

to P. hickersonensis Imlay from the Bathonian of 

Alaska. This evidence does not prove that the uppermost part of the Snowshoe Formation represents the 

very uppermost Bathonian. Evidently that age is 

represented in Alaska by the lowest part of the Chinitna 

Formation that is characterized by the highest occurrences of Iniskinites, Chinitnites, and Xenocephalites 

vicarius Imlay in association with the lowest occurrences of Cadoceras and Lilloettia. That age could be
AGES AND CORRELATIONS 11

represented in eastern Oregon by the lowest part of the 

Trowbridge Shale.

TROWBRIDGE SHALE IN EAST-CENTRAL OREGON

Ammonites have been found in dark shale in the 

Trowbridge Shale in at least four small areas (table 5; 

fig. 6). Most of them were found in the southwestern 

corner of the Izee Quadrangle on the north side of Flat 

Creek in the central and east-central parts of sec. 15, T. 

18 S., R. 27 E., Grant County, at stratigraphic positions 

ranging from about 1,000 to 1,500 feet (305 to 457 m) 

above the base of the formation, which is about 2,250 

feet (686 m) thick. (See localities listed under column 10, 

table 5.)

In the Izee area, the lower part of the Trowbridge 

Shale could be, on the basis of stratigraphic position, of 

latest Bathonian to early Callovian Age or entirely early 

Callovian. Its middle part is dated as early Callovian by 

an association of the ammonites Lilloettia buckmani 

(Crickmay), L. stantoni Imlay, Xenocephalites vicarius 

Imlay, and Kepplerites cf. T. torrensi (McLearn) (table 

5) and by the absence of Iniskinites. Thus, Lilloettia in 

southern Alaska is not known below the Chinitna Formation, Xenocephalites is rare above the lower two-fifths 

of the Chinitna Formation, and Kepplerites ranges from 

the uppermost part of the Bowser Formation 

throughout about three-fourths of the Chinitna Formation (Imlay, 1975, p. 6, 7, 13). The unfossiliferous but 

conformable upper part of the Trowbridge Shale in the 

Izee area is likewise dated as early Callovian on the basis 

of its conformable stratigraphic position below the 

Lonesome Formation, which contains ammonites of late 

early to middle Callovian Age. The unfossiliferous lower 

part of the Trowbridge Shale in the Izee area occupies 

the same stratigraphic position as the basal beds of the 

Shelikof and Chinitna Formations of southern Alaska 

that likewise rest disconformably on beds of late Bathonian to middle Bajocian Age and likewise are conformable upward with beds of early Callovian Age.

It follows that at least part of the unfossiliferous lower 

part of the Trowbridge Shale should be of the same age 

as the basal beds of the Chinitna and Sheilikof Formations that contain as association of Iniskinites and 

Cadoceras. Such an association, according to Hans 

Frebold (written commun., 1978), is definitely late 

Bathonian on the basis of comparison with an ammonite 

assemblage from the northern Yukon that contains 

species in common with the highest Bathonian of East 

Greenland.

In the northwestern corner of the Delintment Lake 

Quadrangle, ammonites from the basal beds of the 

Trowbridge Shale include Parapatoceras and 

Xenocephalites vicarius Imlay (USGS Mesozoic Iocs. 

29799 and 29800); from 600 to 700 feet (183 to 213 m)

above the base, they include Lilloettia stantoni Imlay 

and X. vicarius Imlay. In the southeastern part of the 

Sawtooth Creek quadrangle, X. cf. X. vicarius Imlay 

was collected (USGS Mesozoic loc. 28666) about 1,200 

feet (366 m) above the base of the Trowbridge Shale, 

which is at least 2,000 feet (610 m) thick and may be 

faulted at its top. In the northeastern part of the West 

Myrtle Butte Quadrangle near Jack Andy Creek, Kepplerites sp.(USGS Mesozoic loc. 31454) was collected in 

the upper part of the Trowbridge Shale about 3,100 feet 

(945 m) above its base. Nearby, in the southeastern corner of the Logdell Quadrange, X. cf. X. vicarius Imlay 

(USGS Mesozoic loc. 29419 and 29420) was probably collected near the top of the Trowbridge Shale, which is 

estimated as at least 3,800 feet (1,159 m) thick.

In the Delintment Lake area, the association of 

Parapatoceras and Xenocephalites in the basal beds of 

the Trowbridge Shale shows that those beds are either 

of late Bathonian or early Callovian Age. The presence 

of Lilloettia stantoni Imlay considerably above the basal 

beds shows that the upper part of the formation in that 

area is of early or early middle Callovian Age on the 

basis of a comparison with the ammonite succession in 

southern Alaska (Imlay, 1975), p. 6, 14). Correlation of 

the entire Trowbridge Shale in the Delintment Lake 

area with only the upper member of the Trowbridge 

Shale in the type area near Izee is favored by the fact 

that the lower member disappears southwestward from 

Izee within a few miles and that the middle member 

thins markedly southwestward to only 100 feet (30 m) on 

Flat Creek (Dickinson and Vigrass, 1965, p. 60, 61, 84).

The presence of Kepplerites near the top of the 

Trowbridge shale in the Logdell Quadrangle indicates 

that the formation is not younger than the earliest middle Callovian of Europe or the middle part of the 

Paveloff Siltstone Member of the Chinitna Formation in 

southern Alaska (Imlay, 1975, p. 6, 14).

LONESOME FORMATION IN EAST-CENTRAL OREGON

The Lonesome Formation in east-central Oregon is 

characterized by Xenocephalites vicarius Imlay or by X. 

cf. X. vicarius Imlay throughout its lower 7,000 feet 

(2,134 m), by Lilloettia cf. L. stantoni Imlay at one place 

about 1,250 feet (381 m) above its base, by 

Pseudocadoceras grewingki (Pompeckj) near its middle 

and top, and by P. cf. C. grewingki throughout its upper 

9,500 feet (2,896 m) (see fig. 6 and table 5). When comparisons are made with the Callovian ammonite sequence in southern Alaska, the occurrences of these 

three genera are good evidence that the Lonesome Formation correlates with much of the Alaskan Chinitna 

and Shelikof Formations above the beds characterized 

by Iniskinites and that its age must be late early to middle Callovian.
12 JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES, EASTERN OREGON, WESTERN IDAHO

TABLE 5.-Geographic distribution ofCallovian or possible

[Numbered areas 8-25 are shown

Eastern Oregon

Harney 

County

Delintment 

Lake 

Quadrangle

Grant County

Izee Quadrangle

West Myrtle 

Butte and 

Logdell 

Quadrangles

Trowbridge Shale

8 { 9 | 10 11

Phylloceras sp _____________

Parapatoceras sp __________

Xenocephalites vicarim Imlay 

X. cf. X. vicarius Imlay _____

X X X ____

X? sp

Lilloettia buckmani (Crickmay) _______

L. cf. L. buckmani (Crickmay) ________

L. stantoni Imlay __________________

L. cf. L. stantoni Imlay ______________

L. cf. L. mertonyarwoodi (Crickmay) _ 

L. sp. juv _________________________

L.I sp _________________________

Kepplerites snugharborensis (Imlay) ___ 

K. cf. K. torrensi (McLearn) __________

K. sp ____________________________

Pseudocadoceras grewingki (Pompeckj) 

P. cf. P. grewingki (Pompeckj) ________

Cobbanites! sp. juv _________________

C.I sp ___________________________

Choffatial sp ______________________

Grossouvria sp ____________________

__ X

X

X X

X

X X

X

X X

X

X

JURASSIC BEDS NEAR MINERAL, WESTERN IDAHO

Ammonites from Livingston's locality 88 (Livingston, 

1932, p. 33, 34) near the abandoned mining town of 

Mineral, Idaho, include an association of Lilloettia 

buckmani (Crickmay) and Xenocephalites vicarius Imlay 

(Imlay, 1964, p. D6, D7), which in eastern Oregon occur 

together in the middle part of the Trowbridge Shale and 

in southern Alaska occur together in the lower part of 

the Tonnie Siltstone Member of the Chinitna Formation. 

At another place in the Mineral area (USGS Mesozoic 

loc. 30082), Lilloetia cf. L. buckmani Crickmay is 

associated with Kepplerites snugharborensis (Imlay), 

which in the Tuxedni Bay area, of southern Alaska, occurs in the basal beds of the Chinitna Formation (Imlay, 

1975, p. 4, 6). In addition, near Mineral, the ammonite 

Xenocephalites was found (USGS Mesozoic loc. 28651) in 

association with a small immature ammonite that 

resembles the inner whorls of Cobbanites talkeetnanus 

Imlay (1962, pi. 7, figs. 10,11) from southern Alaska and 

from the highest part of the Snowshoe Formation near 

Izee, in eastern Oregon, as figured herein (pi. 5, figs. 1, 

4-8). If the specimen from the Mineral area actually is

Cobbanites, then beds of Bathonian Age are definitely 

present near Mineral. On the basis of comparison with 

the faunal sequence in southern Alaska, the beds near 

Mineral that contain these ammonites are of latest 

Bathonian to early Callovian Age.

JURASSIC BEDS NEAR PITTSBURG LANDING IN 

NORTHEAST OREGON

Some black shale exposed on the Oregon side of the 

Snake River near Pittsburg Landing likewise may be 

correlated with the Trowbridge Shale of eastern Oregon 

and with the lower part of the Chinitna Formation in 

southern Alaska; the correlation is shown by the association of Lilloettia stantoni Imlay, Xenocephalites vicarius 

Imlay, and Grossouvria. The presence of Grossouvria 

shows that the beds are of early Callovian rather than of 

latest Bathonian Age.

