THE PETRIFACTION FLORA OF THE DEVONIAN­ MISSISSIPPIAN BLACK SHALEl

J. H. HOSKINS' & A T. CROSS"

GENERAL ASPECTS OF THE BLACK compressIOns or impressions found, at least SHALE FLORA OF UNITED STATES in the Interior Region. HERE is an extensive series of fissile The most notable of the black shale black shale exposed in several areas plants occur in, or associated with, phosphatic T of eastern United States. These concretions. Near the top of the New range in age from Middle Devonian to Lower Albany shale concentration zones of these Mississippian. Similar sequences of near­ are found. The nodules are abundant comparable age are known from a number throughout one thin widespread zone called of regions of western North America. Con­ the Falling Run member of the Sanderson temporaneity of all of these is not indicated. formation; fairly abundant in layers near For example, the earliest of mid-Palaeozoic the top of the Henryville and Sanderson black shales in New York are of Middle Devo­ formations; and scattered through the gen­ nian age. Westward development of this or eral matrix of the Sanderson (TEXT-FIG. 4 ). a similar facies in Ohio are of Middle and Up­ The nodules weather out of these concretion per Devonian, and the same strata transgress bands in great quantities. In places where the Devonian-Mississippian time boundary the topography is relatively level, the phos­ in Kentucky, Tennessee and Indiana. phatic nodules form regular pebble flats Recognizable organic remains are usually (TEXT-FIG. 1). Where streams of low gra­ restricted or cancentrated to certain geo­ dient cross these flat-lying concretion zones graphic areas and/or geologic zones. Much (TEXT-FIG. 3), good collections have been of the black shale sequence is essentially made. In such places the isolated wood and devoid of fossils of stratigraphic value. bone fragments (TEXT-FIG. 3a) are often This has led to considerable uncertainty exposed among the nodules. The nodules about the age from place to place. Much themselves must be split open and examined of the dating has been done by inference for wood fragments. In a few places rela­ drawn from study of associated and occa­ tively large isolated stem slabs or segments sionally intercalated strata. The difficulty are found (TEXT-FIG. S). Some of these of recognizing unconformities, diastems and are considerably water-worn, some are split rate of accumulation of these sediments by the secondary accretionary growth of makes precise dating of some of the thicker siliceous material (TEXT-FIG. Sa) which black shales by this procedure difficult. first penetrated the centre, and many had The principal recognizable floral remains decayed considerably before burial. Portions are divisible into three categories: (1) spores, of some of the larger specimens exposed thalloid plant bodies, and dissociated resis­ on steep banks by erosion may break off tant fragments of higher plants; (2) occa­ periodically and the fragments become sional silicified drift logs; and (3) isolated distributed for great distances down the phosphatized or pyritized stems or phosphatic slopes. In such an instance searching may and pyritic concretions containing miscel­ yield a number of pieces which fit together laneous plant and animal debris. In addition, to form a large specimen. The fossils range occasional pockets or fragmen ts of generical­ in size from minute fragments and whole ly unidentifiable coalified plant tissue occur stem segments no more than 2 mm. in throughout the black shales. Rarely are leaf diameter, up to several inches in diameter

1. This is the tenth paper in a series of joint palaeobotanical contributions which we have co-authored. The order of listing of names is not significant here or on any of the previous papers of the series as we are equally responsible for the research leading to the contents of each contribution, and the pre­ paration of the manuscripts. • Department of Botany, University of Cincinnati, Cincinnati, Ohio. ** West Virginia Geological Survey and West Virginia University, Morgantown, W.Va. 216 THE PALAEOBOTANIST and several feet in length. It is often black shales have not been found in the necessary to scrutinize every nodule or Mississippian part. These are generally fragment with a hand lens in order to silicified and are found as isolated sunken distinguish the wood from the matrix which drift logs or as segments forming the nuclei has a similar colour, texture and general in large calcareous or ironstone concretions. appearance. Many of these fossils, especially the The larger logs ( Callixylon., TEXT-FIGS. 2 & Callixylon, give the appearance of having 12 A) of the Upper Devonian portion of the drifted in a quiet sea for some time before

TEXT-FIGS. 1-5 HOSKINS & CROSS - THE DEVONIAN-MISSISSIPPIAN BLACK SHALE FLORA 2t 7 finally becoming water-logged and sinking been derived from the vegetation of an to the black organic mud at the bottom. island in the New Albany sea such as the The smaller plant fragments in some con­ oft-postulated Cincinnatia. The numerous cretions are often found incorporated as geologic evidences against the existence constituents of a coprolitic nucleus composed of such an island are difficult to disprove. of bone, teeth, wood and spores. The The several hundred miles separating the general nature of the enveloping concretions bulk of these plant fossils from t1re known is often constituted largely of spores but land mass of Appalachia to the east and as often of similar appearing porous phos­ south or Ozarkia to the west make such phate rock. sources difficult to envision from the palaeo­ The perplexing problem of the origin of botanical viewpoint. these plants must be considered in this A number of associated faunas have been investigation. They are certainly carried used in an attempt to date these strata as for some distance from their native habitat. of Devonian or Mississippian age. Lingu.la, The water-worn character of rounded or Barroisella, Orbiculoidea, Tornoceras, Mantico­ pebble-like pieces, the occurrence of attached ceras, 5 pathiocaris, and Rhadinichthys are crinoids on the bottom and rarely the sides typical. A great number of conodonts occur of some of the Callixylon logs as embedded throughout the black shales and major in the shale and probably as they ft.oated breaks are indicated by sweeping changes in the sea, the total lack of soils, the foul from one group of these to another, such as black sea type of sedimentation and the from the Ancyrodella group of the Devonian absence of leaf materials or, in fact, any to the Siphonognathus group of Mississippian of such delicate plant fragments, are evi­ portions of the New Albany shale. There dences in favour of the postulation of long is still considerable controversy over the transportation. The presence of numerous age of some of the black shale sequences well-preserved minute stems and good pre­ based on faunal evidence. servation of many larger pieces are against the theory that they could have come from STRATIGRAPHY great distances. Their greater abundance in the vicinity of the Cincinnati Arch and The geologic age of the ft.ora of the upper the numerical decrease of them to the east, part of the New Albany is carefully and south and west would suggest that they had extensively treated in the excellent work of +- TEXT-FIG. 1 - The late Professor Birbal Sahni at tains scattered phosphate nodules (b) in the fissile the classic Linietta Springs locality near Junction shale, and a thin layer of nodules (a) of the Falling City, Kentucky, at the time of his visit there on Run horizon at the top (F.R.). The overlying Henry­ February 27, 1948. The pebbles or concretions and ville (H.) marks the final recurrence of the black isolated pieces of fossil wood weather out of the one­ shale of the New Albany. It is intermingled with foot layer of phosphate nodules ( Falling Run mem­ the Falling Run nodules in the absence of the ber of the Sanderson formation) and inter-mixed Underwood grey shale which is missing here. The grey shale ( Bedford) at the edge of the shrub­ Jacobs Chapel grey shale (J .C.), a weak, fossili­ grass line. The New Providence ( 'Haverly) shale ferous zone, and the more resistant Rockford forms the bare slope visible through the brush in limestone above, are Kinderhook (Mississippian), the upper left corner of the picture. as are the Henryville and Sanderson formations at TEXT-FIG. 2-Large log of Callixylon Newberryi the top of the New Albany shale. The principal and several smaller pieces from the Devonian part of fossil wood horizon is at (a) with scattered pieces the New Albany black shale near Henryville, In­ found throughout the Sanderson. diana. The large log shows the joint-like segmenta­ TEXT-FIG. 5- Several pieces of phosphatic wood tion originating from pre-burial shrinkage and the and concretions from the top of the New Albany upright block to the right shows the same jointing shale at Pine Lick, Kentllcky. One piece of wood in a recently weathered condition. (a) is considerably enlarged and split apart by inter­ TEXT-FIG. 3 - Phosphate nodules in six-inch layer calated silica. The isolated piece (b) is considered of the Falling Run horizon (Sanderson f. ) at the to be very large for these collections. The nodules top of the fissile, black New Albany shale. Well­ at the upper left and at (c) show the water-worn developed joint systems occur throughout the character of some nodules and the enclosed wood shales (b). Large fragments of the head shield of fragments (partially lost here). The amount of a Placoderm (cf. Dinichthys ) are noted at (a). material shown constituted the entire lot collected TEXT-FIG. 4- Upper part of the New Albany shale in four hours' searching by Mr. Guy Campbell and and lower part of the New Providence (N.P.) forma­ us and yet was considered to be an unusually good tion at Henryville, Indiana. The Sanderson (S.) con- collection for that length of time. 218 THE PALAEOBOTANIST

