DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE, Secretary 

UNITED STATES GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, Director 

Professional Paper 95 

SHORTER CONTRIBUTIONS TO 

GENERAL GEOLOGY 

1915 

DAVID WHITE, CHIEF GEOLOGIST 

WASHINGTON 

GOVERNMENT PRJ;NTING OFFlCE 

1916 
THE AGE OF THE OCALA LIMESTONE. 

By CHARLES W jYTHE CooKE. 

INTRODUCTION. 

In 1881 Eugene A. Smith 1 announced the presenc~, underlying large areas in both western and peninsular Florida, of limestone which he correlated with the Vicksburg limestone of 

Mississippi and Alabama and designated by the term Vicksburg limestone. Among the localities he mentioned specifically are Marianna, in Jackson County, and Ocala, in Marion County. 

In the following year Heilprin 2 described a species of Nummulites from fragments of 

rock found by Willcox in Hernando County, on the west coast of Florida, and two years later 

Willcox discovered the nummulitic limestone in place not far away. Heilprin believed the 

rock to be the equivalent, in part, of the "Nutnmulitic" of Europe and, on account of the 

association of the Nummulites with Orbitoides ephippium, considered it to be of Oligocene age. 

At the -meeting of the American Association for the Advancement of Science in 1887 

Johnson 3 said that the rocks mentioned by H ilprin "may be remnants of the Nummulitic 

limestone, which is really a stratum overlying the Vicksburg rocks" near Levyville and is 

apparently conformable with the "Vicksburg stage" but evidently not identical with it. 

The term Ocala appears to have been first formally used by Dall, who described the formation under the heading "Nummulitic beds, Ocala limestone (Oligocene of Heilprin)." He says: 4 

Among the rocks which until recently were not discriminated from the Orbitoides limestone and which appear 

in central Florida directly and conformably to overlie the latter, though no one has described their contact, is a 

yellowish friable rock containing many Foraminifera, conspicuous among which are two species of Nummulites, N. 

willcoxii and N. jloridana Hp. Th.i.s rock was first brought to notice by Mr. Joseph Willcox, and to Prof. Heilprin 

we owe a description of it which discriminates between it and the Vicksburg or Orbitoides rock. The rock was early 

recognized as Eocene, though not discriminated from the earlier beds. It is best displayed at Ocala, Fla., where it 

forms the country rock and has been quarried to a depth of 20 feet without coming to the bottom of the beds. 

Besides Ocala, Dall mentions several localities where the same nummulitic rock is said to 

have been found by Willcox and Johnson. 

At this time little was known of the fauna <J the Ocala limestone, but Dall 5 remarks that 

''vertebrate remains belonging to the cetacean genus Zeuglodon or possibly to Squalodon 

were discovered by Mr. Willcox in the Nummulitic rock of the Ocala quarry, thus adding another 

indication of the close faunal relations of the 1\ ummulitic with the preceding post-Claiborne 

beds." lie adds: 

There is little doubt of the correctness of Prof. Heilprin 's contention that these rocks are the analogue of the socalled Oligocene of the West Indies and of northern Europe. But, while this may be admitted, the propriety of 

regarding the group or series as constituting a distinct epoch, equivalent to or analogous in value to the Eocene, 

Miocene, or Pliocene epochs, which would be inferentially granted by adopting for them the term Oligocene, is a 

very different matter and in Florida receives no justification from the paleontological evidence. 

Four years later, however, a more thorough study of the faunas led to the recognition of 

the correlation of the "Old Miocene," including the Vicksburg limestone, with the Oligocene 

of European geologists. The Oligocene was then accepted by Dall 6 as a separate epoch of 

the North American Tertiary, a view maintained in his subsequent publications. 

1 Smith, E. A., On the geology of Florida: Am. Jour. Sci., 3d ser., vol2L, pp. 292-309, 1881. 

2 Heilprin, Angelo, On the occurrence of nummulitic deposits in Floridt.: Philadelphia Acad. Nat. Sci. Proc., vol. 34, pp. 189-193, 1883. 

a Johnson, L. C., The structure of Florida: Am. Jour. Sci., 3d ser., vol. 6, p. 232, 1887. · 

4 Dall, W.H., Correlation papers-Neocene: U.S. Geol. Survey Bull. 84, pp. 103-104, 1892. 

6 Idem, p. 105. 

6 Guppy, R. J. L., and Dall, W. H., Descriptions of Tertiary fossils from the Antillean region: U. S. Nat. Mus. Proc., vol. 19, No. 1110, pp. 

303-304, ~896. 

107 
108 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1915. 

In 1903 appeared the concluding volume of Dall's monumental work on the Tertiary 

fauna of Florida,t in which is incorporated a brief account of the Ocala limestone, together 

with a list of 59 species of mollusks and foraminifers. The formation is supposed to overlie 

conformably the "Peninsular" limestone, which is believed to represent a higher horizon than 

the typical Vicks burg limestone. 

The next report on the geology of Florida embodying the results of additional field work 

appeared in 1909 and was written by Matson and Clapp,2 who employed the term Vicksburg 

group to include both the Ocala and "Peninsular" limestones of Dall as well as the limestone 

of western Florida, to which they gave the definite formation name Marianna limestone. The 

Marianna, which they considered the stratigraphicequivalent of the upper part of the bluff at 

Vicksburg, Miss., they believed to represent a horizon below the "Peninsular" limestone, but 

they were in doubt as to the stratigraphic relations of the two. They stated that the Ocala 

limestone conforn1ably overlies the "Peninsular" limestone. The geologic conclusions of 

Matson and Clapp were republished with little change in 1913.3 

The most recent contribution to the geology.of Florida•appeared in January, 1915, from 

Dall's pen.4 Although presenting no new information in regard to the Ocala limestone, he 

gives an account of the geologic exploration of the region and repeats his former summary of 

the Ocala fauna. 

The accompanying correlation table shows the present state of knowledge of the sequence 

of Eocene and lower Oligocene formations in Mississippi, Alabama, and Florida. For purposes 

of comparison the sequence for Florida as published by Matson in 1913 is given in a column 

parallel to the one presenting the changes proposed in this paper. 

Correlation table of the Eocene and lower Oligocene formations of Mississippi, Alabama, and Florida . 

.... 

Florida. 

Mississippi. Alabama. 

Matson, 1913. This paper. 

I • 

Ocala limestone. .$~ c:t> ..... 

Cl) ,_....., 

,...,.o ~ ci. '' Peninsular'' lime- O;:::j 

0 <:.>o ...., ;:::j stone. ....,~ 

83 0 <:.>oo 

to ~~ 

Cl) s ~0 

~ ;..:::: Upper bed at Vicks- eP Marianna limestone. r.1'.+3 c:t> & burg.5 ;:::j <:..> ..0 

-~ 00 

~ Lower bed at Vicks- ~ (Buried.) 0 <:..> ~ burg. St. Stephens limestone.6 > <:..> 

~ Red Bluff Marianna lime- clay (Buried.) 

member. stone. 

-- Ocala limestone. 

Jackson formation. (Buried.) 

(Buried.) 

Cl) 

~ 

Claiborne group. (Buried.) (Buried.) c:t> Claiborne group. <:..> 

0 

r.1 

Wilcox group. Wilcox group. (Buried.) (Buried.) 

Midway group. Midway group. (Buried.) (Buried.) 

1 Wagner Inst. Trans., vol. 3, pt. 6, 1903. . 

2Matson, G. C., and Clapp, F. G., Preliminary report on the geology of Florida: Florida Geol. Survey Second Ann. Rept., 1909. 

a Matson, G. C., and Sanford, Samuel, Geology and ground waters of Florida: U.S. Geol. Survey Water-Supply Paper 319, 1913. 

4 Dall, W. H., Fauna of the Orthaulax pug'TULx zone: U.S. Nat. Mus. Bull. 90, 1915. 

s Distinctive names have not been applied to the different beds at Vicksburg. 

