288 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. [FoZ. VI. 



this we found, passing, as before, from above downward, the following 

 succession: 



Section in the no7'thweste7'n IcCke. 



[By S. H. ScuDDEE and A. Lakes.] 



Decimeters (estimated). 



1. Finely laminated yellow-drab shales ; no fossils 12 



2. Coarse decomposing yellowish shales ; no fossils 12 



3. Fine compact drab shales ; perfect remains of plants and insects. Passing 



into 15 



4. Arenaceous shales ; very lignitic 6 



5. Heavily "bedded, coarse-grained, crumbling sandstone, of a grayish yellow 



and -whitish color, becoming ferruginous in places ; partially lignitic 60 



6. Chocolate and drab colored shales having a conchoidal fracture, passing below 



into -whitish paper-like shales inclosed between coarse arenaceous lam- 

 inae; plants and insects 45 



Total thickness of shales above floor deposits (Meters, estimated) 15 



These measurements being estimated are undoubtedly too great. The 

 composition of this bluff is coarser in character than that of the section 

 in the southern extension of the lake. The Ugnitic beds, which have 

 been used for quarrying purposes, contain numerous fragments of reeds 

 and roots not well preserved. The lower portions of the section corre- 

 spond better with the other than do the upper beds, where it is difficult 

 to trace any correspondence; jSTo. 3 of the northwestern seems, however, 

 to correspond to !N"o. 16 of the southern series. The whitish jjaper shales 

 lying at the base of this appear to be entirely absent from the southern 

 section, and the distorted beds which crown the mesa are not apparent 

 in the bluif, or, if present, are wholly regular. A more careful and de- 

 tailed section of the bluff (for which we had not time), and particularly 

 the ti-acing of the beds along the wall of the lake, would probably bring- 

 to light better correspondences. Directly in front of Judge Castello's 

 house, at a level of a little more than 2,400 meters, is a bed of fossil fish. 



Judging from the present physical condition of the basin, its age is 

 marked as later than the movements which closed the cretaceous epoch 

 and earlier than the last upheaval in the tertiary, which seems to have 

 taken place during or after miocene times, but there are no physical 

 data yet at hand to warrant definite conclusions on this head. 



PALEONTOLOGY. 



The insects preserved in the Florissant basin are wonderfully numer- 

 ous, this single locality having yielded in a single summer more than 

 double the number of specimens which the famous localities at Oeningen, 

 in Bavaria, furnished Heer in thirty years. Having visited both places 

 I can testify to the greater prolificness of the Florissant beds. As a 

 rule, the Oeningen specimens are better preserved, but in the same 

 amount of shale we still find at Florissant a much larger number of sat- 

 isfactory specimens than at Oeningen, and the quarries are fifty times 

 as extensive and far more easily worked. 



