The Foerstia Zone of the 

Ohio and Chattanooga Shales

GEOLOGICAL SURVEY BULLETIN 1294 H

The Foerstia Zone of the 

Ohio and Chattanooga Shales

By J. M. SCHOPF and J. F. SCHWIETERING

CONTRIBUTIONS TO STRATIGRAPHY

GEOLOGICAL SURVEY BULLETIN 1294-H

An explanation for the strati graphic 

zonation of the fossils and a report 

on a newly discovered occurrence of 

the Foerstia zone in western Ohio

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1970
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

Library of Congress catalog-card No. 73-607393

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

Washington, D.C. 20402 - Price 30 cents (paper cover)
CONTENTS

	Page

Abstract ..... ....................... ...................... . ............................................... HI

Introduction ..................... ............ . .................. ................................................. 1

Earlier reports .... ..................... ... ..... ... ......................................... 2

The "spores" of Foerstia ................. ... ............. . _........... .. 4

Littoral control ............................. ... . . ............ ........................................ 6

Stratigraphic occurrence of Foerstia ............. ....... ..................................... 8

A new Foerstia locality ........ ... ............................. ................................... ..... 12

Summary ......................................................................................._..._..............-..... 13

References cited .. ....... .......................... ......... ..... .... .................................... 14

ILLUSTRATIONS

[Plates follow references]

PLATE 1. Foerstia ohioensis White. 

2. Foerstia ohioensis White.

Page

FIGURE 1. Map showing Foerstia collection localities in North America ...... H8

2. Geologic cross section across central and northeastern Ohio

showing occurrences of the Foerstia zone .................................... 10

in

CONTRIBUTIONS TO STRATIGRAPHY

THE FOERSTIA ZONE OF THE 

OHIO AND CHATTANOOGA SHALES

By J. M. SCHOPF and J. F. ScHWiETERiNG1

ABSTRACT

Foerstia, long regarded as an inconspicuous problematic fossil, is allied with 

the pelagic algae. It is known to be present only in a zone within the Huron 

Member of the Ohio Shale (Upper Devonian) or its apparent time equivalents, principally in the Appalachian interior basin. Foerstia was restricted 

stratigraphically and geographically by its need for a suitable littoral 

environment for reproduction. Probably such an environment existed for 

a short interval during the Late Devonian along the southeastern shore of the 

transgressive epicontinental sea. The period during which Foerstia was 

fossilized probably coincided with the time during which the reproductive 

habitat persisted. Only about 20 Foerstia localities are known, but this fossil 

genus probably marks a consistent time zone in the Eastern United States. 

Its distribution may be related to tidal currents in the Late Devonian sea.

INTRODUCTION

Foerstia is a plant genus based on small abundant fossils that 

are commonly about the same size as common duckweed and superficially resemble it. We regard these fossils as remains of thallose 

algae. The fossils are found in a restricted zone of the Ohio and 

Chattanooga Shales (Upper Devonian), chiefly within the Appalachian region (Hass, 1956; Winslow, 1962). This paper suggests 

an explanation for the stratigraphic zonation of the fossils and 

reports a newly discovered occurrence of the Foerstia zone in 

western Ohio.

The fossils consist of small carbonaceous compressions2 which 

are oval to bilobate in outline (pi. 1) and show a cancellate surface

1 The Ohio State University, Columbus, Ohio.

2 The coaly cell remains in this material differ slightly from land-plant compression material 

in their reaction to oxidative maceration. Some chemical differences may exist. Although 

resistant to maceration, the cell walls do not show a cuticle in section and seem not to be 

cutinized in any normal manner. Prob^bjy both algal cell-wall and mucilage materials contribute 

in altered condition to the coalified remains of the fossil algae. A discussion of the cell-wall 

chemistry of modern seaweeds is given by Kreger (1962) and by O'Colla (1962).

HI
H2 CONTRIBUTIONS TO STRATIGRAPHY

pattern or texture when viewed under a lens (see especially pi. 1, 

fig. 3). Fragments in cable-tool well cuttings can be identified by 

their characteristic surface texture, which is a reflection of the 

walls of cells that form a dense surficial layer (pi. 2, figs. 5-7). 

This layer is comparable to the surficial meristoderm that forms 

the toughest part of the thallus of many advanced types of modern 

seaweeds. Variation in gross outline of the thalli of the fossil 

Foerstia, aside from results of incidental breakage in preparation, 

seems to have been a function of balance between apical growth, 

periodically dichotomizing, and distal decay. Common floating 

forms of modern marine algae show a similar mode of vegetative 

propagation. No basal or holdfast parts of the foerstian thallus 

have ever been observed, and we believe that all the observed fossils 

originally were floating organisms. Juvenile stages, as yet not 

found as fossils, may well have had a holdfast attachment.

In Devonian black shale, Foerstia is associated with authigenic 

concretions containing Radiolaria (Foreman, 1959) ; with conodonts, fish plates, and other marine fossils (Hass, 1956; Winder, 

1966) ; and with the disseminules of Tasmanites. Tasmanites is 

now recognized to be closely allied with the planktonic marine alga 

Pachysphaera (Wall, 1962), and Tasmanites is also widely distributed in other marine deposits (Winslow, 1962). These consistent associations, and lack of evidence to the contrary, leave no 

reasonable doubt that Foerstia represents marine vegetation.

EARLIER REPORTS

The fossils assigned to Foerstia have a long history of misinterpretation and confusion. Therefore, a brief review of earlier 

reports that relate to the naming and interpretation of Foerstia 

may be helpful. Considerable information can be gained from the 

older literature, if the vagaries in naming are correctly 

interpreted.

