32 THE AMERICAH MONTHLY [February, 



Notes on the Fossil Marine Diatom Deposit from Artesian Wells 



at Atlantic City, N. J. 



ByC. L. PETICOLAS. 



KICHMOND, VA. 



Several interesting articles upon this subject, with illustrations of 

 new species of diatoms found, have appeared in the Bulletin of the 

 Torrey Botanical Club — the joint contribution of Messrs. C. H. Kain 

 and E. A. Schultze. Through the courtesy of Mr. Lewis Woolman, 

 the discoverer of this extraordinary deposit, who vv^ill shortly give an 

 elaborate report on the Geology and Paleontology of these Artesian 

 Wells, I have been enabled to make a somewhat comprehensive exam- 

 ination of this field, during the past year, and the facts developed are 

 of such an interesting character that some additional notes may not be 

 out of place. 



It was at first supposed that the deposit lay in series of strata of va- 

 rying thickness separated by thick beds of clay and sand, showing no 

 diatoms, but a careful examination of some of the most unpromising 

 material has led to the belief that we here have an almost continuous 

 bed of diatomaceous earth, which may be stated, in round numbers, 

 to be 300 feet thick, interrupted in a few places by thin beds of a fine 

 white sand similar to what is deposited with the diatoms, more or less, 

 all the way through. An examination of any rich diatomaceous earth 

 shows that these deposits are not continuous, but periodical with the 

 seasons. The spring and fall being the most favorable times for their 

 growth, we may justly infer that the laminae of about the ^^^th of an 

 inch into which these deposits separate in being first broken down, are 

 the growth of a single season. Twenty years would therefore seem to 

 be a moderate allowance of time for the accumulation of one inch in 

 thickness of strata, and this will, at all events, give us an approximate 

 idea of the enormous lapse of time since these formations were begun. 

 We have been accustomed to view with wonder the diatomaceous 

 strata at Richmond, Petersburg, Nottingham, and other points, some 

 30 or 40 feet thick, and requiring perhaps 10,000 years for their deposit, 

 but here is a bed of diatoms 300 feet thick, which, upon the same cal- 

 culation, must have taken 100,000 years to complete. The time re- 

 quired for the deposition of the 400 feet of non-diatomaceous materials 

 which overlie this deposit must also have been very great. The dia- 

 toms first appear at the depth of 382 feet, and the last showings are 

 obtained at 677 feet. 



Throughout the whole deposit certain forms such as Orthosira 

 marina and several species of Coscinodiscus are constant, but other 

 species vary continually at the various points examined, the appearance 

 and extinction of the difTerent forms bearing a striking analogy to the 

 rise and fall of species in the animal kingdom, or of empires and states 

 in the political world. A number of new species have already been 

 noted and classified, but there are without doubt many more yet to be 

 determined, as at certain points almost every mount shows strange 

 forms, and curiously enough, some of the earth poorest in forms has 

 shown the largest percentage of novelties. At the lowest levels but few 

 diatoms have been found, but at 625 feet the diatoms are abundant and 

 just here the Actinocyclii seem to reach their point of greatest develop- 



