THE ORDOVICIAN FAUNA OF KENTUCKY

By
ARTHUR C. McFARLAN

INTRODUCTION

HIGH BRIDGE SERIES
(M. R. CAMPBELL, 1898)

Fig. 25. Map of Kentucky showing outcrop of Ordovician rocks.

Massive, cliff-forming limestone of Chazy and Stones River age. Three formations are recognized:

CAMP NELSON (A. M. Miller, 1905, p. 10). Limestone composed of irregular patches and ramifications of granular rock of the Oregon type distributed through a matrix of dense limestone of the Tyrone type, presumably algal in origin. On weathering the surface becomes honeycombed. Fossils are not common, the more characteristic being Maclurites bigsbyi, Escharopora ramosa, a species of Rhinidictya, and various cephalopods.

OREGON—Kentucky River Marble (A. M. Miller, 1905, p. 10). Grey to cream colored, granular, magnesian limestone.

TYRONE—Birdseye Limestone of Linney (A. M. Miller, 1905, p. 10). Dense gray, dove, or cream colored limestone, breaking with conchoidal fracture and with small facets of coarsely crystalline calcite. On weathering the surface becomes white, in which the darker facets are conspicuous, giving rise to the name Birdseye. A bed of bentonite, a greenish clay, occurs near the top. Fossils are few and include such forms as Strophomena incurvata, (see p. 80) Orthis tricenaria, Leperditia fabulites, and the cephalopods Endoceras, Actinoceras, and Cameroceras.

Typical stratigraphic sections of the Ordovician.

LEXINGTON LIMESTONE
(M. R. Campbell, 1898)

This is the Trenton of Kentucky. As originally defined it included the strata between the Tyrone and Flanagan Chert. As later applied by Miller (1905, p. 18) and Foerste everything up to the base of the Cynthiana is included. The series is richly fossiliferous and composed for the most part of thin limestone and shale. The following formations are recognized:

CURDSVILLE (A. M. Miller, 1905, pp. 9, 18). Coarsely crystalline limestone with much chert. Characterictic fossils include Orthis tricenaria, Dinortliis pectinella, Rhynchotrema trigonale, Streptelasma profundum, and Plectambonites curdsvillensis.

HERMITAGE (E. O. Ulrich, 1903). A more or less siliceous limestone formerly known as the Logana (A. M. Miller, 1905, pp. 9, 18). Characteristic forms are Dalmanella bassleri, Heterorthis clytie, and Prasopora falesi. Near the top there is commonly a molluscan horizon where Modiolodon oviformis, Protowarthia obesa, P. pervoluta, and Lophospira obliqua stud the limestone.

JESSAMINE (A. M. Miller, 1919, p. 25). Replacing the name of Wilmore (Nickles, J. M., 1905, p. 15). This is the zone of Prasopora simulatrix together with Dalmanella bassleri, Rhinidictya neglecta, Liospira americana and Hebertella frankfortensis. Over much of Jessamine and Fayette counties, at least, the top of the formation is marked by a siliceous limestone containing a profusion of Lophospira and other mollusks.

BENSON (A. F. Foerste, 1913, pp. 365, 389).¹ The association of Rhynchotrema increbescens and Hebertella frankfortensis is more or less characteristic, though both occur lower in the column. The upper beds are characterized by the additional occurrence of Stromatocerium pustulosum, Dinorthis ulrichi, Strophomena vicina, and Cyphotrypa frankfortensis.

BRANNON (A. M. Miller, 1913, p. 324). A fine-grained, siliceous, bouldery or concretionary limestone, with much shale in the lower part. On weathering it gives rise to a conspicuous zone of chert drift and forms the lower part of Campbell's (1898) Flanagan Chert. Fossils are not common except in the shale. The Brannon is the horizon where the remarkable sponges, Brachiospongia digitata, and Pattersonia aurita are usually found. Of interest is the early occurrence of Eridotrypa briareus with Peronopora milleri.

WOODBURN (A. M. Miller, 1913, pp. 326, 327). A crystalline limestone, with unusually high phosphate content. The most useful index fossils are Columnaria halli, and C. alveolata var. associated with Platystrophia colbiensis, Constellaria teres (locally abundant) Cyclora minuta, and Rhynchotrema increbescens.