In referring to similar material, Arnold (1954) preferred to use 

the name Protosalvinia Dawson (1884) rather than Foerstia 

White (1923). However, we agree with Krausel (1941) that the 

typical form of Protosalvinia from Brazil is generically distinct 

from the allied types found in the Ohio and Chattanooga Shales. 

Lang (1945) also substantially agreed with Krausel, but he overlooked the fact that Protosalvinia brasiliensis Dawson (1884) is 

the type species of the genus and must therefore continue to bear 

the generic name. Lang, therefore, used Protosalvinia for the 

North American fossils and assigned the Brazilian ones to a 

new genus he called Orvillea. "Orvillea" can only be a synonym of 

Protosalvinia, but the relationship Lang was attempting to
FOERSTIA ZONE, OHIO AND CHATTANOOGA SHALES H3

express, that the common types of the Brazilian and North American fossils are generically distinct, is apparently correct. Almost 

the same conclusion had been arrived at independently by White 

( in White and Stadnichenko, 1923) and probably constituted his 

reason for proposing the new genus Foerstia. He was, however, 

concerned with the plant materials as a source of oil and did not 

discuss taxonomy. Arnold (1954) suggested that White may not 

have known of Dawson's Sporocarpon paper (1888). White made 

no reference to it, and he did establish F. ohioensis White, 1923, 

as the type species of Foerstia. F. furcata, the species identified 

and misassigned by Dawson (as mentioned later), probably is 

synonymous with F. ohioensis, but F. furcata was not assigned to 

Foerstia until Pia did so (1927). White also continued to use the 

name Protosalvinia for some of the North American material, but 

Krausel (1941) thought that this material should also be assigned 

to Foerstia as F. ravenna (White) Krausel. We agree with Krausel's principal conclusion but prefer to regard F. ravenna as a 

growth form of F. ohioensis. Without indulging in technicalities 

unnecessary for our present purpose, we may say that the genus 

Foerstia White, as employed by Krausel (1941), seems to be a 

usable taxonomic concept that can be applied to nearly all thalloid 

material of this type in North America.

The essential distinction between the Brazilian Protosalvinia 

and North American Foerstia is that the thallus of Protosalvinia 

is virtually salverform (discoidal and naturally flattened), and has 

abundant conceptacles (craters) on the dorsal (upper) surface. 

Some thalli are bilobed (Dawson assigned these to a separate 

species3 ), but they are not bifurcate. Foerstia thalli are characteristically bifurcate, though end-on fossil compression of a very 

short (slow-growing?) tip (the "ravenna" type of growth) may 

simulate the discoidal appearance of the Protosalvinia thallus. The 

crowded abundance of dorsal conceptacles is never observed in 

thalli of Foerstia where conceptacles usually form inside the bifurcation. The individual conceptacles are similar in both genera and 

provide good evidence that the two are related and probably 

should be associated within the same taxonomic family.

Other names also have been applied somewhat indiscriminately 

to Foerstia. Dawson (1888) first identified material sent to him

3 The senior author examined original material distributed by Dawson from Rio Curu& 

in Brazil, and now in collections at the New York State Museum, Albany. The author's findings 

confirm Krausel's and Lang's general observations on Protosalvinia braziliensis and conflict 

with those of Sommer (1962). Some of the thalli shown on the New York Museum specimen 

also agree well with Dawson's illustration and description of P. bilobata, which Sommer said 

never occurs in mixture with P. braziliensis. The new material Sommer illustrated agrees with 

Foerstia more than it does with Protosalvinia.
H4 CONTRIBUTIONS TO STRATIGRAPHY

by Edward Orton from Ohio with a problematical genus that Williamson (1878) had called Sporocarpon. Dawson thought that both 

Williamson's and the Ohio material might be allied with a type of 

free-floating water fern ("Rhizocarpalean") ; it now seems improbable that either is so allied, and the two fossil types are 

evidently unrelated. However, in several papers and books, Dawson continued to speak about the rhizocarps of the Erian when he 

had reference to Foerstia.

Dawson and many others also considered that the disseminules 

of Tasmanites (usually then called Sporangites) represented the 

same plant as Foerstia, because Tasmanites seems always to be 

present wherever Foerstia is found. Foerstia, of course, is much 

more limited in its occurrence than Tasmanites is; however, on 

the basis of association, some authors were willing to draw a 

taxonomic conclusion, and some references to Protosalvinia only 

signify the presence of Tasmanites disseminules. Even if the 

sporelike Tasmanites disseminules were not linked up with Foerstia, a great many authors regarded them as spores of higher 

plants, lycopod megaspores, or almost anything but cysts of 

marine planktonic algae (Wall, 1962). Formerly, it was commonly 

believed that aquatic plants were incapable of producing sporelike 

microfossils that had resistant coats and that the presence of these 

"spores" indicated the presence of land plants. Independently, 

Krausel (1941), Schopf (in Schopf and others, 1944), and Lang 

(1945) considered this complicated problem, and all agreed then 

(and it has become more evident since) that the association is only 

incidental. A summary review of these papers has been given by 

Schopf (1957, p. 712), in which Krausel's assignment of the sporelike Tasmanites fossils to Leiosphaera Eisenack, a possible synonym, rather than to Tasmanites Newton, was discussed.