AMMONITE FAUNAL SETTING

The late Bathonian ammonite genera of east-central 

Oregon are of diverse origin. Those characteristic of the 

Pacific realm include Xenocephalites, Iniskinites,
GEOGRAPHIC DISTRIBUTION 

Callovian ammonites in eastern Oregon and western Idaho

in fig. 1]

13

Eastern Oregon

Harney County

Sawtooth 

Creek 

Quadrangle

12 13

Grant County

Izee Quadrangle

Harney County

Sawtooth Creek 

Quadrangle

Lonesome Formation

14 15 | 16 17 18 19 20

Wallowa County

Pittsburg 

Landing 

area

j

Idaho

Washington 

County

Mineral area

Unnamed beds

21 22 23 j 24 j 25

X 2

X

£

X X X X

X X

X X ______ X X

mi inn inn "x~~ mil mi

X

X X

.__ X 

.__ X

X

X

X

X

X X

X X X

X

X

X

Parareineckeia, and Cobbanites. Those found most commonly in the Boreal realm include Kepplerites and Torricelliceras. Those that occur nearly worldwide but are 

rarely Boreal include Phylloceras, Calliphylloceras, 

Lytoceras, and Choffatia. Ammonites representing the 

Pacific and Boreal realms have much in common 

specifically with ammonites in British Columbia and 

southern Alaska.

The early to middle Callovian ammonites of eastern 

Oregon and western Idaho are likewise of diverse origin. 

Xenocephalites and Lilloettia are characteristic of the 

Pacific Realm. Kepplerites and Pseudocadoceras are 

characteristic of the Boreal realm. Parapatoceras and 

Grossouvria are nearly worldwide outside the Boreal 

realm, and Phylloceras occurs mainly outside the Boreal 

realm. These ammonites occur as two assemblages, of 

which the lower of early Callovian Age includes all the 

genera listed and the upper includes Pseudocadoceras 

and Xenocephalites. Neither assemblage contains 

Cadoceras or its subgenera Paracadoceras and 

Stenocadoceras that are common in Alaska in beds of 

Callovian Age.

GEOGRAPHIC DISTRIBUTION

The geographic occurrences of the Bathonian and 

Callovian ammonites from eastern Oregon and westernmost Idaho described herein are shown in tables 4 and 5 

and figures 1-4. Detailed descriptions of the occurrences are given in table 6.

TABLE 6. -Description of Bathonian and Callovian ammonite localities in east-central Oregon and westernmost Idaho

Area 

No. 

(figs. 1-3)

1

uses

Mesozoic 

locality

No.

30406

Collector's 

field

No.

I73-6-27A

Collector, year of collection, 

stratigraphic assignment, 

descnption of locality

. R W Tmlav and W. O. Ross.

1973. Snowshoe Formation, 

upper member, about 220 ft 

(67 m), below top. North 

side of Wickiser Slough in 

NEV4SWV4NEV4 sec. 13, T. 

17 S., R. 28 E., Izee Quad., 

Grant County, Oreg.
14 JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES, EASTERN OREGON, WESTERN IDAHO

TABLE 6. -Description ofBathonian and Callovian ammonite localities in east-central Oregon and westernmost Idaho-Continued

No. Mesozoic SS5L Collector's

field

Collector, year of collection, 

stratigraphic assignment, 

description of locality

1 —— 30408 I73-7-7A __.

2 —— 30401 I73-6-25A.

2 —— 30402 I73-6-25C

2—— 31407 PSU-A-0744 __

2—— 31409 PSU-A-0753 __

3 —— 30403 I73-6-25C

3 —— 30404 I73-6-26A _____

3 —— 30405 I73-6-26B

W. 0. Ross, 1973. Snowshoe 

Formation, upper member, 

at least 600 ft (183 m) 

below top. North side of 

Wickiser Slough in SE cor. 

SWV4 sec. 12, T. 17 S., 

R. 28 E., Izee Quad., 

Grant County, Oreg.

R. W. Imlay and W. 0. Ross, 

1973. Snowshoe Formation, 

upper member, 110 ft (34 m) 

below top on divide between 

Little Antelope Creek and 

Wickiser Slough in NEV4 

NWASWV4 sec. 13, T. 17 

S., R. 28 E., Izee Quad., 

Grant County, Oreg.

R. W. Imlay and W. 0. Ross, 

1973. Snowshoe Formation, 

upper member 210 ft (64 m) 

below top. About 200 ft. 

(61 m) northwest of USGS 

Mesozoic loc. 30401.

D. W. Taylor, 1973. Snowshoe 

Formation, upper member, 

about 550 ft. (168 m) below 

top. On steep west-facing 

hillside about 600 ft (183 m) 

south of north end of field 

in NE cor. SEViNEVi sec. 

14, T. 17 S., R. 28 E., Izee 

Quad., Grant County, Oreg.

D. W. Taylor, 1973. Snowshoe 

Formation, upper member, 

about 600 ft (183 m) below 

top. On steep south-facing 

hillside in east-central part 

of NE%NE%SE% sec. 14, 

T. 17 S., R. 28 E., Izee 

Quad., Grant County, Oreg.

R. W. Imlay and W. 0. Ross, 

1973. Snowshoe Formation, 

upper member, at least 620 

ft (189 m) below top. 

SWV4NEV4SEV4 sec. 14, T. 

17 S., R. 28 E., Izee Quad., 

Grant County, Oreg.

W. 0. Ross and R. W. Imlay, 

1973. Snowshoe Formation, 

upper member 300-400 ft 

(91-122 m) below top. On 

third low southeasttrending ridge west of head 

of Antelope Creek, slightly 

east of center of SWV4SEV4 

sec. 14, T. 17 S., R. 28 E., 

Izee Quad., Grant County, 

Oreg.

W. 0. Ross and R. W. Imlay, 

1973. Snowshoe Formation, 

upper member, about 700 ft 

(215 m) below top. On 

second low southeasttrending ridge west of head 

of Antelope Creek, 

NEV4SWV4SEV4 sec. 14, T. 

17 S., R. 28 E., Izee Quad., 

Grant County, Oreg.

TABLE 6. -Description ofBathonian and Callovian ammonite localities in east-central Oregon and westernmost Idaho-Continued

Area 

No.

1-3)

USGS

Mesozoic

locality

No.

Collector's Collector, year of collection,

field stratigraphic assignment,

No. descnption of locality

3—— 3U08 PSU-A-0745 __

4 —— 31457 Loc. E

— 30931 I75-8-15B ———— R. w. Imlay, 1975. Snowshoe

Formation, upper member, 

about 640 ft (195 m) below 

top. Near base of north side 

of first gulch south of main 

hayfield in Antelope Creek, 

south-central part of 

NEV4SEV4 sec. 14, T. 17 S., 

R. 28 E., Izee Quad., Grant, 

County, Oreg.

D. W. Taylor, 1973. Snowshoe 

Formation, upper member, 

about 580 ft (177 m) below 

top. At east end of small 

east-trending ridge about 

600 ft (183 m) west of valley 

floor, SE cor. SWViNEttSE 

V4sec. 14,T.17S.,R.28E., 

Izee Quad., Grant County, 

Oreg.

4 —— 26778 F115(3-48-l) —— w. R. Dickinson and R.W.

Imlay, 1957, Snowshoe 

Formation, upper member, 

150 ft (46 m) below top. 

From 50-75 ft (15-23 m) 

northeast of road in eastcentral part of SWViSWA 

sec. 14, T. 17 S., R. 28 E., 

Izee Quad., Grant County, 

Oreg.

Paul Smith, 1975, Snowshoe 

Formation, upper member. 

Float collected about 450 ft 

(137 m) below top. Near 

USGS Mesozoic loc. 30407, 

about 500 ft (152 m) northwest of USGS Mesozoic loc. 

26778, on south bank of 

short gully on east side of 

road to old Parish Ranch in 

SWV4SWV4 sec. 14, T. 17 S., 

R. 28 E., Izee Quad., Grant 

County, Oreg.

R. W. Imlay and W. 0. Ross, 

1973. Snowshoe Formation, 

upper member, about 380 ft 

(116 m) below top. Just 

northwest of road in SWV4 

SWV4sec.l4,T.17S.,R.28 

E., Izee Quad., Grant 

County, Oreg.

4 __ 31410 PSU-A-0811 __ D. W. Taylor, 1973. Snowshoe

Formation, upper member, 

about 150 ft (46 m) below 

top. On hillside east of road 

and 260 ft (79 m) N. 18° W. 

of point where fence line 

along ridge crosses road, in 

SE%SWV4 sec. 14, T. 17 S., 

R. 28 E., Izee Quad., Grant 

County, Oreg.

5 __ 27368 I58-8-28A ____ R. W. Imlay, 1958. Snowshoe

Formation, upper member, 

about 310 ft (94 m) below 

top. East side of Rosebud 

Creek southeast of mouth of 

Capps Creek in SWANWV4 

SWV4 sec. 15, T. 17 S., R. 28 

E., Izee Quad., Grant 

County Oreg.

4 ___ 30407 I73-6-29A
GEOGRAPHIC DISTRIBUTION 15

TABLE 6.-Description of Bathonian and Callovian ammonite localities in east-central Oregon and westernmost Idaho-Continued

Area USGS 

No. Mesozoic 

(figs, locality 

1-3) No.

Collector's 

field

No.

Collector, year of collection, 

stratigraphic assignment, 

description of locality

5 __ 31456 F5-14

6 27369 I58-8-28B

7 __ 30933 175-8-25

8__ 29799 I69-7-15A.

8 __ 29800 I69-7-15B

9 __ 29798 I69-7-9D __.