Guy Campbell (1946). Text-fig. 6 is a river and west of the Cincinnati Arch in general correlation chart of the Middle and Kentucky, the New Providence siltstone and Upper Devonian of eastern United States shale lies nearly in contact with the Falling showing the principal horizons of petrified Run zone, but on the crest of the Cincinnati plants. The stratigraphic sections of the Arch, near Junction City and east of it, east-central Interior Region have been de­ traces of the eastward thickening wedge rived principally from Campbell ( 1946) and of Lower Mississippian Bedford formation the New York-Pennsylvania section is taken inter-fingers with the Falling Run and in from several sources, especially the National fact may furnish the matrix for the Falling Research Council's correlation chart of the Run nodules at these localities. Devonian (COOPER et at., 1942). Discre­ pancies or differences of opinion in the correlation of the New Albany shale with DISTRIBUTION the Ohio shale noted by Hass ( 1947), as based on conodont studies, need not be The Devonian-Mississippian black shales considered here. of the east-central Interior Region outcrop The New Albany shale of Indiana is in a narrow belt through central Ohio, across divided into five formations of unequal north-central Kentucky and south through thickness by Campbell ( 1946). The prin­ south-central Kentucky into Tennessee. cipal thickness is made up of fissile black From central Kentucky the outcrop also shale of the Blocher and the Blackiston extends northward into southern Indiana. which are considered Devonian in age. The The arrows pointing to the collection loca­ lowest of the three Mississippian formations lities (TEXT-FIG. 7) show this distribution of the sequence, the Sanderson, is a black rather clearly. The circumscription of the fissile shale con taining scattered phosphate Cincinnati Arch by the black shale is easily nodules throughout (TEXT-FIG. 4, S. b) with discernible in this figure. The collections a concentration zone of nodules called the around the north end of the Nashville Dome Falling Run member at the top ( TEXT-FIGS. are less complete and the outcrop there is 3, 4a and F.R.). This member is usually less well indicated by Text-fig. 7. only a few inches thick though occasiGnal­ In addition to the outcrops in this area ly it is as much as 18 in. It is in this narrow bands of outcrop of the Chattanooga zone that the main aggregation of petrified shale occur in eastern Kentucky and Ten­ wood is found. Another similar nodule nessee. Beneath the glacial mantle in zone which also contains a concentration of north-western Ohio and northern Indiana a plants occurs about a foot below the Falling considerable area of New Albany shale Run member in southern Indiana. Occa­ outcrops. Near-comparable stratigraphic sional isolated pieces of wood of the same zones of black shale occur in north-eastern floral group occur in the matrix throughout Michigan, the Antrim formation, Text-fig. 13 the remainder of the Sanderson formation. (3) and in south-western Ontario, the Kettle The overlying Underwood is a 6 in. thick Point, Text-fig. 13 (2). Throughout these grey-green shale, bearing a good brachio­ areas the black shales bear abundan t T asman­ pod fauna but virtually no conodonts. One ites spores (" sporangites") and occasional specimen of wood (Periastron) has been specimens of Callixylon. Upper Devonian found in this shale. The uppermost forma­ black shales of western New York have yield­ tion of the New Albany shale is the Henry­ ed several species of Callixylon. ville, a black fissile shale which has yielded The principal flora considered here, i.e. no petrified wood. In some places the from the Mississippian portion of the upper Underwood is missing and the Henryville New Albany shale, is most abundant at lies directly on the Falling Run nodule localities through central Kentucky and zone as shown in Text-fig. 4 at "H." and southern Indiana. A few specimens are "F.R.". found in southern Kentucky, and in Ten­ Above the New Albany shale in the area nessee at locality No. 47, Text-fig. 7. None north of the Ohio river, the Jacobs Chapel have been found in Ohio. shale and Rockford limestone (TEXT-FIG. 4, One additional collection of a repre­ ].c. and R. ) are easily distinguished on the sentative of this flora has been made at basis of lithology and 'characteristic Missis­ Kinderhook, Illinois (TEXT-FIG. 7, locality sippian invertebrates. South of the Ohio No. 49). This will be discussed later. INDIANA KENTUCKY CENTRAL OHIO N.E.OHIO W. NEW YORK-N.W. PENNA. NEW ALBANY ESTILL COUNTY COMPOSITE CUYAHOGA CLEVELAND AREA COMPOSITE z U'WAVr-RL~ I,~gl~ NEW PROVIDENCE l =::l I <[ ~-=o= .J Z .D 0-0-0-0- a: <[ SUNBURY w ~ ~~~> - .~ 0. ~ '--;-~-.BEREA ~ ~- ~ <[ BEDFORD f'- PROVIOEN~~ ~ 0. NEW ~ '~ ~ , , et>z - ROCK FORO 120 --=- BEDFORD ~ eo ~ et - ~ _- ~~ JACOB$CHAPE ~ _- ORANGEVILLE U :i (/) HENRYVILLE ...... _.J et ;: ~ (f) UNOERWOOD ~~O°(/) ~ IHL.L.ING RUN <.> <.:5 o~ U CLEvELAND (f) ,.... -+.....!!li:4<[~Z~ ~ V) ~<4 ;'SANDERSON) Ie' It: ~ ~o.Jo~~ ~ ... '\---'-=------'-=-"---j III c> .J (.) 0 . C ~ Z f----"-.:.:.::c:...:---1 Ul et - 0 Z .J .J et ~:t V) - I- 1o<--4....:.:.::..::..:..:.::..z:~+:....:.o ·········t ~ ~."."... ".. I i .. '. ' .. '7 Ul <[ Callixylon ~ OUISTED -=--CHAGRIN It: Ul ~ Z (·U.BLACKISTON) - I newberryl == -?------I(.ERIE) ~ ~~ ~ <[ It: § (OR L. CLEVELA NO) .... :::l 0 ::> ~et (.) 0 ... ::> zl I Ia- ~ <[ <[ '" / z~ ------­ ~ ~ t- <[ - o ::> Z ~ I I~ <[ <[ <[ - >- (f) I o~ ';i (.) ; z t-- HURON zlZ (.) 0 0 <[ 0 53' (f) .=L:'l Foerslio > ~ ItI > lXl .... ~ lJJ Ill) :::) 0 I&J .J ~ 1- w z 0 <[I", ~ 1 <[ a:: U - -? ~_ ___ (.) lJJ et ...... lJJ 0. ~ a: ...J r...... ______lJJo.Z I&J I&J al Q. - --- GO"OJ (/) ::> Z It: ------... Borrol llo ------Q. .. --.- ~ ----- OLENTANGY :::) TROUSDALE ------0