THE "SPORES" OF FOERSTIA

One reason Krausel, Schopf, and Lang could be confident that 

Tasmanites had nothing to do with Foerstia, in spite of their general association, was that White and Stadnichenko (1923) and 

Kidston and Lang (1924) had independently demonstrated the 

presence of tetrads retained within conceptacles of Foerstia thalli 

(see pi. 2, fig. 6). The members of the tetrads are more sporelike 

than the disseminules of Tasmanites, for they show a contact configuration in addition to having a resistant coat.

The sporelike members of the Foerstia tetrads may have functioned both as true spores (haploid chromosome member; the 

initial stage of a gametophyte generation) and as egg cells, as in
FOERSTIA ZONE, OHIO AND CHATTANOOGA SHALES H5

modern Fucales (Kylin, 1917, 1918; Smith, 1938; Caplin, 1968). 

The Fucales are basically heterosporous, having unilocular megasporangia producing megaspores that function as egg cells. The 

condition in Foerstia seems to suggest that this extreme condensation of the haploid generation (with the endogametophyte represented by only a single cell) may have persisted among brown 

algae since the Devonian. The fact that a distinctive spore coat 

was present at that time also suggests that a prior dispersal 

phase, possibly with spores that produced a free-growing external 

gametophyte which produced gametangia, might have been present 

in the early Paleozoic or even late Precambrian. Evidently the 

brown algae have a long history and are not given to rapid 

evolutionary changes.

It seems most likely to us that the tetrads functioned as a group 

of oospheres or aplanospores, as in Fucus, rather than as tetraspores, and that the fossils generally agree in structure and organization with modern members of the Fucales. The character of the 

meristoderm and conceptacles that contain the tetrads is exceedingly difficult to explain in alliance with any other group of 

organisms. Agreement with algal structure must be the deciding 

feature. If the plants represent an advanced type of algae, the 

tetrad members could not have served the same function as spores 

in the life cycle of vascular cryptogams or other land plants. Of 

course, interpretation of function is always difficult to prove from 

fossil material.

The senior author has studied much North American material 

and views the circumstantial evidence as follows: The most 

remarkable feature of these tetrads is that the members remain 

associated in the conceptacles on the thalli. Even where fertile 

specimens of Foerstia are relatively common, the tetrad members 

are almost never found dissociated. The tetrad members have not 

yet been reported in the course of normal palynologic studies, 

except when thallus fragments themselves were macerated or the 

members isolated by direct physical manipulation. Whether the 

tetrads functioned as spores or eggs or both, this repeated observation seems unusual. In view of the abundance of foerstian fossils, 

one would expect either spores or eggs to be dispersed from conceptacles if the well-formed tetrads were really functional. Certainly they could not function in any normal manner unless they 

were dispersed. Lack of any evidence of dispersal leads us to suspect that although eggs were matured (the unusually heavy coat 

may be an indication of over-maturity), they may not have been 

capable of functioning in a floating habitat. An incidental circumstance that fits the hypothesis of nonfunctionalism is that no
H6 CONTRIBUTIONS TO STRATIGRAPHY

structures have been discovered that resemble male sex organs 

(antheridia). Of course, many other reasons might be advanced 

to explain why fertilization was not completed, but no evidence 

from the available fossils indicates that the tetrad members 

actually fulfilled a generative function in the pelagic environment. 

We may refer to modern algae for a plausible explanation.

In members of the Fucales, germination of fertilized eggs 

occurs in salt water along rocky coasts, where young plants find 

a suitable substrate for initial attachment (see Fritsch, 1945, p. 

377). Eggs are extruded from conceptacles by an associated mucilaginous vehicle, following a change in turgor that is induced by 

altered salinity or, in the intertidal zone, by desiccation. Retention 

of tetrad members in fossil conceptacles of Foerstia might readily 

be explained by the presence of a gelatinous envelope that failed 

to expand. A mucilaginous deposit would be most difficult to identify specifically in fossil condition. The evidence available shows 

no disagreement with an algal reproduction cycle of the type 

exemplified by the modern genus Sargassum.

The life cycle of Sargassum is initiated by germination of egg 

cells along coasts, where the young plants become attached to a 

substrate. Some algae require a fairly specialized littoral environment for attachment and early growth. We suspect that this was 

true for Foerstia.

No juvenile stages of Foerstia are known, and the attached 

state is not known among these fossils. The specimen illustrated 

on plate 1, figures 9 and 10, is the smallest, and may possibly be 

the youngest, of any observed. In Sargassum, many attached 

plants break loose after a time and continue to grow vegetatively. 

The number of vegetative fragments increases by separation at 

dichotomies as the proximal parts decay, but sexual reproduction 

does not occur while the plant is in a free-floating condition. 

Essentially the same sort of free-floating vegetative growth and 

remission of sexual reproduction among the floating thalli is 

suggested by the fossil occurrences of Foerstia.

LITTORAL CONTROL

Some circumstantial confirmation of this interpretative account 

of Foerstia may be derived from its restricted stratigraphic occurrence. Although related forms (Protosalvinia, Spongiophyton) 

are abundant in Devonian rocks of Brazil (Krausel, 1941, 1960), 

only one possible example of Protosalvinia, as far as we know, has 

been recognized in North America (Arnold, 1954, pi. 1, fig. 9). 

