WASHAKIE BASIN. 219 



To the south of the Little Snake Eiver, extending eastward to the 

 foot of the Elkhead Mountains, is a dry region of low rolling hills about 

 25 miles in diameter, the interior of which was not explored by our parties. 

 From the general color of the soil of the region, and the position and character 

 of the beds on its circumference, it has been assigned without hesitation 

 to the Vermillion Creek series. 



From Otter Gap to Elk Gap, the course of the Little Snake River 

 indicates roughly the dividing line between the Vermillion series and the 

 Green River group. The beds of the former rise generally to the east- 

 ward. About 12 miles from Otter Gap, the river cuts a canon through 

 hills of drab clayey beds, underlaid by reddish sandstones, which prob- 

 ably represent the base of the Green River series. The line of depression to 

 the west of this point, occupied by the dry water-courses south of Cherokee 

 Ridge, shows but few outcrops ; toward the Little Snake River, however, 

 the red Vermillion Creek beds are exposed, as indicated, by the color of tlie 

 soil. To the south of this line, the strata rise gently to the broad plateau, 

 which extends from Sunny Point to Vermillion Bluffs. 



This plateau represents a gentle undulation, or broad, anticlinal fold, 

 in the beds of the Vermillion Creek series, of which a section is given in 

 the bluffs facing the depressions of the basin of Vermillion Creek on the 

 west, and the Little Snake River on the east, from which the upper beds 

 have been removed by erosion. From the summit of this plateau, the strata 

 slope off very gently toward the north at an angle of not more than 1° or 

 2°. To the south and west, they follow the general slopes of the topograph}^ 

 sinking into the shallow synclinal basin which lies between Elk Gap and 

 Vermillion Bluffs, where a remnant of the beds of the Bridger group still 

 remains. On the soft slopes of the cliffs which border the Little Snake River 

 on the west, from the bend southward, the line of division between these 

 two groups can be traced by the characteristic coloring of. the upper beds 

 of the Vermillion series ; it. is seen to rise from the bend toward Sunny 

 Point, and from there southward to descend gradually, until, a few miles 

 above Elk Gap, the Green River beds come down to the river's bank. A 

 section, taken on the cliffs at Sunny Point by the aid of an aneroid barom- 

 eter, gave a thickness of about 2,000 feet of beds exposed from the river to 



