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EARLY DIAGENETIC CALCAREOUS BALLS AND ROOF FROM THE PENNSYLVANIAN (ALLEGHENY SERIES)1

LON A. McCULLOUGH, Department of Geology and Mineralogy, Ohio State University, Columbus, OH 43210 Abstract. The calcareous concretions studied formed in different depositional en- vironments associated with the Pcnnsylvanian eyclothems of cast central Ohio. The late syngenetic to early diagenetie coal balls from Lower Frecport Coal in Jefferson County were formed by cellular permineralization of decaying terrestrial plants in a swamp. These coal balls, composed of N9.N% , 7.0% , and 2.(3% organic material, preserve six identifiable plant genera, Sphenophyllum, Stigmaria, Medulosae, Taxospermum, Psaronius, and Myeloxylon, as well as fusain and spores. The early diagnetic nodules from roof shale overlying Middle Kittanning Coal in Tuscarawas County, Ohio were formed by authigenic of marine that contained brachiopods, including Mesolobus, Lingula, and several productid , bryozoan fronds, ostracodes, gastropods, crinoids, cephalopods, as well as coprolites, terrestrially-derived fusain, root casts, and megaspore coats. These nodules, composed of 84.5% calcite, 11.3% illite, 1.5% , 0.9% pyrite, and 0.5% organic material, have calcite-filled septarian fissures.

OHIO J. SCI. 77(3): 125, 1977

Coal balls, or concretions that formed 1976) including large-scale marine inun- in peat, and roof shale nodules preserve dations that carried marine organisms a portion of that was not se- into a peat swamp environment (Mamay verely compressed before . and Yochelson 1962). Most coal balls, As such, they provide a key for decipher- however, including those so far described ing the diagenetie history of the strata from Ohio, were formed in situ under in which they formed and also for recog- relatively quiescent conditions in peat nizing original depositional features. Al- swamps. Roof shale nodules, such as though roof shale nodules, such as those those described in my study, were formed found in the blue shale overlying the Mid- in marine muds that often transgressed dle Kittanning Coal (No. 6) in Tusca- over peat deposits (Stopes and Watson rawas County, are common in near shore 1909). At the locality in Jef- of Pennsylvanian age rocks of ferson County, Ohio there is no known Ohio, coal balls have been described from example of a marine directly only in the Monongahela (Good and above the Lower Freeport Coal (Lam- Taylor 1974) and Conemaugh Series born 1930). Instead, the coal commonly (Rothwell 1976) in Ohio. My study occurs below a that shows no compares the diagenetie concretions noted indication of marine origin. Weller (1930) above and coal balls found near Wells- observed in Illinois that such sandstone ville, Ohio in the Lower Freeport Coal deposits above coals signify a period of (No. 6a) of the Pennsylvanian Allegheny erosion in which originally cov- Series. ering the coal were removed before the Some coal balls show textural varia- sandstone was deposited. The coal prob- tions that indicate formation under a ably was represented at that time by com- wide range of energy conditions (Perkins pressed peat that resisted erosion. Ma- rine deposits that may have occurred 1Manuscript received lanuary 10, 1977 and in above the Lower Freeport Coal in the revised form March 25, 1977 (#77-1). Wellsville area probably were removed 125 126 LON A. McCULLOUGH Vol. 77 The coal contains coal balls for a dis- during the diastemic interval prior to the tance of about 18 m in a north-south deposition of the overlying sandstone. trend (fig. 1). The coal balls appear DESCRIPTION OF THE WELLSVILLE either as aggregated masses or as isolated EXPOSURE units in the coal with ratio of height to The coal ball collecting locality near width on the order of 1:5. Bandings in Wellsville, Ohio is a deep sidehill roadcut the coal, which are prominently warped on the west side of Ohio Route 7 in Saline around individual coal balls, show dis- Township, Jefferson County within T. 9 turbance vertically in either direction up N. and R. 2 W. in the north central part to 0.25 m from isolated concretions. of Section 7, Wellsville Quadrangle, 0.74 km south of the Columbiana and Jeffer- DESCRIPTION OF THE GNADENHUTTEN son County line. The locality was recog- LOCALITY nized in 1961 by Horace Collins, Chief of Roof shale nodules occurred in 2 strip the Ohio Geological Survey. Several pits operated by the Empire Coal Com- specimens were collected at that time and pany of Gnadenhutten, Ohio. They are a few preliminary peels were prepared. located in Township, Tuscarawas A brief mention of the deposit appeared County within T. 6 N. and R. 2 W. in in Denton et al (1961). the northeastern part of Section 3, 2.12 At the collecting locality, the concre- km southwest of Gnadenhutten and in tion-bearing coal rests upon 0.5 m of the western part of Section 1, 0.74 km light gray, non-bedded underclay. The southwest of the village (Gnadenhutten coal varies in thickness from 1.4 m in Quadrangle). Both localities are just areas where coal balls are more prominent south of Tuscarawas County road 16. to 0.6 m where they are more lenticular, Concretionary nodules occur in the flattened, or absent. The coal is over- shales above the Middle Kittanning Coal lain by a massive sandstone, 3 to 3.5 m (No. 6) and to a lesser extent above the thick, which, in the outcrop, extends be- Lower Kittanning Coal (No. 5) in this yond the coal. area. At the two localities nodules for