PERRYVILLE (J. M. Nickles, 1905, p. 15). This formation is best developed in the southern and western Bluegrass but outliers of both Salvisa and Faulconer occur in the vicinity of Lexington and Paris. Three members are recognized:

FAULCONER (A. F. Foerste, 1912, p. 32). A porous, coarsely crystalline, light gray, massive limestone, in its typical development a crowded mass of gastropod shells, chiefly Bellerophon troosti, Oxydiscus subacutus, and Lophospira medialis. Silicification of this bed, in weathering, gives rise to the third chert, horizon of the series, a fossiliferous chert.

SALVISA (A. M. Miller, 1913, p. 329). Upper Birdseye limestone of Linney. A compact limestone suggesting the Tyrone, including some of black color. Characteristic fossils include Isochilina jonesi, Leperditia (several species), and Orthorhynchula linneyi. Locally it is softer and more argillaceous.

CORNISHVILLE (Foerste, 1912, p. 32). Crystalline fossiliferous limestone characterized by the recurrence of the upper Benson fauna. It is restricted to the counties of the southern Bluegrass.

As indicated in the Garrard and Jessamine County section the development of the upper Lexington limestone is different in the southern area. In southern Jessamine County, except in the eastern part, the Cynthiana rests directly on the Benson. In central Garrard and northern Lincoln and Boyle counties, the interval between the Jessamine and Perryville beds is occupied by the lower Benson only.

CYNTHIANA
(A. F. Foerste, 1906, pp. 10, 13)

Fossiliferous limestone and shale. Bassler, (1915), recognizes four divisions, the Greendale, Bromley, Gratz, and Rogers Gap members.

GREENDALE (A. F. Foerste, 1909c, p. 295). The characteristic faunal assemblage includes Cyclonema varicosum, Eridotrypa briareus, Orthorhynchula linneyi, Herbertella maria parkensis, Homotrypa norwoodi, Constellarla emaciata, C. fischeri, Heterotrypa parvulipora, Allonychia flanaganensis, Rafinesquina winchesterensis, Platystrophia colbiensis, and Escharopora maculata. A more richly fossiliferous and rubbly phase occurring in the eastern area of outcrop is known as the Millersburg. The faunal difference is quantitative rather than qualitative. It is in this bed that the precursors of the Fairmount forms are best developed.

BROMLEY (Bassler, 1906, p. 9). The name was given to the thirty feet of drab to blue shales outcropping in the lower part of the river bank at Cincinnati.

GRATZ (undescribed in the literature). The name is taken from a village on the Kentucky River in western Owen County. It consists of a series of rather unfossiliferous shales. Its geographic extent is not known by the writer.

Overlying the Millersburg in Nicholas County is a coarse-grained limestone to which Foerste has given the name Nicholas limestone (A. F. Foerste, 1909, p. 210). At Carlisle a similar limestones overlying the Millersburg contains Clitambonites.

ROGERS GAP (A. F. Foerste, 1914, pp. 109-156). The essentials of the type section are as follows:

(a) Lower coarse-grained crinoidal limestone up to eighteen feet thick. This may be the equivalent of the limestone with Clitambonites mentioned above.
(b) Argillaceous strata containing Eridorthis nicklesi, E. rogersensis, and Clitambonites rogersensis in the lower part.
(c) A gastropod horizon with Belleophon rogersensis, Tetranota obsoleta, Liospira vitruvia, and Lophospira sp., a constant and well marked horizon.
(d) Argillaceous strata with Eridorthis at top.
(e) 20-25 above (a) an upper coarse grained crinoidal limestone with Eridorthis, which is most common just below it.
(f) Zone of abundant Plectambonites rugosus with associated Strophomena halli introduced about five feet above (e). This zone (Plectambonites does occur lower but not in the same abundance) has been regarded as marking the base of the Eden (Million) in Central Kentucky by Miller and others. It is one of the most conspicuous and consistent horizons throughout the area.

These beds are of wide extent in Central Kentucky. Eridorthis has been identified along the Ohio River at a level well below the Fulton layer (A. F. Foerste, 1914, pp. 119, 120), also in the lower Economy at several localities in that region (Foerste, 1909, p. 294). The stratigraphic relationships of this bed are not well known.

EDEN
(E. ORTON, 1873, pp. 370, 371)

At Cincinnati four divisions are recognized:

FULTON (A. F. Foerste, 1905, p. 151). Shales characterized by Triarthus becki, Leptobolis insignis, Plectambonites plicatellus, and Merocrinus curtus.

