PEALE.] PEEMO-CAEBONIFEEOUS STRATA OF EAGLE EIVEK. 119 



group is iu immediate superposition to this tJpper Carboniferous. 

 This is probably a mistake, as we will see further on. In going down 

 Eagle Eiver we find that these layers, like those of the lower formation, 

 cross the river and are shown on the western side. From the mouth of 

 the Piuey to the head of the second canon of the Eagle, the prevailing- 

 rocks on the hills bordering the valley on either side, are probably of 

 Permian age. On the eastern side the Ked Beds (Trias"?) show above 

 them on the summits of the hills, which are comparatively low and rounded. 

 On the western side the Red Beds do not appear until we reacli the head 

 of the canon. The beds here that I have referred to the Permian consist 

 of a series of gypsiferous beds, shales, and sau(istones, with probably a 

 few bands of limestone. I was unable to make any section of them. 



Dr. Hayden, in the report for 1873, refers them all to the Carbonifer- 

 ous, finding species of Froductus and Spirifer in the lower part of the 

 series, and in the upper part a specimen of Orhicula. I have given my 

 reasons for calling, at least the upper portion, Permo-Carbouiferous, and 

 Professor Lesquereux has shown that Carboniferous foruis are mingled 

 with Permian in the fossils I collected on Eagle Eiv^er. In Mr. Marviue's 

 district the gypsiferous beds extended down into the Carboniferous. 



Above the caiion ou the west or south side of the river the area occu- 

 pied by the gypsiferous series extends some distance back from the edge 

 of the valley. At the head ot the caiion ou the west side the dip is south 

 80° west. The strata cross the river, conforming to the overlying Triassic 

 and Cretaceous layers which make the spoon-shaped curve that is repre- 

 sented in Plate II, and vvliich has already been relerred to. Tlie angle of 

 inclination at this point is 60°. This, of course, diminishes as the strike 

 turns and is parallel to the course of the river. 



The following is a general section at this point : 



No. 5. — Section of Fermo-Carhoniferous. 



Feet. 



1. Gypsiferous shales and sanrlstones. The gypsum occurs in great quantity 



and is rather impure. The sandstones are lamianted and generally of a 

 pink or red color. I was unable to get the exact thickness, but the out- 

 crop was from ^ 500 to 800 



2. Shales, sandstones and limestoiies, alternating colors, pink, brown, gray, 



yellow, white, cream color, and blackish. These beds are best shown ou the 

 north side of the river. They incline generally about 60°. In some places 

 they are inclined past the vertical, especially in the upper portion. The 

 thickness is about 500 



3. Pink, brown, and graj' shaly sandstones with interlaminated thin beds of 



blile limestone. These beds resemble those I noticed in 1873 in South Park, 

 which are given in the rejiort of 1873, in sections 9, 10, and 11. The thick- 

 ness on Eagle Eiver is about 200 



Total thickness 1.500 



The gypsiferous series is probably tipped up with the overlying beds, 

 £f8 represented in Fig. 1, Plate I, at e, although they are hidden by the 

 volcanic overflow. Below the caiion they occupy the greater part of the 

 valley. This area is indicated on the map A. It is difflcult here to re- 

 duce the strata to any order. Their softness has caused them to yield 

 readily to eroding influences, and they have weathered into low hills, in 

 which they are for the most part concealed. There are one or two folds 

 in them of some extent. These 1 referred to in the chapter ou Eagle 

 Kiver Valley. Besides, however, there are numerous minor foldings, 

 which it would require more time than we could give to reduce them to 

 any system. Mr. Marvine will probably have some additional notes, as 

 they extended into his district. 