Regardless of how one chooses to interpret these fossils, they must
FOERSTIA ZONE, OHIO AND CHATTANOOGA SHALES H7

have had ancestors, and if they are related to the modern Fucales, 

as we believe, they also had descendants. In general, the lack of 

fossil representation within a time zone in which such fossils 

occur is attributable to poor or intermittent opportunity for preservation, but the abundance of the foerstian fossils in only a 

single thin zone within the black shale of the Appalachian region 

poses a perplexing problem. The general facies uniformity of the 

black shale above and below the Foerstia zone is a sufficient indication that preservation was possible throughout the period of blackshale deposition, if a continuing abundance of plant remains had 

been available. In this particular instance, we must be dealing 

with an episodic proliferation of the plants themselves; that is, 

fossil occurrence depended on more than the mere opportunity 

for preservation.

The Devonian black shale has long been recognized as a generally transgressive phase of the Late Devonian epicontinental 

sea. Owing to its stratigraphic position, singular distribution, and 

distinctive lithology, it has been much referred to in discussons 

relating to the Devonian-Mississippian boundary. There is reason 

to believe that, during the period of Late Devonian time represented by the Foerstia zone, limestone formations may have been 

overlapped by the sea at the southeast margin of the broad epicontinental basin (Conant and Swanson, 1961). These paleogeographic relationships may have had a great deal to do with 

temporary proliferation of Foerstia and its distribution by sea 

currents for a limited time within the Appalachian interior basin.

If Foerstia is an alga, like Sargassum, that was dependent on a 

special type of littoral environment for completion of the sexual 

phase of its life cycle, exposure of the rocky margins of the basin 

may have been a critical factor for several reasons. Initially, rock 

exposures along the coast may have presented a favorable colonization habitat for migrant Foerstia washed in by the sea from 

distant areas. Later on, drowning of rocky ledges by the transgressing sea may just as effectively have cut off the favorable 

foerstian "spawning ground." Subsequent lack of a littoral site 

suitable for juvenile growth may have doomed the whole colony 

in this area of the sea. The specific causal mechanism may never 

be pinpointed, but littoral control of the occurrence of Foerstia 

within the black shale of the Appalachian basin seems plausible 

and consistent with algal alliance that is suggested by structural 

features of these plants. None of the alternative explanations we 

can think of is equally consistent with botanical considerations and 

with the associated paleoecologic indicators that are generally 

recognized as applying to the Upper Devonian black shale.
H8 CONTRIBUTIONS TO STRATIGRAPHY

STRATIGRAPHIC OCCURRENCE OF FOERSTIA

Hass (1956), basing his opinion on conodonts, was inclined to 

regard the interval in which the foerstian fossils occur (specifically, see fig. 1, loc. 4, 6, 8, 9, 11-16) as correlative with the lower 

faunal zone of the Gassaway Member of the Chattanooga Shale 

(equivalent to part of the Huron Member of the Ohio Shale). Hass 

(1958) later discussed the more extensive correlation of this zone 

which he then called Zone III. Probably all the collections listed 

here are of the same age. Subsurface records are consistent with 

this age assignment and with other information obtained from 

plant microfossile (Winslow, 1962).

Known localities from which Foerstia has been collected are 

shown on the map in figure 1. Material from nearly all localities 

has been checked by the senior author. All but one collection 

(No. 13, Littlestone Mountain, Jefferson County, Va.) consists 

of thalli associated with the characteristic black or dark-gray 

shale matrix. The Littlestone Mountain collection is from a buff

O24 /

25 X 6 I \ WEST 

V; VIRGINIA

200 MILES

FIGURE 1. Map showing1 Foerstia collection localities in North America. 

Solid circle, outcrop locality; open circle, subsurface locality; dot, gamma 

ray-neutron (GR-N) log. Localities, together with reference (in parentheses) or collector and date, are given in the explanation (facing page); 

numbers refer to Ohio Department of Natural Resources (ODNR) and 

to Ohio Division of Geological Survey (OGS) reference files.
FOERSTIA ZONE, OHIO AND CHATTANOOGA SHALES H9

or tawny siltstone and signifies that preservation of the algae did 

not depend entirely on the black-shale facies. Possibly this locality 

may be closest to the area of foerstian reproduction. Tasmanites is 

associated with foerstian remains at all the localities.

On the basis of these occurrences and stratigraphic studies carried out by the junior author, other possible occurrences may be 

predicted. The Foerstia zone should be present about 600 to 800

EXPLANATION FOR FIGURE 1

1. Kettle Point, Ontario (Winder, 1966)

2. Frink Run, south of Monroeville, Huron County, Ohio; Thomas Schopf, 

1958

3. Bristol Ridge, east of Zanesfield, Logan County, Ohio; J. F. Schwietering, 

1968

4. Glen Mary, Flint Park, The Narrows, 1-3 miles north of Worthington, 

Franklin County, Ohio; J. M. Schopf, 1951-3

5. 4th Street and 17th Avenue, Columbus, Franklin County, Ohio (Orton 

Museum, Ohio State University)

6. Vanceburg, Lewis County, Ky.; David White, 1923

7. 10 miles southeast of Winchester, Clark County, Ky. (Bharadwaj and 

Venkatachala, 1960)

8. Clay City, Powell County, Ky.; David White, 1923

9. Ravenna and Irvine, Estil County, Ky.; David White, 1923

10. 3 miles west of Berea, Madison County, Ky.; J. M. Schopf, 1963

11. Junction City, Boyle County, Ky.; David White, 1923

12. Burkesville, Cumberland County, Ky. (Hass, 1956)

13. Littlestone Mountain, Jefferson County, Va.; W. H. Hass, 1953

14. Glendale, Hamilton County, Tenn. (Hass, 1956)

15. Apsion, Hamilton County, Tenn. (Hass, 1956)

16. Spavinaw Dam, Delaware County, Okla. (Hass, 1956)

17. Kaiser-Pinney 1 (cable-tool well cutting), Ashtabula County, Ohio; depth 

135-215 ft.; Schwietering, 1969; samples studied 115-305 ft. (ODNR 

P-16; OGS S-615)