&Vaughan's statement that the Vicksburg and Jackson formations can be discriminated in Alabama cu. S. Geol. Survey Prof. Paper 71, pp 

738, 739, 1912) has been fully confirmed by my own unpublished studies, which show that the St. Stephens limestone is susceptible of division. 

into several lithologic and faunal units. 
THE AGE OF THE OCALA LIMESTONE._ 109 

RELATIONS OF THE MARIANNA LIMESTONE TO THE OCALA LIMESTONE. 

During a recent investigation of the stratigraphy and paleontology of the St. Stephens limestone of Alabama I discovered a startling similarity between the fauna of the beds which are 

considered to represent the upper part of the Jaekson formation (the "Zeuglodon bed" of Mississippi and western Alabama) and that of the Ocala limestone of Florida. It became apparent 

not only that many species of the Ocala are present in the Jacksonian deposits of Alabama 

but that they are restricted to that horizon and are not present in the overlying Vicksburgian 

members of the St. Stephens limestone. This conclusion is the more surprising in view of the fact 

that the Ocala limestone has been correlated with the very top of the Vicksburg limestone and, 

if present at all in Alabama, should overlie the Vicksburgian "chimneyrock" of the St. Stephens 

limestone. 

As the work progressed, mo·re and more species of mollusks and echinoids were found to be 

common _to the two faunas, and in i913 a portion of the jaw of Basilosaurus cetoides 1 (the 

Zeuglodon), which had hitherto been thought to be exclusively of Jackson age, was obtained at 

the type locality of the Ocala limestone. 

The obscurity in regard to this similarity of faunas was illuminated by the discovery at 

Marianna, Fla., of soft nummultic limestone containing an abundance of Amusium ocalanum 

and lying unmistakably beneath the Marianna limestone, which is the equivalent of the lower 

Vic\ffiburgian "chimney rock" of Alabama an carries the exclusively Vicksburgian Pecten 

poulsoni,2 as well as many Orbitoides. The section at Marianna is as follows: 

Section on the west bank of Chipola River at the 1JJagon bridge one-half mile east of Marianna, Fla. 

Marianna limestone: 

5. Alternating hard and softer beds of light-colored limestone, very hard and compact in 

places, locally semicrystalline. The lowe! portion contains a considera.ble amount 

of glauconite. The upper portion has been quarried for building stone and contains 

Orbitoides, Pecten poulsoni (var. ?)~ Clypeaster rogersi, and casts of other fossils. The · Feet. 

floor of the. bridge is 9 feet above the base cf this bed ..... · ...... .. ............... ~. 33 

Ocala limestone: 

4. Concealed.......... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

3. Hard creamy-white semicrystalline limestone, apparently a more indurat ed phase of 

bed No. 1. Contains Orbitoides (stellately marked species), Area, Glycymeris, 

Amusium ocalanum, Plicatula (Ocala species), Venericardia..... .. ................. 1! 

2. Concealed ...... . ............... -..... . . . . _._.. ........... .. ..... .. ..... . ..... . .. . .. 4 

1. Soft cream-colored porous [limestone or marl, composed largely of Foraminifera loosely 

packed together. Contains Nummulites, Orbitoides (stellately marked species), 

Bryozoa, Amusium ocalanum, Cardium. Extends beneath water in the river. . . . . . . 5 

The intervals concealed at the bridge are exposed near the mouth of a cavern abou~ 200 

yards below the bridge, where the following supplementary section was observed: 

Section 200 yards below the wagon bridge east ojMarianna, Fla. 

Marianna l~mestone: Feet. 

5. White limestone, the same as bed No.5 of the section at the bridge............... .... . 33 

Ocala limestone: 

4. Soft cream-colored limestone with several species of Orbit~ides and some Bryozoa. . . . . · 1 

3. Hard semicrystalline pinkit?h limestone with large Orbitoides, Flabellum, and Amusium 

ocalanum ............ ........... . .. .. . .. . .... ...... .. ...... . .. .. ... ·. . . . . . . . . . . . . . . 6l 

2. Soft granular cream-colored limestone much like No. 1 of section at bri<,lge but with 

fewer Foraminifera. Contains Orbitoides (stellately ma:rked species), Flabellum, 

Bryozoa, Terebratulina lachryma?, Natica, Area, Pecten indecisus, Amusium ocalanum, 

and Plicatula (Ocala species)....... .. ... ... ................ ... .................. 3 

1. Concealed to water level in Chipola River ... ... ...... . ... . . .. . ... .......... -.. . . . . . . 3 

1 Identified by J. W. Gidley. 

2 Erroneous statements regarding the stratigraphic range of Pecten pou.~ soni and of Pecten perplanus have from time to time appeared in the 

literature. Contrary to the general opinion, the two species cited do not occur together. Pecten poulsoni is exclusively Vicksburgian, whereas 

Pecten perplanus is restricted to deposits older than the Red Bluff clay member and is probably confined to the Jackson formation, though it may 

range down into the upper Claiborne. As these two pectens have a narrow stratigraphic range and a wide areal distribution and flourished in 

great abundance under very dissimilar conditions of sedimentation, they fcrm exceptionally good index fossils. Moreover, they may readily be 

distinguished from each other and are not likely to be confused with other species. 

82646°-16-8 
110 SHO~TER CONTRIBUTIONS TO GENERAL GEOLOGY, 1915. 

Bed No. 5 of these sections. is the Marianna limestone, the lower portion of which is the 

stratigraphic equivalent of the Red Bluff clay member of the Vicksburg limestone of Mississippi 

and western Alabama. Beds 1 to 4, inclusive, belong to the Ocala limestone, as is shown by the 

included fossils. 

The·lower bed of the Marianna limestone forms a hard projecting ledge which in several 

places in the vicinity serves as the roof to small caverns excavated in the softer Ocala limestone. 

I could detect no evidence of unconformity between the two formations. 

The same nummulitic limestone crops out along Flint River in the vicinity of Bainbridge, 

Ga., where it is almost identical in lithologic appearance and fossil content with the exposure 

at Marianna. In 1900 the identity of the rock near Bainbridge with the Ocala limestone was 

recognized by Vaughan/ and 11 years later his notes on the geology of this region were incorporated in a report by Veatch and Stephenson.2 My own observations, made during a twoweeks' stay at Bainbridge, have confirmed in every respect Vaughan's account of the stratigraphic relations of the rocks exposed along Flint River. . . · 

The lowest rock exposed in the vicinity of Bainbridge is a white to yellow, partly consolidated foraminiferal limestone like that of the lower bed at Marianna. It is separated by a 

well-marked erosional unconformity from the overlying series of irregularly bedded sands and 

variegated clays with chert blocks carrying corals and mollusks of earliest Chattahoochee age. 

At Red Bluff,3 7 miles above Bainbridge, the following fossils were obtained from the 

Ocala limestone: 4 

Orbitoldes papyracea (Boubee). 

Orbitoides n. sp. (stellately marked form). 

Nummulites willcoxi Heilprin. 

Echinolampas sp. 

Cassidulus sp. 

Clypeaster sp. 

Pecten suwaneElnsis Dall. 

Pecten indecisus Dall. 

Amusium ocalanum Dall. 

From the Ocala limestone at a bend in the river near the old factory three-fourths of a mile 

north of the Atlantic Coast Line Railway station at Bainbridge, the following species have been 

recently collected: 

Orbltoides sp. 

Nummulites sp. 

Bryozoa, many species. 

Ostrea sp. 

Oligopygus haldermani Conrad. 

Agassizia conradi (Bouve). 

Eupatagus sp. 

Pecten perplanus Morton. 

Amusium ocalanum Dall. 

REVIEW OF DALL'S LIST OF SPECIES FROM THE OCALA LIMESTONE. 

In order to find out whether the fossils which are known to occur at the type locality of 

the Ocala limestone justify the reference of the formation to the high stratigraphic position which 

is assigned to it in all accounts of the geology of Florida, I have undertaken a critical analysis 

of the Mollusca enumerated in 1903 by Dall 5 in his list of species from the Oca)a limestone. 

