344 THE AMERICAN MONTHLY [Nov. 



Nevada, and, as I have said, excited considerable dis- 

 cussion. Prof. Blake, who examined them, does not 

 say what they are. Dr. Harkness thinks them those of 

 a man covered by moccasins. Certainly they do resem- 

 ble hnman footprints. And the sandstone, it must lie 

 remembered, is ranked by good geologists as Tertiary. 

 But Tertiary is a term not very uncertain, since Prof. 

 Lawson says the Tertiary sandstone of Monterey. Cali- 

 fornia, may be recent al&o. But if they are ranked as 

 older Tertiary, Eocene, as I do, then they carry man and 

 his footprints far back, and this is the earliest that man has 

 been put without finding fossil bones to confirm it. I 

 have examined the sandstone which X got with a por- 

 tion of one of the footprints itself. For these I am in- 

 debted to Mr. Frank Bell, the warden of the state prison, 

 and although the sandstone is coarse, containing very 

 little clay, and therefore does not contain any Bacillari- 

 acese, as I at lirst exi)ected, it looks like the sandy 

 clay that is left Avhen the water washed over it and 

 thereby removed by solution the Bacillarian shells. That 

 the shells of Bacillariacea? are truly soluble, and very 

 soluble, we have only to place on a filter some of the 

 fresh water deposits, such as the Keene, N. H., or 

 Weequatrick Lake, N. J., and permit the water to flow 

 through it. In time we shall find it grow smaller by 

 degrees and beautifully less until it all disappears. In 

 the Carson City earth the sand is left behind, being less 

 soluble than the Bacillarian shells, or the shells pass 

 down to a lower spot. We must look for them at a 

 lower point. 



Mr. Bell has an idea "that the sand hill is the bar 

 formed at a mouth of a river in a large lake." Perhaps 

 it is so, l)ut I have not examined it personally. At any 

 rate it was on the borders of a sea, the Occidental Sea, 

 and Bacillarian shells are found near the bottom, as at 

 Five Mile Canon, Virginia City, in Nevada. There is also 



