220 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



turned edges are much eroded. Tliey contain abundant but imperfect 

 plant remains. Shells are rare, but were found at four localitie.'^. These are 

 only i)artially fossilized, but the larger ones are compressed and broken by 

 the weight of the superincumbent strata or by the movement accompany- 

 ing their njdift. Most of these were found in light-colored, calcareous, soft, 

 and excessively fnie-grained material, manifestly a lake deposit. 



The character of the deposits and the fact that the area occupied by 

 them is continuous with a portion of Clear Lake led me to infer that Cache 

 Lake nn'ght be regarded as representing Clear Lake at a more or less distant 

 period. The recent lake de])osits seem at some points to rest immediately 

 upon those of Cache Lake, and I was unable to see any distinction between 

 the fossil Anodonta and a species which is now abundant in Clear Lake 

 These fiicts seemed to indicate that, in spite of very considerable upheaval, 

 there existed a continuity of sedimentation and of life from the Cache Lake 

 epoch to the present The shells were referred to ]\Ir. R. p]. C. Stearns, 

 who fully confirmed my views from a paleontological standpoint, as the 

 following abstract of his report will show: 



The most conspicuous form among the fossils is Anodonta Xnttidliana 

 Lea, of the winged or connate variety, described by that author as A. 

 tmldanndensis. The numerous examples of this shell collected in the 

 Cache Lake beds vary in no respect from living specimens readily obtain- 

 able in the present lake. The living specimens from Clear Lake are also 

 characteristic and remarkable for the extreme development of the dorsal 

 wing. The prominence of this feature Mi: Stearns has observed to coin- 

 cide with areas subject to periods of drought and severe freshet. It cer- 

 tainly appears from the deposits of Cache Lake that there nuist have been 

 great periodical variations in the quantity of sediments emptied into it. In 

 Mr. Stearns's opinion this shell implies tluit the character of the streams 

 emptying into Cache Lake was not markedly different from that of the pres- 

 ent streams of the same area. The specimens range from an inch (adoles- 

 cent) to over three and a half inches in breadth. 



Another shell represented by numerous specimens from the Cache 

 Lake beds is Vcdvata vircns Tryon. This species was originally described 



