1890.] NATURAL SCIENCES OF PHILADELPHIA. 135 



C — The dci)th last named marks the passage from these nearly hor- 

 izontal Quaternary strata to the commencement of a long series of 

 INIiocene beds with slightly increased dip. The uppermost bed of 

 this series consists of 118 feet of reddish-brown sand ranging from 

 light to dark in color. 



It contains a dark clay seam at 289 feet and another at 320 feet 

 described as "green clay;" each of these is about 5 feet thick; from 

 beneath the latter the first flow already noted in well No. 4, was 

 obtained. This red sand bed contains wood throughout that was 

 continually brought up by the hydraulic process in very small 

 fragments, otherwise it is nonfossiliferous. 



D — Below these red sands, or from 383 to 658 feet, occurs the most 

 remarkable development of diatomaceous clays yet discovered in 

 the Avorld, being 275 ^ feet in vertical extent. Excepting a few pure 

 sand beds, not over from one to ten feet in thickness, this entire 

 horizon is more "or less made up of this low order of microscopic 

 plants. As might be expected the diatoms of this deposit are marine 

 forms. 



Associated with the diatoms are also a number of sponge spicules, 

 many of them of the pin-head forms that are characteristic of salt 

 water sponges. 



At 540 feet were fouufl a few clam and other shells in fragments, 

 but so worn and broken as to be unidentifiable si^ecifically. One, 

 however, was either a Modiola or a Mytilus. 



This deposit is already especially interesting to microscoj)ists, and 



will become increasingly so until it will attain world-wide publicity. 



On this account a minute description is here inserted : — 



383 to 390, Clay ; 1 t.- i • j- 



o<.A * '>ni o 'i 1 -^ ^ich in diatoms exce])t the sand 



390 to 391, band, pure white ; )■ '■ 



391 to 406, Clay. j '^^'^^■' 

 406 to 410, Gray sand — No diatoms. 



410 to 429, Clay — Moderately rich in diatoms. 



429 to 430, Dark sand — No diatoms. 



430 to 480, Clay — Diatoms associated with about 5 forms of for- 



aminifera and much comminuted shell. 

 480 to 510, Sandy clay — Moderately diatomaceous. 

 510 to 535, Clay — Very rich in diatoms. 



1 Since the preparation of the section, diatoms have been noticed, though very 

 sparingly, in the next lower 20 feet. This would increase the total thickness of the 

 diatom beds to nearly 300 feet. 



