240 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



probabilities, liowever, seem to me in favor of the supposition that these 

 really exist, but thus far have escaped detection. Even on this assumption 

 I believe it impossible to reduce the estimate of the thickness of this deposit 

 below 1,000 feet. 



Cache Lake fossils. — The argillaccous strata of the Cache Lake period are 

 full of organic remains, but unfortunately these are chiefly vegetable. 

 Shells were detected in only four localities: on the Grizzly Canon road 

 near the top of the divide between Burns's Valley and the north fork of 

 Cache Creek; at an exposure on the hillside about a quarter of a mile north 

 of this point; close to the mouth of Indian Creek; and in an exposure on 

 Cache Creek a cpuu-ter of a mile below its intersection with the road from 

 Lower Lake to Sulplnir Bank. Of these the first and second are much the 

 richest. They show a series of mollusks, the most important of which are 

 identical with those now abundant in Clear Lake, while all of them survive 

 on the Pacific slope, and not improbably in Clear Lake itself. They have 

 been enumerated and discussed in Chapter V. According to Mr. Stearns, 

 who is unquestionable authority on this subject, tlie}^ show that the phy.si- 

 cal conditions prevailing in Cache Lake were not markedly different from 

 those of the present Clear Lake. The peculiarities of form of one of the 

 shells, tlie ordinary Amdon of Clear Lake, are also such as to show that in 

 spite of the difference of position and notwithstanding the very great oro- 

 graphical modification which the countr}' has undergone, there has been an 

 absolute continuity of life from the Cache Lake period to the present time. 

 No doubt mollusks, and particularly locomotory species like this Aiiodon, 

 are able to survive tolerably vigorous disturbances, but the facts show that 

 from a faunal point of view the elevation of these lake beds was not cata- 

 strophic. In spite of careful search vertebrate remains were found in only 

 two localities. These points are a small side ravine leading into Grizzly 

 Canon from the north and a vineyard near Lower Lake. 



other characteristics. — As uiight be cxpected froui the character of the Cache 

 Lake deposits, they are extensively eroded. In many cases the resulting 

 forms are strongly suggestive of those of the Bad Lands of Wyoming, 

 showing fantastic pinnacles, pillars, and gorges. This is especially notice- 

 able north of Chalk Mountain and in Cub Gulch. In most portions of the 