18. Horizon Oil-Rhoa 1 (GR-N log), Trumbull Township, Ashtabula County, 

Ohio (ODNR P-191)

19. Atlas Minerals Kemmery-Smith 1 (GR-N log), Suffield Township, 

Portage County, Ohio (ODNR P-419)

20. Barberton Core Test, Norton Township, Summit County, Ohio; depth 

1436.5-1519 ft. (interval 82.5 ft.) (Winslow, 1962) ; (OGS S-955)

21. Natol-H. Johnson 1 (GR-N log), Monroe Township, Coshocton County, 

Ohio (ODNR P-1330; OGS S-821)

22. Pure-Dalier 3 (cable-tool well cutting), Newcastle Township, Coshocton 

County, Ohio, Foerstia zone depth 1640-1740 ft. (sample description, 

Winslow, 1962; OGS S-493)

23. Kin-Ark Oil-Boyd-Young Unit 1 (GR-N log), Harlem Township, Delaware County, Ohio (ODNR P-251)

24. Logan (cable-tool well cutting), Hocking County, Ohio, Foerstia zone 

depth 1430-1571 ft. (Winslow, 1962)

25. Chillicothe core test, Ross County, Ohio, Foerstia zone depth 320-376.7 

ft. (Winslow, 1962)
H10 CONTRIBUTIONS TO STRATIGRAPHY

feet above the top of the Dunkirk Shale Member of the Perrysburg 

Formation in northwestern Pennsylvania and western New York. 

This estimate has been based on eastward projection of the base 

of the Huron Member of the Ohio Shale, as correlated from gamma 

ray-neutron well logs from test drilling in Ohio, recognition of 

the Foerstia zone by Winslow (1962) in the core record at Barberton, Ohio, and the new identification of the Foerstia zone in the 

shallow subsurface from cable-tool well cuttings in the city of 

Ashtabula, Ohio. The relations of the Foerstia zone to Upper 

Devonian and Lower Mississippian formations in central and

34 miles 12 

.Columbus miles 

Limestone

15 

miles

EXPLANATION

Berea Sandstone and 

Bedford Shale

Lower part, 

Olentangy Shale

Foerstia zone

Upper part, 

Olentangy Shale

FIGURE 2. Geologic cross section across central and northeastern Ohio showing1 occurrences of the Foerstia zone. Datum taken at the top of the thick 

Middle Devonian carbonate deposit (Delaware and Columbus Limestones 

and "Big Lime") ; not a structure cross section. Based on published 

records, outcrop and sample study, and gamma ray-neutron log interpretation by J. F. Schwietering, July 1969. Locality numbers and locations as 

given for figure 1.
FOERSTIA ZONE, OHIO AND CHATTANOOGA SHALES Hll

northeastern Ohio is shown in the geologic cross section in figure 2. 

Further investigations of stratigraphic relationships are being 

carried out by the junior author. It is most desirable, of course, 

to record additional occurrences of the Foerstia zone as a means 

of testing this and further possible hypotheses that attempt to 

account for the singular ditribution of these fossils.

Apparently all material reported in the literature is included 

in the list of localities (fig. 1). Kidston and Lang (1924) studied 

one shale specimen sent by J. W. Dawson and another sent by 

Professor H. S. Williams of Cornell. Presumably that transmitted 

by Dawson may have originally been given him by Edward Orton. 

Kidston and Lang said only that the material was from the Upper 

Devonian shales, Columbus, Ohio. Krausel's (1941) North American material was all listed as Upper Devonian, Ohio, or Columbus, 

Ohio, and was derived from several sources, all of which may refer 

to the Columbus locality. Labels on material in the Orton Museum 

at The Ohio State University refer to a excavation near 4th 

Street and 17th Avenue in Columbus, a few blocks east of the 

university, but no collector's name or date is given. Abundant material from several related localities probably became available 

from time to time. Arnold (1954) listed no specific locality for 

his material, but in a letter (Mar. 13, 1969) he stated that associated museum material indicates that all this material probably 

came from a few miles north of Columbus where we have 

repeatedly collected it (our loc. 4).

The only Foerstia species that seems clearly distinguished from 

Foerstia ohioensis is that named Protosalvinia arnoldii by Bharadwaj and Venkatachala (1960). The species is here reassgined to 

Foerstia as Foerstia arnoldii n. comb. The type material came from 

the black-shale outcrop zone 10 miles southeast of Winchester, Ky., 

and about 12 miles north-northwest of Foerstia locality at Irvine 

and Ravenna. In 1952, the senior author found what is apparently 

F. arnoldii at an outcrop in Glen Echo Park, at a horizon a short 

distance above the main Foerstia zone in Columbus; and about 

4 miles north of there at a similar level at Flint Park, about 2 

miles north of Worthington. Although the botanical interpretation 

of this species seems less certain, its association with the same 

stratigraphic interval seems definite.

