174 REPORT UNITED STATES GEOLOGICAL SURVEY. 



branch of West Salt Creek is reached, when an abrupt turn to the" 

 northeast is made. At the head of West Salt Creek the course is som^ 

 ■what winding between the branches of that creek and those of the 

 White Eiver streams. The plateau character so noticeable farther west 

 is lost here. The general direction of the divide is east and west to the 

 head of Eoan Creek. East of Eoan Creek the plateau character again 

 prevails, especially along Grand Eiver, as shown in Fig. 2, Plate X (a 

 sketch of the cliffs and plateau on the north side of the Grand from Eoe^ 

 Creek to Cactus Valley, made by Mr. Holmes). The dip of the strata here 

 is to the northward. Between Salt Creek, Eoan Creek, and the Littki 

 Book Cliffs the country is considerably broken up. The drainage is 

 generally to the east, and remnants of the plateau are left as long tongue- 

 like mesas between the branches of Eoan Creek. 



The surface rocks on the plateaus everywhere throughout this region 

 are the white shales of the Green Eiver group of Tertiary Between 

 Desert Creek and Bitter-water Creek, the summit of the cliffs is about 

 12 miles from the edge of Green Eiver Valley. The intervening country 

 is verj' rugged. Spurs extend southward from the cliffs between the 

 streams. These spurs are composed mainly of Wahsatch beds, which, 

 toward the west, are composed of sandstones, generally white in color, 

 but with layers of a pink color. 



We reached the summit of the cliffs by following an old and rough 

 Indian trail that led up Desert Creek. This part of the cliffs was out- 

 side of the district, but it presented the only means of access to the pla- 

 teau, which here is 3,787 feet above the valley. At the entrance of 13ie 

 creek to the valley there are low hogbacks, in which the beds dip about 

 6° toward the cliffs. The general dip appears to be a little east of north, 

 and this becomes more easterly as we follow the cliffs to the westwjir<i. 



The following section was made at the exit of Desert Creek, the thick- 

 ness being estimated : 



Section. 

 Base. F*«i. 



Colorado ... 1. Colorado shales about 200 



[ 2. Sandstone 75 



3. Shales with lignite band ZOO 



4. Sandstone SO 



Fox Hills . . . <; 5. Shales 100 



I 6. Sandstones 25 



I 7. Shales with lignite band , ^5 



I 8. Sandstones 2.5 



Laramie?... 9. Massive sandstones with thin bands of shales 60O 

 [ 10. Heavy bands of white and yellowish sand- 



Wahsatch ? . •{ stones with interlaminated red and reddish 



(^ shales and sandstones J' 4, Ooo 



i 11. Greenish laminated shales and white sand- 

 ( stones and shales. 



Green Eiver 



Bed 1 represents only a portion of the Colorado group. 



The sandstones 2 and 4 form escarpments facing the valley. As 

 No. 4 is traced up the creek, it is seen to thin out as it sinks Into tKe 

 hills beneath the upper beds. Instead of one baud of sandstone "thcvi? 

 are several, and the line between 4 and 5 becomes very indefinite. This 

 we find to be the case very frequently in this region. A band of Sand- 

 stone may be very persistent for a long distance, and then split ir\iQ 

 several layers and perhaps disappear. The line between the lyaraThift 

 group and the Fox Hills is especially indistinct. The time at our dis- 

 posal did not permit of careful search for fossils. 



