1918] Moody-Taliaferro : Anticlines Near Sunshine, Wyoming 455 



bright red clays, the red clays predominating. This formation was 

 not studied in detail. It is limited to the southern part of the area 

 and occupies only the highest points and ridges. 



The tuffaceous beds form only a small part of the formation, 

 usually being thin intercalations in the sandstone. Some of the beds 

 are as much as 8 feet thick. In the hand specimen they are white 

 to light gray in color, rather hard and well cemented and usually 

 pebbly, with small subangular pebbles up to one-fourth inch in diam- 

 eter. These pebbles are usually volcanic rock. 



In this area at least the Wasatch was laid down on a surface of 

 moderately high relief. Section C-D through the Gooseberry Creek 

 anticline shows the Wasatch lying unconformably on the older for- 

 mations (pi. 34b and 35). 



QUATERNAEY SYSTEM 



Terrace Gravels. — The Quaternary was marked by active erosion 

 in the high mountainous regions to the south and west, and by the 

 deposition of rather extensive sheets of terrace gravels far out into the 

 basin. There are at least two distinct periods of gravel deposition. 

 The earlier is represented in this area by coarse gravels capping the 

 higher terraces, remnants of which are found on both sides of Wood 

 and Greybull Rivers. Along Wood River the elevation of these higher 

 terraces is about 7000 feet. They slope gently to the north at about 

 90 feet to the mile. Subsequent erosion has removed all but relatively 

 small areas of these gravels. The terraces produced during the second 

 period of gravel deposition are about 400 feet lower than the earlier 

 and 200 to 250 feet above the present stream valleys. These later 

 terraces are extensively developed along Wood and Greybull Rivers. 

 No terraces, except the present flood plain, were seen along Gooseberry 

 Creek. 



The deposits of both periods are essentially the same. They con- 

 sist of silt, sand, and fine to coarse gravel. Boulders up to 8 or 10 

 inches in diameter are common. The boulders are chiefly porphyritic 

 volcanic rocks derived from the near-by moiintains. Boulders of 

 quartzite and limestone are also common. All of the pebbles and 

 boulders are well rounded. 



Alluvium. — Alluvium covers the flat bottomed, rather narrow 

 valleys of Wood and Greybull Rivers, Gooseberry Creek and their 

 tributaries. It consists of sand, silt and some coarse gravels and 

 varies in thickness from to 20 feet. 



