378 University of California Publications in Geology [Vol. 8 



Professor Jones informs the writer that the material obtained by 

 him was found in a railway cut in gravel deposits at Astor Pass four 

 miles west of the north end of Pyramid Lake. The gravel beds at this 

 point lie on the western slope of a narrow ridge of andesite, and are 

 largely composed of andesitic pebbles evidently derived from this 

 outcrop. The gravels are covered by a four-foot layer of dendritic 

 tufa similar to that found above the thinolite tufa in the Lahontan 

 deposits. A few isolated crystals of thinolite were found at the base 

 of the gravel deposit. In the midst of the gravels, and about ten feet 

 below the dendritic tufa cap, there is a layer of typical lithoid tufa 

 several inches in thickness. Judging from all the evidence available, 

 Professor Jones is convinced that the gravel deposit was formed along 

 the shore of Lake Lahontan. 



The occurrence of the fossil remains is described by Professor 

 Jones as follows : 



The majority of the bones were found in the outward end of the bar and 

 in the upper twenty feet of the deposit. All of them were isolated from each 

 other and no complete skeletons were reported. Many of them were more or 

 less coated with the dendritic tufa and in excavating a ditch through a layer 

 of the dendritic tufa one hundred and fifty feet to the east of the deposit, a 

 skull of a horse was found in the tufa. In addition to the bones secured, a 

 large number, including several skulls and a large leg-bone described as being 

 the size of an elephant's, were uncovered and afterwards lost. 



It is evident from the disjointed condition of the bones that they were 

 washed about by the waves to a considerable extent before their final burial 

 in the gravels. Two hypotheses may be considered as to the time when the 

 animals lived: first, they may have existed in pre-Lahontan time and been 

 first covered by an earlier deposit that was reworked by the waters of Lahontan; 

 second, they may have lived in Lahontan time and were buried in the deposits 

 of that lake. 



As the deposit is composed exclusively of the basic andesite found in the 

 ridge to the immediate south, evidence of a deposit earlier in age should be 

 found along its flanks. While it was impossible in the time available to 

 entirely cover the ridge, no such evidence could be found within a mile of 

 the gravels and as no evidence of shore drift could be found south of the end 

 of the bar, it is not probable that the bones and gravel could have been washed 

 from a pre-existant deposit. An alternate suggestion would be that the gravel 

 deposit was formed in an earlier lake and was simply worked over by the 

 waters of Lake Lahontan. If this were true, the entire bar must have been 

 worked over, for no evidence could be discovered in the exceptionally good 

 exposures of the cut and gravel pit of any structural discordance. The tufas 

 are entirely conformable with the gravels and it is known that the thinolite 

 at least is characteristic of the Lr.hontan period in this basin. Further, if the 

 deposit was worked over in its entirety, it seems remarkable that the bones 

 should be limited practically to the upper and outer parts of the bar rather 

 than being promiscuously scattered through the deposit. The only other pos- 