ECONOMY (R. S. Bassler, 1906, pp. 8-10). The Aspidopora newberryi zone of Nickles. It is characterized by Coeloclema commune, Crepipora venusta, and several species of Aspidopora (R. S. Bassler, 1903, p. 9).

SOUTHGATE (Bassler, ibid). The zone of Ctenobolbina ciliata., Aspidorpora eccentrica and Batostoma jamesi. Cummings and Galloway regard Climacograptus typicalis and Bythocypris cylindrica as characteristic in the Tanners Creek section.

MCMICKEN (Bassler, ibid). The zone of Dekayella ulrichi of Nickles. Limestone is a more conspicuous element than in the lower members. The typical fauna includes D. ulrichi, Coeloclema commune, C. alternatum, Batostoma Jamesi, B. implicatum, and Hallopora onealli.

In Central Kentucky the Eden is divided into two members, the Million (J. M. Nickles, 1905, p. 25), and the overlying Paint Lick (A, F. Foerste, 1909c, 293) constituting the lower, massive part of the Garrard sandstone of Campbell (1898). The Paint Lick is quite barren of fossils. Among the more characteristic forms of Million are Plectambonites rugosus, Dalmanella multisecta, and Ectenocrinus simplex. The base is marked by the appearance in great numbers, commonly in a crinoidal limestone, of Plectambonites rugosus and Hallopora onealli. In some sections, at least, D. multisecta is introduced in equally large numbers ten or fifteen feet lower.

MAYSVILLE
(A. F. Foerste, 1905, pp. 149-52)

FAIRVIEW (R, S. Bassler, 1906, p. 10). This is the Plectorthis plicatella zone of Cumings and Galloway (1913, p. 2) and includes Nickles' Mt. Hope or Amplexopora septosa beds (1902, p. 76) and his Fairmont or Dekayia aspera beds (ibid, p. 78). The faunal change from the McMicken is not abrupt. Common forms are Plectorthis plicatella, Platystrophia laticosta, Amplexopora septosa, Batostoma implicatum, Dekayia aspera, Eschapora falciformis, E. pavonia, Hallopora andrewsi, H. dalei, Heterotrypa subfondosa, Homotrypa curvata, Constellaria florida, and Peronopora vera.

MT. HOPE. This formation overlies the Dekayella ulrichi zone and is characterized by the introduction of a rich bryozoan fauna and of Platystrophia. Plectorthis neglecta is regarded as characteristic. In Central Kentucky this horizon is represented in the upper Garrard. Strophomena maysvillensis occurs in moderate numbers.

FAIRMOUNT. At Cincinnati the Fairmount is marked at its base by the Strophomena Planoconvex zone, a limited horizon where this species occurs in great numbers. The occurrence of several species of Plectorthis, P. plicatella, P. fissicosta, and P. aequivalvis, is characteristic. In the central and southern Bluegrass the fauna is that of the Maury phase (A. F. Foerste, 1912, p. 19). The base is marked by a profusion of Strophomena maysvillensis and Constellaria florida. Other characteristic forms are Orthorynchula linneyi (upper), Escharopora hilli, Cyrtoceras valandinghami, Platystrophia ponderosa (lowest occurrence), Hallopora dalei, Monticulipora mammulata, and Homotrypa cincinnatiensis.

MCMILLAN
(R. S. Bassler, 1906, p. 10)

This series includes the Bellevue, Corryville and Mt. Auburn formations as exposed in the region around Cincinnati. In the southern Bluegrass it is represented by the Tate, Gilbert and Mt. Auburn, with the Bellevue appearing as the lower Tate farther north.

BELLEVUE, the Monticulipora molesta beds of Nickles (1902, p. 82) and the Rafinesquina ponderosa zone of Cumings and Galloway (1913, p. 2). This highly fossiliferous zone of thin bedded limestone extends south into Montgomery County on the east and Shelby County on the west.

CORRYVILLE, the Chiloporella nicholsoni (C. flabellata) zone of Nickles, (1902, p. 83). Other more or less characteristic fossils are Bythorpora gracilis, Rafinesquina fracta, Amplexopora filiasa, Hallopora andrewsi, Dekayia appressa, and Heterotrypa paupera.

