THE MUDDY MOUNTAIN OVERTHRUST IN NEVADA 65 



differential erosion on tilted strata. These ridges trend generally 

 north and south and are elevated only a few hundred feet above the 

 bordering valleys. Similar ridges, trending northeastward, form 

 the southern part of the mountains. The central division consists 

 of faulted portions of an overthrust block, and is the dominating 

 part of the range. This division of the mountains is shaped roughly 

 like a letter C, with the opening toward the south. It is a dis- 

 tinct unit, made conspicuous by its superior average elevation, by 

 the abrupt faces bounding it on practically all sides, and by the dark 

 Paleozoic hmestones that form the greater part of the mass. For 

 convenience in reference the unit has been called Callville Moun- 



FiG. 3. — View of White Basin and part of Callville Mountain, looking northwest 

 from the south end of the White Basin fault scarp. 



tain. Its upper surface is rugged, and a number of sharp peaks rise 

 prominently above the general elevation. Muddy Peaks, the high- 

 est points, are nearly 5,800 feet above sea-level. Immediately 

 north of the peaks the continuity of the mountain has been some- 

 what broken by faulting and erosion, and Jurassic sandstone is 

 exposed in a depression known as Muddy Peaks Basin. White 

 Basin, a low area floored by light-colored Tertiary deposits, lies 

 within the curve of the C formed by Callville Mountain (Fig. 3). 



STEATIGRAPHY 



Except for small amounts of igneous materials, all of the rocks 

 exposed in the Muddy Mountains are sedimentary. They include 

 strata of Paleozoic, Mesozoic, and Cenozoic age. The Callville 

 Mountain block consists of four formations, chiefly heavy limestones. 



