THE NONMETALLIC MINERALS. 219 



depth and temperature. They may be found in living forms in almost 

 any body of comparatively quiet water in the United States. The 

 exploring steamer Challenger dredged them up in the Atlantic from 

 depths varying from 1,260 to 1,975 fathoms and from latitudes well 

 toward the Antarctic Circle. Mr. Walter Weed, of the U. S. Geolog- 

 ical Survey, has recently reported them as living in abundance in the 

 warm marshes of the Yellowstone National Park, while Dr. Blake 

 reported finding over 50 species in a spring in the Pueblo Valley, 

 Nevada, which showed a temperature of J 63 F. 



Although beds of diatomaceous earth are still in process of forma- 

 tion, and in times past have been formed at various epochs, the Tertiary 

 period appears for some reason to have been peculiarly fitted for the 

 growth of these organisms, and all of the known beds of any impor- 

 tance, both in America and foreign countries, are of Tertiary age. The 

 best known of the foreign deposits is that of Bilin, in Bohemia. This 

 is some 14 feet in thickness. When it is borne in mind that, according 

 to the calculations of Ehrenberg, every cubic inch of this contains not 

 less than 40,000,000 independent shells, one stands aghast at the mere 

 thought of the myriads of these little forms which such a bed repre- 

 sents. Some of the deposits in the United States are, however, con- 

 siderably larger than this. What is commonly known as the Richmond 

 bed extends from Herring Bay, on the Chesapeake, Maryland, to 

 Petersburg, Virginia, and perhaps beyond. This is in some places not 

 less than 30 feet thick in thickness, though very impure (Specimen 

 No. 67984, U.S.N.M., from Calvert County, Maryland, is fairly repre- 

 sentative). Near Drakes ville, in New Jersey, there occurs a smaller 

 deposit, covering only some 3 acres of territory to a depth of from 1 to 

 3 feet. Some of the largest deposits known are in the West. Near 

 Socorro, in New Mexico, there is stated to be a deposit of fine quality 

 which crops out in a single section for a distance of 1,500 feet and 

 some 6 feet in thickness. 



Geologists of the fortieth parallel survey reported abundant deposits 

 in Nevada, one of which showed in the railroad cutting west of Reno 

 a thickness not less than 300 feet, and of a pure white, pale buif, or 

 canary yellow color (Specimen No. 67916, U.S.N.M.). Along the Pitt 

 River, in California, there is stated to be a bed extending not less than 

 16 miles and in some places over 300 feet thick (see Plate 7). Near 

 Linkville, Klamath County, Oregon (Specimens Nos. 53402, 53093, 

 U.S.N.M.), there occurs a deposit which has been traced for a dis- 

 tance of 10 miles, and shows along the Lost River a thickness of 40 

 feet. Beds are known also to occur in Idaho (Specimens Nos. 63843, 

 66950, U.S.N.M.), near Seattle, in Washington (Specimen No. 53200, 

 U.S.N.M.), and doubtless many more yet remain to be discovered. A 

 deposit of unknown extent, pure white color, and almost pulp-like 

 consistency has been worked in South Beddington, Maine (Specimens 