SOUTH NORTH

Lower Freeport Coal

- Arenaceous Shale Calcareous Coal Balls

Underclay SCALE IN METERS Tal us

FIGURE 1. Schematic drawing to scale of the Wellsville coal ball outcrop showing the three mam concretionary pockets, A, B, and C, in the Lower Freeport Coal (No 6a) The scale shown applies to both horizontal and vertical profiles. Ohio J. Sci. COAL BALLS AND ROOF SHALE CONCRETIONS 127 my study were found along the highwalls confirm the presence of calcite and pyrite in the coal balls. in place in the shale above the Middle Six roof shale nodules were sawn and the slices Kittanning Coal. The shale is about 20 crushed and thoroughly mixed before separating m thick at the first locality and 2.5 m into 2 portions. Each sample was weighed and thick at the second. The concretions, ex- placed in 10% HC1 to remove the fraction, then dried and reweighed. One sub- posed irregularly on the highwalls, are sample was mixed into 1,1,2,2-Tetrabromo- seldom aggregated but are roughly ori- ethane (Sp. Gr. 2.89) to separate the heavy ented in horizontal lines separated ver- and light fractions. The lighter por- tically by 15 to 30 cm intervals. Where tion was isolated, dried, weighed and the is superficially exposed (fig. organic material was completely oxidized with dilute H2O2. The resultant residue, after dry- 2), the major axis is oriented horizontally ing and reweighing, was washed until all the and the shale is visibly arched around it. clay was removed and the final residue was again dried and weighed. The other subsample METHODS AND MATERIALS was analyzed chemically for average composi- Individual concretions were cleaned of tion and by x-ray diffraction to determine car- and fragments of coalified material and then bonate-free mineral constituents. numbered to assure proper identity in all sub- The evaluation of organic material in the coal sequent procedures. Each concretion was balls was based on peel studies from 50 ran- sawed (with a diamond-bladed slab saw) normal domly selected coal balls from all areas of the to its major axis, into roughly parallel 3 cm crop. Each coal ball regardless of size was slices. The sawed surfaces were smoothed of considered as one unit. From many of the coal imperfections with carborundum powder (#600) balls numerous peels were obtained but only 2 and etched in 10% HC1 for 20 to 45 seconds. peels oriented normally to each other were The wet etched surfaces were studied with a evaluated from each concretion. Each identi- low-power binocular . Dilute saf- fiable plant structure or other component was ranine Y dye (2%) was used to stain the plant tabulated only once regardless of the number of material exposed on the etched surfaces of the occurrences within that peel. Percentage of coal balls (Kosanke 1945). occurrence of plant material in the coal balls The rapid peel technique of Joy el al (1956) was calculated on the basis of all 50 units in the was employed to remove material from the study. etched surface. Before the peels were re- moved, the mineralogy and organic content was RESULTS AND DISCUSSION recorded. Some peel sections were removed and mounted on slides with Permount for high COAL BALLS power microscopic examination (Stewart and The initial mineralization, which Taylor 1965). formed the coal balls, was the result of Vertically and horizontally oriented thin sections were prepared for mineralogical study cellular permineralization of the plant of the concretions to show morphological struc- material present (Schopf 1975). The tures, septaria, and other types of secondary yellow-brown primary calcite, which com- mineralization that were not distinct in the prises the bulk of the matrix, was char- acetate peels. Detailed analysis of the micro- scopic organic constituents of the concretions acteristically bladed or fibrous in crystal was accomplished by using solution residues form. In thin section the calcite crystals (Schopf 1965). Rock fragments were dissolved appear to radiate outward from various in dilute HC1 and the carbonate-free residue loci within the concretion, passing un- was washed and decanted several times, re- sulting in a sludge which was examined with a disturbed through interstitial spaces and microscope. material was removed and cell walls. As was found also by Darrah placed in water for more detailed study. This (1941), cell walls in several cases served method was especially effective for removal of as terminating boundaries for crystals of isolated pyritized microfossils, fusain-like ma- fibrous calcite radiating from different terial and megaspore coats. loci. The cell wall material, however, The present in coal balls and their average composition by weight were deter- was not replaced by the calcite, as or- mined by chemical analyses. X-ray diffrac- ganic plant tissues were not affected by tion was used to identify mineral content of the etching. In one gymnospermous seed clays and . Unweathered sections (probably Taxospermum undulatum) fi- of