COAL BALL PEEL TECHNIQUE

Coal balls are spherical to ellipsoidal masses of calcium carbonate (or calcium magnesium carbonate) in which plant tissues are tree dimensionally preserved, embedded within the carbonate matrix. The carbonate essentially impregnates the residues of the plant cell walls and fills the cell cavities. Concentration of the carbonate occurred by localized precipitation from solution at a time when the plant tissues were at the peat stage and the solid matrix of the coal ball thus formed prevented compression of the entrapped tissues into coal. Coal balls occur sporadically in Carboniferous coal seams of Kansas, Iowa, Indiana, and Illinois. After coal balls are collected they are cut on saws specially equipped with diamond-edged blades. The cut surfaces are then ready to be lapped (rough ground) with No. 400 carborundum powder. A final polishing is accomplished using No. 600 carborundum powder on plate glass. The polished surfaces are then ready to be etched a 5% HCl Required etching time may vary but 20..30 seconds in the above solution often is adequate. As the etching process progresses the carbonate matrix is slowly dissolved away leaving a layer of plant cells standing in relief. Great care must be taken so that the surface is not touched and is kept free of loose materials. Gently flowing tap water can be used to wash away excess acid, The etched surface is then allowed to dry upright. Many investigators pour a few drops of acetone on the etched surface to speed up the water evaporation rate and consequently increase the number of peels which may be made in one period. The dry coal ball segment is placed on an acetone proof surface with the top surface of the segment at a alight {5° -.10°) slant. Enough acetone is applied to moisten the entire etched surface with any excess acetone collecting at the lower elevation. A sheet of 3ml acetate is then gently laid on the etched surface in`a manner that permits the acetone to distribute itself. evenly between the surface of the ball and the acetate. One or two milliliters of acetone is sufficient for making an average coal ball peel. Excessive acetone between the acetate and the coal ball may cause bubbling and wrinkling in the peel. The acetone partially dissolves the acetate and consequently allows it to flow in and around the cell wells which stand in relief upon the surface. As the acetone evaporates the raised parts of the etched surface becomes.. firmly embedded in the lower surface of the cellulose acetate and will break away from the coal ball when the peel is removed. Drying time is dependent upon temperature, air circulation, and quantity of acetone involved but 15 to 30 minutes is the range. Insufficient drying time results in a faint print; excessively dry peels may be difficult to remove. The peel is removed by pulling up on the acetate that overhangs the edge of the coal ball. Care should be taken to get the peel off in one piece. The peel is now ready to be identified.

Adapted from "The Coal Ball Peel Technique" by Thomas N. Taylor, Fast Journal, 1962, MCALASTER SCIENTIFIC CORPORATION „ EDUCATIONAL DIVISION 60 ARSENAL ST. „ WATERTOWN, MASS. 02172

TECHNICAL BULLETIN

care must be taken so that the surface is not touched Parts List – MSC 53700 and is kept free of loose materials. Gently flowing tap 1 60271 Calcified plant specimen, with water can be used to wash away excess acid. identified peel and map The etched surface is then allowed to dry upright. Many 1 60276 6" x6" glass plate investigators pour a few drops of acetone on the etched 60277 300 sheets cellulose acetate 2" x 3" surface to speed up the water evaporation rate and 1 60279 Coal Ball, unidentified consequently increase the number of peels which may 60280 #600 emery in 1-oz. bottle with be made in one period. CAUTION: Acetone is a highly dispensing cap inflammable substance and calls for suit-able safety precautions. The dry coal ball segment is placed on an acetone proof surface with the top surface of the segment at a slight (5 – 10° degree) slant. Enough acetone is applied to moisten MSC 53701 Kit the entire etched surface with any excess acetone Comparable to 53700 but lacks #60271, Calcified collecting at the lower elevation. A sheet of 3 ml acetate plant specimen with identified peel and map. is then gently laid on the etched surface in a manner that permits the acetone to distribute it-self evenly between the surface of the ball and the acetate..