...J

CJiiij z z <[ HAMILTON z - <[ o I~=-=-­ z ca:liLEDYARD - CORRELATION OF .... 0 .J a:: > r- DEVONIAN-M I SSISSI PPIAN lJJ lJJ -> Z...J - et... 0 lJJ BLACK SHALES > .... "' .... 0 G: 'r'T"T _ III et Z TEXT-FIG. 6-Geologic cor­ o AND PRINCIPAL PLANT HORIZONS ~ ~I W relation chart showing the o --=----=--::::- BASED ON REPORTS BY CAMPBELL, I (l,3) ':::l N ~ principal petrified plan t-bear­ a- ~ ~r::::l <[ -- CASTER, COOPER, WILLARD B STOCKDALE ~ ... (.) ing horizons of the black shales --- ~ffT -- o 10 20 30 > of the eastern Interior Region , I I lJJ ,t! SC~Lf VfRTICAL o and the general correlations fOR COLUMNAR SfCTIONS .J with the New York-Pennsyl­ ~ ~ ~ ~ b'~;:,j oNla,KENTUCKY ~ ~NDIANA ~ E--- j c=:=J vania fossil-bearing zones. C. Cone - In - c one Phosphatic concretions Calc. $h. limeslone Sand-or siltslone Black sh. Gray sh. Co 1 concretions ~ PetrifIed ...ood horizon

HOSKINS & CROSS - THE DEVONIAN-MISSISSIPPIAN BLACK SH,\LE FLORA 223

COLLECTIONS tucky, as recorded in literature, includes The first study of the plan ts of the upper forty described species in twenty-nine part of the black shale sequence in the genera. The identification and proper as­ United States was contained in the report signment of a few of these will ultimately by Scott and Jeffrey (1914). This funda­ have to be checked when additional material mental study concerned some excellent is found. A number of new species and material from "the base of the Waverly genera await description. Vve h

10 ------9/":iJi~\/~~·0·",hS~~' I Q .~Q\ /9 ,,0 00Q 1 I~~~ " I ... ~I I • if G c 0 I I··· I:;;I~ ~, 10 Q9. Q (j) 0 I 6em \G~O.G (C) O(;).1 \ '>""4~/ ,file e 0.'? oQ ...... / " " ifilW4ll",/ ,~oe G) q~...... _-- ....- --- ~-I I A .'" ::. I .. " I G •.....' .. " .'': 13 14Ev}" -- - ...... / ;9' :r w@ o ,••.__.---"---'- :~~eo\,. " ',:. ," 15/~ 0._ 0 0 .,': ..... ~.': '. ,, 0 0 10 0, :. 0 ~6o. D.B):O:':"~:O'\ \0 0 \ ~.: :: : I301m •. ,0, 0 . ... "::. . ::~~. " '-,Q ••••: \. ~:.Q :~.o.~(!:.

TEXT-FIG. 8 . HOSKINS & CROSS - THE DEVONIAN-MISSISSIPPIAN BLACK SHALE FLORA 225

cross-hatched areas in 2, 5, 6. 8,11,12,15,17 and several genera is the calamopityan­ and 18 indicate primary wood or metaxylem. pityan alliance. Abundant pieces of secon­ The cross-hatching in number 3 is for primary dary wood and quite a number of complete wood ( complete bundles) but in number 21 stems of the Cycadofilicales and Cordaitale3 it indicates secondary wood. The solid are available.' An extensive study of the black circles, dots or areas in Nos. 1, 4, 7, distinguishing features of secondary wood 16,19 and 20 also indicate the whole primary will be requisite to the proper dispensation wood area or bundles. The radially aligned of much of this material. lines indicate secondary wood in 4, 7, 12, 15 B, 16, 19 and 20. AN EVALUATION OF RECORDED The grouping of many of these genera DEVONIAN COMPONENTS into families or orders is difficult principally because of inadequate information or mate­ Four genera, Protolepidodendron, Astero­ rial. The genera appear to include root xylon, Reimannia, and Callixylon, which axes and leaf petioles, or their divisions, have been reported from the black shales as well as stems. The few stems assigned of the east-central Interior Region of the to psilophytalean genera are insecure and, United States, are known elsewhere only therefore, do not allow inferences or specula­ from Devonian strata. Protolepidodendron, .tion on the primitive character of the flora. Potonie & Bernard, was founded essential­ The specimens of familiar lycopods such as lyon compression material and its anatomy Lepidodendron and Lepidostrobus are scarce is inadequately known. Kidston and Lang but several species of the former are indicated first reported Asteroxylon from the Rhynie and two well-developed species of Lepido­ Chert of Middle Devonian age. Later strobus are thoroughly described and illus­ Krausel and Weyland described a second trated. Specimens of articulatalean affinity species of comparable age from rocks near are rare. One species has been described Elberfeld, Germany. Reimannia was based as Protocalamites (21) and recently a speci­ on a small collection of a single species men of peculiar but unmistakable articulate described by Arnold in 1935 from the character, probably Calamitean, was placed upper Middle Devonian of New York State. in our hands by Guy Campbell. A number Several species of Callixylon. have been of species of fern-like plants are known described. The genus was founded by from numerous specimens, one of the largest Zalessky in 1911 based on material from the groups of these, the cladoxylalean assem­ Upper Devonian of the Donetz Basin in blage, is a diverse group possibly containing South Russia, but is perhaps best known in addition to Cladoxylon (13), and its form from American species occurring in several or organ genera based on differen t orders horizons throughout the Upper Devonian. of branching, such genera as Steloxylon (to) The upper portion of the New Albany Stereopteris (18) and Pietzschia (19). An­ shale of Indiana and Kentucky is placed other group which is especially well repre­ in the Mississippian as the result of recent sented by a large number of specimens extensive stratigraphic studies. It is perti­ nent, therefore, to re-examine the structural -E-- characteristics of these plant fossils occurring TEXT-FIG. 8-Diagrammatic cross-sections of the in the Mississippian portion of the black principal genera of fossil woods heretofore recorded occurring in the Mississippian portion of the New Al­ shales which have been assigned to the bany-Ohio black shales. 1, Microzygia ; 2, Reiman­ four genera mentioned above, and to eva­ nia; 3, Periastron ; 4, Calamopitys ; 5, Mesoneuron; luate the assignment of these specimens to 6, Siderella ; 7, Diichnia ; 8, Plicorachis ; 9, Pietzs­ established Devonian genera. chia; 10, Stetoxylon; 11, I