approximately equal weight were removed from each concretion crushed, well mixed, and brous calcite had penetrated the mega- divided into two subsamples. Half a sample spore membrane and two layers of was weighed and placed in 10% HC1 to remove sclerenchyma without disturbing the the carbonate fraction. Half of this residue continuity of its crystal form. Schopf was placed in dilute H2O2 to oxidize the organic material and the other half sample was analyzed (1971) noted that calcite can interpene- by x-ray diffraction (G. E. Model X RD-6) to trate cell walls, lumens, and intracellular 128 LON A. McCULLOUGH Vol. 77 spaces without disturbing the histological of morphological plant structures in the structures due to the large amount of in- coal balls was far from perfect. The herent moisture, which the permineraliz- most abundant component of the coal ing mineral displaces. balls, in fact, was unidentifiable plant Cracks representing the second gen- debris consisting of litter and smaller eration of mineralization have been at- plant parts. This material was disin- tributed to compaction after lithification tegrated and often heavily pyritized. (Mamay and Yochelson 1962) or contrac- Prior to permineralization, it had fil- tion during the final stages of lithification tered into recesses between larger pieces (Evans and Amos 1961). These were of lycopod periderm (fig. 3) and other evident in every coal ball examined. resistant plant organs. Lycopod peri- Sometimes they were rather isolated derm was the only identifiable floral pockets having a vuggy appearance, but constituent in 36% of the concretions. usually they formed calcite-filled veins, Twenty percent of the coal balls con- which cut across plant tissue often sepa- tained some amount of fusain-like ma- rating morphologically continuous struc- terial, which was typically blocky and tures by as much as 12 mm. fibrous, but had fairly well-preserved cell Calcite in coal ball veins was present lumens. in three forms: fibrous calcite, prismatic Compaction, presumably due to over- calcite or both varieties together in a burden pressure, was evident in all coal given vein. When both morphological balls examined. Plant organs, such as forms of calcite were present, the fibrous lycopod periderm, that were more re- variety grew inward from the walls of the sistant to decay usually resisted compac- vein indicating earlier deposition, while tion. The result was that differential the interior portion was filled with pris- compaction of material occurred in many matic calcite. Lindholm (1974) also of the concretions. Most of the root noted this relationship in septarian veins. material (which is nearly circular in cross Crystals of pyrite commonly occur in section) shows some indication of com- small isolated concentrations along the paction before permineralization. The line where the two varieties of calcite root cells in direct line with overburden were in contact. Very little coloration pressure show some elimination of air was apparent in either of the calcitic spaces but little alteration otherwise. forms but, of the two, the prismatic cal- The peat deposit in which the coal balls cite had less coloration and probably less formed was probably the result of an ac- impurities. cumulation of fresh plant material and its subsequent degradation to form decom- TABLE 1 posed leaf litter, disintegrated cells, fusain- Relative Abundance of Floral Material in Coal like fragments, and small resistant plant Balls from Lower Freeport Coal parts. The juxtaposition of fragile plant organs with similar organs in various Floral Component % Occurrence stages of suggest that in 100 Peels there was a continuous addition of new material into the peat swamp environ- Lycopod periderm 84 ment. Sections of fairly well-preserved Stigmaria sp. 48 Myeloxylon petioles showed secretory Myeloxylon sp. 44 canals and sclerenchyma around the Psaronius sp. 24 Medulosae sp. 4 periphery, and collateral vascular bundles Sphenophyllum sp. 4 with well-preserved xylem strands. Par- Taxospermum undulatum 1 enchymatous ground tissue, which usually Sporangia 1 decays first, was not evident. Other Myeloxylon petioles studied were par- tially compressed and their internal tis- The coal balls in my study were "nor- sues were more or less disorganized. mal" coal balls (Mamay and Yochelson Plant roots present in the coal balls 1962) that is, they contained only fossil probably represent the last growing, plant material (table 1). Preservation freshest plant parts introduced prior to Ohio J. Sci. COAL BALLS AND ROOF SHALE CONCRETIONS 129 permineralization. Although they con- Sections of Stigmaria showed an elimi- sist chiefly of thin-walled parenchymat- nation of air spaces but their vascular ous tissues, the roots showed the least ef- bundles and thin-walled cortical cells fect of compaction and commonly re- were seldom compressed. In many cases, tained their shape in the coal balls. roots penetrated pieces of lycopod peri-