It must be emphasized that although generalized locality designations may lead to the assumption that foerstian remains are 

ubiquitous in the Devonian black shale of the Eastern United 

States, such is not the case. Foerstia occurs in a variable, but relatively thin, zone in the lower part of the shale sequence and is not 

present elsewhere. A characteristic part of its range is illustrated
H12 CONTRIBUTIONS TO STRATIGRAPHY

on the geologic cross section shown in figure 2. Its geographic 

occurrence also seems limited, although in several places the 

inconspicuous fossils have probably been misidentified or overlooked. Except for one locality in northeastern Oklahoma, where 

it was collected by H. D. Miser of the U.S. Geological Survey 

(Hass, 1956), Foerstia has not been reported west of the Cincinnati arch. If our interpretation of a littoral control of the 

occurrence of these fossils is approximately correct, the geographic 

distribution of the fossils may provide additional information 

about tidal currents in the Late Devonian epicontinental sea.

The same variations in thickness of the Foerstia zone may 

signify differences in rate of deposition; some may also signify 

distance from the source of the foerstian remains. The absence 

of Foerstia from the Indiana-Illinois embayment suggests that 

a barrier along the line of the Cincinnati arch interfered with 

westward distribution of these algae. However, relations of the 

section near Beliefontaine (see below) do not suggest that the arch 

at this time was subaerially exposed. An effective barrier could 

have consisted chiefly of tidal currents. After all, the only noteworthy occurrence of floating Sargassum is in the Sargasso Sea, 

but its modern distribution is much more extensive (Setchell, 

1935).

A NEW FOERSTIA LOCALITY

The farthest west in Ohio that Foerstia has been found is at a 

locality in the Bellefontaine outlier at Bristol Ridge, east of 

Zanesfield. Here the zone is thin, only about 5 feet thick. The 

following is a description of the black shale section as measured 

by the junior author in September 1968. The section extends along 

a ravine on the south side of the ridge from a point about 2.25 

miles east of Zanesfield, Jefferson Township, Logan County, Ohio.

1. Shale, dark-brown to black, thinly laminated and fissile, mi . 7

,, . ,, , i i n !,, i Thickness weathering papery, alternating visible lamellae, silty and (feet)

micaceous; two soft blocky gray mudstone beds; each

about 1.5 feet thick at base and 6 feet above base . .. .. ........ 14.5

2. Shale; as above, containing five thin (0.1-0.2-ft. thick) 

cone-in-cone brown limestone layers interspersed at intervals of 6-25 feet. A few pyritic nodules present in the 

lower part. Base of unit at lowest cone-in-cone layer 

observed ..... ......... ...... ....... ........ ........ ... . ... . ............... . .... 63.9

3. Shale; as above ... . ..... ...... ........................ . ... . ....... . .......... 34.1

4. Shale; as above, including numerous Foerstia specimens

scattered along bedding planes. (Foerstia zone) . ........ ........ ........ 5.0

5. Shale; as above, containing large carbonate and septarian 

concretions 8-15 feet above base, scattered smaller concretions elsewhere ................. .. . ...................................... .. . ...... 41.9
FOERSTIA ZONE, OHIO AND CHATTANOOGA SHALES H13

6. Mudstone, blocky, gray to brown, mostly hard, pyritic; 

three dark shale interbeds, 0.3-1.0 foot thick, that have 

"worm tubes" with gray silty filling-; shale otherwise as Th(fe )8S 

described above. Base of unit at lowest mudstone layer 

observed . . . .......... .... .. ... ...... .. .. .... 5.6

7. Shale; as described for units 1-5 above, including1 one

2-foot covered interval near the top .. . . 24.5

8. Sandstone, gray, iron-stained on weathering, medium- to 

coarse-grained, pyritic, argillaceous; containing a scattering of scolecodonts. (Base of Ohio Shale) . .. .. . .3

9. Sandstone, carbonate-cemented; with brachiopods (equivalent to Columbus Limestone) . ... ..... ........... ......... .... 1.0 +

SUMMARY

Foerstia is a problematic type of plant fossil that has a confusing scientific history. These fossils occur within a zone in the 

Huron Member of the Ohio Shale (Upper Devonian) and in correlative beds in the Eastern United States. Foerstia is regarded as 

an advanced type of pelagic alga that depends on an association 

with a particular type of littoral environment for its reproduction. 

Its limited stratigraphic and geographic distribution may be explained as a result of edaphic change that rendered the environment only temporarily accessible, a condition dependent on interaction between the variable character of the littoral zone and 

transgression of an epicontinental sea.

Examples of Foerstia from several localities, including several 

growth forms, have been illustrated. Most of these previously 

studied seem to have come from Ohio and probably are best 

identified with the type species that David White named Foerstia 

ohioensis. Foerstia should be distinguished from Protosalvinia 

Dawson, but the two genera are related and probably belong in 

the same family. Protosalvinia occurs most abundantly and typically in Brazil. Both genera probably should be assigned to the 

Order Fucales, which also includes many advanced types of 

modern seaweeds.

According to the hypothesis of littoral control that is advocated 

herein, it is reasonable to expect Foerstia to be easily recognized 

over a large area as an excellent guide to a thin stratigraphic zone 

related to a particular level of the ancient sea. Foerstia can be 

identified both in cuttings and in outcrop. Its geographic distribution may signify the course of tidal currents. Further studies 

should aid in testing the littoral control theory for foerstian occurrence, and, if confirmed, the localities should outline in detail 

the paleogeography of at least a part of the black-shale basin 

through a restricted interval of time.
H14 CONTRIBUTIONS TO STRATIGRAPHY

REFERENCES CITED

Arnold, C. A., 1954, Fossil sporocarps of the genus Protosalvinia Dawson, 

with special reference to P. furcata (Dawson) comb. nov.: Svensk Bot. 

Tidskr., v. 48, no. 2, p. 292-300.

