133 Notice of Geological Surveys. 



tion of the stone was taken, and by the process of "medal ruling," 

 a perfect engraving was made by the tracer, and a picture is given 

 in the report (p. 230) of great distinctness. The blue limestone 

 abounds with the Strophomena of Raf., while the cliff has few 

 of them. The shell of the fossils is often preserved in the blue, 

 while in the cliff limestone only the cast is found. 



6. The argillaceous shale, or " bituminous slate," occurs 

 next. This is black and highly fissile ; in some parts very bitu- 

 minous and fetid, and when accidentally ignited will burn for 

 several days. It absorbs water freely, and then exfoliates. It 

 contains spheroidal septaria of an impure blue limestone, from a 

 few inches to three feet in diameter, that are filled with crystals 

 of carbonate of lime, or sulphate of barytes. 



It crops out on a line from the east side of Adams county, pass- 

 ing north through Columbus, and is two hundred to three hun- 

 dred feet thick. Balls of iron pyrites are found in it, Vvhich de- 

 compose and form copperas and alum. 



Mineral springs, charged with these and magnesian salts, abound 

 in this and the bed of clay between it and the cliff limestone, and 

 cause the numerous "licks," which are now resorted to by do- 

 mestic animals as they were formerly by the herds of wild ani- 

 mals. 



7. The ^'fine grained Waverly sandstone'^ succeeds the shale. 

 It is white, yellowish, purple and blue, but more commonly drab ; 

 more or less argillaceous in some parts, and contains oxide of iron, 

 that causes ready decomposition — ^in others exceedingly compact 

 and adapted to building, and for hearth-stones in furnaces. As 

 the superior rock, it occupies, in the central part of the state, a 

 band running about east north east, twenty miles wide, and with 

 a dip east south east thirty feet in a mile, and a thickness of near- 

 ly four hundred or five hundred feet. The upper part abounds 

 in Encrini, Ammonites, Productas, Terebratulos and Spiriferse, and 

 in the southern part of the state. Fncoides are found. A bed of 

 clay appears to separate this from 



8. A ^^ conglomerate''^ or "millstone grit," that underlies the 

 coal measures, and which is generally composed of quartz peb- 

 bles, and coarse-grained sand, or it assumes a fine texture and be- 

 comes a hard compact sandstone with but few pebbles, and crops 

 out at short intervals in its line of junction with the sandstone 

 in abrupt precipitous ledges of one hundred feet high. The nu- 