FIGURES 2-5* FIGURE 2. A roof shale concretion in place along the highwall above the Middle Kittanning Coal (No. 6). Note the shale appears to be deflected around the concretion. X3.5. FIGURE 3. Two portions of lycopod periderm from a coal ball peel showing the disinte- grated cell material and leaf litter that had filtered around them before permineralization. X0.4. FIGURE 4. A roof shale showing an etched surface. The smaller at the top has a crack through the center that is due to overburden pressure, while the rest of the concretion shows typical septarian development. XI.3. FIGURE 5. A septarian vein from an etched roof shale nodule. Fibrous calcite lines the walls and prismatic calcite fills the interior of the vein. A brachiopod shell in section, shown by arrow, was disrupted by the venation. X0.3. *When multiplied by factor shown will give normal dimensions. 130 LON A. McCULLOUGH Vol. 77 derm indicating that the peat actually ated outward as small wiry cracks. Oc- formed a substrate that supported grow- casionally, the smaller peripheral cracks ing vegetation before permineralization. appeared to be diverted by brachiopod Barghoorn (1952) suggested that plant shells in the matrix, however, the larger material, such as roots and rhizomes, that fissuring commonly displaced fossil ma- entered a peat deposit by growth, may not terial (fig. 5). In some of the concre- have been exposed subsequently to aero- tions the calcite-filled cracks were ex- bic processes that cause decomposition. posed superficially as lattice-like struc- tures that extend up to 6 mm above the ROOF SHALE NODULES surface. The mode of preservation of roof shale The amber calcite, which fills the nodules appears to be by "authigenic septaria, occurred primarily as the coarse cementation" (vSchopf 1975). Durable prismatic form of the mineral and fibrous fossil organisms were probably preserved calcite was found only in some of the in the soft sediment prior to the carbonate larger fissures. Where both forms of the cementation. There was no evidence of mineral occurred in the same crack-filling, any permineralization or distortion of the walls of the filling were lined with fossil components after their encasement fibrous calcite and prismatic calcite filled in the nodules. the interior. Pyrite was confined to the In many nodules the primary cementa- periphery of the nodules, especially in the tion was disrupted by radiating sep- area bordering separate concretionary tarian fissures (fig. 4). In some con- units in an aggregate. cretions the central portions were devoid Only a small amount of organic ma- of cracks, while in others the septaria oc- terial was preserved in the roof shale curred throughout the matrix. The fis- nodules. This consisted of a hetero- sures were usually distinctly polygonal in geneous assemblage of both marine ani- section toward the center of the nodule mals and terrestrial plant parts (table 2). but decreased in diameter as they radi- The most abundant faunal component in TABLE 2 Comparison of the Two Types of Concretions