Bharadwaj, D. C., and Venkatachala, B. S., 1960, On Protosalvinia arnoldii 

n. sp. from Upper Devonian of Kentucky, U.S.A.: Senckenbergiana 

Lethaea, v. 41, no. 1-6, p. 27-35, 2 pis., 1 fig.

Caplin, S. M., 1968, The Fucus life cycle; time to correct textbooks: Bioscience, v. 18, no. 3, p. 193.

Conant, L. C., and Swanson, V. E., 1961, Chattanooga Shale and related 

rocks of central Tennessee and nearby areas: U.S. Geol. Survey Prof. 

Paper 357, 91 p., 17 pis., 18 figs.

Dawson, J. W., 1884, On rhizocarps in the Palaeozoic period [abs.]: Am. 

Assoc. Adv. Sci. Proc., v. 32, p. 260-264.

 1888, On sporocarps discovered by Prof. E. Orton in the Erian shale

of Columbus, Ohio: Canadian Rec. Sci., v. 3, no. 3, p. 137-140, 1 fig. 

Foreman, H. P., 1959, A new occurrence of Devonian Radiolaria in calcareous

concretions of the Huron Member of the Ohio Shale: Jour. Paleontology,

v. 33, no. 1, p. 76-80, pi. 15, 1 fig. 

Fritsch, F. E., 1945, The structure and reproduction of the algae: London,

Cambridge Univ. Press, 2 v. (Repr. 1959.) 

Hass, W. H., 1956, Age and correlation of the Chattanooga Shale and the

Maury Formation: U.S. Geol. Survey Prof. Paper 286, 47 p., 5 pis., 1 fig.

 1958, Upper Devonian conodonts of New York, Pennsylvania, and 

interior states: Jour. Paleontology, v. 32, no. 4, p. 765-769.

Kidston, Robert, and Lang, W. H., 1924, On the presence of tetrads of 

resistant spores in the tissue of Sporocarpon furcatum Dawson from the 

Upper Devonian of America: Royal Soc. Edinburgh Trans., v. 53, pt 3, 

no. 28, p. 597-601, 1 pi.

Krausel, Richard, 1941, Die Sporokarpien Dawsons, eine neue ThallophytenKlasse des Devons: Palaeontographica, v. 86, sec. B, pt. 4-6, p. 113-133, 

pis. 28-34, 3 figs.

 -1960, Spongiophyton nov. gen. (Thallophyta) e Haplostigma Seward 

(Pteridophyta) no Devoniano Inferior do Parana: Brazil, Div. Geologia 

e Mineralogio Mon. 15, 41 p., 11 pis.

Kreger, D. R., 1962, Cell walls, in Lewin, R. A., ed., Physiology and biochemistry of algae: New York and London, Academic Press, p. 315-335, 

3 figs.

Kylin, Harald, 1917, Uber die Entwicklungsgeschichte und die systematische 

Stellung der Tilopterideen: Deutsche bot. Gesell., Ber. v. 35, no. 29, 

p. 298-310.

 1918, Uber den Generationswechsel der Phaeophyceen, in Studien iiber 

die Entwicklungsgeschichte der Phaeophyceen: Svensk Bot. Tidskr., 

v. 12, no. 1. p. 40-59.

Lang, W. H., 1945, Pachytheca and some anomalous early plants (Prototaxites, Nematothallus, Parka, Foerstia, Orvillea n. g.) : Linnean Soc. 

London Jour., Botany, v. 52, no. 347, p. 535-552, pis. 22-25.

O'Colla, P. S., 1962, Mucilages, in Lewin, R. A., ed., Physiology and biochemistry of algae: New York and London, Academic Press, p. 337-356, 

5 figs.
FOERSTIA ZONE, OHIO AND CHATTANOOGA SHALES H15

Pia, Julius, 1927, Algae incertae sedis, in Hirmer, Max, Handbuch der Palaobotanik: Munich and Berlin, R. Oldenbourg, v. 1, p. 109. 

Schopf, 3. M., 1957, "Spores" and problematic plants commonly regarded

as marine annotated bibliography, in Hedgpeth, J. W., and Ladd, H. S.,

eds., Treatise on marine ecology and paleoecology: Geol. Soc. America

Mem. 67, v. 2, p. 709-718. 

Schopf, J. M., Wilson, L. R., and Bentall, Ray, 1944, An annotated synopsis

of Paleozoic fossil spores and the definition of generic groups: Illinois

State Geol. Survey Rept. Inv. 91, 73 p., 3 pis., 5 figs. 

Setchell, W. A., 1935, Geographic elements of the marine flora of the North

Pacific Ocean: Am. Naturalist, v. 69, no. 725, p. 560-577, 12 figs. 

Smith, G. M., 1938, Algae and fungi, volume 1 of Cryptogamic botany: New

York, McGraw-Hill Book Co., 545 p., 299 figs. 2d ed., 1955. 

Sommer, F. W., 1962, On Protosalvinia bilobata Dawson from the Devonian

of Para and its taxonomic situation: Acad. Brasileira Ciencias, Anais,

v. 34, no. 4, p. 465-475, 2 pis., 1 fig. 

Wall, David, 1962, Evidence from Recent plankton regarding the biological

affinities of Tasmanites Newton 1875 and Leiosphaeridia Eisenack 1958:

Geol. Mag., v. 99, no. 4, p. 353-362, pi. 17, 8 figs. 

White, David, and Stadnichenko, Taisia, 1923, Some mother plants of petroleum

in the Devonian black shales: Econ. Geology, v. 18, no. 3, p. 238-252,

5 pis. 