Technique One or two milliliters of acetone is sufficient for making an average coal ball peel. Excessive acetone between the Coal balls are spherical to ellipsoidal masses of acetate and the coal ball may cause bubbling and calcium carbonate (or calcium magnesium carbonate) wrinkling in the peel. The acetone partially dissolves the in which plant tissues are three dimensionally pre- acetate and consequently allows it to flow in and around served, embedded within the carbonate matrix. The the cell walls which stand in re-lief upon the surface. carbonate essentially impregnates the residues of the As the acetone evaporates the raised parts of the plant cell walls and fills the cell cavities. etched surface becomes firmly imbedded in the lower Concentration of the carbonate occurred by localized surface of the cellulose acetate and will break away precipitation from solution at a time when the plant from the coal ball when the peel is removed. tissues were at the peat stage and the solid matrix of the coal ball thus formed prevented compression of Drying time is dependent upon temperature, air cir- the entrapped tissues into coal. Coal balls occur culation, and quantity of acetone involved but 10 to 30 sporadically in Carboniferous coal seams of Kansas, minutes is the range. Insufficient drying time results in Iowa, Indiana, and Illinois. a faint print; excessively dry peels may be difficult to remove. The peel is removed by pulling up on the After coal balls are collected they are cut on saws acetate that overhangs the edge of the coal ball. Care specially equipped with diamond-edged blades. The cut should be taken to get the peel off in one piece. surfaces are then ready to be lapped (rough ground) with No. 400 Carborundum powder on a piece of heavy The peel is now ready to be identified with the coal ball iron plate. A final polishing is accomplished using No. and preparator. This is usually done with an envelope 600 Carborundum powder on a piece of plate glass. for the peels from each coal ball segment and a numbering system for the individual peels. Envelope The polished surfaces are then ready to be etched in a storage helps keep the peels flat enough for gross solution made by adding 2 ml of concentrated hy- examination. drochloric acid to 98 ml of water. Required etching time may vary but 2 minutes in the above solution often is adequate. As the etching process progresses the carbonate matrix is slowly dissolved away leaving a layer of plant cells standing in relief. Great Slides for microscopic examination may be made of 3. Mount the tape and peel on a microscope slide selected peel parts in the following manner. and trim off excessive tape. 1. Procure a roll of transparent cellulose acetate ad- The slide is now ready for use. The peel section is hesive tape of a width to accommodate the size of flat and is held down by, a cover thin enough to peel segment being mounted. permit inspection under a 43X objective lens. 2. Cut out the desired section of the peel and posi- A recent college text on paleobotany that is suitable tion its shiny side on the sticky side of the tape. for a high school reference book is the following: Be careful to leave a border of tape on all edges of the peel. Andrews, H.N. Jr., 1961, Studies in Paleobotany, John Wiley & Sons, Inc., New York (about $10.00)

Maps of Selected Coal Ball Peels Showing Some Commonly Found Structures.

STEM OF A PRIMITIVE FERN STEM OF SPHENOPHYLLUM

cortical tissue branch of stem stele of stem

SEED OF CORDITES

female gametophyte LEAF OF CORDITES

outer integument fibers epidermis vascular mesophyll bundle attachment Photographs from Paleontology Laboratory, Harvard University 1999 GEOLOGIC TIME SCALE CENOZOIC MESOZOIC PALEOZOIC PRECAMBRIAN MAGNETIC MAGNETIC POLARITY POLARITY AGE BDY.

AGE . PICKS AGE . PICKS UNCERT. AGE PICKS . .

N N PERIOD EPOCH AGE PERIOD EPOCH AGE EON ERA . PERIOD EPOCH AGE . AGES M M T T O O (m.y.)

O (Ma) O (Ma) (Ma) S S R R (Ma) I (Ma) I (Ma) (Ma) N N H H H H (Ma) A A C C HOLOCENE 65 .2 1 C1 QUATER- 0.01 C30 NARY PLEISTOCENE CALABRIAN 30 248 543 1.8 31 MAASTRICHTIAN TATARIAN 2 C2 70 C31 L 252 L 71.3 1 N UFIMIAN-KAZANIAN 2A PIACENZIAN 256 C2A PLIOCENE 32 C32 KUNGURIAN 3.6 A 260 260 I 3 E ZANCLEAN 33 CAMPANIAN LATE 5 C3 5.3 ARTINSKIAN 750 C33 M 3A MESSINIAN 80 LATE C3A 269 7.1 83.5 1 R E S SANTONIAN SAKMARIAN