10 129a

10

10

10

129b 

130 _

131

Paul Smith, 1975. Snowshoe 

Formation, upper member, 

about 400 ft (122 m) below 

top. Near USGS Mesozoic 

loc. 27368 in NWASWA 

sec. 15, T. 17 S., R. 28 E., 

Izee Quad., Grant County, 

Oreg.

R. W. Imlay, 1958. Snowshoe 

Formation, upper member, 

85 ft (26 m) below top. East 

side of Rosebud Creek just 

east of old farmhouse in 

NEV4NEV4NEV4 sec. 21, T. 

17 S., R. 28 E., Izee Quad., 

Grant County, Oreg.

R. W. Imlay, 1975. Snowshoe 

Formation, upper member, 

165 ft (50 m) below top. SW 

V4SEV4 SWV4 sec. 21, T. 17 

S., R. 28 E., Izee Quad., 

Grant County, Oreg.

R. W. Imlay, 1969. Trowbridge Shale, near base. 

About 450 ft (137 m) south 

and 100 ft (30 m) east of 

NW cor. sec. 2, T. 19 S., R. 

25 E., Delintment Lake

§

uad., Harney County, 

reg.

R. W. Imlay, 1969. Trowbridge Shale, near base. 

About 500 ft (152 m) south 

and 20 ft (6 m) east of NW 

cor. sec. 2, T. 19 S., R. 25 

E., Delintment Lake Quad., 

Harney County, Oreg.

W. 0. Ross, 1969. Trowbridge 

Shale, 600-700 ft (183-213 

m) above base. Roadcut on 

west side of Warm Spring 

Creek in NEV4NW1/4NE 1/4 

sec. 6, T. 19 S., R. 26 E., 

Delintment Lake Quad., 

Harney County, Oreg.

R. L. Lupher, 1930. Trowbridge Shale, estimated 

1,000-1,250 ft (305-380 m) 

above base. On north side of 

Flat Creek above mouth of 

Spoon Creek and 200 ft (61 

m) above creek level, 

probably a little northeast 

of center of sec. 15, T. 18 S., 

R. 27 E., Izee Quad., Grant 

County, Oreg.

R. L. Lupher, 1937. Trowbridge Shale. Porbably 

same location as L129a.

R. L. Lupher 1937. Trowbridge Shale, estimated 

1,500 ft (460 m) above base. 

On next spur east of loc. 

129b.

R. L. Lupher, 1937. Trowbridge Shale, near middle. 

N9rth side of Flat Creek 

midway between loc. 129b 

and first tributary of Flat 

Creek that comes in from 

west below Big Flat.

10

10

TABLE 6. -Description of Bathonian and Callovian ammonite localities in east-central Oregon and westernmost Idaho-Continued

Collector's Collector, year of collection,

field stratigraphic assignment,

No. description of locality

10 _ ___ 132 ________ R. L. Lupher, 1937. Trowbridge Snale, lower middle 

part, about 300 ft (91 m) 

below green sandstone that 

overlies concretionary 

shale. Next gully northwest 

from loc. 131.

10 _ ____ 139 ________ R. L. Lupher, 1937. Trowbridge Shale. Near top of 

shale exposures at either 

loc. 131 or 132.

___ F121 _______ S. W. Muller, R. W. Imlay, W.

R. Dickinson, L. W. Vigrass 

and John Beason, 1956. 

Trowbridge Shale, about 

1,000 ft (305 m) above base. 

On north slope of Flat 

Creek a little east of center 

of sec. 15, T. 18S..R.27E., 

Izee Quad., Grant County, 

Oreg.

___ F122 _______ W. R. Dickinson and others,

1956. Trowbridge Shale, 

about 1,250 ft (381 m) above 

base. A little northeast of 

loc. F121 in south-central 

part of SWV4NEV4 sec. 15, 

T. 18 S., R. 27 E., Izee 

Quad., Grant County, Oreg.

11 _ 29419 166-8-5 _____ R. W. Imlay and W. 0. Ross,

1966; Trowbridge Shale, 

probably near top. On ridge 

between Flat Creek and 

Jack Andy Creek in NEVi 

SEV4SW1A sec. 16, T. 18 S., 

R. 31 E., Logdell Quad., 

Grant County, Oreg.

11 _ 29420 I66-7-22B ____ R. W. Imlay and W. 0. Ross,

1966. Trowbridge Shale, 

probably near top. Conglomerate on low ridge 

about 300 ft (91 m) east of 

USGS Mesozoic loc. 29419 

in SWV4SEV4 sec. 16, T. 

18 S., R. 31 E., Logdell 

Quad., Grant County, Oreg.

11 _ 31454 Buddenhagen 85 __ H. J. Buddenhagen, 1959.

Trowbridge Shale, about 

3,100 ft (945 m) stratigraphically above sandstone 

unit that was mapped as top 

of Snowshoe Formation. 

On south side of Jack Andy 

Creek in NWV4SWV4 sec. 

21, T. 18 S., R. 31 E., West 

Myrtle Butte Quad., Grant 

County, Oreg.

12 _ 28376 B-94 _______ Marvin "Beeson, R. L. Bateman, and R. W. Imlay, 

1961. Shale probably in 

Trowbridge Shale. South 

side of road near junction 

of Bear Creek and a small 

tributary, in NWV4NWV4 

sec. 4, T. 19 S., R. 29 E., 

Sawtooth Creek Quad., 

Harney County, Oreg.

13 _ 28666 B-87 _______ Marvin Beeson and R. L.

Bateman, 1959. Trowbridge 

Shale, about 800 ft (245 m)
16 JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES, EASTERN OREGON, WESTERN IDAHO

TABLE 6. -Description ofBathonian and Callovian ammonite localities in east-central Oregon and westernmost Idaho-Continued

Area USGS

No. Mesozoic

(figs, locality

1-3) No.

Collector's Collector, year of collection,

field stratigraphic assignment,

No. description of locality

13 __ 28377 B-87

14 __ 26782 F125

15 __ ___ F124

15 __ 27372 I58-9-1B

15 __ 27373 I58-9-1C

16 __ 26780 DDV (4-82-20) __

17 _ 31411 Buddenhagen 148 _

below top and perhaps 

1,200 ft (366 m) above base. 

Light-colored tuff near 

Sawtooth Creek in SE'ANW 

V4 sec. 13, T. 20 S., R. 28 E., 

Sawtooth Creek Quad., 

Harney County, Oreg.

Maryin Beeson, 1960. Trowbridge Shale, from about 

same place as USGS Mesozoic loc. 28666. Sawtooth 

Creek in center of sec. 13, 

T. 20 S., R. 28 E., Sawtooth 

Creek Quad., Harney County, Oreg.

R. W. Imlay, 1957. Lonesome Formation, 1,250- 

1,500 ft (380-455 m) above 

base. Roadcut in Antelope 

Creek about 1 lk miles (2 

km) by road southwest of 

Emil Hyde ranch house, 

near SE cor. NWXA sec. 27, 

T. 17 S., R. 28 E., Izee 

Quad., Grant County, Oreg.

L. W. Vigrass, 1956. Lonesome Formation, about 

7,000 ft (2130 m) above 

base. On crest of highest 

hill near north edge of the 

NWV4 sec. 3, T. 18 S., R. 28 

E., Izee Quad., Grant 

County, Oreg.

R. W. Imlay and Reed 

Christner, 1958. Lonesome 

Formation, about 4,000 ft 

(1,200 m) above base. Roadcut near bend in South Fork 

of John Day River about 1 

mile (1.6 km) below mouth 

of Antelope Creek in SW 

cor. sec. 34, T. 17 S., R. 

28 E., Izee Quad., Grant 

County, Oreg.

R. W. Imlav and Reed 

Christner, 1958. Lonesome 

Formation, about 8,000 ft 

2,440 m) above base. Near 

beginning of big bend in 

South Fork of John Day 

River in south-central part 

of NWV4 sec. 3, T. 18 S., R. 

28 E., Izee Quad., Grant 

County, Oreg.

John Beeson, 1957. Lonesome 

Formation, near middle. 

About 0.5 mile (0.8 km) 

south of Flat Creek in SWV* 

sec. 18, T. 18 S., R. 28 E., 

Izee Quad., Grant County, 

Oreg.

H. J. Buddenhagen, 1967. 

Lonesome Formation, 

1,250-1,300 ft. (381-396 m) 

above base. From mudstone 

bed below thin sandstone 

bed on treeless southeastfacing slope about 350 ft 

(107 m) northwest of Alder 

Creek, in NEV4SWV4 sec. 

25, T. 18 S., R. 27 E., Sawtooth Creek Quad., Grant 

County, Oreg.

TABLE 6. -Description of Bathonian and Callovian ammonite localities in east-central Oregon and westernmost Idaho-Continued

Area USGS

No. Mesozoic

(figs, locality

1-3) No.

Collector's Collector, year of collection,

field stratigraphic assignment,

No. description of locality

17 _ 31412 Buddenhagen 149 _

17 __ 31413 Buddenhagen 150 _

18 __ 28667 No field number __

18 __ 29421 I66-7-31A.

19 __ 30143 29593B

20 __ 31455 Buddenhagen 86 __

21 __ 29771

22 __ 28651

H. J. Buddenhagen, 1967. 

Lonesome Formation, from 

float about 600 ft (183 m) 

above base. On ridge top 

about 650 ft (198 m) N. 

10°W. of SE cor. SEV4 sec. 

25, T. 18 S., R. 27 E., 

Sawtooth Creek Quad., 

Grant County, Oreg.

H. J. Buddenhagen, 1967. 

Lonesome Formation. Float 

probably from a higher 

stratigraphic position than 

USGS Mesozoic loc. 31411. 