Williamson, W. C., 1878, On the organization of the fossil plants in the CoalMeasures, Part IX: Royal Soc. London Philos. Trans., v. 169, pt. 3,

p. 319-364. 

Winder, C. G., 1966, Conodont zones and stratigraphic variability in Upper

Devonian rocks, Ontario: Jour. Paleontology, v. 40, no. 6, p. 1275-1293,

pi. 156, 9 figs. 

Winslow, M. R., 1962, Plant spores and other microfossils from Upper

Devonian and Lower Mississippian rocks of Ohio: U.S. Geol. Survey

Prof. Paper 364, 93 p., 27 pis., 12 figs.

PLATES 1 AND 2
PLATE 1

[All fossils photographed with unidirectional illumination. Specimens have been entirely 

separated from matrix by HF treatment]

FIGURES 1-10. Foerstia ohioensis White.

1. 3. Top (fig. 1, X 5) and bottom (fig. 3, X 10) of large thallus from 

Foerstia zone, Bristol Ridge. Fig. 3 shows pattern of meristoderm cells 

radiating from ragged proximal margin.

2. Discoidal thallus with acute apical lobes. Orton Museum specimen, 

collected at former exposure of Foerstia zone near 4th Street and 17th 

Avenue in Columbus, Ohio. X 10.

4, 5. Top and bottom of characteristic bilobed form of thallus, Foerstia 

zone, Bristol Ridge. Proximal margin in fig. 5 is partly indicated by 

black line. X 10.

6, 7. Top and bottom of compressed, strongly bilobed thallus. Note the 

similar infolding of apical grooves on the two surfaces. From collections submitted by W. H. Hass from Glendale Locality (see Hass, 1956, 

loc. 225, p. 35), Hamilton County, Tenn. X 10.

8. Discoidal thallus showing asymmetrical dichotomous apical lobing 

(not to be confused with trilete apical segments of lycopsid megaspores) . Orton Museum specimen, The Ohio State Univ., collected 

at former exposure of Foerstia zone near 4th Street and 17th Avenue 

in Columbus, Ohio. For reverse surface, see pi. 2, fig. 3. x 10.

9. 10. Top and bottom view of smallest (youngest?) whole thallus noted. 

From Foerstia zone, Bristol Ridge section. X 10.
GEOLOGICAL SURVEY BULLETIN 1294-H PLATE 1

9 10

FOERSTIA OHIOENSIS WHITE
PLATE 2

FIGURES 1-7. Foerstia ohioensis White.

1, 2. Top and bottom surfaces of compressed whole thallus. The "bumps" 

near the apical lobes of fig. 1 are impressions of mineral grains; 

photographed with Ultropak (cone of incident light) ; for view with 

unidirectional lighting, see pi. 1, fig. 2. Fig. 2, with unidirectional 

lighting, shows the proximal opening clearly, x 10.

3, 4. Bottom (fig. 3, x 10) and top (fig. 4, x 5) surfaces of discoidal 

compressed whole thallus; unidirectional illumination. Note proximal 

opening shown in fig. 3. See pi. 1, fig. 8, for enlarged view of top 

surface. Orton Museum specimen, 4th Street and 17th Avenue, 

Columbus, Ohio.

5. Cellular pattern of double thickness of meristoderm; focus on the 

upper layer. Specimen cleared and mounted in balsam; photographed 

by transmitted light. Specimen from Foerstia zone, Bristol Ridge 

section, x 100.

6. A single conceptacle with four contained oospheres (margins dotted, 

numbered 1-4). Overlap of oospheres by the margin of the crater 

suggests that the uncompressed conceptacle originally had much 

greater depth. Source and lighting as for fig. 5. X 100.

7. A few cells of the meristoderm (single thickness). Source and lighting as for fig. 5. X 300.
GEOLOGICAL SURVEY BULLETIN 1294-H PLATE 2

FOERSTIA OHIOENSIS WHITE

Contributions to

Stratigraphy,

1969

GEOLOGICAL SURVEY BULLETIN 1294

This volume was published 

as separate chapters A-H
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director
CONTENTS

[Letters designate the separately published chapters]

(A) Changes in stratigraphic nomenclature by the U.S. Geological Survey, 

1968, by George V. Cohee, Robert G. Bates, and Wilna B. Wright.

(B) Probable Permian age of the Rampart Group, central Alaska, by W. P. 

Brosge, M. A. Lanphere, H. N. Reiser, and R. M. Chapman.

(C) The Shenango Formation (Mississippian) in northwestern Pennsylvania, 

by Grant E. Kimmel and George R. Schiner.

(D) Cretaceous and lower Tertiary stratigraphy in northwestern Puerto Rico,

by David H. Mclntyre, John M. Aaron, and Othmar T. Tobisch. 

(E) The Bates Mountain Tuff in northern Nye County, Nevada, by K. A.

Sargent and E. H. McKee. 

(F) Cretaceous and lower Tertiary stratigraphy of the Gurabo and El

Yunque quadrangles, Puerto Rico, by Victor M. Seiders. 

(G) Age of the Bedford Shale, Berea Sandstone, and Sunbury Shale in the

Appalachian and Michigan Basins, Pennsylvania, Ohio, and Michigan,

by Wallace de Witt, Jr. 

(H) The Foerstia zone of the Ohio and Chattanooga Shales, by J. M. Schopf

and J. F. Schwietering.

 &U.S. GOVERNMENT PRINTING OFFICE. I97O O 383 286