Parameter Roof Shale Nodules Coal Balls

Surrounding Material Gray shale overlying Middle Upper part of the Lower Freeport Kittanning Coal (No. 6). Coal (No. 6a). Form Mostly isolated concretions; also Mostly aggregated masses up to 1 m aggregates from 30-37 cm along thick and 3 m long; seldom as indi- major axis. Units within aggre- vidual concretions. Units within gate may be separated by a dense aggregate may be separated by 2-3 concentration of pyrite. mm streaks of coaly material. Relation to Sediment is deflected around the Stratum is deflected around the concretions (fig. 2). concretions. Light to medium gray, very light Dark gray, brown to black or red- Color gray to yellowish on weathered dish brown on weathered surfaces. surfaces. Size 2.5-3.7 cm for major axis of iso- 5-50 cm for major axis of isolated lated specimens. specimens. Shape Lenticular, discoidal, spheroidal, Lenticular, spheroidal, or subangular. or lobate. Surface Texture Relatively smooth to pitted with Rough with projecting edges, coaly exposed and septarian veins. veneer, and exposed plant material. Specific Gravity 2.45 g/cm3 average. 2.71 g/cm3 average. Fossil Fauna Abundant brachiopods, including None Mesolobus, Lingula, several pro- ductid species, some gastropods, bryozoan and crinoid parts, ostracodes, and cephalopods. Fossil Flora Megaspore coats. Lycopods, pteri do sperms, spores (table 1). Ohio J. Sci. COAL BALLS AND ROOF SHALE CONCRETIONS 131