Collected on a tractor road 

about 1,350 ft (412 m) west 

of NE cor. NEV4 sec. 36, T. 

18 S., R. 27 E. Sawtooth 

Creek Quad., Grant County 

Oreg.

Marvin Beeson, 1959. Lonesome Formation, about 

10,006 ft (3,050 m) above 

base. On road from Sawtooth Creek to Yellowjacket 

Creek in SE cor. sec. 25, T. 

19 S., R. 28 E., Sawtooth 

Creek Quad., Harney 

County, Oreg.

R. W. Imlay and Wm. 0. Ross, 

1966. Lonesome Formation, 

about 10,000 ft (3,050 m) 

above base. Roadcut about 

0.25 mile (0.4 km) west of 

Yellowjacket Creek, SEV4- 

SWV4 sec. 30, T. 19 S., R. 29 

E., Sawtooth Creek Quad., 

Harney County, Oreg.

Standard Oil Company of 

California, 1970. Lonesome 

Formation, about 500 ft 

(152 m) above base. NE cor. 

SEV4 sec. 28, T. 20 S., R. 

28 E., Sawtooth Creek

§

uad., Harney County, 

reg.

H. J. Buddenhagen, 1960. 

Lonesome Formation, probably about 3,000 ft (915 m) 

above base in NEV4SWV4 

sec. 11, T. 20 S., R. 28 E., 

Sawtooth Creek Quad., 

Harney County, Oreg.

T. L. VaUier and H. C. Brooks, 

1968. Black shale and brown 

graywacke on Oregon side 

of Snake River near Pittsburg Landing, Idaho, altitude 1,450 ft (442 m), NWV4- 

NWV4SWV4 sec. 28, T. 2 N., 

R. 51 E., Grave Point 

Quad., Wallowa County, 

Oreg.

R. W. Imlay and H. C. Brooks, 

1962. Black shale from roadcut on North Fork of Dennett Creek just below abandoned mining town of Mineral, near center SWV4- 

NWV4 sec. 9, T. 14 N., R. 6 

W., Mineral Quad., Washington County, Idaho.
SYSTEMATIC DESCRIPTIONS 17

TABLE 6.—Description of Bathonion and Callovian ammonite localities in east-central Oregon and westernmost Idaho -Continued,

Area 

No. 

(figs. 

1-3)

USGS

Mesozoic

locality

Collector's 

field 

No.

Collector, year of collection, 

stratigraphic assignment, 

description of locality

23 __ ____ Livingstone 88 __

24 __ 30082

25 __ ____ Hendrickson

D. C. Livingstone, prior to 

1932. Black shale in canyon 

of Dennett Creek near Mineral, Washington County, 

Idaho.

Gabriel Paris, 1968. Black 

shale containing limestone 

nodules exposed in roadcut 

extending from gypsum 

mine to highest part of 

ridge. About 0.37 mile (0.59 

km) N. 82° E. of Tate's 

cabin near Dennett Creek, 

NEV4NEV4 sec. 9, T. 14 N., 

R. 6 W., Mineral Quad., 

Washington County, Idaho.

Tom Hendrickson, 1972. 

Black shale in NWV4NW% 

sec. 10, T. 14 N., R. 6 W., 

Mineral Quad., Washington 

County, Idaho.

SYSTEMATIC DESCRIPTIONS

Family SPIROCERATIDAE Hyatt, 1900

Genus PARAPATOCERAS Spath, 1924

Parapatoceras sp.

Plate 1, figure 1

One laterally crushed external mold of the adoral part 

of an uncoiled ammonite bears ornamentation similar to 

that on Spiroceras and Parapatoceras. Its flank ribs are 

low, fairly narrow, rather closely spaced, incline considerably forward, become a little stronger ventrally, 

and terminate ventrally in fairly prominent conical 

tubercles. In addition, a row of weak tubercles occurs on 

the ribs high on the flanks. The venter is not preserved.

This specimen has ribs similar to those on 

Parapatoceras distans var. densicostatum (Quenstedt) 

(1886, p. 581, pi. 70, fig. 19; Potonie, 1929, p. 254, pi. 19, 

fig. 59) in density and in forward inclination but appears 

to have somewhat stronger ventral tubercles. The ribs 

appear to be weaker and lower than on densely ribbed 

species of Spiroceras, such as S. annulatum (Deshayes) 

from eastern Oregon (Imlay, 1973, p. 55, pi. 1, figs. 

9-16). Assignment of the specimen to Parapatoceras 

rather than Spiroceras is favored by its association with 

Xenocephalites of late Bathonian to early Callovian Age, 

whereas Spiroceras is of late Bajocian age.

Figured specimen. - USNM 248071.

Occurrence. -Trowbridge Shale, near base at USGS 

Mesozoic loc. 29799.

Family TULITIDAE Buckman, 1921

Genus BULLATIMORPHITES Buckman, 1921

Bullatimorphites sp.

Plate 1, figures 2-5, 7

Bullatimorphites is represented in eastern Oregon by 

two small slightly crushed specimens on which only one 

side is preserved. Both specimens are microconchs, as 

shown by the presence on each of an apertural constriction. Their outer whorl appears to be nearly as high as 

wide. Their body chamber occupies about three-fourths 

of a whorl and is markedly contracted. One specimen 

bears a broad ventral collar that is not prefectly preserved but does not appear to be strongly flared.

Their ornamentation consists of thick, irregularly 

spaced ribs that trend radially on the lower part of the 

flank and irregularly in direction on the upper part of 

the flanks. Some of the ribs bifurcate low on the flanks, 

many bifurcate on the middle part of the flanks, and 

some remain simple. The secondary ribs are a little 

weaker than the primary ribs. One specimen bears 

somewhat stronger ribbing than the other.

The suture line is poorly preserved and cannot be 

traced.

These specimens differ from most microconchs of 

Bullatimorphites by being much smaller and less inflated. In size, coiling, ribbing, and apparently also in 

whorl shape they are similar to B. laurenti (Enay) (1959, 

p. 253, 254, pi. 7b, figs. 4a-c; Hahn, 1971, p. 108, pi. 8, 

figs. 7a, b) and to B. crimaciense (Enay) (1959, p. 255, pi. 

7b, figs. 5a, b, 6a, b; Quenstedt, 1886, pi. 78, fig. 8). Both 

those species were placed in a new genus, Treptoceras, 

by Enay (1959, p. 253) but were considered by Hahn 

(1971, p. 106) to be merely compressed taxa of Bomburites (Arkell, 1952, p. 90; Grossouvre, 1891, p. 261, pi. 

9, figs. 6a-c) to which he assigned a subgeneric rank 

under Bullatimorphites.

The correct subgeneric assignment of the Oregon 

specimens of Bullatimorphites must await the discovery 

of adult specimens in which the ventral part of the adult 

apertural collar is well preserved. They cannot be 

assigned to either Bomburites or Treptoceras unless the 

ventral part of that collar is strongly flared.

Figured specimen. - 248072, 248073.

Occurrence. - Snowshoe Formation, upper member, 

about 450 feet (137 m) below the top at USGS Mesozoic 

loc. 31457.
18 JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES, EASTERN OREGON, WESTERN IDAHO

Family MACROCEPHALITIDAE Buckman, 1922

Genus XENOCEPHALITES Spath, 1928

Xenocephalites vicarius Imlay

Plate 1, figures 6, 8-18

Xenocephalites vicariits Imlay, 1953, U.S. Geological Survey Professional Paper 249-B, p. 78, pi. 28, figs. 1-8.

Xenocephalites vicarius Imlay, 1964, U.S. Geological Survey Professional Paper 483-D, p. D14, pi. 1, figs. 23-27.

The characteristics of this species have been summarized by Imlay (1964, p. D14). The species is 

represented in the Izee-Seneca area in eastern Oregon 

by about 45 specimens, near Pittsburg Landing on the 

Snake River in easternmost Oregon by 20 specimens, 

and near Mineral, Idaho, by 4 specimens.

Hypotypes.-USNM. 248074-248078.

Occurrences. -Lonesome Formation at Dickinson's 

loc. F124; Trowbridge Shale at USGS Mesozoic Iocs. 

28376, 29419, 29420, 29798, and 29799; upper member 

of Snowshoe Formation at USGS Mesozoic Iocs. 26778, 

30403, and 31456; unnamed beds at Pittsburg Landing 

on the Snake River at Mesozoic loc. 29771; unnamed 

beds near Mineral, Idaho, at Livingston's loc. 88. The 

species ranges through the upper 600 feet (183 m) of the 

Snowshoe Formation, all of the Trowbridge Shale, and 

the lower 7,000 feet (2,134 m) of the Lonesome Formation.

Genus LILLOETTIA Crickmay, 1930 

Lilloettia stantoni Imlay

Plate 1, figues 20-26

Lilloettia stantoni Imlay, 1953, U.S. Geological Survey Professional Paper 249-B, p. 77, pi. 29, figs. 1-5, 9, 10.

Lilloettia cf. L. stantoni Imlay, 1964, U.S. Geological Survey Proffessional Paper 483-D, p. D14, pi. 2, figs. 13, 16.

The presence of L. stantoni in eastern Oregon has 

been confirmed now at three localities.

Hypotypes.-USNM. 132365, 248079, 248080, 

252631-252633.

Occurrences.-Trowbridge Shale at USGS Mesozoic 

Iocs. 28376 and 29798; unnamed beds at USGS Mesozoic 

loc. 29771 on Oregon side of Snake River at Pittsburg 

Landing.

