CHAPTER VI. 



ORGANIC GEOLOGY. 



In 1840, Dr. C. T. Jackson stated, as a result of his survey of the Coal 

 Measures in Rhode Island, that, "from the fossil contents of the Carbonifer- 

 ous clay slate, we have reason to regard it as a fresh-water deposit, either 

 from lakes or from the estuary of some ancient river, whose waters may 

 have brought down from the lowlands on its banks an abundance of these 

 specimens of the ancient flora." 1 No observations of more recent date have 

 been published to overthrow Jackson's hypothesis of the nonmarine origin 

 of the sediments now preserved in the basin. Knowledge regarding the 

 fauna and flora has been gained slowly, and mainly through the work of a 

 few students resident in the Rhode Island part of the field. 



Besides insects, the Pawtucket shales, according to Prof. A. S. Pack- 

 ard, 2 have afforded "the impression of an annelid worm, several shells of 

 Spirorbis, and what appears to be the track of a gastropod mollusk." 



INSECT FAUNA. 



Mr. Samuel H. Scudder has described and figured a small insect fauna 

 collected by various persons in the shales about the head of Narragansett 

 Bay. The following list is compiled from his paper, Insect Fauna of the 

 Rhode Island Coal Field : 3 



Insect fauna about the head of Narri 



'Eeport on the Geology and Agriculture of Ehode Island, pp. 37-38. 



2 Am. Jour. Sci., 3d series, Vol. XXXVII, 1889, p. 411. 



3 Bull. U. S. Geol. Survey No. 101, 1893, 27 pp., 2 pis. 