MT. AUBURN, the Platystrophia lynx beds of Nickles (ibid., p. 85). Platystrophia ponderosa auburnensis is characteristic. Associated forms are Coeloclema oweni and Homtrypa pulchra. In the southern Bluegrass it is a similarly highly fossiliferous rubbly limestone with Platystrophia ponderosa and Heterospongia subramosa common. A third common species is Amplexopora robusta. Lithologically it is well marked, resting on the dense limestone of the Gilbert, and beneath the non-fossiliferous Sunset.

HARMON (Cumings and Galloway, 1913, pp. 2, 7), referred to as the Rafinesquina fracta zone, including the Corryville, Mt. Auburn, and Arnheim formations of Indiana. The most common fossils are R. fracta and Hallopora ramosa. Characteristic forms according to Cumings and Galloway are Atactoporella ortoni, Coeloclema oweni, Homotrypa pulchra, and Dinorthis retrorsa (carleyi).

TATE (A. F. Foerste, 1912, p. 18). A non-fossiliferous, gray shale and shaly limestone section of the southern Bluegrass. Northward on the eastward flank of the arch fossiliferous zones become more common and in northern Clark and Montgomery counties it is abundantly fossiliferous with Platystrophia ponderosa, Amplexopora robusta, and Cyphotrypa clarksvillensis (cc.). Here it overlies the Bellevue.

GILBERT (Foerste, ibid.). A zone of dove to gray, fine-grained to dense, hard limestone restricted to the southern Bluegrass. It grades into the Mt. Auburn. Platystrophia ponderosa and Lophospira bowdeni are common. The Tate and Gilbert of Lincoln, Garrard, etc., counties together fill the interval of the Bellevue and Corryville to the north.

RICHMOND
(Winchell and Ulrich, 1897, p. 53, formerly known as the Lebanon beds Orton, 1873, p. 371)

The Richmond has customarily been recognized as beginning with the Arnheim though the latter had originally been classified with the Maysville and was again referred to it in 1913 by Cumings and Galloway (1913, pp. 2, 8).

ARNHEIM (A. F. Foerste, 1905, p. 150), the Warren beds of Nickles (1902, p. 86). At the type locality in Brown County, Ohio, he placed the top at the lumpy limestone containing Strophomena concordensis. In the eastern and southern area of outcrop two divisions are recognized:

SUNSET (A. F. Foerste, 1910, p. 18). A relatively non-fossiliferous argillaceous series, comparable to the Tate and Waynesville, sometimes dolomitic. Throughout the region of Garrard, Lincoln, Clark, and Montgomery counties it is capped by a few feet of hard limestone, mostly of the Gilbert type, in some layers of which ostracods are very common. Northward in Ohio the Sunset becomes quite fossiliferous.

OREGONIA (A. F. Foerste, ibid.). A highly fossiliferous, rubbly limestone, in which the characteristic Richmond brachiopods Rynchotrema dentatum (var. arnheimensis), Leptaena richmondensis (var. precursor), and Dinorthis carleyi (rare in Kentucky) are introduced. The association of any one of these species with Platystrophia ponderosa (upper limit of range) is regarded as diagnostic. Heterospongia knotti is rather characteristic in the area between Lincoln and Marion counties. Over much of this area the top is marked by about two feet of light colored shale, full of slender bryozoa, including a form resembling Hallopora dalei and a Homotrypa (see p. 93).

In Jefferson County which may be regarded as typical of the western area, Butts (1915, pp. 41-49) has divided the Arnheim into three members:

(a) Platystrophia ponderosa zone. According to Butts it rests disconformably on the Bellevue at Sulphur in Henry County and at Madison, Indiana. McEwan (1920) has shown the presence of the Corryville and Mount Auburn in the latter section.
(b) Rhynchotrea dentatum zone (assoc. L. richmondensis).
(c) Constellaria polystomella zone. Other common fossils are Anomalodonta gigantea, Homotrypa bassleri, Hallopora subnodosa, and Platystrophia cypha. Platystrophia ponderosa ranges through all these zones, Dinorthis carleyi is rare in both (a) and (c), and Cyclonema bilix var. fluctuatum occurs
in all three.

WAYNESVILLE (Nickles, J. M., 1903, p. 205). In 1910 Cumings used the term Dalmanella meeki zone. Three members are recognized (Foerste, A. F., 1909, pp. 291-292) in Ohio.

FORT ANCIENT. Characterized by the abundance of Dalmanella meeki and absence of other characteristic Richmond brachiopods and corals. Anomalodonta gigantea, Modiolopsis concentrica, M. pholadiformis, Opisthoptera fissicosta, and Pterinea demissa are common. The top is marked by the Orthoceras fosteri (duseri) bed.