Family KOSMOCERATIDAE Hang, 1887

Genus KEPPLERITES Neumayr and Uhlig, 1892

Kepplerites snugharborensis (Imlay)

Plate 2, figures 1, 2

Gowericeras snugharborensis Imlay, 1953, U.S. Geological Survey 

Professional Paper 249-B, p. 99, pi. 53, fig. 9.

The holotype is characterized by a rather stout ovate 

whorl section, a moderately wide umbilicus; moderately 

strong primary ribs that incline slightly forward on the 

lower third of the flank and terminate in small conical 

tubercles; and fine, closely spaced secondary ribs that 

outnumber the primary ribs about 3.5 to 1. The species is

now considered to include an Alaskan specimen that has 

slightly weaker ribbing and was originally described as 

Gowericeras sp. (Imlay, 1953, p. 100, pi. 53, figs. 6, 7, 

10).

The species is represented at one locality in western 

Idaho by three specimens. Of these, the smallest bears 

ribbing similar to that on the holotype of K. snugharborensis (Imlay). The largest specimen, herein figured, 

has similar ribbing that becomes a little finer and denser 

adorally.

In Alaska, K. snugharborensis was collected near the 

base of the Chinitna Formation within a sequence 

characterized by Iniskinites intermedius (Imlay) (Imlay, 

1953, p. 65; 1975, p. 4, 6). In western Idaho, the species 

was collected with Lilloettia buckmani (Crickmay), a 

genus that in eastern Oregon is not known below the 

Trowbridge Shale and in Alaska is not known below the 

Chinitna Formation.

Hypotypes.-USNM. 252634.

Occurrence. -Unnamed beds near Mineral, Idaho, at 

USGS Mesozoic loc. 30082.

Kepplerites cf. K. plenus (McLearn) 

Plate 2, figure 9

One large laterally crushed ammonite from the Izee 

area of eastern Oregon is represented by three whorls, 

of which the inner two are mostly septate and the outer 

is nonseptate. The ornamentation on the middle whorl is 

similar to that on the outermost septate whorl and on 

the adapical end of the body chamber of Kepplerites 

plenus (McLearn) (McLearn, 1927, pi. 1, fig. 1; 1929, pi. 

1; Imlay 1953, p. 99, pi. 49, fig. 21). The outer whorl of 

the Oregon specimen bears much coarser ornamentation 

than do those of the illustrated specimens of K. plenus 

just mentioned, but it is much larger and could represent 

that adult body chamber of the same species.

Figured specimen. -USNM 252635.

Occurrence. - Snowshoe Formation about 550 ft (168 

m) stratigraphically below the top of the upper member 

at USGS Mesozoic loc. 31407.

Kepplerites sp. 

Plate 2, figures 12, 13

This species is represented by two laterally compressed specimens. It has a subovate whorl section that 

is higher than wide, an evenly rounded venter, a fairly 

wide umbilicus, and evolute coiling that becomes more 

evolute during growth. Its umbilical wall is low, nearly 

vertical, and rounds evenly into the flank.

Its ribs curve backward on the umbilical wall, incline 

gently forward on the flanks, and cross the venter 

transversely. Its primary ribs are sharp, moderately 

spaced, and terminate in fairly sharp tubercles at about 

two-fifth of the height of the flanks. From these 

tubercles pass pairs of weaker secondary ribs. Most rib
SYSTEMATIC DESCRIPTIONS 19

'S

p. 57, 

12,14) 

(May, 

laving

pairs are separated by single ribs that arise freelj 

the zone of tuberculation. The suture line caniot 

traced.

The species shows some resemblance to Kep^lerite, 

lindgreni Hyatt from California (Crickmay, 1933 

pi. 17, figs. 9,10; Imlay, 1961, p. D-20, pi. 1, figs, 

and to a similar species from southern Alaska 

1961, pi. 1, fig. 13), but it differs from both by 

fewer secondary ribs per primary rib. 

Figured specimens. -USNM 252636 and 252664 

Occurrence. -Trowbridge Shale at USGS M« 

loc. 31454. This occurrence is about 3,100 feet 

above a massive sandstone unit about 700 feet (! 

thick, whose uppermost beds about 3 miles (4.8 

the southwest, near the center of sec. 36. T.18 S. 

E., have furnished Chondrocerasl sp. of probable 

cian Age.

Genus TORRICELLICERAS Buckman, 1922

along 

be

(945

esozoic 

m) 

13m)

km) to 

R. 30 

BajoTorricelliceras izeeensis Imlay, n. sp.

Plate 3, figures 6-10

This species is represented by one much-weathered 

septate specimen whose inner whorls are well preserved 

and by one adult specimen, of which only one side and 

part of the venter is exposed. On the small inner whorls 

(pi. 3, figs. 7-10), the whorl section is depressed ovate; 

the umbilicus is moderate in width; the umbilical wall is 

moderate in height, is vertical at its base, and rounds 

evenly above into low, fairly flat flanks. During growth, 

the umbilicus gradually becomes fairly wide and the 

whorl section higher. On the adult specimen, the body 

chamber is ovate and is apparently as high as wide. The 

body chamber is completely preserved, bears a lateral 

lappet, and occupies about three-fourths of a whorl. It is 

broken at its adapical end by a small fault and as a result 

has moved slightly ventrally with respect jo the 

penultimate whorl. The venter appears to be evenly 

rounded.

The innermost preserved septate whorls bear sharp, 

fairly widely spaced primary ribs that curve slightly forward and terminate in tubercles just below the line of involution, which is near the widest part of the whorl. 

From the tubercles pass pairs of slightly weaker ribs 

that cross the venter transversely and are weakly 

sulcate along the midline of the venter.

Adorally on larger septate whorls and on the body 

whorl, the primary ribs gradually become stronger and 

sharper, curve strongly forward near the aperture, and 

terminate in small conical tubercles at about two-fifths 

the height of the flanks.

Adorally on the larger septate whorls, the secondary 

ribs gradually become much finer than the primaiy ribs, 

branch from the lateral tubercles by twos, or rarely by 

threes, or arise singly between branched ribs, and outnumber the primary ribs three to one. All these secondary ribs incline forward on the flanks but apparently 

cross the venter transversely.

The secondary ribs on the adult body chamber become 

stronger, sharper, and sparser adorally, arise in pairs or 

singly from the tubercles, or rarely arise singly between 

the tubercles, and outnumber the primary ribs two to 

one.

The holotype at a diameter of 109 mm has a whorl 

height of 35 mm and an umbilical width of 51 mm. The 

innermost whorl (pi. 3, figs 8-10) of the paratype at a 

diameter of 17 mm has a whorl height of 6 mm, a whorl 

thickness of 9.5 mm, and an umbilical width of 6.5 mm.

This species bears considerable resemblance to Torricelliceras spinosus (Imlay) (1953, p. 99, pi. 53, figs. 8, 

11) but is more evolute, has much weaker ribs and 

tubercles, has fewer secondary ribs per primary rib on 

its adult body chamber, and apparently has a more compressed whorl section. It is more evolute than T. 

newcora&M(Whiteaves)(McLearn, 1929, p. 12, pi. 5, figs. 

2-4) and has more secondary ribs per primary rib except 

on its body chamber. T. approximatum (Buckman) 

(1922, pi. 336) has similar ribbing on its adult body 

chamber and much coarser ribbing on its septate whorls.

Types.- Holotype USNM 252637; paratype USNM 

252638.

Occurrence. -Snowshoe Formation, upper member, 

about 580 ft (177 m) below the top at USGS Mesozoic 

loc. 31408; about 450 ft (137 m) below top at USGS 

Mesozoic loc. 31457.

Torricelliceras cf. T. spinosus (Imlay)

Plate 3, figure 5

One small fragment bears ribs and tubercles similar to 

those on the outer whorl of T. spinosus (Imlay) (1953, p. 

99, pi. 53, figs. 8, 11; this report, pi. 3, figs. 1-4) from 

the Iniskin Peninsula west of Cook Inlet, Alaska, but differs by having shorter and more prominent primary 

ribs. The Alaskan species occurs a little below the middle 

of the Tonnie Siltstone Member of the Chinitna Formation (Imlay, 1975, p. 5, 6) in association with Cadoceras 

and Pseudocadoceras grewingki (Pompeckj) and a little 

above the range of Iniskinites. In contrast, the Oregon 

specimen was collected within the range of Iniskinites 

and considerably below the beds containing Pseudocadoceras.

Figured specimen. -USNM 252639.

Occurrence. - Upper Member of Snowshoe Formation, 

about 150 feet (48 m) below its top at USGS Mesozoic 

loc. 26778.
20 JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES, EASTERN OREGON, WESTERN IDAHO

Family CARDIOCERATIDAE Siemiradzki, 1891

Genus PSEUDOCADOCERAS Buckman, 1918

Pseudocadoceras grewingki (Pompeckj)

Plate 2, figures 3-8

For synonymy and description see Imlay, 1953, p. 93.

This species is represented in eastern Oregon by at 

least 120 molds, of which the best preserved are from 

USGS Mesozoic loc. 29421. It has a narrowly rounded 

venter, a fairly wide umbilicus, and strong sharp ribs 

that coarsen adorally, incline forward on the venter, and 

bifurcate fairly regularly a little below the middle of the 

flanks. On the body whorl, the secondary ribs tend to be 

loosely united with the primary ribs, and some primary 

ribs remain unbranched.

.ffypofr/pes.-USNM 252640-252644.

Occurrence. - Lonesome Formation at USGS Mesozoic 

Iocs. 26780 and 29421, which are respectively near the 

middle and top of the formation. P. cf. P. grewingki 

(Pompeckj) occurs at USGS Mesozoic Iocs. 30143, 

31455, and 28667 at positions ranging from 500 to 

10,000 feet (152 to 3,049 m) above the base of the 

Lonesome Formation.