Dall's summary of the list is as follows: 

The total is about 59 species, of which about 25 appear to be peculiar, 15 are inherited from the Vicksburgian, and 

11 persist as far as the silex beds of Tampa. Two Ocala species are present in the Eocene, four as far up as the Chipola, one reaches the Miocene, and one survives to the present day. · 

Inspection of the list brings to light the fact that among "those also known from Vicksburg" are mentioned Papillina dumosa, Oassis globosa, Oyprt£dia fenestralis, Pinna quadrata, 

1 Vaughan, T. W., A tertiary coral reef near Bam bridge, Ga.: Science, new ser., vol. 12, p. 873, 1900. 

2 Veatch, Otto, and Stephenson, L. W., Preliminary report on the goology of the Coastal Plain of Georgia: Georgia Geol. Survey Bull. 26, pp. 

321-322, 3~333, 1911. ' 

a Not to be confused with the type locality of the Red Bluff clay member of the Vicksburg limestone, which is on Chickasawhay River, Wayne 

County, Miss. 

· 4Veatch, Otto, and Stephenson, L. W., op. cit., p. 320 . 

. 5 D~l, W. H., Tertiary fauna of Florida: Wagner Inst. Trans., vol. 3, pt. 6, pp. 1557, 1558, 1903. 
THE AGE OF THE OCALA LIMESTONE. lll 

Pecten perplanus, Pecten indecisus, Amusium ocalanum, and Plicatula densata, none of which 

have ever been found at Vicksburg. It is evident that Dall intended to imply the "Vicksburg 

or Peninsular limestone" rather than the specific locality Vicksburg, Miss. 

Species from Ocala.-By excluding the ForaJninifera, which require study by a specialist 

on that group, ~nd eliminating those species which are not credited to Ocala, the number is 

reduced to 32 mollusks, of which three (Serpulorbis granifera, Turritella gatunensis, and Pecten 

centrotus) appear to have been referred \0 Ocala by mistake. The abbreviated list is given 

below. 

Those marked 0 are from Ocala; M, from Martin station. Those also known from Vicksburg are marked V, while 

those followed by S are also known from the silex beds of Tampa. An asterisk denotes the survival of the species to 

the recent fauna. 

Aturia (near alabamensis Morton), 0. 

Helix (Cepolis?) sp., 0 . 

Scaphander grandis Aldrich, 0; also Jacksonian. 

Eucymba ocalana Dall, 0; also. Eocene. 

Caricella sp., 0. 

Lyrla musicina Heilprin, 0, S. 

Turbinella polygonata Heilprin, 0, S; also Chipola.? 

Mitra like millingtoni Conrad, 0, V? 

Fusus (Papillina) dumosus Conrad, 0, V. 

Cassis globosa Dall, 0, V. 

Transovula multicarina.ta Dall, 0, M. 

Cyprrea heilprini Dall, 0, S; also Tampa limestone .. 

Cyproodia fenestralis Conrad, 0, V. 

Rim ella smithii Dall, 0 , M. 

Cerithium ocalanum Dall, ·0, M. 

Cerithium sp., 0. 

Turritella var. martinensis Dall, M, 0. 

*Xenophora conchyliophora Conrad, 0, S, V . . 

Amauropsis ocalana Dall, 0. 

Leda multilineata Conrad, 0, M, V. 

Pinna quadrata Dall, 0, V? 

Pecten (lEquipecten) perplanus Morton, 0, V. 

Pecten sp., 0. 

Amusium ocalanum Dall, 0, M, V, S. 

I 

Plicatula densata Conrad, 0, M, V, S. 

Crassatellites sp., M, 0. 

Diplodonta sp., M. 0. 

CJ.rdium sp., 0. 

Fistulana ocalana Dall, 0. 

Of the 29 species in this list, seven are not Famed specifically and seven others ~ppear to be 

peculiar to the Ocala limestone. The peeuliar fpecies are Ovula multicarinata, Rin~ella smithii, 

Oerithium ocalanwm, Turritella martinensis, Amauropsis ocalana, Pinna quadrata, and Fistulana 

ocalana. Two species, Eucymba ocalana and Cassis globosa, are apparently elsewhere restricted 

to the Claiborne group. Seven, Aturia alabamensis, Scaphander grandis, Mitra millingtoni, 

Papillina dumosa, Oyprrea fenestralis, Pecten pe~·planus, and Amusium ocalanum, are restricted 

to the Jackson or have their closest affinities in that formation. Four, Lyria musicina, Turbinella polygonata, Oyprrea heilprini, and Plicatula jdensata, have not been found in beds older than 

the "silex beds" of the Tampa formation. One, Xenophora conchyliophora, is supposed to range 

from the Cretaceous to the Recent, and one, Le(la multilineata, occurs in the Claiborne group of 

Mississippi and Georgia, is very abundant at Jackson, Miss., and is doubtfully reported from 

Vicksburg. J · 

Presenting the preceding statement in ta,ular ,form, we have: 

r:~~t:~~:~~~~:_:::::: : ::::::::::: :::. r:: ::::::::::::::::: : : ::::.:::::::::::::::: ~ Peculiar to the Jackson ........ . ........... . ... . . ... -- ...... -- . .. . -··-·--················· 7 

"Silex beds" of Tampa formation or later........ ..... .. . ........ .. .... . .................... 4 

Cretaceous to Recent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Claiborne W Vicksburg ........................ -- .. .. . .. . .. . . . .. .. .. .. . .. . . .. .. .. .. .. .. .. . 

2

: 

An examination of the specimens on which the determinations of the four species from the 

"silex beds" were based showed that all were ~dentified from poor material and that the correctness of the identifications appears doubtfJI. Two of them apparently occur also in the 

Castle Hayne limestone at Wilmington, N.C., i hich is of Jackson age. 
112 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1915. 

The summary may now be restated as follows: 

Undetermined and peculiar species ... ~...................................................... 14 

Known to occur in the Jackson or earlier ............................ , ____ ...... _............. 13 

Supposed to occur also in the Vicksburg .. _ ....... __ ....... _ ........... _ ........ __ . . . . . . . . . . 2 

Post-Vicksburg (2 doubtful) ......................... _._ ............................. _ .. _.... 3 

32 

Counted twice ............. __ .......... ___ .... __ ._ ... __ .... _ ... __ . __ .. _ ...... _............ 3 

29 

The foregoing analysis shows that the molluscan fauna of the Ocala limestone at the type 

'locality is decidedly Jacksonian in its affinities. The testimony of the mollusks is amply corroborated by that of the vertebrates, echinoids, and bryozoans, 1 and the foraminifers, which 

are now being studied, apparently point to the same conclusion. . 

Species from Martin.-Those species in Dall's.list which are not from. Ocala come, with one 

exception, from Martin, Fla. In addition to some species of undoubte<:tOcala age, the fossils 

listed from Martin include ~hree .Vicksburg species, Drillia servata, F1tsus mississippiensis, and 

Pita ria astartiformis, and four ('silex beds'' spe~ies, Conus planiceps, Latirus florida nus, S erpulorbis granifera, and Ostrea mauricensis. These Vicksburg and "silex beds" species are represented in the collection by siliceous pseudomorphs which n1ay have come from a different 

horizon; the oyster certainly did not come from the Ocala limestone but is probably from the 

Alum Bluff ("Hawthorn") formation, which overlies the Ocala limestone at many localities 

in peninsular Florida. Until f"!Jrther investigations have been made these doubtful species 

had better be eliminated from lists of the Ocala: fauna. 

RELATION OF THE "PENINSULAR" LIMESTONE TO THE OCALA LIMESTONE. 