Campbell (1939) report the occurrence of Asteroxylon. There is Iittle cortical dif­ a new species, A. Setchelli, from the black ferentiation in the New Albany species, shales of the New Albany area. As has certainly no differentiation of the main body been pointed out, these plant-bearing beds of the cortex into an inner and outer compact are now considered to be of Lower Missis­ zone separated by trabecular tissue. No sippian age. leaf traces are found in the Indiana material. The description of the species is quoted Normally Asteroxylon shows a number of in full : leaf traces passing outward through the " l. Stems small, the specimens seen less cortex. One specimen which is specifically than 5 mm. in diameter. distinct from A. Setchelh has a lateral branch "2. Stele stellate, consisting of five ra­ of great size with a double bundle. diating arms cen trally united to form Thus the shape of the stele, the large a relatively stocky cylinder. size and mesarch position of the protoxylem, " 3. Phloem and outer stelar tissues prob­ the simple and very narrow cortex without lematical but probably concentric. leaf traces, and features of branching furnish "4. Protoxylem exarch to slightly im­ adequate basis for excluding the New mersed. Albany material reported by Read and " 5. Outer tissues parenchymatous as Campbell from the genus. In another observed, with some traces of a paper under publication elsewhere, the full. thick-walled hypodermis." description and illustration of this interesting A reinvestigation of the type slides of species is given and is assigned to another A. Setchelli suggests certain modifications genus. We are not certain of the natural and additions to the description given above affinities of this species but regardless of to the extent that it appears impossible to that, its occurrence in the New Albany retain this species within the genus Aster­ shale cannot be used as evidence for either oxylon. Much more needs to be known Mississippian or Devonian age. from more critical sections of this species B. The Genus Protolepidodendron - A por­ or from better material before it can be tion of a small stem imbedded in a phosphate assigned with any degree of certainty to nodule from the lower of the two nodule its proper systematic position. beds at the top of the Falling Run horizon Text-fig. 9 A illustrates the general outline of the Sanderson formation (Lower Mis­ and tissue arrangement of the stem. The sissippian) near the type locality of the stellate shape of the stele is probably the Jacobs Chapel shale furnished the basis for principal basis for the original assignment the description of a new species of Proto­ of this species to Asteroxylon. Actually, lepidodendron, P. microphyllm1t Read & the stele appears to be basically four-rayed Campbell ( 1939). A series of five trans­ with two of the rays more prominent and verse sections taken from this specimen in slightly divided at the edge. The stelar sequence but at unknown intervals is in column would appear as a deeply fluted the collection of the U.S. National Museum four-angled col.umn with two of the ridges and was made available to us. The being more prominent and slightly grooved remainder of the specimen, if any, has been or furrowed. misplaced. More importan t is the character of the A detailed account of this specimen has protoxylem areas. They are mesarch with been prepared for publication elsewhere, a number of cells between them and the outer some salient features of which will be edge of the stele ( TEXT-FIGS. 9 D, lower left mentioned here. The exceedingly brief and of 9 B,and dotted outlines in 9 A). Further­ scarcely diagnostic original description fol­ more, there are two other protoxylem areas lows essentially as given: Stem small, very deeply situated as can be seen at the about 8 mm. in diameter; stele trilobed, the centre of the stele in the positions indicated three lobes united to form a central column; by the dotted lines and small arrows (TEXT­ xylem mesarch, the protoxylem situated FIG. 9 N). This is not a feature of the genus near the apices of the arms and forming Asteroxylon. Also, the protoxylem areas are loops; outer stelar tissues not preserved; quite large, much larger than generally given cortex parenchymatous and limited by a for the genus. sclerotic hypodermis ; leaves scale-like both The relatively great size of the stele to in aspect and in origin, parenchymatous; the whole stem is certain ly unusual for the leaves bifurcating a short distance HOSKINS & CROSS - THE DEVONIAN-IVIISSISSIPPIAN BLACK SHALE FLORA 227

o '00

A

":~., t ;... ,

TEXT-FIG. 9 - Transverse section of a small stem from the New Albany shale originally referred to the genus A steroxylon. The position of the three enlargements 9 E, 9 C and 9 D are indicated in Text-fig. 9 A. Dotted lines in the stele of 9 A indicate the position of the protoxylem areas. Note especially the two areas indicated by small arrows. above the point of attachment, exact out­ Our studies of this material show certain line unknown, but probably linear. points at variance with, and some additional There is no further discussion of the features of, this description such as the species. Its reference to Protolepidoden­ position of the protoxylem areas, the nature dron may have been based on the reported and position of hypodermis, the character trilobed nature of the stele and the occur­ of the outer stelar tissues which are well rence of the apparently microphyllous leaves. preserved and, especially, details relative to 228 THE PALAEOBOTANIST

the onglO, structure and bifurcation of the leaves themselves may be readily interpreted leaves and the probable form of the stele. on such a premise, but can be explained At some level each xylem arm represented with difficulty, or in the case of certain in the stele offers evidence that a leaf trace leaves not at all, on the assumption of a originates at its extremity. For example three-lobed stele. We believe the inter­ in Text-fig. 10 the xylem arm to the left pretation of the stele as three-lobed cannot (A) shows a double protoxylem area. At be maintained, and thus one of the principal a higher level this arm becomes extended bases for referring the specimen to Proto­ radially affording evidence of the origin of lepidodendron is untenable. a leaf trace which then passes through the The stem is well covered with spirally cortex into the base of a leaf. Such a trace is arranged, sessile, decurrent leaves. The seen in Text-fig, 10 (Lt.) a short distance from single leaf trace present in the base of the the tip of the xylem arm (B) to the right. leaf divides as the leaf itself bifurcates When all the leaf traces are plotted immediately after becoming free from the throughout the range of the five sections stem. Each of these divisions again divides available, together with the position of the so that each leaf has four ultimate segments. leaves into which these traces enter, grave The leaves are appressed to the stem and doubts arise as to the trilobed nature of all the bifurcations are in the same plane the stele. Quite another possibility exists, and at a very low angle. Following the namely that the preserved specimen de­ first bifurcation the leaf rapidly becomes monstrates but a part of the entire stele, reduced in size and develops a conspicuous which might well have been composed of sclerotic strand near its centre (D, scl.). several discrete strands such as are common­ This is the dominant tissue of the leaf tips ly found in Cladoxylon, or perhaps it con­ following the second bifurcation and the sisted of a single polyarch central strand. vascular strands are usually not distinguish­ The anatomy of the available material, able at this level. The bundles do not the position of the leaf traces and the extend to the leaf tips.

