436 OSCAR H. HERS HEY 



that there was such an abundance of material that it succeeded 

 also in submerging the higher channel remnants. 



At the mouths of Big Bend and Grizzly creeks, a belt of 

 chlorite schist enabled the excavation of a basin about i,ooofeet 

 square. The river makes a large bend around by the south, and 

 descends rapidly, so that the terraces are higher above the 

 stream on the downstream than the upstream side. In the east 

 central portion of the basin there was a flat whose surface rose 

 about 30 feet above the river on the upstream side, and whose 

 bed-rock floor rises 10 to 15 feet above the same portion of the 

 river. This is Channel D and the gravel was not covered by the 

 local alluvium. On its downstream side there is a broad terrace 

 rising 12 feet above the river. On the other side of the river 

 there is a terrace whose bed-rock floor is 10 to 15 feet above 

 the river and surface 20 to 25 feet above the stream. There is 

 no local alluvium on it. It seems to be the last development , 

 upstream of Channel E. Back of it there is a marked rem- 

 nant of a terrace whose bed-rock floor seems to be about 75 

 feet above the river. The surface is possibly 100 feet above the 

 river. Within the canyon at the lower end of Big Bend basin, 

 remnants of this channel occur on both sides of the river and 

 lead directly to the last discussed development of Channel C. 

 Similarly, the next lower channel occurs in the gorge as a long 

 narrow bench on the north side, with rock floor 20 feet above 

 the river. 



At the mouth of Big Bend Creek there is an alluvial fan 

 apparently made by that stream. If rests on the same bed-rock 

 surface as the " 15-foot channel" (Channel D) which is 25 feet 

 above the river at the downstream end of the basin. The gravel 

 is 65 feet thick and remarkable for the many large granite 

 bowlders of Big Bend granite, some of which are so large that it 

 seems incredible that the Big Bend Creek could have carried 

 them. The surface is rough and bowldery, and sloped, distinctly 

 toward the river. Some features indicate a glacial origin but 

 the deposit seems waterlaid. The age is the same as that of the 

 gravel of Channel D. 