·Regarding the relation of the "Peninsular" to the Ocala limestone, it may be said that 

the name "Peninsular" is a general term, without type locality, applied to the· "Orbitoidal 

limestone which forms the mass· of the Floridian plateau and which has been * * * generally 

called the Vicksburg limestone" but which "may really form a different [higher] horizon altogether from the typical Vicksburgian and be intermediate between the latter and the nuinmulitic Ocala limestone." 2 ''The two are distinguishable only by their contained fauna, the 

nummulites, a great profusion of other Foraminifera, and a certain number of mollusks being 

characteristic of the Ocala limestone. " 3 

The presence of nummulites in the Ocala limestone appears to have been the chief reason 

for the separation of that- fonnation from the "Peninsular" limestone and the presence or 

absence of nummulites to have been the essential criterion for distinguishing between the two 

formations. Inasmuch as nummulites are known to occur at several different horizons, the 

mere presence of the genus, when not specifically determined, can have very little bearing on 

the correlation of the strata containing it, and its apparent absence from strata whose fauna 

has been insufficiently explored seems scarcely sufficient cause !or discriminating between 

formations which in other respects appear identical. Whether the "Peninsular" limestone or 

any part of it can be distinguished from the Ocala remains to be ascertained. It is certain that 

at ma:r;ty localities in north-central Florida, which are cited in the following section of this paper, 

the twQ appear to beidentical. It is quite possible, however, as Dall has suggested, that more 

than one horizon may be represented in the "Peninsular" limestone, and I have seen places 

where the fauna has a different aspect from that of the Ocala. However, the discrimination 

of. these .beds must await further investigation. 

1 Since the above was written the study ~i the typical Ocala bryozoan fauna ~f north-cen~al Florida has been co~pleted by F. Canu and R. s. 

Bassler, who ha.ve identified accurately the same fauna in the vicinity of Bainbridge and at Rich Hill, Crawford County, Ga . . Dr. Bassler authorizes the statement that this assemblage of Bryozoa shows a marked resemblance to upper Jacksonian faunas, especially those of the "Zeuglodon 

bed" of Alabama, the Castle Hayne limestone of North Carolina, and the corresponding strata at Eutaw Springs, S.C. The result of these studies 

shows that the Bryozoa of the Ocala limestone are quite distinct from typical Vicksburgian faunas and can be correlated only with faunas of upper 

Jacksonian age. 

2 Dall, W. H., Tertiary fauna of Florida: Wagner Inst. Trans., vol. 3, pt. 6, p. 1554, 1903. 

a Idem, p. 1556. 
THE AGE OF THE OCALA LIMESTONE. 113 

LOCAL DETAILS OF TfE OCALA LIMESTONE. 

It may not be out ~f place her~ to anticipate a more comprehensive report by the insertion 

of a few notes on the Ocala limestone at the the locality and at other places in north-central 

Florida. 

Ocala and vicinity.-At plant No. i of the Frlorida Lime Co., on the southwest edge of Ocala, 

the fresh face of the quarry exposed, at the time of my visit in 1913, 40 feet of white lime~tone, 

for the most part amorphous, soft, and porous, but containing scattered lumps of cherty limestone. Fossils are very abundant, especiallyOr?itoides and Amusium ocalanum. I collected also 

Oligopygus haldermani, Laganum floridanum ?, Laganum sp., Mitra aff. ~· millingtoni, Oerithium 

ocal,anum, Turritella aff. T. mississippiensis, Ovula multicarinata, Fissuridea, Pecten suwaneensis, 

Cardium sp., Tellina n. sp. 2 and many others. I All are preserved only as casts except the sea 

urchins and the pectens. The rock contains ~ cavities which are filled with sand, clay, and 

fragments of small bones. On the southern face of the most recent ~orking is a mass of sand 

and ch1:y resembling fuller's earth which has !evidently fallen to its present position by the 

collapse of a cavern roof. The clay resembles t!hat of the Alum Bluff formation. 

· The quarry of the Oakhurst Lime Co. (plartt o. 2, Florida Lime Co.) is south of the tracks 

of the Atlantic Coast Line Railway about 2 miles southeast of Ocala. The rock exposed consists of 52 feet of light cream-colored, very hdmogeneous limestone resembling the· "chimney 

rock" of Alabama. The basal 9 feet is below lthe floor of the quarry but is visible in a small 

cavern. The overburden consists of 1 or 2 feet of dark sandy loam containjng much veg~tbable 

matter. Several crevices and solution cavities, 11 e:x:cept1the cavern mentioned filled with sandy clay and humus, extend to the floor of the pit. !They contain fragments of bones of living species 

of animals. The rock is exceedingly fossilifer9us, containing several species of Orbitoides and 

other ·Foraminifera, several echinoids, and mollusks. Mr. G. C. Fraser, one of the proprietors, 

presented to me several large bones of Basilosaurus cetoides 1 which had been blasted from the 

rock. I obtained also Flabellum, Oligopygus hdldermani, Conus, Cyprrea cf. O.fenestralis, Papilli:W dumosa, Sol~rium, Spondylus, Pecten S'z:-w{neensis, P. P.erplanus, :4-musium ocaZa:nurr:, Cardium, Crassatelhtes, and other forms. This ·1uarry contatns. very ht. tle cher. t, whiCh Is confined mostly, if not entirely, to residual blocks embedded in the clay of the cavity fillings. 

A quarry in the Ocala limestone 1-t miles ea t of Ocala and 100 yards north of the Silver 

Springs road sho~s about 30 feet of massive pprous white limestone with Orbitoides, Amusium 

ocalarium, and other species. The upper portion is cherty, and there are some thin vertical bands 

of chert filling crevices. The overburden cqnsi

1

sts of 2 or 3 feet of soil. 

Zuber.-At plant No. 3 of the Florida Ltme Co., at Zuber post office, 6t miles north of 

Ocala, the quarry is 35 feet deep, exposing 33 feet of soft white porous limestone overlain by 2 

feet of brown sandy soil. The limestone is re rkably homogeneous and free from impurities. 

Fossils are very abundant, the following being represented: Orbitoides, Flabellum, Oligopygus haldermani, 0. wetherbyi, Laganum, 2 sp., Agassizia conradii, Polygyra, Conus, Ovula 

multicarinata, Xenophora, Ostrea, Pecten per'R

1

1

z. anus, Pecten sp., A musium ocalanum, Spondylus, Cardium, and Tellina. ' 

Martin.-About one-eighth of a mile soutlieast of Martin station, 9 miles north of Ocala, a 

small quarry exposes about 15 feet of soft whii e porous limestone, highly fossiliferous in places, 

with very abundant Foraminifera, Oligopygus "fetherbyi?, and Amusium ocalanum. The upper 

portion of the rock is much weathered. In <;>no place near the top is a mass of light-green 

siliceous clay or fuller's earth, and on the surfal e above are fragments of sandstone intermingled 

with limestone and chert. I was unable to detrrmine whether the clay had been deposited in a 

hollow in, the surface of the limestone or whelher it had fallen to its present position by the 

collapse of a cavern roof. The latter suppositipn is the more probable. . 

I I Identified by 1. W. Gidley. 
114 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1915. 

Newberry and vicinity.-In the vicinity of Newberry the Ocala limestone is well exposed in 

many phosphate mines of the ''hard rock'' type. The upper surface of the Ocala is very irregular, 

with high pinnacles projecting above the general level of the rock. In the process of mining, 

the ore, which in most places immediately overlies the limestone, is stripped of£7 leaving the 

uneven surface of the Ocala exposed to view. A photograph showing this feature may be found 

in Sellards's report on the Florida phosphate deposits. 1 The Ocala limestone in this region 

is soft, white, porous, and apparently very pure. It is very fossiliferous and in places is composed almost entirely of Foraminifera. 

At plant No.6 of the Cummer Lumber Co., 1! miles south of Newberry, the following fossils 

were collected: Orbitoides, Lunulites, Agassizia ~' Amblypygus merrilli?, Laganum, Olivula, 

Rimella cf. R. smithii, Pecten suwaneensis, Spondylus, Plicatula, and Cardium. 

