BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 28, pp. 347-350, PL. 21 JUNE 11, 1917 



BULT. LAKE CREEK EOCK SLIDE IN THE WIND KIYER 

 ]\rOITNTAIN8 OF WYOMINCV 



{Bead hpforc the Society Decemhev 20, 1916) 



BY R. B. BRANSO?^ 



CONTKNTv'^; 



Page 



Regional relations 347 



Description of the Bull T.nke Creek slide 348 



Rate of movement of the slide 349 



Origin of the slide 349 



Other slides in the Wind River Mountains 350 



Regional Relations 



Bull Lake Creek is a swift stream tributary to Bull Lake, iu Fremont 

 County, Wyoming. For a stretch of from 7 to 12 miles west of the lake 

 it occupies a canyon 2,000 to 4,000 feet deep with walls developer] at two 

 levels. The inner canyon is cut in granite to a depth of 2,000 feet. Tlie 

 walls of the outer canyon, separated from the rim of the granite gorge by 

 a steeply sloping terrace 1 to 2 miles wide, rise to heights of 800 to 1,000 

 feet (plate 21, figure 1). The total Avidth of the outer canyon is 3 to 1 

 miles at its western end, hut decreases to about li/^ miles at a point 7 

 miles fartlier east. Tlie walls of the outer canyon are composed of sedi- 

 mentary rocks, wliicli range from Cambrian to Peunsylvanian in age. At 

 its west end the r>ull Lake- Creek (Cambrian), Slioshoni (Cambrian), 

 and Bighorn (Ordovician) formations make u]) the 1,000-foot cliff. Tlie 

 l)eds forming the cliff dip eastward at about 17 degrees, and almost oppo- 

 site 3, plate 21, figure 1, the Madison limestone (Mississippian) comes 

 in above the Bighorn and forms the top of the cliff, while the Bull I^ake 

 Creek formation dro^is out at the liottom. Eastward the Amsden (Mis- 



^ Manuscript received by llie Secretary of tlie Society February 12, 1017. 

 -Formation names user] by tbc writer in m pnpei- in preparation. 



(317) 