Genus INISKINITES Imlay, 1975 

Iniskinites acuticostatus Imlay, n. sp.

Plate 4, figures 3-14

This species is represented by 21 specimens, of which 

two are adults. The whorl section is ovate, a little higher 

than wide, and widest on the lower fourth of the flanks. 

The umbilicus is extremely narrow but opens slightly 

near the aperture of the adult body chamber. The umbilical wall is low, vertical at base, and rounds evenly into the flanks. The flanks are gently convex and merge 

into an evenly rounded venter. The body chamber occupies about three-fourths of a whorl and apparently 

becomes a little higher adorally. The aperture is marked 

by a shallow, forwardly inclined constriction, as exposed 

on the lower part of the flank on one specimen.

The ribs on the septate whorls are high, sharp, 

moderately spaced, and become stronger ventrally and 

adorally. They arise on the umbilical wall, incline gently 

forward on the lower part of the flanks, recurve slightly 

at about the top of the lower third of the flanks, and then 

cross the venter transversely. Most ribs bifurcate between the lower fourth and lower third of the flanks, but 

some remain simple and alternate with single ribs that 

arise along the zone of rib furcation.

The ribs on the body chamber are sharp and high 

where the shell is preserved and gradually become more 

widely spaced. Unforked primary ribs become common 

adorally. Some short ribs arise between simple or forked 

primary ribs. The zone of rib furcation gradually rises 

adorally to a little above the middle of the flanks. This

ribbing persists to near the aperture without reduction 

in strength.

The suture line is poorly preserved and cannot be 

traced accurately.

The holotype at a diameter of about 105 mm has a 

whorl height of 50 mm, an estimated whorl thickness of 

46 mm, and an umbilical width of 9 mm. At a diameter of 

about 80 mm, the whorl height is about 45 mm, the 

estimated whorl thickness is 36 mm, and the umbilical 

width is 7 mm. One small paratype (pi. 4, figs. 3-5) at a 

diameter of 57 has a whorl height of 30 mm and a whorl 

thickness of 27 mm.

This species is more compressed than any other 

described species of Iniskinites. Its features are most 

similar to those of/, intermedius (Imlay) (1953, p. 81, pi. 

31, figs. 1-4, pi. 32, figs. 2, 3, 5, 7, 8; 1975, p. 24, pi. 3, 

figs. 3, 4), from which it differs by having a more compressed whorl section and sharper, higher, and sparser 

ribbing.

Types.- Holotype, USNM 252645; paratypes, USNM 

252646-252653.

Occurrences. -Upper member of the Snowshoe Formation at USGS Mesozoic Iocs. 26778, 30401, 31408, 

and 31410 in eastern Oregon. On the basis of these occurrences, /. acuticostatus occurs from 110 to 600 feet 

(33 to 183 m) below the top of the Snowshoe Formation. 

The species is probably represented also by many small 

immature specimens at USGS Mesozoic Iocs. 30403, 

30404, 30406, and 30933.

Iniskinites cf. I. intermedius (Imlay)

Plate 1, figure 19

One partly crushed and much worn adult body 

chamber bears fine, fairly closely spaced ribbing, which 

is identical with that on /. intermedius (Imlay) (1953, pi. 

31, figs. 1-4, pi. 32, figs., 2, 3, 5, 7, 8; 1975, pi. 3, figs. 3, 

4) and which is much finer and sparser than that on 

specimens of /. acuticostatus Imlay n. sp., which are 

described herein. The smoothness of the venter on the 

adoral third of the body chamber is due to weathering.

Figured specimen. - USNM 252654.

Occurrence. - Snowshoe Formation, upper member, at 

USGS Mesozoic loc. 31409 about 600 feet (183 m) below 

the top of the formation.

Iniskinites martini (Imlay)

Plate 4, figures 1, 2

Kheraiceras martini Imlay, 1953, U.S. Geological Survey Professional

Paper 249-B, p. 80, pi. 32, figs. 1, 4, 6. 

Iniskinites martini (Imlay), 1975, U.S. Geological Survey Professional

Paper 836, p. 24, pi. 4, figs. 1, 3-6.

This species differs from /. intermedius (Imlay) by 

being much stouter and somewhat larger. 

Hypotype.-USNM 252655. 

Occurrence. -Upper member of Snowshoe Formation
REFERENCES CITED 21

at USGS Mesozoic loc. 30931, eastern Oregon. Its occurrence is about 640 feet (195 m) below the top of the 

member.

Family PERISPHINCTIDAE Steinmann, 1890

Genus COBBANITES Imlay, 1962

Cobbanites ochocoensis Imlay, n. sp.

Plate 5, figures 1, 4-8

Cobbanites aff. C. talkeetnanus Imlay, 1964, U.S. Geological Survey 

Professional Paper 483-D, p. D16, pi. 4, figs. 10-13.

Nine specimens from the Snowshoe Formation in 

eastern Oregon differ from C. talkeetnanus Imlay in 

southern Alaska by having a lower, broader whorl section and coarser ribs that are more closely spaced on the 

inner septate whorls and much more widely spaced on 

the outer septate whorls. The adult body whorl becomes 

smooth as in C. talkeetnanus Imlay (1962, p. C 27, pi. 8, 

fig. 1).

Types. -Holotype, USNM 252656; paratypes, USNM 

252657-252660, 132371a, and 132371b.

Occurrences. - Snowshoe Formation, upper member, 

from 85 to 700 feet (26 to 213 m) below the top at USGS 

Mesozoic Iocs. 26778, 27369, 30402, 30404, 30405, 

30406, and 30408.

Genus CHOFFATIA Siemiradzki, 1898 

Choffatia? sp.

Plate 2, figures 10, 11

One immature ammonite represents parts of three 

whorls. Its umbilicus is fairly wide. Its outer whorl is 

subovate and a little higher than wide. Its umbilical wall 

is low and steeply inclined. Its flanks are fairly flat. The 

innermost preserved whorl bears strong, radially trending primary ribs and one constriction. The next larger 

whorl bears slightly stronger radial ribs, one of which 

bifurcates near the middle of the exposed flanks. The 

outermost whorl bears moderately spaced primary ribs 

that are strongest on the umbilical wall and on the lower 

half of the flanks. Some primary ribs remain simple, but 

most bifurcate between the middle and upper third of 

the flanks into much weaker secondary ribs. One 

primary rib bifurcates near the middle of the lower third 

of the flanks, and resulting secondary ribs fork again 

near the middle of the flanks. All secondary ribs trend 

nearly radially on the flanks, cross the venter 

transversely, and become weaker but sharper on the 

venter. Some secondary ribs arise freely near or a little 

above the middle of the flanks.

This specimen is assigned to Choffatia rather than to 

Procerites because of its fairly evolute coiling and the 

presence of constrictions and because its primary ribs 

are somewhat stronger than its secondary ribs. Its 

preservation does not permit a positive generic determination.

Figured specimen. -USNM 252661. 

Occurrence. -Trowbridge Shale, from 600 to 700 feet 

(183 to 213 m) above base at USGS Mesozoic loc. 29798.

Genus GROSSOUVRIA Siemiradzki, 1898 

Grossouvria sp.

Plate 5, figures 2, 3, 9

Two small, laterally crushed fragments of immature 

ammonites are characterized by evolute coiling; by a 

wide shallow umbilicus; by variably strong, variably 

spaced, partly forked ribs that incline forward on the 

flanks and in places curve backward on the venter; and 

by many constrictions. On the outermost preserved 

whorl, about half the ribs fork near the middle of the 

flanks. Simple and forked ribs may or may not alternate. 

Those features all favor an assignment to Grossouvria 

rather than to Siemiradzkia.

Figured specimen.-USNM. 2526662 and 252663.

Occurrence. -Unnamed beds at Pittsburg Landing on 

west side of Snake River in Oregon at USGS Mesozoic 

loc. 29771.

REFERENCES CITED

Arkell, W. J., 1950-1958, Monograph of the English Bathonian 

ammonites: London, Palaeontographical Society, 8 v., 33 pis., 83 

text-figs.

———1956, Jurassic geology of the world: London, Oliver & Boyd, 

806 p., 46 pis., 102 figs.

Arkell, W. J., Kummel, Bernhard, and Wright, C. W., 1957, 

Mesozoic Ammonoidea, in Moore, R. C., ed., Treatise on invertebrate paleontology, Part L, Mollusca 4, Cephalopoda, Ammonoidea: New York and Lawrence, Kans., Geological Society of 

America and University of Kansas Press, p. L80-L437.

Buckman, S. S., 1909-1930, Type ammonites: London, privately published, 7 v. (v. 7 (1930), edited by A. M. Davis.)

Crickmay, C. H., 1933, Mount Jura investigation: Geological Society 

of American Bulletin, v. 44, no. 5, p. 895-926, pis. 23-34.

Detterman, R. L., and Hartsock, J. K., 1966, Geology of the 

Iniskin-Tuxedni region, Alaska: U.S. Geological Survey Professional Paper 512, 78 p., 6 pis., 7 figs.

Dickinson, W. R., 1962a, Metasomatic quartz keratophyre in central 

Oregon: American Journal of Science, v. 260, no. 4, p. 249-266, 6 

figs.

———1962b, Petrology and diagenesis of Jurassic andesitic strata 

in central Oregon: American Journal of Science, v. 260, no. 7, p. 

481-500, 6 figs.