...~'\. / / -"' ,--"'_....,""" .....'-.",~.... J ", 1 ,.I 1

/ /A ...... ' / /

TEXT-FIG. 10 - Diagram of transverse section of fragment of stem formerly attributed to Protolepidodendron. The two lobes of the remaining portion of the stele contain five protoxylem areas or loop structures. The leaf bases at E with its leaf trace. ( Lt. ) is about to become free from the stem. The tips of several remaining leaves, all bifurcated twice, are seen. The sclerotic central zone ( scI. at D) makes up the larger part of the tissue followed by the second bifurcation. One vascular bundle (v.b. at C) is to be seen in one leaf. HOSKINS & CROSS - THE DEVONIAN-MISSISSIPPIAN BLACK SHALE FLORA 229

While there are certain apparent simi­ evidence of a shallow depression opposite larities between the organization of this the upper end of the central aml of the fragment of stem and Protolepidodendron, "T ". There is no indication of branching which is all too little understood, in some or leaf traces. respects it departs rather widely from our In R. aldenense the axis is angular, possibly conception of that genus. The bifurcation related to frequency of leaf formation. The of the leaves not once but twice, their stele which is basically triarch and radial, bifurcation near their bases and their occupies approximately one-sixth the total appressed character indicate marked differ­ diameter of the axis. The cortex is bounded ences. The probability is that the stele is by a cutinized epidermis within which is not three-lobed at all and that only a portion a zone of sclerized cells which grade gradually of a more extensive stele is present in the into larger, thin-walled, homogeneous inner preserved part. These considerations and cortical tissue. The stele has the three others make its retention within the genus arms rounded, with very shallow embay­ Protolepidodendron untenable, and else­ ments between the xylem arms. Traces in where we have proposed another genus to the cortex may be referable to leaf traces. include it. A more detailed study and comparison of C. The Genus Reimannia - The genus the two species is being published elsewhere. Reimanm'a, established by Arnold (1935) to Thus, while both axes are of essentially accommodate a single species, R. aldenense, the same size, both possessing a single central was based on several petrified specimens fluted column of primary xylem with three preserved in marcasite from the Middle flanges, while both steles are mesarch and Devonian Ledyard member of the Ludlow­ both lack secondary xylem, they are more ville formation of New York. The description than sufficiently different in detail to warrant of the species was based mainly on one the exclusion of the Indiana specimen from small specimen which was best preserved. the genus Reimannia. What its true syste­ This specimen, most unfortunately, has matic position may be is uncertain. Its entirely disintegrated and is no longer disposition must be delayed until additional available for comparison. Thus our basis specimens provide adequate material for for review of this species is necessarily study. In the meantime it is rejected from limited to Dr. Arnold's published description the genus Reimannia, and transferred to an­ and to two fine negatives used in illustrating other genus. Any stratigraphic connotation the type species which he kindly loaned suggested by this plant having been placed to us. in the genus Reimannia is unwarranted. In 1939 Read and Campbell described a D. The Genus Callixylon - Callixylon New­ second species, R. indianensis, from the berryi (Dawson) Elkins & Wieland is the Falling Run horizon of the Sanderson best established of the several American formation (Lower Mississippian) near New species of Callixylon. It is not uncommon Albany, Indiana. Their brief description in the Devonian portion of the New Albany in the absence of any elaborating comment shale (Upper Blackiston). Other species is insufficient for comparison. Three of occur in various horizons of the Upper probably four original thin sections and the Devonian and the genus has come to be specimen were loaned to us for examination considered as an index fossil indicating the by the U.S. National Museum. Upper Devonian age of the beds in which The two specimens can scarcely be retained it occurs. within the same genus. R. indianensis (TEXT­ Read and Campbell in 1939, without com­ FIG. 11A) is seen to be circular in outline, ment other than horizon and localities, with a T-shaped stele occupying from one­ included a new species of Callixylon in their half to one-third the total diameter of the table of species from the upper portion of axis. The cortex appears heterogeneous, the New Albany shale (principally the with smaller cells both toward the periphery Upper Sanderson formation and the Falling and adjacent to the stele. The stele itself is Run member). There is no doubt that mesarch (TEXT-FIG. 11B) ; deep embayments material in the collection of the U.S. National occur between the arms of the "T" and Museum labelled C. Brownii was the basis the stem. In one section there is indication not only of this report but also that of Pitys of the arms of the "T" being recurved Brownii (READ, 1936) which was accom­ back toward the stem of the "T", and panied by a brief preliminary description, FIG. 1\ B

o .5 I I ! I I I mm.

TEXT - FIGS. 11 A& 11 B- Fig. 11 A is a diagram of a transverse section of a stem from the New Albany shale previously assigned to the genus Reimannia. Fig. 11 B is an enlarged portion of the stele (see inset in 11 A) showing two protoxy­ lem loop areas. "px .... protoxylem; "disint". indi~~t~stissue d,~stroy'­ ed; c • cortex; hy • hypodermis. HOSKINS & CROSS - THE DEVONIAN-MISSISSIPPIAN BLACK SHALE FLORA 231