At plant No. 10, 1 mile northwest of Newberry, I obtained Orbitoides, Pectensuwaneensis, P. 

perplanus, Spondylus, Plicatula, Crassatellites, and casts of other fossils. Scattered among 

the phosphate rock and on top of the limestone are many lumps of chert that contain Oassidulus 

gouldii and are apparently residual from a younger formation. Similar chert with the same 

species of Cassidulus was found near the top of the pit in plant No. 11. 

At the Franklyn phosphate mine, 1! miles northwest of Newberry, the limestone contains 

Orbitoides, Bryozoa, Oligopygus haldermani, Laganum floridanum, Ostrea, Amusium ocalanum, 

Pecten suwaneensis, P. perplanus, Plicatula, and Crassatellites ~. 

Clark station.-At Clark station on the Atlantic Coast Line Railway, 5 miles south of High 

Springs, there are many abandoned phosphate pits. The Ocala limestone is exposed in the 

bottoms of the pits and in places reaches the surface. The top of the limestone, as laid bare by 

the workings, contains high pinnacles separated by narrow channels from which the phosphatic 

ore has been extracted. The limestone is soft and white, as at the other mines visited. It 

contains Orbitoides, Oligopygus haldermani, and Pecten perplanus. 

Fort White.-At the Fort White phosphate mine, now abandoned, a quarter of a mile 

northwest of Fort White·, Orbitoides, Bryozoa, Oligopygus haldermani?, Pecten perplanus, 

Amusium ocalanum, and Cardium occur in the Ocala limestone. Lying loose in the quarry is 

an enormous bowlder of light-colored silicified limestone containing Oassidulus gouldii, Cylichna ~' 

Glycymeris cf. G. lameyi, and Modiolus cf. M. grammatus. The bowlder is of post-Ocala age. 

SECTIONS IN MISSISSIPPI AND ALABAMA. 

In order that the stratigraphic equivalents of the Ocala limestone in its western extension 

may be available for comparison, several sections from Mississippi and western Alabama are 

given below. . · 

Jackson, Miss.-The following generalized section of the Jackson formation in the Vicinity 

of Jackson, Miss., was published by Hilgard. 2 · 

Sect·ion of Jackson strata at Moody's Branch and McNutt Hills. 

Yellowish-white marl, more or less sandy, sometimes indurate and forming a soft rock; gives 

rise to "bald prairies" in the McNutt Hills. Contains bones of Zeuglodon, vertebrre and 

teeth of fish, Echinus!, Scutella, Hemiaster?, and casts of univalves and bivalves of the Feet. 

Jackson group ....................................................................... 30-45 

Yellowish-white clayey marl, with few fossils-Pecten nuperus, Pinna, Ostrea................ 6-10 

Coarse yellow sand, somewhat clayey, with "Jackson fossils" in a fine state of preservation... 8 

Blue sand with Jackson fossils, mostly detritus............................................. 2 

:Blue sandy clay, fetid, somewhat micaceous; its upper portion filled with oddly shaped ferrugino-siliceous concretions. No fossils.................................................. 10 

Earthy lignite............................................................................ 1 

·Gray laminated clay, interstrati:fied with sand, with traces of stems and leaves................ 10 

1 Sellards~ E.-H., A preliminary paper on the Florida phosphate deposits: Florida Geol. Survey Third Ann. Rept., pl. 2, fig. 1, 1910. 

2 Hilgard, E. W •. Agriculture and geology of Mississippi, p. 131, 1860. 
THE AGE OF THE/ OCALA UMESTONE. 115 

Willow Branch, Ala.-An instructive section showing nearly the entire Jackson formation 

and much of the Claiborne group is exposed i~ the valley of Willow ~ranch, Choctaw County, 

Ala., about 4 miles from Silas on the road to Fail. . I 

Section at WiZlo·w Branch, Ala. 

Post-Vicksburg: . / · · · Feet. 

13. Red sand to top of hill; about........... . . . ........................................ 50 

Jackson formation: J . 

12. Drab calcareous clay with white calcare~us concretions................................ 25 

11. Yellowish marl with Pecten perplanus and Pe1'iarchus pileus-sinensis?. Indurated in lower 

portion .... · ......................... 1.... ........................................ 11 

10. Fine-grained yellow sand ...............•. . ............. ~..... ..... .. .............. 21 

9. Argillaceous yellow sandy marl with shells; grades into the underlying bed............ 9 

8. Greenish-yellow clay with shells, forming a gentle slope; about........................ 50 

Claiborne group: I 

7. Hard gray indurated marl with small grains of glauconite and a few fragmentary shells.... It 

NoTE.-The measurements of the bed~ above No.7 were made on the south side of the 

valley; of those below, on the north side. 

6. Reddish-brown ferruginous glauconitic sand containing casts of mollusks, with a i-foot, 

shell bed at bottom ............. . ... . . J ............... : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

5. Dark-gray to black sandy clay with shells. . .. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3! 

4. Laminated gray sand and clay with Ore daphne inequilateralis and Mespilodaphne columbiana1 ................ : ....................................•.....••.•.•........ 7 

3. Dark-green to black glauconitic sand o~ded with Claiborne shells...................... 2 

2. Dark.:green to black, somewhat sandy lclay. Weathers with fissile parting resembling 

"coal blossom " . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

1. Reddish-brown ferruginous sand to stre,~ be d(~ or 2 feet concealed at bottom)......... 10 

Most of the fossils in the following list were collected by W. C. ·Mansfield from bed No. 9 

of the ~ection, but some came from bed ;No. 8. · 

Endopachys shaleri Vaughan. Pecten (Pseudamusium) scintillatus Conrad. 

Scala sp. Pteria limula (Conrad). 

Turritella sp. Corbula alabamiensis Lea? 

Natica sp. Corbula wailesiana Harris? 

Dentalium sp. Tellina aff. T. vicksburgensis Conrad. 

Nucula spheniopsis Conrad. Spisula sp. 

Leda mater Meyer? Lucina sp. 

Ostrea trigonalis Conrad? Phacoides (Mil tha) claibomensis (Conrad) var.? 

Pecten aff. P. membranosus Morton. r Venericardia planicosta Lamarck. 

The evidence afforded by these fossils is scarcely sufficient in itself to determine positi~ely 

whether the beds from which they came are pf Chiiborne or of J ackson age, but as the beds lie 

above the horizon of the sand bed of the Cl~iborne and resemble more closely the Jackson in 

lithologic appea.rance, they are tentatively referred to the Jackson formation. 

There can be no question as to the Claib ne age of the fossils in the following list, collected 

by W. C. Mansfield from beds Nos. 3 to 6 of ~he section: · 

Turbinolia pharetra Lea. 

Endopachys maclurii (Lea). 

Cyiichua sp. 

Ringicula sp. 

Pleurotoma sp. 

Olivula staminea (Conrad). 

Marginella sp. 

Ptychosalpinx altilis (Conrad). 

Mazzalina inaurata Conrad. 

Pseudoliva vetusta (Conrad). 

Plejona petrosa (Conrad). 

Fusus bell us Conrad, var. 

Calyptraphorus velatus (Conrad). 

Turritella, 2 sp. 

Eulima sp. · 

Natica sp. 

Teinostoma subrotunda Meyer. 

Solariella lineata (Lea). 

Crepidula_lirata Conrad. 

Dentalium sp. 

Nuculasp. 

Led a media (Lea). 

Trinacria cunea (Conrad). 

Corbula, 2 sp. 

Lucina sp. 

Myrtrea curta (Conrad). 

Phacoides alveatus (Conrad). 

V enericardia parva Lea. 

V enericardia planicosta Lamarck. 

Crassatellites protexta (Conrad), var.? 

Meretrix, 2 sp. 

1 Identi.fi d by E. W. Berry. 
116 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1915. 

Oullomburg, Ala.-The relation of the "Zeuglodon bed" to the Red Bluff clay member of 

the Vicksburg limestone is well shown on the road from Millry to Bladon Springs, Ala., 3 or 4 

miles from Millry and about 3! miles southeast of Cullomburg. The section extends from a 

small branch southward along the road. 

