272 W. LINDGREN — TWO NEOCENE RIVERS OF CALIFORNIA. 



North Columbia ; this grade would be approximately 158 feel per mile 

 in a distrance of 3 miles, an extraordinary contrast indeed. Mr Pettee* 



assumes an even grade of 72 feet per niile.f 



North Bloomfield to Snow Paint. — There has been a belief prevalent for 

 a long time that the Bloomfield channel connects eastward with the 

 Woolsey flat, Moores flat, and Snow Point areas. The line of connec- 

 tion is given by Mr PetteeJ as being via the Derbec and Watts shaft-, 

 and necessitates the very improbable grade of 290 feet per mile between 

 North Bloomfield and the latter place, while the grade between Watts 

 shaft and Woolsey flat would only lie 60 feet per mile. Mr Pettee 

 thinks faults or rapids might possibly occur some distance east of North 

 Bloomfield. 



As to the Derhec shaft, it certainly is not on the main channel ; neither 

 is it very well possible that the Watts shaft is, for there is an inlet north 

 -of Backbone house which is considerably lower than the lowest point 

 in the Watts channel ( 3,800 feet). At this point there is a steep lava 

 bluff underlain by heavy masses of clay; enormous slides have taken 

 place, obscuring the relations of the strata, and the lowest bed-rock point is 

 not easily ascertained with precision. My elevation for this point 

 was made with an aneroid from the known elevation of Backbone 

 house directly above; the lowest bed-rock point would be about 700 feel 

 below the Backbone house, and the elevation 3,400 feet, with a probable 

 error of 50 feet. This is just above the point where Bloody Run makes 

 a sharp turn to the east; on both sides of the creek north of this inlet 

 there are benches of gravel at least as low down as 3,500 feet, indicating 

 plainly, with their bed-rock rising eastward and westward, that a new 

 eroded channel once occupied the space between them. Prom here the 

 Bloomfield channel must have curved eastward and followed the pres- 

 ent canyon up to near Woolsey flat, where it again made a bend south- 

 ward. The gravel exposed on the opposite side of the Middle fork of 

 the Yuba on the ridge between Kanaka creek and the river at an eleva- 

 tion of 4,0,00 feet, with rising bed-rock northward, lends additional 

 strength to this view. Watts shaft in all probability only represents a 

 tributary to the main river. 



From Woolsey flat the continuation of the channel is very distinctly 

 indicated by Moores Hat, Orleans and Snow Point, as pointed out by 

 Mi- Pettee;§ at Orleans and Snow Point the stream flowed in a com- 

 paratively steep, narrow valley. The bed-rock immediately to the south 



♦ Auriferous Gravels, i>. 392. 



t Mr Pettee's distances vary somewhat from those here Adopted, which 1 have endeavored to 

 measure along the probable curves of the stream. 

 | Auriferous i rra\ els, p. 309 el seq. 

 I Auriferous Gravels, p. 203, 



