Figure 7. — Granitic rooks in the Idaho Batholith exhibit various degrees of 

 weathering. Road outs in the more highly weathered types continue to 



supply sediment for years. 



1970) indicate that sediment production increases greatly after a major storm event 

 such as occurred in December 1964 in California. The same storm hit Deep Creek and, 

 coupled with the April 1965 event, apparently caused the increases found in Deep Creek. 

 Anderson reports that high poststorm sedimentation tends to decrease with time; however, 

 this trend was not detected in Deep Creek for the measurement periods following the 

 April 1965 storm. 



Actually it is doubtful that erosion on roads in the Idaho Batholith will per- 

 manently decrease within a reasonable time to the level that existed before disturbance. 

 The road tread and steep cut slopes in the Deep Creek area are composed of weathered 

 granitic bedrock that continues to disintegrate after exposure faster than natural 

 stabilization can take place (fig. 7). The material resulting from bedrock disintegra- 

 tion is readily transported during subsequent runoff events. Similar bedrock conditions 

 are found throughout much of the unglaciated portions of the Idaho Batholith. 



K) 



