iVo. 2.] SCUDDER ON GEOLOGY OF FLORISSANT, COLORADO. 285 



Centimeters. 



16. Drab shales; leaves, seeds, aud otlior parts of plants, and insects, all in 



abundance 61 



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



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



19. Interstratified shales, resembling 17 and 18 ; leaves and other parte of 



plants, with insects 17.8 



20. Thickly bedded chocolate-colored shales ; no fossils 41 



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



shales; plants 7.5 



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 liglit-drab shales, weathering very light ; without fossils ; 



passing into 20 



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



titute of fossils 18 



26. Coarse arenaceous shale ; unfossiliferous 9 



27. Gray sandstone, containing decomposing fragments of some white mineral, 



perhax^s calcite ; no fossils 178 



28. Coarse, fen-uginous, friable sandstone, with concretions of a softer mate- 



rial ; fragments of stems 60 (?) 



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



uitic, with fragments of roots, &c 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 (meters) 6. 668 



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, Ko. 16, lying half-way uj) 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 occiuTcd 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 beds 18 and 21 in the 

 lower half and bed 6 in the upi)er half; or were rare, as in beds 10 and 

 14 above the middle and bed 23 below ; the coarser lignites occurred 

 only near the base. 



'i'he thickest unfossiliferous beds, ISTos. 20 and 27, were almost uniform 

 in character throughout, and did not readily split into laminae, indicat- 

 ing an enormous shower of ashes or a mudilow at the time of their dep- 

 osition ; their character was similar to that of the floor-beds of the basin. 



These beds of shale vary in color fi-om yellow to dark brown. Above 

 them all lay, as already stated, from fifteen to twenty-five decimeters of 

 coarser, more granulated sediments, all but the lower bed broken up aud 

 greatly contorted. These reached almost to the summit of the mesa, 

 which was strewn with granitic gravel and a few pebbles of lava. 



Specimens of these upijer irregular beds, and also of the underlying 

 shales, were submitted to Dr. M. E. Wadsworth, of Cambridge, who 



