University of California. 



[Vol. 3. 



sandy silt, and finally twenty feet of red clay and slate debris, 

 some of the latter occurring in large masses. In fact, nearly all 

 the slate seen is probably of the nature of a landslide deposit 

 which came down over the river deposits. Above the bank there 

 is a steep slope leading up to Kentucky Flat. 



The second channel of the Graham Flat Mine has an average 

 height above the river of 120 feet, or thirty feet lower than 

 the high rock platform. It is characterized by small basins, 

 from ten to thirty feet deep, which give it an irregularity not 

 usual to the old channel floors of this region. About two acres 

 of the outer portion of Graham Flat remain, and the very even 

 surface has a height of 145 feet above the river. (This level 

 corresponds to the 110-foot level of the Upper Basin.) The 

 inner bank contains moderately coarse river gravel until within 

 a few feet of the surface, where it is replaced by a reddish 

 brown sandy clay, except that toward Camp Creek similar 

 reddish silt layers occur lower. 



Opposite Camp Creek from Graham Flat there is another 

 extensive remnant of the same terrace, opened as the Salstrom 

 Mine. About six acres have been removed and about the same 

 amount is left. The surface of the flat appears to have a height 

 similar to the upper levels of Graham Flat, but the bed-rock 

 floor seems to correspond to the lower channel under Graham 

 Flat. The surface has a marked slope and rises in a distinct 

 alluvial cone, whose apex is at the mouth of the valley of the 

 comparatively small Salstrom Creek, while there is no corre- 

 sponding cone apexing on the line of the large Camp Creek. 

 Over the regular river gravel the mine bank shows much reddish 

 brown sandy silt nearly free from pebbles, and near the top of 

 the bank there is a heavy bed of slate gravel. A new cut just 

 opened near Salstrom Creek shows that near the "apex of the 

 cone the red silt is replaced by coarse slate gravel. 



Camp Creek has cut a canon 500 feet wide and 150 feet deep 

 between Graham and Salstrom flats, and this is partly floored 

 by long, narrow strips of lower terraces. 



The Rough and Ready Mine, owned by A. B. Wilder, is situ- 

 ated on the south of the river above Boise Creek. About one 

 and one-half acres have been mined, exposing the rock floor of 