inadequate in itself for the assignment of the pian. This doe; not necessarily preclude material either to Pitys or to Callixylon. the use of certain well-established species, As several specimens in our collections such as C. Newberryi, which may prove to show affinities to Callixylon, we re-examined have useful limits of occurrence through the material labelled C. Brownii and have time. However, the recognition of the published elsewhere the detailed evidence genus alone cannot be utilized as evidence upon which we concluded that reference of of the De von ian age of the plant-bearing it to the genus Callixylon is correct. This horizon. conclusion was given weight by significant E. The Genus Cladoxylon - One genus collateral evidence. In the absence of pre­ which has received little attention as indi­ served pith and primary wood, several cating a Devonian range and which has species have been referred to the genus based not been recorded with certainty above upon an examination of secondary wood the Cypridina shales in which it is abundant only with special reference to the character­ is Cladoxylon. The genus was established istic radial alignment of discontinuous pit on some material from the Cypridina shales groups. The assumption is that the occur­ of Saalfeld, and has recently been restudied rence of this single feature is adequate by Bertrand (1935). The identity of C. evidence for the assignment of a species to Kidstom' from the Lower Carboniferous of the genus Callixylon as no other example; Berwickshire is quite uncertain. More im­ of this arrangement of pits are known to portant are two Devonian records. The occur in plants, living or fossil (ARNOLD, earlier of these, though little noticed, was 1947, p. 283). When a number of pieces reported by Dawson ( 1882). Read ( 1935) of secondary wood from the Mississippian has called attention to this specimen found portion of the black shales were split longi­ by the eminent palaeontologist, John M. tudinally along radial surfaces and observed Clarke, in the Genundewa limestone ( Upper under reflected light, radial banding of Devonian) of New York State, and described discontinuous pit groups was obvious. In it as a new species, C. dmPJsoni Read. Ber­ some instances, radial thin sections confirm trand examined the only known slide of the observations. Text-fig. 12 A is a photo­ this species and agreed with Read on the micrograph of a portion of a thin section identification. We have compared this slide of the silicified wood of C. Newberryi from with cladoxylalean material from the New the Blackiston ( Upper Devonian) of Nelson Albany shale and are, in general, satisfied County, Kentucky. This is to be compared as to the general affinities exhibited by the with Text-fig. 12 B which is not a thin section, material from the east-central Interior Region but a specimen split along a radial surface with the older species from New York. and photographed by means of reflected The other Devonian record, C. scoparium, light. This specimen is not C. Newberryi described by Krausel and \Veyland from but an undescribed species from the Falling Elberfeld, Germany, is considered to be Run member of the Sanderson formation outside the generic limitations according ( Mississippian) from Crab Orchard, Ken­ to Bertrand, Sahni and others. Thus this tucky, locality No. 14, Text-fig. 7. We can genus, Cladoxylon, though principally known demonstrate the same structural organization from beds of an age equivalent, or nearly in specimens from Junction City, Kentucky, so, to the Upper New Albany shale, has a locality No. 19; New Albany, Indiana, single recognized Upper Devonian represen­ locality No. 36 ; and elsewhere, with special tative. reference to material from the type locality of the Kinderhook series, the lower division AN EVALUATION OF RECORDED of the Mississippian, at Kinderhook, Illinois, MISSISSIPPIAN COMPONENTS locality No. 49. These various specimens differ among A study of the ranges for the genera themselves in detail and all differ from recorded from the Upper New Albany shale, Callixylon Newberryi. Their specific assign­ illustrated here in Text-fig. 14, shows that ments are being published elsewhere. four of these genera, Lepidostrobus, Lepidoden­ These studies have the effect of removing dron, Calamopitys and Lyg£norachis, have a the genus Callixylon from the role of an continuous representation into the Upper index fossil of the Upper Devonian as its Mississippian or higher. Another genus, range is extended into the Lower Mississip- Steloxylon, has no representation known TEXT-FIGS. 12 A & 12 B-Comparison of radial pitting on Devonian and Mississippian Callixylon. 12 A, photomicrograph of thin radial section of Callixylon Newberryi from Nelson Co., Kentucky. 12 B, reflected light photomicrograph of radially split specimen of Calltxylon from tbe Mississippian part of the New Albany shale, Crab Orchard, Kentucky. HOSKINS & CROSS - THE DEVONIAN-MISSISSIPPIAN BLACK SHALE FLORA 233 above the transitional Devonian-Mississip­ tucky, MATHEWS, 1940, p. 36). and are of pian black shales except in the Permian. the opinion that the specimen could be Two other genera, Protocalamites and Steno­ from an eastward extension of the Falling myelon, range at least into later Lower Run nodule zone of the Sanderson or its Mississippian strata and possibly a little equivalent, possibly the Bedford formation. higher as evidenced by their occurrence in There is every reason to consider these two the Calciferous Sandstone series of Scotland. well-described species as valid early repre­ In the evaluation of the Devonian com­ sentatives of Lepidostrobus which ranges ponents of the Upper New Albany shale continuously up through the Permian. ( Sanderson) flora we have shown that Calamopitys, which was first described three of the four components previously from the Cypridina shales of Saalfeld (c. identified are now reassigned and the fourth, saturni) by Unger (1856), has also been Callixylon, is now known to have Lower recorded from the Lydiennes horizon of Mississippian representatives. An examina­ France (C. blayaC'i Corsin, in BERTRAND, tion of those genera with a more extensive BOHM& CORSIN, 1935). and from the New Mississippian range or higher is, therefore, Albany shale of Kentucky (c. americana in order. Scott & Jeffrey and C. foerstia Read), Lepidode·ndron is represented by a number both horizons being somewhat comparable of specimens. Two species have been des­ to the Cypridina shale. It is also known cribed in a preliminary fashion, as already from one Upper Mississippian species, C. noted, and there is no reason to question zonata, of the Carboniferous Limestone of the validity of the assignment to the genus. Ayrshire and an older species from the Several additional specimens that are out­ Calciferous Sandstone of Dumbartonshire, side the specific limits for those described C. j'adiata. Two other closely related forms are known and are to be treated in a which have been transferred from Calamo­ later paper. Lepidostrobus specimens are pitys to Eristophyton have the same general quite infrequent in the collections. Two range. Two more species of close relation­ species have been described in considerable ship to the Eristophyton type of Calamo­ detail. The earliest known from the New pityan stems are known from the Lower Albany shale is L. kentuckiensis (originally Carboniferous of Falkenberg, Silesia and L. Fischeri) which was found at Junction from Balaton See, Hungary. Only one City, and completely described by Scott and species recorded appears to be earlier than Jeffrey in 1914. The other species has not Lower Mississippian and this, from the been called to general attention inasmuch Upper Devonian of New York, has been as it was a "weathered out" or "float" transferred to a new genus [Sphenoxylon specimen. The original extensive descrip­ (C.) eupunctata (Thomas) Read (1937)J tion by Mathews ( 1940) indicated that it was which is believed to be closely related to from either the Upper Devonian Ohio shale the Bilignea group. or the Mississippian New Providence shale. Lyginorachis is known from only two It was compared with numerous other species outside the New Albany shale. The species of Lepidostrobus including L. ken­ older of these, L. Papilio (Kidston) Scott, tuckiensis but no thought or stress was given is from the Cement-stone group or older to the fact that it might be another repre­ part of the Calciferous Sandstone series and sentative of the New Albany shale flora. is of near-comparable age to the New However, we have examined the type mate­ Albany. The other species, L. Tailiana rial of this species, LepidostrobuslWet', and Kidston, is somewhat younger, occurring find that its preservation medium is not in the lower part of the Upper Mississippian calcium carbonate as recorded (MATHEWS, (Carboniferous Limestone). 1940, p. 37) but it is calcium phosphate and Two more genera which possibly range is very similar, in fact indistinguishable, stratigraphically higher than the New Albany from other specimens of the phosphatized or equivalent horizons are Protocalamites plant fossils from the New Albany shale. and Stenomyelon. Protocalamites pettycuren­ We have visited the region where the speci­ sis (Scott) Lotsy, the genotype and the men was found (locality No. 13, TEXT-FIG. 7), only species recorded outside the New in the vicinity of Paint Lick near Cartersville, Albany, is from the Calciferous Sandstone Garrard County, Kentucky (originally mis­ series of Pettycur, which is approximate­ printed as Gartersville, Gorrand Co., Ken- ly the equivalent of the upper Kinderhook 234 THE PALAEOBOTANIST or lower Osage, both Lower Mississippian. We have seen that of the five genera Stenomyelon is known from two species previously reported, which are generally (c. tuedianum Kidston and C. tripartitum known to range back into the Devonian, Kidston, in Scott) from the Calciferous three of them, Asteroxylon, Protolepidoden­ Sandstone series of Berwickshire. Scotland. dron. and Reitnannia. have been reassigned One species remains to be discussed of to other genera and. therefore, are not known those showing range later than the New to occur in these strata. The species which Albany shale. Steloxylon was originally were included under these genera are for described as a M edullosa by Goeppert and this reason of no stratigraphic significance, Stenzel but was later renamed Steloxylon irrespective of their earlier presumed affinity (M.) LudlC'igii by Solms in 1896. The to known Devonian genera, except in so far material was found in some secondary as their primitive characters suggest early deposits in the Permian of Siberia and thus stock. Of the two genera with proven it may be considerably older. Professor Devonian representatives, Cladoxylon, which Paul Bertrand, in his study of the Clado­ is known from the Upper Devonian by but xylales of the Cypridina shale (1935), a single specimen of a distinct species, is a considered that at least one of the species of representative common not only in the flora Cladoxylon originally described from the of the Mississippian portion of the black Cypridina shale is generically referable to shales. but also of a number of other floras the genus Steloxylolt. Thus with three elsewhere of near-comparable or equivalen t species of Steloxylon now known in the age. Only one genus. Callixylon. which New Albany and Cypridina shales, and occurs throughout the Upper Devonian, with the possible affinity of the genus to can be considered a true Devonian genus Cladoxylon. it is with reservation that we of all the 29 reported heretofore, and it in­ consider the range to extend to the cludes at least several species now known Permian. also from the Lower Mississippian, including In summary, then, of the seven genera one from the type locality of one of the which are known to have younger repre­ major divisions, the Kinderhookian series. sentatives than those found in the Sanderson In a similar manner we have demonstrated fonnation of the New Albany shale, two that the flora is broadly differentiated from lycopods. Lepidodendron and Lepidostrobus. the better-known Mississippian flora though range through the strata at least as late as perhaps not quite so sharply. It may be the Permian; two others. Lyginorachis and useful to call attention to the fact that in Calamopitys are known from some species every instance where the geologic range of in the Upper Mississippian as well as the a genus found in the New Albany shale large number from the Lower Mississippian extends on up into the later Mississippian equivalents; two more, Pl'otocalamites and or still higher strata, that genus is known Stenomyelon. are limited to the Lower Car­ to occur also at one or more localities of boniferous but may have a slightly later generally comparable age elsewhere (see range than that exhibited by the New TEXT-FIG. 14). Approximately two-thirds of Albany: and the seventh genus, Steloxylon all the genera reported are known only from is now best known from specimens of the the black shale flora. or in addition, from Upper Devonian-Lower Mississippian transi­ one or more of the following localities; the tion beds with one species. the genotype, Cypridina shale. Saalfeld, Thuringia ( locality of questionable Permian age. No. 20, TEXT-FIG. 13); Wildenfels shale, Saxony (locality No. 21, TEXT-FIG. 13); THE DISTINCTIVE NATURE OF THE Calciferous Sandstone. Scotland (locality UPPER NEW ALBANY SHALE FLORA No. 19, TEXT-FIG. 13) ; and the Lydiennes horizon, Montaigne-Noire, southern France We have endeavoured to analyse the longer (locality No. 23. TEXT-FIG. 13). ranging components of the remarkable Of the four localities just mentioned, three petrifaction flora which occurs in the upper of them, the Cypridina shale, the Wildenfels part of the New Albany-Ohio black shale shale and the Lydiennes horizon, are quite of the east-central Interior Region of United similar in character of sedimen ts and in States in order to clarify the general charac­ overlapping of floral components. They ter of the flora and determine the possible are also comparable to the New Albany stratigraphic significance. shale in these features. All of these and 180 ISO 120 60 30 o