Section 3! miles southeast of Cullomburg, Ala. ·Feet. 

8. Concealed to top of hill; about....................................................... 50 

Red Bluff clay member of Vicksburg limestone: 

7. Very plastic gray clay with crystals of gypsum. Contains Pieurotoma plutonica?, P. congesta, Busycon spiniger, B. nodulatum, Phos macilentus, Ostrea vicksburgensis, Pecten aff. 

P. poulsoni, Spondylus dumosus, Corbula perdubia.................................... 22 

6. Green-gray or buff glauconltic marl, consisting of grains of green glauconite the size of bird 

shot, in a white calcareous clay matrix. In the upper portion are several discontinuous 

ledges, and at the top is a more persistent ledge. Contains Balanophyllia caulijera, 

Ostrea vicksburgensis, Pecten cocoanus, Pecten aff. P. poulsoni, Spondylus dumosus, Corhula sp., and Astarte triangulata. The Ostrea and Spondylus weather out of the lower 

2 feet in great abundance but are difficult to see in the unweathered material. . . . . . . . . 9 

Jackson formation: 

5. Stiff calcareous clay, yellow or buff on weathered surface, bluish green on damp, fresh 

surface. Contains small irregular concretions. Merges into the overlying bed......... 8 

4. "Zeuglodon bed," buff argillaceous marl, merging into the overlying bed. Forms a 

gentle slope. Contains Flabellum, Schizaster armiger, Ostrea falco, 0. trigonalis, Gryph~Eostrea, Pinna, Modiolus cretaceus, Pecten perplanus, Terebratulina lachrym(l...... . . . 9 

3. Gray to yellow, very calcareous, argillaceous marl with some hard ledges. Forms steep 

slope. Pecten perplanus, Ostrea trigonalis, and Bryozoa abundant; other fossils represented by casts .................. :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

2. Yell ow calcareous sand with poorly preserved shells and casts of Leda. Some calcareous 

concretions at base................................................................. 18 

1. Steel-gray sandy calcareous clay; about................................................ 3 

It is believed that beds 2 to 5 inclusive are the equivalent of beds 9 to 12 of the section at 

Willow Branch. 

Cocoa, AZa.-Near the site of Cocoa post office, which was located on the road from Gilberttown to Melvin, Choctaw Coun.ty, Ala., about 2! miles east of Melvin, the "Zeuglodon bed," 

No. 3 of the Cullom burg section, is very fossiliferous. The following section was measured at 

the place where the large Zeuglodon skeleton in the National Museum was obtained: 

Section half a mile southwest of Cocoa, Ala. 

4. Concealed. Exposures elsewhere in the vicinity show that above No. 3 is yellowish-brown · 

argillaceous marl with Spondylus dumosus and Ostrea ticksburgensis, overlain by gray to 

yellow clay with crystals of gypsum and many Red Bluff fossils. Feet. 

3. Drab clay with irregular calcareous concretions in lower portion. Thickness seen, about..... 10 

2. "Zeuglodon bed," gray or drab sandy and argillacoous marl with harder ledges and irreglilar 

calcareous concretions; very argillaceous in the upper part; about......................... 11 

1. Fine yellow sand with soft white calcareous lumps and large irregular lumps of hard yellow 

sandy marl. Grades upward into bed No.2. Thickness seen............................. 6 

From bed No. 2 the following fossils were collected: 

Flabellum sp. 

Lunulites distans Lonsdale. 

Many other Bryozoa. 

Terebratulina lachryma (Morton). 

Aturia alabamensia (Morton). 

Scala ranellina Dall. 

Turritella alveata Conrad. 

Ostrea trigonalis Conrad. 

Ostrea vicksburgensis Conrad (perhaps derived from 

higher bed). 

Ostrea falco Dall. 

Gryph£eOStrea sp. 

Pecten perplanus Morton. 

Pecten n. sp.? 

Panopea oblongata Conrad? 

Protocardia sp. 

Schizaster armiger Clark. 

Shark teeth. 

Fish vertebr£e. 

Coprolites. 
THE AGE OF THE OCALA LIMESTONE. 117 

In addition to the species enumerated in the list, the old collections in the National 

Museum contain from this locality Oyprrea fe f estralis Conrad~' Orassatellites fiexura (Conrad), 

Leda multilineata Conrad, and Venericardia pldnicosta Lamarck. 

Those species which the "Zeuglodon bed" has in common with the Ocala limestone, or 

which have near relatives in the Ocala, are thJ following: 

Flabellum (perhaps not the same species; the genus is rar I Cyprrea fenestralis. 

in the Vicksburgian beds). Leda multilineata. 

Terebratulina lachryma (doubtfully at Marianna). Pecten perplanus. 

Aturia alabamensis. Basilosaurus cetoides. 

That more species do not appear to be c mmon to the two may be attributed partly to 

ecologic and geographic causes (Cocoa is mor than 400 miles from Ocala) and partly to the 

unexplored state of the fauna. 1 . . 

From the hillsides near by the following Red Bluff fossils were collected: · 

Balanophyllia caulifera var. multigranosa Vaughan. 

Conus protractus Meyer. · 

Pleurotoma congesta Colll]ad. 

Pleurotoma plutonica Casey. 

Pleurotoma tantula Conrad. 

Pleurotoma (Drillia) caseyi Aldrich. 

Pleurotoma (Gemmula) arnica Casey. 

Pleurotoma (Gemmula) sp. 

Cancellaria mississippiensis Conrad var. 

Mitra lintoidea Aldrich. 

Latirus protractus (Conrad). 

Busycon nodulatum (Conrad). 

Triton conradianus Aldrich. 

Phos macilentus Casey. 

Murex mississippiensis Conrad. 

Eulima sp.? 

Turritella sp. 

Lunatia sp. 

Solarium hargeri Meyer. 

!De:ritalium sp. 

C+lycymeris intercostata (Gabb). 

Ostrea vicksburgensis Conrad. 

Pecten aff. P. poulsoni Morton. 

Spondylus dumosus Morton. 1 Corbula engonata Conrad. 

Oorbula perdubia Gregorio. 

Astarte triangulata Meyer. 

Myrtrea curta (Conrad)? 

Cardium sp. 

Toward the east the Red Bluff member ~hins, becomes calcareous, and merges into the 

Marianna limestone. The underlying beds ~Jso become more calcareous and can scarcely 

be distinguished · from those of the Vicksburg group except by their fossils. In general, 

however, the lower beds are less pure and in many places contain a considerable amount of. 

glauconite. 1 

CONCIJUS IONS. 

It has been shown that the Ocala limestone is the equivalent in age of the upper part 

of the Jackson formation as defined in Alaba:ba and Mississippi and that it underlies Vicksburgian limestone in western Florida. As the relations are conformable, the Ocala must 

represent at least the upper portion of the Jackson formation, but whether the lower portion 

of the Jackson in peninsular Florida is different from the Ocala, either lithologically or faunally, 

is at present unknown. I -

The "Penmsular" limestone is in large part idemtical with the Ocala, but further investigations are required to determine what other formations may be included in the "Peninsular." 

The Vicksburg group is represented in 1 western Florida by the Marianna limestone; . 

although it may be present in peninsular Florida, it is of much less areal extent than has 

hitherto been supposed. · 

INDEX. 

,---- A, 

Page. 

Ackerman formation, character of............................... 76 

Adams, L. H., acknowledgmeut to ............................ .. 

Ash, volcanic, drifts of, on foothills of St. Elias Range, Alaska, 

plate showing ..................................... .. 

volcanic, in the Yukon ·basin, distribution and character 1

96 

60 

of .............................................. . . 59-Q1,63 

in the Yukon basin, source of .. .. .. . .. .. .. .. .. .. .. .. .. .. 1 61 

volume of .......................................... ·. 62--Q3 

layer of, _in peat bluff on White River, Alaska, plate I 

.showmg............................................. eo 

Ash landscape near Mount Natazhat, Alaska, plate showing.. . . 60 

Atwood, Wallace W., Eocene glacial deposits in southwestern 

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-26 

Axial, Colo., section at ............................... _ . . . . . . . . . . 5,-55 

B. 