4 85.8 1 E C4 900 CONIACIAN 280 282 4A 89.0 P L TORTONIAN U 1 C4A 90 ASSELIAN 10 5 TURONIAN 1000 C5 E 93.5 4 290 E

11.2 N O . A N S GZELIAN

CENOMANIAN I N S 296 C N U

E 99.0 5A 1 I SERRAVALLIAN 34 C34 A KASIMOVIAN E 300 MIDDLE C5A 100 E V 303 L O C

G M Y L 14.8 MOSCOVIAN . O

5B S 1250 W

15 C R

O 311 C5B ALBIAN N O I LANGHIAN N

5C Z E

C5C 16.4 E BASHKIRIAN 110 A E M P . 5D EARLY 112 2 320 F I C5D N 323 O T 5E N C5E BURDIGALIAN N SERPUKHOVIAN N

A 327

APTIAN I

6 1500 R P

20 C6 E E O 20.5 120 M0 P 6A 121 3 I VISEAN S B M1 E E

N 1600

C6A S

340 I AQUITANIAN M3 R BARREMIAN 342 R A 6B S T C6B M5 I 127 3 S I 6C C6C 23.8 A TOURNAISIAN M M 130 C HAUTERIVIAN

M10 1750 O C 7 E 132 4 25 C7 O 7A M12 354

C7A N C Y 8 CHATTIAN M14 VALANGINIAN R C8 L 360 L FAMENNIAN E M16 O 137 4 9 C9 R 364 P

140 E C FRASNIAN EARLY 10 BERRIASIAN A C10 28.5 N 370

M18 N I O 144 5 2000 30 11 C11 M20 A GIVETIAN I T 12 G

I TITHONIAN E RUPELIAN M22 380 M 380 N

R 150 C12 L 151 6 LATE KIMMERIDGIAN EIFELIAN O E O 154 7 13 33.7 M25 391 V C13 T OXFORDIAN 2250 15 159 7 EMSIAN E C15 C 35 160 M29 400 400

16 C16 L PRIABONIAN I CALLOVIAN

D PRAGHIAN 164 8 37.0 17 C17 S BATHONIAN 412 169 8 LOCKHOVIAN 170 MIDDLE 417 2500 S PRIDOLIAN 2500

18 S N 419 40 C18 BARTONIAN E BAJOCIAN 420 L A

G LUDLOVIAN 176 I 423 N 8

19 A

E WENLOCKIAN R

41.3 A C19 AALENIAN 428 H 180 180 8 U C N

E E

L LATE

20 R

I LLANDOVERIAN Y 2750 E T N

440 S C20 M I TOARCIAN 443 R U 45 E G A LUTETIAN N ASHGILLIAN 190 L 190 8 C L 449 J O A O

21 I P PLIENSBACHIAN N CARADOCIAN C21 O 195 8 D E

I 458 C E 460 I P EARLY 3000 3000 LLANDEILIAN A L 49.0 SINEMURIAN 22 200 A M 464 V 50 C22 R A 202 8 LLANVIRNIAN 470 E 23 HETTANGIAN O C23 P 206 8 MIDDLE H E YPRESIAN D 24 RHAETIAN ARENIGIAN 210 210 8 480 R E 3250 C24 C 54.8 485 C O TREMADOCIAN 55 490

I NORIAN R 25 E LATE SUNWAPTAN* C25 THANETIAN * D 495 3400 N 220 STEPTOEAN* A S 221 9 500 26 N 500

E 57.9 MARJUMAN* 3500

CARNIAN A C 506

C L S C26 9 I DELAMARAN* 60 227 512 O SELANDIAN EARLY 230 R DYERAN*

27 61.0 A MIDDLE LADINIAN B 516 E

B MONTEZUMAN* C27 I 234 9 520

L 520

28 M

A 3750 C28 E DANIAN ANISIAN R P 240 A A 3800? 29 242 9 65 C29 65.0 C T OLENEKIAN EARLY 245 9 30 C30 INDUAN 248 10 540 543

© 1999, The Geological Society of America. Product code CTS004. Compilers: A. R. Palmer, John Geissman *International ages have not been established. These are regional (Laurentian) only. Boundary Picks were based on dating techniques and fossil records as of 1999. Paleomagnetic attributions have errors, Please ignore the paleomagnetic scale. Sources for nomenclature and ages: Primarily from Gradstein, F., and Ogg, J., 1996, Episodes, v. 19, nos. 1 & 2; Gradstein, F., et al., 1995, SEPM Special Pub. 54, p. 95–128; Berggren, W. A., et al., 1995, SEPM Special Pub. 54, p. 129–212; Cambrian and basal Ordovician ages GEOLOGICAL SOCIETY adapted from Landing, E., 1998, Canadian Journal of Earth Sciences, v. 35, p. 329–338; and Davidek, K., et al., 1998, Geological Magazine, OF AMERICA v. 135, p. 305–309. Cambrian age names from Palmer, A. R., 1998, Canadian Journal of Earth Sciences, v. 35, p. 323–328.