751 III J "-In J Iv \,..,l:~t:Lu-;:~I f' \. I .'E;!~I I

A I 'if? , .' I~·"'~L 601 • Q.P /UJ· ...... :,;;..1\ \ >::: J I I " \! I' ) I ;. I III ;r ? C7 '1

.i~·'

-451 ) -I t' .r

301 I I ~\ ~'I?~ ,,< I

• Plant-b~"'lngshales, North Amerlco 151• Plant-bearing chert or novicu'ite, NorthAmll/.Cli - " .....\..'==, : I f • CalciferousI sandstone,I Scotlond I I I I • Crprldlnla Ihale. Saalfeld, Thuringia

(;k:}~1~:::bJ r-If='tr1l¥~ o WildenfelllhJI Wilden~elssaxo~I-A --1 . Lrd enne hori~on,Montalgne Noire, ranee WORLD DISTRIBUTION OF DEVONIAN AND MISSISSIPPIAN BLACK SHALE FLORAS(PRINCIPALLY PETRIFIED

IS INCLUDING SEVERAL OTHER TYPES OF HORIZONS OF COMPARABLE AGE AND FLORAL NATURE.

TEXT-FIG. 13 - Distribution of Devonian and Mississippian black shale plant localities (principally petrified wood) including seveml other types of horizons of near­ comparable age and flora. 1, New York-Pennsylvania; Marcellus, et seq., M. and U. Dev. 2, Sonth-western Ontario; Kettle Point sh.. U. Dev. 3, Michigan; Antrim sh., U .. Dev.-L. Miss. 4, Ohio; Ohio Black sh., U. Dev.-L. Miss. 5. Tennessee; Chattanooga sh" L. Miss. 6. Indiana-Kentucky; New Albany sh., U. Dev.-L. Miss. 7, Illinois; Kinderhook grey sh., L. Miss. 8. Missouri; Reeds Spring fm. (chert), L. Miss. but slightly younger (Osage) age. 9, Arkansas; Arkansas novaculite, U. Dev. 10, Oklahoma; Woodford chert, U. Dev. 11, Texas (iVIarathon district) ; Caballos chert, U. Dev. 12, New Mexico (Sacramento) and West Texas (Franklin and Hueco Mts.); Percha sh. (and upper dark sh. of Canutillo fm. ), L. Miss. 13, Idaho; Milligen sh., L. Miss. 14, Montana-North Dakota; Three Forks sh. (Milligen and Exshaw), L. Miss. 15, Alberta; Exshaw sh., L. Miss. 16, Yukon area, Alaska; Nation river fm. (in part), L. Miss.-U. Dev. 17. Killik river area, Alaska; Noatak fm., L. Miss. 18, Cape Lishurne area, Alaska; Noatak fm., L. Miss. 19, Scotland-N.E. England; Calciferous ss. (espec. Cement-stone Group), L. l\Iiss, 20, Saalfeld, Thuringia; Cypridina sh., U. Dev.-L. Miss. 21, Wildenfels, Saxony; Wildenfels sh., U. Dev.-L. Miss. 22, Montaigne-Noire, Southern France; Lydienne horizon, L.-M. Miss. HOSKINS & CROSS - THE DEVO~[AN-M[SSISSIPPr.\"BLACK SHALE FLORA 237

c 0 "0 c: '"Q) u> c 0 0 C Q) ~ '"::> .-'" 0 C E 0 r. '">- "0 D 0 C '" '"~ '">- C "0 a. 0 c u '" 0 0 c E 0 0 0 c Q) ~ r. c 0 c ~ ~ 0 E 0 - 0 Q) 0 0' - ~ 0 0 0 0 C 0- - "0 Q) ::> c 0 r. a. 0 >- ~ u - 0 - - >- ~ - 0 0 - >- "0 0' 0 Q) >- "0 a. 0 E ~ 0 0; Q) x 0. c ~ N x U >- - E Q) 0 0 0 c ~ >- 0 '" u 0 ~ 0 0' >- x ~ 4~ >. 0 0 c 0 VI Q) E E 0 c x ~ "0 "0 a. 0 ~ 0 N 0 r. 0 >< 0 0 0 E Q) "0 ~ '" .... 0 u >- C - u 0 r. .- Q) u> U a. Q) ~- 0' >- - a. 0 u "0 0 Q) Q) ~ 0; Q) - - - .- C - U - ~ 0 Q) 0 Q) Q) .- 0 .- Q) >- .... ~ .... Q) >- 0 - - 0 0 (j) ~ 0 ~ (j) --.J « Cl. --.J --.J --.J ~ ~ a: u I U n: (j)- if, u Cl. Cl. « Cl. « U u (j) (j) « a: ? I- :'j U. ;;; a: w L. ? Cl. z I « MON. I Z I « > CON. ? --.J )- 1 (j) ALL. I z I Z w I Cl. POTTS. I I (j) u. I (j) I - n 2 L. f7I ~J 171 t • • ~.1.1 I 'J ~a:.11.1J J ~ ~ l.I ~~~a z· I~ ? 7 7 •••• « U. z 0 M. > w I 0 L.