Beaver Creek, Ridgway till west of.. : . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 

Bennett, H. R., acknowledgment to .................... _ ...... _ 13 

Berry, Edward Wilber, Erosion intervals in the Eocene of the 

Mississippi embayment ...... _ .... _ ............. _ . . . 73-82 

Black Mesa coal field, section in ........................... _ ... _. 47-48 

Blacktail Mountain, Utah, section on .... _ ..... ____ ... __ ...... .. 53 

Book Cliffs, Utah, section in . .. .. .. .. . .. .. . .. .. . . . .. .. .. .. .. .. .. 

1

52 

Boulder, Colo., section at.: .........•..................... __ ... __ 43 

Brooks, A. H., on the correlation of rocks of Gravina Island ... 104,105 

c. Cabezon, N. Mex., section at.................................... 45 

Canon City, Colo., section at .................... ~............... 43 

.Capps, Stephen R., An ancient volcanic eruption in the upper 

Yukon basin .. .. .. . . .. . . . . . . .. . . . . . . . . .. .. .. .. .. . .. . 59-64 

Carthage, N.Mex., section at................................. . . 41 

Casa Salazar, N.Mex., section near ....................... _..... . . 4-5 

Cerrillos, N.Mex., section at .............................. . ...... 41-43 

Cerro till, occurrence of, in the southwestern part of Montrose I 

quadrangle, Colo ___ ............ ___ .. _ ... _. _ ... __ .... 14-15 

Claiborne and Jackson epochs, erosion interval between .. . .... . . 81-82 

Claiborne and Wilcox epochs, erosion interval between ......... 78-8(,) 

Claiborne group, section of .......... . ~...... ................. . Ius 

Clark station, Fla., Ocala limestone and fossils at................ 114 

Coal Basin, Colo., section near................................... 52 

Coal-bearing formations, evidence of, concerning the Cr.etaceous 

sea ............................... . .................. 37-38 

·Coal beds, occurrence of, within the Cretaceous .. _ . . . . . . . . . . . . . . . 28 

Coal fields in th~ southern Rocky Mountain region, map of.. . . . . I 40 

.cocoa, Ala., fossils from .. .. .. . .. . .. .. .. .. .. .. .. . .. . .. .. .. .. .. . 116l 117 

Coleman, W. J., acknowledgment to............................ 13 

Colob Plateau, Utah, sections on ................................ 49-50 

Colorado formations, distribution of ............................ . . 38-39 

Colorado Springs, Colo., section at ................... . ........... 52-53 

Columbus Marsh, Nev., descriptio~ of.~......................... 1 1 

muds from, analyses and classificatiOn of ................... 3-4, U 

collection of . • • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

- water from, analyses of.. .. . .. . .. . .. .. . .. .. .. . . .. . . . . .. . . . . . . 8-9 

potash content of.. .. .. .. .. . . .. .. .. .. . . . .. . .. . . . .. . .. . .. . 4, 9 

well900 in, analyses of muds and water from................ 5-9 

drilling of ............................................. _ . I 4 

record of.............................................. . . 5 

wells drilled in ............................ __ .............. .. 1-2 

Comanche sea, extent of ......................................... 32-33 

-constants of diffusion, evaluation of, methods of. ............. . . 8S-90 

Cooke, Charles Wythe, The age of the Ocala limestone._ ...... 107-117 

Correlation of sediments, difficulty of............................ 28 

·Cretaceous formations ~ attitude of, toward the Rocky Mountains. 3(}.32 

relations of, to the Rocky Mountains, conclusions on .. . ... . . sd-58 

source of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1

4

3

0 

Cross, Whitman, acknowledgment to .......................... . 

.()ullomburg, Ala., section near.................. .. .. .. .. .. .. .. .. 116 

D. 

Page. 

Dakota fire clay, position of. .............................. ,..... 33 

Dakota sandstone, character and possible origin of . . . . . . . . . . . . . . 36-37 

distribution of... .. . .. .. . .. .. .. .. .. .. .. . . .. . .. . .. . . .. .. . . . . .. 34-36 

occurrence of, in the southwestern part of Montrose quadrangle..... .... ...................................... 14 

Dall, W. H., on the Ocala limestone .......................... 107,110 

Datil Mountains, N.Mex., section in .......... ,................. 44 

Dawson, G. M., on volcanic ash in the upper Yukon basin.... . . 63 

Deep Creek, Utah, section at. ................................ ;.. 53 

Dewey, F. P., Van Orstrand, C. E., and, Preliminary report on 

the diffusion of solids ................................ 83-96 

Diffusion, theoretical phenomena of. ............................ 84-87 

Diffusion of solids, experiments on .............. ........... __ ... 87-88 

experiments on, results of, compared with computed results. 90-94 

Diffusivity, variation of the coefficient of.. ...................... 94-95 

Durango, Colo., section at ......................... ·.... . ......... 4S 

Durango till, occurrence of, in the southwestern part of Montrose 

quadran~le, Colo . .......... _ . ....................... 14-15 

E. 

Emery, Utah, section near ...... . ........... ,................... 50 

Eocene glaciers, character of, in Colorado........................ 21 

Eocene till, occurrence of, in the southwestern part of Montrose 

quadrangle, Colo .................................... 14,16 

r;;:~~~~i~:t:~.s~~~- ~:: ::-:::::: ::::: ::::::::::::::::::::::: 16-~; various sections of. .. .. .. .. .. . .. . .. . . . . .. . .. . .. . .. . .. .. .. .. . . 18-21 

Equivalency, homogenetic versus time .......................... 29-30 

Evaluation of constants of diffusion, methods of ................ 88-90 

Evaporation of potash brines, experiments on ................... 65-71 

F. 

Fort White, Fla., Ocala limestone and fossils at................. 114 

Fort Wingate, N.Mex. , section west of .............. ! .......... 46-47 

G. 

Gale, Hoyt S., work of, on Columbus Marsh .................... . 

Gallina, N.Mex., section near................................... 45 

Gallup, N. Mex., section at .. . ...... ·............................. 47 

Girty, G. H., fossils from Gravina Island determined by ...... 10(}.101 

Glacial deposits in Montrose quadrangle, map showing.......... 14 

Glacial deposits of the earth, range of, in geologic time .......... 24-26. 

Grand Mesa, Colo., section on................................... 52 

Gravina Island, Alaska, fossils from ........................... 100~103 

geology of ...... , ... . ................ : ...................... · 97-105 

igneous rocks on_. . .•.... . ...... , .......................... 10 4-105 

oldest rocks on .... ... ....................................... 97-98 

rocks near Vallenar Bay on ................................ . 98-99 

schists on northeast coast of. ............................... 99-100 

Triassic rocks on .......................................... 100-104 

plate showing .. . . . . . . . .. . . . . . .. . .. .. . . . . .. .. .. . . . .. . .. .. . 100 

Grenada formation, character of................................. 76 

H. 

Hatchetigbee formation, desJription of. ......................... 75-76 

Hayden, Colo., section near .. . .. .. .. .. . .. .. .. . . .. . .. .. .. .. .. .. .. 55 

Henry Mountains, Utah , section in .. .. .. .. .. .. .. .. .. .. .. .. .. .. . 50 

Hicks, W. B., Evaporation of potash brines ..................... 65-72 

The composition of muds fr.om Columbus Marsh, Nev . . . . . . 1-11 

Holly Springs sand, character of................................. 76 

J. 

Jackson, Miss., section of Jackson formation near .. .... .. .... .. . 114 

Jackson and Claiborne epochs, erosion interval between ..... : .... 81-82 

Jackson formation, sections of.. ........................... 114,115,116 

Johnston, John, acknowledgment to............................ 96 

Jurassic epicontinental sea, evidence of.......................... 32 

119 
120 INDEX. 

