OF THE GREEN RIVER GROUP. 133 



Ft. In. 



15. Alternating layers of darker and lighter gray and brown ferru- 



ginous sandstone; no fossils 4 



16. Drab shales; leaves, seeds, and other parts of plants, and in- 



sects, all in abundance 24 



17. Ferruginous, porous, sandy shale; no fossils 2 4 



18. Dark-gray and yellow shales; leaves and other parts of plants.. 3 4 



19. Interstratified shales, resembling Nos. 17 and 18; leaves and 



other parts of plants, with insects 7 



20. Thickly bedded chocolate-colored shales; no fossils 17 



21. Porous yellow shale, interstratified with seams of very thin 



drab-colored shales ; plants 3 



22. Heavily bedded chocolate-colored shales; no fossils 11 6 



23. Thinly bedded drab shales; perfect leaves, with perfect and 



imperfect fragments of plants and a few broken insects 7 6 



24. Thinly bedded light-drab shales, weathering, very light; without 



fossils; passing into 7 6 



25. Thick-bedded drab shales, breaking with a conchoidal fracture ; 



also destitute of fossils 7 



26. Coarse arenaceous shale ; unfossiliferous 3 4 



27. Gray sandstone, containing decomposing fragments of some 



white mineral, perhaps calcite ; no fossils 70 



28. Coarse, ferruginous, friable sandstone, with concretions of a 



softer material ; fragments of stems 23 



29. Thinly bedded drab shales, having a conchoidal fracture; some- 



what lignitic, with fragments of roots, etc 10 



30. Dark chocolate shales, containing yellowish concretions; filled 



with stems and roots of plants 10 



Total thickness- of evenly-bedded shales (D. of Dr. Wadsworth's 



note) above floor deposits 23 



"The bed which has been most worked for insects and leaves, and in 

 which they are unquestionably the most abundant and best preserved, is 

 the thick bed. No. 16, lying half way up the hill, and composed of rapidly 

 alternating beds of variously-colored drab shales. Below this, insects 

 were plentiful only in No. 19. and above it in Nos. 7 and 9; in other beds 