TABLE 2. Continued

Parameter Roof Shale Nodules Coal Balls

Miscellaneous Coprolites, fusain-like material, Fusain-like material. material and root casts. Mode of Preservation Authigenic preservation. Cellular permineralization. Quality of Preservation Only the durable fossil components Most of the plant material is dis- resistant to decay and transport integrated, only some leaf and root abrasion are represented. material is delicately preserved. Minerals Present Calcitc (84.5%) with illite (11.3%), Calcite (89.8%,) with minor amount quartz (1.5%), and pyrite (0.9%). of pyrite (7.6%). Initial Mineralization Calcareous, but cloudy due to Translucent fibrous calcite radiating finely disseminated clay. from various loci. Secondary Radiate scptarian cracks (fig. 3), Non-septarian veins, which often dis- polygonal near the center and wiry rupt or displace fossil material. toward the periphery. Some are Mineralization diverted by fossil material (fig. 4). Mostly filled with amber prismatic Veins filled with brown fibrous cal- calcite. Fibrous calcite line the cite oriented normal to the walls, walls in only a few septaria. Py- clear prismatic calcite, or both forms Fabric of Veins rite is mostly absent. with some pyrite. Mostly septarian development pri- Resulted from cracking due to set- marily due to shrinkage of clay tling of substrate and overburden minerals. Some cracks were due pressure. Origin of Venation to overburden pressure and settling. Environment of Deposition Formed in off-shore marine muds. Formed in a freshwater peat swamp Some movement of sediment indi- under static conditions. cated but quiet conditions gen- erally prevailed. Origin of Carbonates Probably derived from the sur- Probably derived from a marine rounding sea water. transgression over unconsolidated peat. (Direct evidence was re- moved by erosion). Time of Formation Early diagenetic (fig. 6). Late syngenetic to early diagenetic (fig. 6). Chemical Conditions An oxidizing environment is Only limited oxidation occurred. indicated. The environment was mainly anoxygenic. Depth of Formation Probably less than 0.5 m from the Probably less than 1 m from the sediment-water interface. sediment-water interface. the nodules was Mesolobus sp., a small root casts appeared in the solution articulated brachiopod, which occurred residues. in great abundance in certain units of the Only the more resistant fossil parts Allegheny Series of Ohio (Sturgeon 1936). were evident in the roof shale nodules. Rust-colored megaspore coats were the The soft parts of organisms were not most easily identified terrestrial plant preserved presumably because they were component. These were largely un- oxidized, consumed, or removed by compressed and distorted, although a mechanical transport prior to lithifica- few were broken. Size variation was tion. The fossil shells were either cal- minimal with an average diameter of careous or pyritized and many shells of 0.25 cm. Unidentified fusinized fibrous- the same species exhibited both types of tissue fragments from 0.10 to 0.30 cm in mineral composition within the same diameter were also commonly distributed nodule. The formation of roof shale throughout the nodules. Coalified plant nodules in marine mud probably pro- stems were present on the surface of 2 ceeded relatively rapidly once initiated. nodules and a small number of pyritized This is indicated by megaspores in the 132 LON A. McCULLOUGH Vol. 77 EUGENESI S SYNGENESI 1 DIAGENESI EPIGENESI BIO-DEVELOPMEN T |DEAT H ACCUMULATIO N | BURIA L CONSOLIDATIO LITHIFICATIO

