22 TERTIARY INSECTS OF NORTH AMERICA. 



(>. Ferruginous shale ; unfossiliferous 1.5 



7. Resembling No. 5, but having no conchoidal fracture: srcms of plants, insects, and a small 



bivalve mollnsk : 9 



8. Very line gray ochreous shale; uon-fossiliferoiis 0. 5 



9. Drab shales, interlaminated with finely divided paper shales of light-gray color; stems of 



plants, reeds, and insects 46 



10. Crumbling ochreous shale; leaves abundant, insects rare 7.5 



11. Drab shales; no fossils 7.5 



12. Coarse, ferruginous sandstone; no fossils 3. 8 



13. Very hard drab shales, having a conchoidal fracture and tilled with nodules; unfossilif- 



erous (33 



14. Finely laminated yellowish or drab shales; leaves and fragments of plants, with a few 



insects 30 



15. Alternating layers of darker and lighter gray and brown ferruginous sandstone ; no fossils . . 10 



16. Drab shales ; leaves, seeds, and other parts of plants, with insects, all in abundance 61 



17. Ferruginous, porous, sandy shales; no fossils 5.7 



18. Dark gray and yellow shales; leaves and other parts of plants 9 



11). Interstratifled shales, resembling 17 and 18; loaves and other parts of plants, with insects.. 17.8 



20 Thickly bedded chocolate-colored shales; no fossils 41 



21 Porous yellow shale, interstratitied with searus of very thin drab-colored shales; plants .. 7. "> 



22. Heavily bedded chocolate-colored shales; no fossils 30 



23. Thinly bedded drab shales; perfect leaves, with perfect and imperfect fragments of plants, 



and a few broken insects 20 



24. Thinly bedded light drab shales, weathering very light; without fossils 20 



25. Thick bedded drab shales, breaking with a conchoidal fracture; also destitute of fossils.. 18 



26. Coarse arenaceous shale ; unfossiliferous 9 



27. Gray saudstoue, containing decomposing fragments of some white mineral, perhaps calcite ; 



no fossils 178 



28. Coarse, ferruginous, friable sandstone, with concretions of a softer material ; fragments of 



stems perhaps.. 60 



29. Thinly bedded drab shales, having a conchoidal fracture, somewhat liguitic, with frag- 



ments of roots, etc 25 



30. Dark-chocolate shales, containing yellowish concretions; filled with stems and roots of 



plants 25 



Total thickness of evenly bedded shales (" D," of Dr. Wadsworth's note) above floor 

 deposits (Meiers).. 6. G08 



The bed which has been most worker! 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 they 

 occurred only rarely or in fragments. Plants were always abundant where 

 insects were found, but also occurred in many strata where insects were 

 either not discovered, such as Nos. 18 and 21 in the lower half and No. 6 in 

 the upper half, or were rare, as in Nos. 10 and 14 above the middle and No. 



23 below; the coarser lignites occurred only near the base. 



The thickest unfossiliferous beds, Nos. 20 and 27, were almost uniform 

 in character throughout, and did not readily split into laminae, indicating 

 an enormous shower of ashes or a mud flow at the time of their deposition; 

 their character was similar to thaf*6f the floor-beds of the basin. 