Dickinson, W. R., and Vigrass, L. W., 1965, Geology of the SupleeIzee area, Crook, Grant and Harney Counties, Oregon: Oregon 

Department of Geology and Mineral Industries Bulletin 58, 109

PEnay, Raymond, 1959, Note sur quelques Tulitides (Ammonitina) du

Bathonian: Societe Geologique de France Bulletin, ser. 7, v. 1,

no. 3, p. 252-258, pi. 7b. 

Grossouvre, A. de, 1891, Sur le Callovien de 1'ouest de la France et

sur sa faune: Societe Geologique de France Bulletin [3d ser.], v.

19, p. 247-262, pi. 9. 

Hahn, Wolfgang, 1971, Die Tulitidae S. Buckman, Sphaeroceratidae

S. Buckman und Clydoniceratidae S. Buckman (Ammonoidea)

des Bathoniums (Brauner Jura e) im sudwestdeutschen Jura:
22 JURASSIC (BATHONIAN AND CALLOVIAN) AMMONITES, EASTERN OREGON, WESTERN IDAHO

Baden-Wurttemberg Geologisches Landesamt Jahreshefte, v. 

13, p. 55-122, 13 figs.

Imlay, R. W., 1953, Callovian (Jurassic) ammonites from the United 

States and Alaska-Part 2. Alaska Peninsula and Cook Inlet 

regions: U.S. Geological Survey Professional Paper 249-B, p. 

41-108, pis. 25-55, figs. 3-9.

———1961, Late Jurassic ammonites from the western Sierra 

Nevada, California: U.S. Geological Survey Professional Paper 

374-D, 30 p., 6 pis., 3 figs.

———1962, Jurassic (Bathonian or early Callovian) ammonites from 

Alaska and Montana: U.S. Geological Survey Professional Paper 

374-C, 32 p., 8 pis., 7 figs.

———1964, Upper Jurassic mollusks from eastern Oregon and 

western Idaho: U.S. Geological Survey Professional Paper 

483-D, 21 p., 4 pis., 3 figs.

———1968, Lower Jurassic (Pliensbachian and Toarcian) ammonites 

from eastern Oregon and California: U.S. Geological Survey Professional Paper 593-C, 51 p., 9 pis., 8 figs.

———1973, Middle Jurassic (Bajocian) ammonites from eastern 

Oregon: U.S. Geological Survey Professional Paper 756, 100 p., 

47 pis., 8 figs.

———1975, Stratigraphic distribution and zonation of Jurassic 

(Callovian) ammonites in southern Alaska: U.S. Geological 

Survey Professional Paper 836, 28 p., 6 pis., 9 figs.

———1979, Middle Jurassic (Bathonian) ammonites from southern

Alaska: U.S. Geological Survey Professional Paper 1091, 42 p., 

12 pis., 11 figs.

Imlay, R. W., and Detterman, R. L., 1973, Jurassic paleobiogeography 

of Alaska: U.S. Geological Survey Professional Paper 801, 34 p., 

15 figs.

———1977, Some Lower and Middle Jurassic beds in Puale BayAlinchak Bay area, Alaska Peninsula: American Association of 

Petroleum Geologists Bulletin, v. 61, no. 4, p. 607-611, 2 figs.

Livingston, D. C., 1932, A major overthrust in western Idaho and 

northeastern Oregon: Northwest Science, v. 6, no. 2, p. 31-36.

McLearn, F. H., 1927, Some Canadian Jurassic faunas: Royal Society 

of Canada Transactions, 3d ser., v. 21, sec. 4, p. 61-73, pi. 1.

———1929, Contributions to the stratigraphy and paleontology of 

Skidegate Inlet, Queen Charlotte Islands, British Columbia: 

Canada National Museum Bulletin 54, p. 1-27, 16 pis.

Potonie, Robert, 1929, Die ammonitischen Nebenformen des Dogger 

(Apsorroceras, Spiroceras, Parapatoceras): Preussische 

Geologische Landesanstalt Jahrbuch, v. 50, pt. 1, p. 216-261, pis. 

17-19.

Quenstedt, F. A. von, 1886-87, Die Ammoniten des 

Sehwabischen Jura, v. 2, Der Braune Jura: Stuttgart, E. 

Schweizerbart, p. 441-672, pis. 55-78 (1886); p. 673-815, pis. 

79-90 (1887).

Vallier, T. L., 1968, Reconnaissance geology of the Snake River 

Canyon between Granite Creek and Pittsburg Landing, Oregon 

and Idaho: Ore Bin, v. 30, no. 12, p. 233-252, 12 figs.
INDEX

[Italic page numbers indicate major references]

acuticostatus, Iniskinites ______________ 9, 10, 20; pi. 4

Alaska, southern ____________ 5,7,9,10,11,12 

Alaska Peninsula ____________________ 7 

Alder Creek, Oreg ___________________ 4 

Ammonite faunal setting _______________ 12 

annulatum, Spiroeeras _________________________ 14

approximatum, TorriceUiceras ____________ 19

B

Basey Member, Snowshoe Formation _________ 5 

Bear Creek, Oreg ____________________ 4 

Bibliography ______________________ 21 

Big Flat, Oreg ______________________ 4 

Biologic analysis _____________________ 2 

Bomburites _________________________________ 9, 17

Bowser Formation ______________ 5,9,10,11 

buckmani, Lilloettia ___________________ 10,11,12,18

Bullatimorphites __________________________ 2, 7, 17

crimaciense _______________________________ 17

laurenti __________________________________ 17

sp _____________________ 9, 17; pi. 1

Cadoceras _____

catostoma zone __

____ 7,9,10,11,19 

___________ 10

Cadoceratinae _____________________ 2 

Cattiphyttoceras _____________________________ 2, 13

sp __________________________ 9 

Calliphylloceratinae ___________________ 2 

Cardioceratidae _____________________ 2 

catostoma, Cadoceras, zone ______________ 10 

cerealis, Choffatia_______________________________ 9

Chinitna Formation ____________ 5, 7, 9,10,11 

Chinitnites ___________________________________ 10

Choffatia ___________________________ 2, 7,10,13,21

cerealis ____________________________________ 9

sp ____________________ 12, 21; pi. 2 

Cobbanites ________________________ 2, 7,9,10,13,2/

ochocoensis _________________________ 9, 2i; pi. 5

talkeetnanus ____________________________ 12,21

sp _________________________ 12 

Cook Inlet, Alaska ________________ 5, 9,10 

costidensus, Cranocephalites ___________________ 9,10

Cranocephalites ___________________ 10 

costidensus ______________________________ 9, 10

crimaciense, Butlatimorphites ___________________ 17

Gryphaea ______________________________ 7

D

Delintment Lake, Oreg _______________ 11 

densicostatum, Parapatoceras distorts _____________ 17

distorts densicostatum, Parapatoceras _____________ 17

E

Emigrant Creek, Oreg _________________ 5 

Erycitoides ____________________________________ 7

Eudmetoceras __________________________________ 7

Flat Creek, Oreg __________________ 4, 11 

Formations, ages and correlations of _________ 7 

Fossil collections, nature of _______________ 1

Page

Geographic distribution ________________ IS 

Gowerieeras snugharborensis ____________________ 18

Grant County, Oreg ___________________ 7 

grewingki, Pseudocadoceras ________ 11,12,19, 20; pi. 2

Grossouvria _____________________________ 2, 13, 21

sp ______________________ 12, 2-; pi. 5 

Gryphaea culebra _______________________________ 7

H

Harney County, Oreg __________________ 7 

s, Parareineckeia _________________ 9,10

Iniskin Bay, Alaska ____ 

Ini&kinites ___________ ._ 2,7,10,11,12,19,1

aotticostoti-s ______________ 9, 10, 20; pi. 4 

intermedius ___________________ 9,10,18,20; pi. 1

zone ______________________ 10 

martini ____________________________ 9, 20; pi. 4

sp __________________________ 9

intermedius, Iniskinites _ 

zone _____________

Introduction ____________

izeeensis, TorriceUiceras __

___ 9,10,18,20; pi. 1 

.___________ 10

____________ 1 

____________ 9, 19; pi. 3

Jack Andy Creek, Oreg. 

John Day River, Oreg _.

._ 4, 11

_____ 7

Kepplerites.

snugharborensis ____ 

torrensi ____ ___

_ 2, 7, 10, 12, 13, 18 

________________ 19

_____ 9, 18; pi. 2 

._____ 12,18; pi. 2 

._______ 9, 11, 12

sp _____________________ 11, 18; pi. 2 

Kheraiceras martini ___________________________ 20

Kosmoceratidae _____________________ 2

laurenti, Bullatimorphites

Leptosphinctinae ___________________. 

Lewis Creek, Oreg __________________ 3, 4 

Lilloettia ___________________________ 2, 9,10,13, 18

buckmani ________________________ 10, 11,12,18

mertonyarwoodi ___________________________ 12

stantoni ________________________ 11, 12, 18; pl.l

sp _________________________ 12 

lindgreni, Kepplerites __________________________ 19

Lonesome Formation ______________ 3, 7, li 

Lytoceras __________________________________ 2, 13

sp ____________________________ 9 

Lytoceratidae ______________________ 2

Macrocephalites macroephalus zone _ 

Macroecephalitidae

macroephalus, Macrocephalites, zone _________ 9

martini, Iniskinites ______________ 9,20; pi. 4

Kheraiceras _____________________ 20

mertonyawoodi, Lilloettia.