FIGURE 6. Sesquence of paragenetic events that led to the formation of coal ball and roof shale concretions. Ohio J. Sci. COAL BALLS AND ROOF SHALE CONCRETIONS 133 matrix of the nodules being quite rounded Robert Wilkinson, jay Spielman, Karen Tyler, and John Ghist. Kenneth Beamer and Michclc and complete and showing little evidence McCullough assisted in the field. Dr. Stig of compression prior to the authigenic Bergstrom, Dr. K. O. Stanley, and Stephen cementation of the surrounding matrix. jacobson read drafts of this paper in various The calcareous and pyritic shell com- stages of completion. The employees of The Empire Coal Company of Gnadenhutten, Ohio ponents were naturally much more re- provided valuable information and free access sistant to compression, whereas the to operating strip pits. The Friends of Orton fragile megaspores could not have re- Hall fund contributed a grant towards pub- sisted much overburden pressure and lication. still retain their spheroidal form. LITERATURE CITED COMPARATIVE ANALYSES OF THE Barghoorn, E. S. 1952 Degradation of plant tissues in organic sediments. J. Sed. Petrol. CALCAREOUS CONCRETIONS 22:34-41. Physical and chemical differences in Darrah, W. C. 1941 Studies of American coal balls. Amer. 1. Sci. 239: 33-53. coal balls and roof shale nodules arose Denton, G. H., H. R. Collins, R. M. DeLong, primarily as a result of their formation B. E. Smith, M. T. Sturgeon, and R. A. in different environments. Twenty-three Brant 19G1 Pennsylvanian geology of east- different parameters (listed in table 2) ern Ohio. p. 131-205. In: Guidebook for Field Trips, Cincinnati Meeting, Geol. Soc. were used to compare the 2 types of con- Amer., 1901. 350 p. cretions. Four separate categories: eu- Evans, W. D. and D. H. Amos 1961 An ex- genesis, syngenesis, diagenensis, and epi- ample of the origin of coal balls. Geol. genesis were used to represent increasing Assoc, Proc. 72: 445-454. Good, C. W. and T. N. Taylor 1974 Struc- lithification of the enclosing sediment in turally preserved plants from the Penn- which the concretions formed (fig. 6). sylvanian (Monongahela Series) of south- Various overlapping genetic classifica- eastern Ohio. Ohio J. Sci. 74: 287-290. tions have been used to indicate the Joy, K. E., A. J. Willis, and W. S. Lacey 1956 origin of concretions (Tarr 1921; Nor- A rapid cellulose peel technique in paleo- wood 1958; Pantin 1958). My classifica- botany. Ann. Bot. 20: 635-637. Kosanke, R. M. 1945 plant remains tion, with the addition of eugenesis to in- in calcareous coal balls. J. Paleontol. 19: dicate the period of development and 658. death of the organic material found in Lamborn, R. 1930 Geology of Jefferson County. the concretions, allows a more temporal Geol. Surv. Ohio, 4th Series. Bull. No. 35. 304 p. comparison of the genesis of the concre- Lindholm, R. C. 1974 Fabric and chemistry tions with changes in and of pore filling calcite in septarian veins: lithification. Models for limestone cementation. J. Sed. Petrol. 44: 428-440. Although both types of concretions Mamay, S. H. and E. L. Yochelson 1962 _ Oc- were decidedly diagenetic in origin, it currence and significance of marine animal appears that the coal balls began to form remains in American coal balls. U. S. Geol. during late syngenesis, while the roof Surv. Prof. Paper 354-1: 193-224. Norwood, E. M., Jr. 1958 Origin of the car- shale nodules began to form later during bonate concretions of the Marcellus shale. burial, or in early . The or- The Compass 35: 173-190. ganic material in the coal balls was per- Pantin, H. M. 1958. Rate of formation of a mineralized early enough so that bac- diagenetic calcareous concretion. J. Sed. Petrol. 28: 366-371. terial activity, decay, and overburden did Perkins, T. W. 1976 Textures and conditions not destroy cellular features. The less of formation of Middle Pennsylvanian coal durable organic matter in the roof shale balls, central United States. Univ. nodules was destroyed either by trans- Paleontol. Contrib. Paper No. 82. 13 p. port erosion or by decay prior to the Rothwell, G. W. 1976 Petrified Pennsyl- vanian age plants of eastern Ohio. Ohio J. formation of concretions by authigenic Sci. 76:128-132. cementation during burial and consoli- Schopf, J. M. 1965 A method for obtaining dation. small acid-resistant fossils from ordinary solution residues, p. 301-304. In: Hand- Acknowledgments. The author acknowledges book of Paleontological Techniques. Kum- the guidance, suggestions, and interest of Dr. mel, Bernhard and David Raup (Eds.). W. James M. Schopf, who directed my attention to H. Freeman, San Francisco 852 p. the Ohio coal ball locality and supervised the • 1971 Notes on plant tissue preserva- project. Technical assistance was provided by tion and mineralization in a deposit 134 LON A. McCULLOUGH Vol. 77

of peat from Antarctica. Amer. }. Sci. 271: as "coal balls." Roy. Soc. Phil. Trans. 522-543. (London) 200B: 167-218. 1975 Modes of fossil preservation. Sturgeon, M. T. 1936. Allegheny fauna of Rev. Palaeobot. Palynol. 20: 27-53. eastern Ohio. Unpubl. PhD Thesis Ohio Stewart, W. N. and T. N. Taylor 1965 The State University, Columbus. 174 p. peel technique, p. 224-232. In: Kummel, Bernhard and David Raup (Eds.). Hand- Tarr, W. A. 1921 Syngenetic origin of con- book of Paleontological Techniques. W. H. cretions in shale. Bull. Geol. Soc. Amer. 32: Freeman, San Francisco 852 p. 373-384. Stopes, M. C. and D. M. S. Watson 1909 On Weller, J. M. 1930. Cyclical sedimentation the present distribution and origin of the in the Pennsylvanian and its significance. J. calcareous concretions in coal seams, known Geol. 38: 97-135.