CLARKSVILI.E. This member includes all strata up to the lower Hebertella insculpta horizon (Austin, G. M., 1927, includes the Hebertella insculpta zone in the Clarksville.). Streptelasma vagans, Plectambonites rugosus, Strophomena planumbona, S. sulcata, Rhychotrema capax, and Leptaena richmondensis are common. It may be traced southward into Fleming County, Kentucky, (Foerste) but is not recognized in the western area of outcrop.

BLANCHESTER. Terminated by the upper Hebertella insculpta horizon which has commonly been recognized as marking the basal Liberty but has more recently been included in the Waynesville (A. F. Foerste, 1909, p. 290). It has the richest fauna of the Waynesville and may be traced south into Bath County. Strophomena nutans, S. neglecta, and S. vetusta form a well-marked horizon in the middle. Leptaena richmondensis, Rhynchotrema capax, Platystrophia clarksvillensis, and P. cumingsi are common.

In Jefferson and adjoining counties the Waynesville is a series of shales and shaly limestones, the base marked by the occurrence of Columnaria alveolata and Tetradium minus (Fisherville coral reef of Foerste, 1909, p. 29). Above is a zone of shale with Cyphotrypa clarkvillensis (cc.). The rest of the formation is sparingly fossiliferous with C. clarksvillensis and Zygospira kentuckiensis characteristic.

Across the southern Bluegrass the Waynesville is almost void of fossils but, becomes fossiliferous again to the north in Montgomery County.

Because of the close faunal relationship between the Waynesville and Liberty Foerste (1912, p. 22) proposed the name Laughery formation for the combined sequence.

LIBERTY (Nickles, 1903, p. 207)—The Strophomena-Rhynchotrema bed of Cumings (1900), and Strophomena planumbona zone of Cumings and Galloway (1913, p. 2). Over most of its area of outcrop in Kentucky the base is marked by a coral reef, the Bardstown reef of Foerste (1909, p. 290) composed of Columnaria alveolata, C. vacua, Tetradium minus, Calapoecia cribriformis, and the associated Beatricia undulata, and B. nodulifera. It may be traced southward into Lincoln County on the one side, and Marion County on the other. The Liberty is missing along the axis of the arch. The more characteristic species include Dinorthis subquadrata, Plectambonites rugosus, Rhynchotrema capax, Strophomena planumbona, Streptelasma rusticum, Rhombotrypa quadrata, R. subquadrata, Protarea richmondensis, and Homotrypa austini. In the region between Lincoln and Montgomery counties, at least, the basal reef is often missing and the bottom of the formation is marked by a massive dolomitic limestone. The presence of Hebertella insculpta would place this bed at the top of the Waynesville. The rest of the limestone over this same region is more or less dolomitic and fossils not well preserved. Strophomena sulcata, Bythopora meeki, B. delicatula, and occasionally R. capax are present. The upper part of these beds may include the Whitewater.

SALUDA—WHITEWATER

The SALUDA (A. F. Foerste, 1902, p. 369) is a dolomitic limestone, scantily fossiliferous except for an upper member, the Hitz limestone (A. F. Foerste, 1903b, p. 347), earlier designated as the Murchisonia hammeli bed (A. F. Foerste, 1896, pp. 218-222) which contains a Whitewater fauna. In the lower part of the formation, a few feet above the base, a reef of Columnaria and Tetradium, similar to the lower reefs is a characteristic horizon marker. This is the Madison coral reef of Foerste, (1909, p. 290).

The WHITEWATER (J. M. Nickles, 1903, p. 208) and Saluda are contemporaneous phases of sedimentation, the former wedging out and overlapping the Saluda to the south where it is represented by the Hitz member, the latter (Saluda) thinning northward. The Whitewater may be represented in the upper part of the "Liberty" on the eastern flank. The fauna is much like that of the Liberty, the bryozoa, Batostoma variable, Homotrypa nicklesi and H. nitida being restricted to it. Other common forms include Bythopora delicatula, Homotrypa constel- [sic, ends abruptly]

Footnotes

¹ The Bigby formation of Ulrich (Columbia Folio) has been listed as equivalent to the Benson but is regarded as including the Benson, Brannon and Woodburn. The Paris bed (J. M. Nickles, 1905, p. 15) covers the same interval.