K. 

Page. 

Kindle, E. M., on fossils from Gravina Island ...... _._ .. ____ __ ._ 99 

Kirk, Edwin, fossils from Gravina Island determined by. ..... .. 102 

Knopf, Adolph, on the age of diorite on Gravina Island ___ . __ ..• 105 

on volcanic ash in the White River basin .. _ ..... __ .. . . __ .... 63 

L. 

Le Due, Lloyd, acknowledgment to._ ................... _....... 13 

Lee, Willis T., Relation of the Cretaceous formations to the 

Rocky Mountains in Colorado and New Mexico . _ .. _ 27-58 

Leighton, M. M., acknowledgment to ............... _ .... ____ . _.. 13 

Log H1ll Mesa, Ridgway till on._ ........... ·--··--._ .......... _. 20-21 

M. 

Me Elmo formation, occurrence of, in the southwestern part of the 

Montrose quadrangle .............. _ ... _ ....... _..... 14 

Mancos, Colo., section at .......... _ ....... _ .. _ .......... _ .. __ .... 48 

Mancos shale, occurrence of, in the southwestern part of the 

Montrose quadrangle .......... _____ . ___ .. __ .. _...... 14 

Maple Creek, Utah, section on ..... _._. ___ ........... __ .......... 49 

Marianna limestone, relations of, to Ocala limestone._ ... _._ ... 109-110 

Martin, Fla., fossils from _ ... _. _ .................... _____ .... _.. . 112 

Ocala limestone and fossils at ........ _ .. _ ..... _ . ___ . _ ... ___ . 113 

Mather, Kirtley F., acknowledgment to ...... _ ...... _ .. ___ ...... 13 

Midway and Wilcox epochs, erosion interval between._._._ .. _ .. 73-78 

Miller, Walter R., acknowledgment to. __ ........... ---·-_....... 13 

Miller Mesa, Ridgway till on the west side of._. ____ ........... __ 19 

Montana formations, distribution of. ...... __ . ____ _ .. ... . ____ ... _ 39-40 

Montrose quadrangle, Colo., southwestern part of, descriptive 

geologyof .........•............ ..... ................ 14-15 

southwestern part of, physical geography of . __ .. ___ ...... . .. 13-14 

map of ...•.....•..................•......... __ .......... 14 

Morrison formation, distribution of. ........... _ ..... _ ... _ ....... 32-33 

Mount Cannel, Utah, section on ................... _. ___ . ___ ..... 49 

N. 

Nanafalia formation, description of ...... __ ................... __ . 74-75 

Near-shore deposits, correlation of, with offshore deposits ....... _ 29-30 

Newberry, Fla., Ocala limestone and fossils at. ........ _ .. _ ... _._ 114 

North Park, Colo., section in .....................•....•... _..... 55 

0. 

Ocala limestone,•age of ........................... -.. _ ... __ ._ ... 107-117 

fossils from ...............•.....•.................. 110-112,113-117 

localities of, in Florida .................................... 113, 114 

relation of Marianna limestone to ..•....... _ ............... 109-110 

relation of " Peninsular" limestone to . . . . . . . . . . . . . . . . . . . . . . . 112 

Offshore deposits, correlation of, with near-shore deposits ........ 29-30 

P. 

Pagosa Springs, Colo., section at................................. 49 

•" Peninsular" limestone, relation of, to Ocala limestone......... 112 

Pinedale, Ariz., section at . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 

Pleasant Valley, Ridgway till on the west wall of................ 18 

Plummer, F. B., acknowledgment to ..... _ ....... _ .... _ ....... _. 13 

Potash, search for, in Columbus Marsh, Nev.................... 1-11 

Potash brines, evaporation of, experiments on ___ . ____ . __ . _. ___ . 65-71 

Purgatoire formation, position of. ..•............... ___ ._-_._..... 33 

R. 

Railroad Valley Co., search for potash by __ . . . . . . . . . . . . . . . . . . . . . . 4 

Raton, N.Mex., section at...................................... 43 

Ridgway till, age of. ........••...•.. . .... _ ........ _... . . . . . . . . . . . 21 

near Ridgway, Colo., plates showing ....................•. 16, 18,20 

Page. 

Ridgway till, occurrences and character of....................... 16-21 

sources of . . . . . . . . . . . . . . . . . . . . . . . . . . • • . • . . . • • . • . . • • • • . . . . . . . . 21 

summary of facts concerning ...•.....•....••...•.•......... _ 22 

Rio Puerco field, N. Mex., section in ...... _.................. . . . 44-45 

Rocky Mountains, attitude of Cretaceous formations toward ... . _ 30-32 

summits of, ancient peneplain possibly marked by ........ _.. 34 

s. San Juan Basin, sections in . . . . • . . . . . • . . . . • • . . . • . • . . • • . • . . . • . • . . 48 

San Juan Mountains, geographic history of. ..........•••.... _._. 22-24 

San Juan tuff, description of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

occurrence of, in the southwestern part of the Montrose quadrangle............................................... 14 

Selfridge, Frank, acknowledgment to •..•............. _ ... _..... 13 

Smith, Philip S., Notes on the geology of Gravina Island, 

Alaska ....•....•••...•••......................•.. _. 97-105 

•South Park, Colo., section in ••••••..••.. _ ... _. __ .. _._ ......... _. 52-53 

Stanton, T. W., fossils from Gravina Island determined 

by······-···················--··-·---·---····· 101-102,103 

Stinking Spring, N.Mex., section at ....... _ ... _ ..... _ ........•.. 46-47 

Striated stones, abundance of __ .... _ ..... __ .. _._ ............ _.... 17 

from the Ridgway till and Telluride conglomerate, plate 

showing ......................•.................. __ . . 18 

Sunnyside area, Utah, formations in ...•.....•...........•.•.. _. 50-52 

T. 

Telluride conglomerate, description of ....•...........•......... _ 18 

occurrence of, in the southwestern part of the Montrose quadrangle............................................... 14 

striated stones from, plate showing ...•.. _ .......... _. ______ . 18 

Tijeras, N.Mex., section at ..........•.....•............. _...... . 41 

Triassic formations on Gravina Island, Alaska, plate showing __ . 100 

Tuscahoma formation, description of . . . . . . . . . • . . . • • • . . . . . . . . . . . . 75 

u. 

Uinta Basin, sections in ........ -....................•...•.•...... 50-55 

Uncompahgre Valley, Ridgway till on the west side of .. _ ..... _. 18 

Upper Kanab, Utah, section on ....•....................... :.... 49 

v. 

Vallenar Bay, Gravina Island, rocks near ...••....•.....••.... _. 98-99 

Van Orstrand, C. E., and Dewey, F. P., Preliminary report on 

the diffusion of solids ........ __ .•.................. __ 83-96 

Volcanic eruption in the upper Yukon basin, time of..... . . . . . . . 63-Q4 

W. 

Wellington, Utah, section at-·········---------·········---····· 50-52 

Wells, L. E.,acknowledgment to ............. ___ .. ---- .. -~--.... 13 

Wells, R. C., acknowledgment to .....•.................. _._ .... _ 96 

Wilcox and Claiborne epochs, erosion interval between ...... ___ . 78-80 

Wilcox and Midway epochs, erosion interval between .. _ ..... _ .. 73-78 

Wilcox flora, character of. ..•............. __ ..................... 76-77 

Willow Branch, Ala., section at·············-------···---....... 115 

Wisconsin till, occurrence of, in the southwestern part of Montrose quadrangle, Colo .................... _._ ... ____ .. 14-15 • 

Wooten, V. L., acknowledgment to ........... ____ .. ____ . __ ...... 13 

Wright, F. E. and C. W., on certain rocks of Gravina Island._. 99,105 

Y. 

Yukon basin, ancient volcanic eruptions in .......... _._ ...... _ .. 59-Q4 

z. 

Zuber, Fla., Ocala limestone and fossils at ...............•.... _.. 113 

0