544 EEPORT UNITED STATES GEOLOGICAL SURVEY. 



liere cuts quite a deep cailon, from which it emerges into the broadest 

 valley along its course. This valley extends northward about six miles, 

 to the mouth of McDougaPs Creek. It is nearly a mile wide in the 

 widest part, and near the lower end the river includes quite a large 

 island. The valley is covered with a growth of sage interspersed with 

 good grass. The red sandstones outcrop on the east side until within 

 about a mile of McDougal's Creek, when the gray Jurassic limestones 

 cross from the west side about opposite the lower end of the island. The 

 river here bends to the westward, and thence northward appears to be 

 in a monoclinal of Jurassic rocks. 



Station a was located on quartzite on the north side of McDougal's 

 Creek, opposite its mouth. 



Station h was located on red quartzitic sandstone, on the east side of 

 John Day's Eiver, about five miles south of Station a. Near Station a 

 the sandstones outcrop at the angle of McDougal's Creek, about a mile 

 and a half above its mouth. 



Between the two stations they rise on the western slope of the Wyo- 

 ming Eange. At one point the fold in these red beds is unbroken. They 

 appear to be horizontal on the summit of the range.. 



Between Station a and the top of the red beds exposed to the east- 

 ward at the angle of the creek there is exi30sed about 1,500 feet of con- 

 formable beds dipping to the westward 25° to 30°. 



The following ia.:Uie section at this point : 



Section No. 11. 

 Top. 



1. Quartzite. 



2. Reddish arenaceous shales. 



3. Green laminated sandstones. 



4. Greenisli-gray limestones with very irregular structure. Some of the layers appear 



to be arenaceous. The following fossils were obtained : Belemnites densus, Avica- 

 lopecten Idahoensis (?) Gryphcea, and other undetermined Mvalves. 



5. Reddish and gray shales and sandstones. 



6. Gray limestones and shales, near the top of which are Pentacrirms asteriscus, &c. 



7. Blue laminated limestones with Fentacrinus asteriscus, Canipfanecies CelKstriatus, 



Trigonia, sp. ? and Myacites, sp. ? 



The thickness of this section is about 1,500 feet. Below are the red 

 beds, of which the best section made is the one at Station 55 (No. 10). 



Bed jSTo. 1 may represent the base of the Cretaceous, but no proof 

 was found. West of John Day's Eiver is a thickness of from 2,000 to 

 4,000 feet of beds, mainly shales and sandstones, as observed in the very 

 few outcrops seen. They appear to abut against the limestones of the 

 east side of Salt Eiver Eange, although the line of junction was not 

 Seen at any place. The Salt Eiver Eange was crossed at only one point. 

 These shales and sandstones have been colored on the map to represent 

 the Cretaceous formation, from the fact that, tracing the outcrops south- 

 ward, they appear to be the direct continuation of the Cretaceous beds 

 noted on La Barge and Fontenelle Creeks.* Following down the river 

 from McDougal's Creek we found the red sandstones forming hogbacks 

 on the east side. The dip of these beds increases towards the north. 

 West of Station 53 the angle is 43°. The strike of the beds is a little 

 west of north, while the river flows directly north. The Jurassic beds 

 outcropping, at the mouth of McDougal's Creek therefore soon cross to the 



* During the explorations of 1878, Cretaceous fossils were obtained in beds on Ho- 

 back's River, directly north of this valley, in about the same relative position with 

 regard to the Jurassic. ■ 



