OF THE GREEN RIVER GROUP. 129 



in which are good exposures of the various beds. The following section 

 gives them from top downward: 



"1. Coarse conglomerated sandstone. 



"2. Fine-grained, soft, yellowish-white sandstone, more or less argil- 

 laceous, and containing fragments of stems and leaves. 



"3. Coarse gray and yellow sandstone. 



"4. Chocolate-colored clay shales with fossil leaves. At the upper 

 part the shales are black, and below pass into — 



"5. Whitish clay shales. 



"These last form the base of the hill. The beds are all horizontal." 



After remarking on the presence of fragments of trachyte scattered 

 around and found in layers near the surface, as seen by the boring of a 

 well in the vicinity, Dr. Peale continues: "The lake basin may possibly 

 be one of a chain of lakes that extended southward. I had thought it 

 possible that the beds were of Pliocene age. The specimens obtained from 

 No. 4 of the section above were submitted to Mr. Lesquereux, who informs 

 me that they are Upper Tertiary, and says that he does not believe, as yet, 

 that the plants of the Green River Group, to which are referable the speci- 

 mens sent to him, authorize the conclusion of Pliocene age. He rather 

 considers them, as yet, as Upper Miocene. The species known of our 

 Upper Tertiary are, as yet, too few and represented in too poor specimens 

 for definitive conclusion. Those sent from Florissant have a Myrica, a 

 Cassia, fragments of leaves of Salix angustata, Al. Br., a Rhus, an Ulmus, 

 and a fragment of Poa or Poacites." 



I give the end of the quotation in order to show that the first opinion 

 I expressed on the age of the Green River Group from its vegetable 

 remains was based upon the examination of too insufficient materials. 



After Dr. Peale the lake basin of Florissant has been carefully 

 explored by Professor Sam. H. Scudder, who, in " Bulletin of the Geol. 

 Survey,'* vol. vi, No. 2, has given in great detail the most precise and 

 interesting account of his researches. It comprises not only the topo- 

 graphical description of the basin, the geology and stratigraphy of the 

 beds formed by deposits of the lake, but a preliminary report on the 

 insects and the plants obtained there by himself in an immense number 



CF 9 