Mineral, Idaho __________

Jurassic beds near _

Page

__ 12 

7, 12 

__ 12

N 

newcombii, TorriceUiceras ______________ 19

0 

ochocoensis, Cobbanites ____________ 9,21; pi. 5

P

Paracadoceras _____________________ 13

Parapatoceras ________________ 2,11,13, 17

distorts densicostatum _______________ 17

sp _____________________ 12, -7; pi. 1

Parareineckeia, __________________ 2, 7,13

hickersonensis _________________ 9, 10

shelikofana _____________________ 10

Paveloff Siltstone Member, Chinitna Formation ___ 11

Perisphinctidae _____________________ 2

PhyUoceras _________________________________ 2, 13

sp ________________________ 9, 12 

Phylloceratidae ____________________ 2 

Phylloceratinae _____________________ 2 

Pitsburg Landing, Oreg _________________ 7 

Jurassic beds near _________________ 12 

plenus, Kepplerites ______________________ 9, 18; pi. 2

Procerites ____________________________________ 21

Pseudocadoceras _____________________ 2, 9,13,19,20

grewingki ____________________ 11,12,19,20; pi. 2

Pseudoperisphinctinae _________________ 2

Reineckeiidae ___ _ 2

Seimiradzkia _________________________________ 21

Shelikof Formation _____________ 5, 7, 10, 11 

shelikofana, Parareineckeia, _____________ 10 

Silvies Member, Snowshoe Formation _________ 3 

Snake River ______________________ 12 

Snake River Canyon area _______________ 7

Snowshoe Formation.________

snugharborensis, Gowerieeras ___ 

Kepplerites ________________

spinosus, TorriceUiceras ________

____ 1, 3,4,5,10,12 

_________ 18 

____ 12, 18; pi. 2 

_____ 9, 19; pi. 3

Spiroeeras annulatum __________________________ 17

Spiroceratidae _____________________ 2 

stantoni, Lilloettia ___________________ 11,12, 18; pl.l

Stenocadoceras ____________________ 13 

Stratigraphic summary _________________ 3

Talkeetna Mountains, Alaska _____________ 5 

talkeetnanus, Cobbanites _____________________ 12, 21

Tmetoceras ____________________________________ 1

Tonnie Siltstone Member, Chinitna Formation _ 9,10,12 

torrensi, Kepplerites ______________________ 9, 11, 12

TorriceUiceras _________________________ 2, 7,13, 19

approximatum _____________________________ 19

izeeensis ____________________________ 9, 19; pi. 3

newcombii ________________________________ 19

spinosus ____________________________ 9, 19; pi. 3

23
24 INDEX

Page Page Page 

Treptoceras _________________________________ 9,17 V X

Trowbridge Shale ____________ 3, 4, 5, 7, 11, 12

Tulitidae __ ___ ____ ____________ _ 2 vicarius, Xenocephalites _________ 9,10,11,12, 18; pi. 1 Xenocephalites _________________ 2, 7,10,12,13,17, 18

Tuxedni Bay, Alaska __ __ 5, 12 vicarius ___________________ 9,10,11,12, 18; pi. 1

w sp __________________________ 9, 12

Wide Bay, Alaska _____________________ 10

•6 U.S. GOVERNMENT PRINTING OFFICE: 1980 O— 341-614/225
PLATES 1-5

Contact photographs of the plates in this report are available, at cost, from U.S. Geological Survey 

Library, Federal Center, Denver, Colorado 80225
PLATE 1

[Figures natural size unless otherwise indicated]

FIGURE 1. Parapatoceras sp. (p. 13).

Specimen, USNM 248071 from USGS Mesozoic loc. 29799. 

2-5, 7. Bullatimorphites sp. (p. 17).

2-5. Ventral and lateral views of specimen,.USNM 248072 from USGS Mesozoic loc. 31457. Note that figures 1 and 2 are (X 2).

7. Lateral view (X 2) of specimen, USNM 248073 from USGS Mesozoic loc. 31457. 

6, 8-18. Xenocephalites vicarius Imlay (p. 18)

6, 16. Lateral and ventral views of hypotypes, USNM 248076 from USGS Mesozoic loc. 29799.

8, 9. Hypotype, USNM 248074 from USGS Mesozoic loc. 26778.

10-12. Ventral and lateral views of hypotype, USNM 248077a from USGS Mesozoic loc. 29420.

13, 14. Hypotype, USNM 248075 from USGS Mesozoic loc. 30403.

15. Lateral view of small hypotype, USNM 248077b from USGS Mesozoic loc. 29420.

17, 18. Laterally crushed hypotypes, USNM 248078 from USGS Mesozoic loc. 29771. 

19. Iniskinites cf. /. intermedius (Imlay) (p. 20)

Laterally crushed adult body chamber of specimen, USNM 252654 from USGS Mesozoic loc. 31409. 

20-26. Lilloettia stantoni Imlay (p. 18)

20. Hypotype, USNM 248079 from USGS Mesozoic loc. 29798.

21. 22. Lateral and ventral views of immature specimen. Hypotype, USNM 252633 from USGS Mesozoic loc. 28376.

23. Hypotype, USNM 252632 from USGS Mesozoic loc. 28376.

24. Hypotype, USNM 248080 from USGS Mesozoic loc. 29798.

25. 26. Hypotype, USNM 252631 from USGS Mesozoic loc. 28376.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1142 PLATE 1

19 20 ~24 ~25 26 

PARAPATOCERAS, BULLATIMORPHITES, XENOCEPHALITES, INISKINITES, AND LILLOETTIA
PLATE 2

[All figures are natural size]

FIGURE 1,2. Kepplerites smigharborensis Imlay (p. 18).

Ventral and lateral views of hypotype, USNM 252634 from USGS Mesozoic loc. 30082. 

3-8. Pseudacadoceras grewingki (Pompeckj) (p. 20).

3. Hypotype, USNM 252640 from USGS Mesozoic loc. 29421.

4. 5. Hypotype, USNM 252643 from USGS Mesozoic loc. 29421.

6. Hypotype, USNM 252641 from USGS Mesozoic loc. 29421.

7. Hypotype, USNM 252642 from USGS Mesozoic loc. 29421.

8. Hypotype, USNM 252644 from USGS Mesozoic loc. 29421. 

9. Kepplerites cf. K. plenus (McLearn) (p. 18).

Figured specimen, USNM 252635 from USGS Mesozoic loc. 31407. 

10, 11. Choffatia! sp. (p. 21).

Ventral and lateral views of specimen, USNM 252661 from USGS Mesozoic loc. 29798. 

12, 13. Kepplerites sp. (p. 18).

12. Laterally crushed specimen, USNM 252636 from USGS Mesozoic loc. 31454.

13. Rubber imprint of external mold of inner whorls of specimen, USNM 252664 from USGS Mesozoic loc. 31454.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1142 PLATE 2

KEPPLERITES, PSEUDOCADOCERAS, AND CHOFFATIA?
PLATE 3

[Figures natural size unless otherwise indicated]

FIGURES 1-4. Torricelliceras spinosus (Imlay) (p. 19).

Holotype, USNM 108138 from USGS Mesozoic loc. 22432 in the Chinitna Formation west of Cook Inlet (Imlay, 1953, p. 99, pi.

53, figs. 8, 11). 

5. Torricelliceras cf. T. spinosus (Imlay) (p. 19).

Specimen, USNM 252639 from USGS Mesozoic loc. 26778. Bears ribbing similar to that shown in figure 2. 

6-10. Torricelliceras izeeensis Imlay, n. sp. (p. 19).

6. Holotype, USNM 252637 from USGS Mesozoic loc. 31408. Shows adult body chamber.

7-10. Paratype, USNM 252638 from USGS Mesozoic loc. 31457. Figures 8-10 (X 2) show the features of the small innermost 

whorls.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1142 PLATE 3

TORRICELLICERAS
PLATE 4

[All figures are natural size]

FIGURES 1, 2. Iniskinites martini (Imlay) (p. 20).

Hypotype, USNM 252655 from USGS Mesozoic loc. 30931. 

3-14. Iniskinites acuticostatus Imlay, n. sp. (p. 20).

3-5. Intermediate size septate whorl of paratype, USNM 252649 from USGS Mesozoic loc. 31408.

6, 7, 10, 11. Small septate whorls assigned respectively to paratypes USNM 252650-252653 from USGS Mesozoic loc. 31408.

8. Paratype, USNM 352646 from USGS Mesozoic loc. 31410. Note shallow constriction at adoral end of body chamber.

9. Paratype, USNM 252648 from USGS Mesozoic loc. 30401. Well-preserved ribbing occurs on nonseptate part of specimen. 

12, 13. Holotype, USNM 252645 from USGS Mesozoic loc. 31410. About three-fifths of outer whorl appears to be nonseptate. 

14. Paratype, USNM 252647 from USGS Mesozoic loc. 30401. Well-preserved ribbing occurs on nonseptate part of specimen.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1142 PLATE 4

INISKINITES
PLATE 5

[Figures natural size unless otherwise indicated]

FIGURES 1, 4-8. Cobbanites ochocoensis Imlay, n. sp. (p. 21).

1. Paratype, USNM 252659 from USGS Mesozoic loc. 30406.

4. Paratype, USNM 252658 from USGS Mesozoic loc. 30406.

5. 8. Paratype, USNM 252660 from USGS Mesozoic loc. 30408. Laterally compressed fragments of a large specimen show 

part of the nearly smooth outer whorl and most of the ribbed inner whorls.

6. Paratype, USNM 252657 from USGS Mesozoic loc. 26778.

7. Holotype, USNM 252656 from USGS Mesozoic loc/ 30402. 

2, 3, 9. Grossouvria sp. (p. 21).

2 (X2) and 3. Lateral views of specimen USNM 252662 from USGS Mesozoic loc. 29771. 

9. Lateral view of specimen, USNM 252663 from USGS Mesozoic loc. 29771.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1142 PLATE 5

COBBANITES AND GROSSOUVRIA