ICYPRIDINA SH .•SAALFELD, THURINGIA ... WILDENFELS SH., SAXONY NEW ALBANY SH. (ONLYlg • LYDIENNES HORIZON, MONTAIGNE NOIRE,FRANCE + CALCIFEROUS 55., SCOTLAND UNCERTAIN?

TEXT-FIG. 14 - Chart of the geologic range of the principal genera recorded from the upper part of the New Albany shale and the occurrence of these genera in near-comparable horizons elsewhere. Asteroxylon. Protolepido­ dendron and Reimallnia, though previously reported from the black shales, have been reassigned and are not now recognized in the collections studied.

the New Albanv included are of controversial equivalent black shales of Tennessee and age; in fact, in" several instances the dating Ohio, are now approximately dated. The of one of these sediments has resulted in principal flora is of Lower Mississippian age the similar dating of the others. When ( Kinderhookian). Through the combined the Scott and Jeffrey report first appeared, work of three French geologists, Joseph and the sediments were presumed to be Blayac, Rodolphe Bi:ihm and Gaston Delepine Mississippian in age by reason of the proxi­ ( 1935) the age of the Lydiennes horizon is mity to Mississippian strata identified on reasonably well established as Lower Visean the basis of invertebrates (" at the base on a faulla of seven different species of of the Waverley shale" ), then the Saalfeld goniatites, three of which are limited to the and Wildenfels beds were so identified. Lower Visean and the remainder extend Through the meritorious work of Guy through more or less of the Upper Tournasien, Campbell, the Devonian-Mississippian transi­ and Orthoceras. phyllopodes, cirripedes and tional black shales of Indiana and Kentucky, crinoids. This would be the equivalent of and to a certain extent equivalent or near- the Lower Meremacian strata of North 238 THE PALAEOBOT ANIST

America which directly overlies the Osagean of type of flora found in these lithologically series. Therefore, the Lydiennes horizon dissimilar deposits. appears to be somewhat younger than the This Lower Mississippian-New Albany New Albany shale. The genera of plants shale flora and its counterparts elsewhere, which are common to the New Albany and thus, appear to constitute a flora unique Lydiennes horizons may be quickly deter­ in their restricted range through geologic mined from Text-fig. 14. Because of the very time. It has some Devonian aspects but close lithologic similarity of the Lydiennes is not a true Devonian flora as we under­ horizon, with its phosphate nodules, to the stand the Devonian. It is not Mississippian Cypridina shale, and the similarity of the in the sense of being pre-Pennsylvanian. flora, analogies are drawn from that source for It cannot be said to inter-grade into either dating the floras of Thuringia and Saxony. the earlier Devonian or the later Mississip­ One horizon in America which has but pian, for on the whole we know little of three recorded species, two of which are in its progenitors or its progeny. It is a new genera, is the Reeds Spring formation distinctive flora based upon diverse stems of of Lower Osagean age in south-western Mis­ little known plants. The nature of its leafy souri (locality No.8, TEXT-FIG. 13 ). There counterparts is virtually unknown. It is is too little known of that flora to derive broad in its geographic distribution, res­ inter-regional or inter-continental correlations tricted in its geologic range, varied in its from it. The Calciferous Sandstone of composition, interesting in its relation to Scotland is more nearly comparable to the floras of somewhat comparable horizons Reeds Spring formation or other Osagean of near-equivalent age elsewhere, and is strata than to the slightly older New Albany certainly a remarkable flora requiring further shale, but there is considerable similarity exploration.

REFERENCES

ARNOLD, CHESTER. A. (1947). An Introduction to READ, CHARLES B. ( 1935). An Occurrence of the Paleobotany. McGraw-Hill, New York. p. 283. Genus Cladoxylon Unger, in North America. BERTRAND, PAUL ( 1935 ). Contribution a I'etude des Jour. Washington Acad. Sci. 25: 493-497. Cladoxylees de Saalfeld. Paleontographica. Idem (1935). A Devonian Flora from Kentucky. Abt. B. 80: 101-170. Jour. Paleont. 10 (J): 215-227. BERTRAND, P., BOHM, R. & CORSIN, P. (1935). Idem (1937). The Flora of the New Albany Decouverte d'une flora dans les Iydiennesdu Shale. Part II. The Calamopityeae and their Carbonifere de la Montagne-Noire it Saint­ Relationships. U.S. Geol. Surv. Prof. Pap. 186­ Nazaire-de Ladarez (Herault). Compt. rend. E: 81-105. hebdomad. Sci. Acad. Sci. 200: 1344-1345. READ, CHARLES B. & CAMPBELL, GUY (1939). BLAYAC, J., BOHM, R. & DELEPINE, G. (1935). Preliminary Account of the New Albany Shale Sur rage de I'horizon it lydiennes de la base du Flora. Amer. Midi. Nafur. 21 : 435-453. Carbonifere de la Montaigne-Noire. Compt. rend. SCOTT, D. H. & JEFFREY, E. C. (1914). On fossil hebdomad. Sci. Acad. Sci. 200: 476-478. plants showing structure, from the base of CAMPBELL, GUY (1946). New Albany shale. the Waverley Shale of Kentucky. Phil. Trans. Geol. Soc. Amer. Bull. 57: 829-908. Roy. Soc. London. Ser. B. 205: 315-373. COOPER, G. A. et al. (1942). Correlation of the SOLMS-LAUBACH, H. GRAF ZU (1896). Ueber die Devonian sedimentary formations of North seinerzeit von Unger beschriebenen Struktur­ America. Geol. Soc. Amer. Bull. 53: 1729-1794. bietenden pflanzenreste des Unterculm von DAWSON, J. W. (1882). The fossil Plants of the Saalfeld in Thiiringen. Abh. g. g. Preuss. Erian (Devonian) and Upper Silurian for­ Geol. Landes. 23. mations of Canada. Part II. Geol. Surv. of UNGER, FR. ( 1856). Schiefer und Sandsteinflora, Canada 1882: 126. . in R. Richter und Fr. Unger, Beitrag zur HASS, WILBERT H. (1947). Conodont zones in paleontologie des Thuringer V>'aldes. Denkschr. Upper Devonian and Lower Mississippian For­ g. K. Akad. Wissensch. Wien. 11: 177. mations of Ohio. Jour. Paleont. 21: 131-141­ WELLER, J. MARVIN et al. ( 1948). Correlation of MATHEWS, G. B. (1940). New Lepidostrobi from the l\Iississippian formations of North America. Central United States. Bot. Gaz. 102 (1): 26-49. Geol. Soc. Amer. Bull. 59: 91-196.