364: W. Upham — Marine Shells and Fragments 



numbers to a height only one or two feet below the sod forming 

 the surface of the hill and brink of the cliff. The highest were 

 in a soft and crumbling condition, and those found thence 

 downward in the yellow till showed a gradation to the hard 

 and strong character of the shell fragments in the dark blue 

 till. These observations indicate that the transported and bro- 

 ken fossils were probably originally as plentiful in the upper 

 as in the lower part of this drumlin, and perhaps likewise of 

 all the others, but that they have been mostly dissolved out of 

 the upper part by infiltrating water. 



Great Head is a typical drumlin, the eastern third of which 

 has been eroded by the sea, forming a cliff about 100 feet high. 

 This consists of ordinary till, yellowish above and dark bluish 

 below, from its top to within 20 or 15 feet above mean tide, 

 where its base, exposed a few years ago during the construction 

 of a railroad, was observed by Mr. Dodge to be a somewhat 

 arched bed of " loose, clean, rather fine gravel filled with small 

 fragments of shells. Venus mercenaria and Cardium Islan- 

 dicum (?) were the only shells identifiable with any reasonable 

 degree of certainty among the fragments." This was seen to 

 be overlain by till, which exhibited traces of an imperfect strati- 

 fication close to their line of separation but above is entirely 

 unstratified. The till contains fragments of shells up to a height 

 of about 80 feet. A similar structure of the drumlins of 

 Third and Fourth cliffs on the east shore of Scituate, each of 

 which includes extensive anticlinal beds of modified drift, 

 overlain by a thick covering of till, and in Fourth cliff also seen 

 to be underlain by till and interbedded with it, promises to 

 contribute much to our knowledge of the mode of deposition 

 of these remarkable drift hills, as I shall hope to show in a 

 future paper. 



Following the nomenclature and arrangement of the cata- 

 logue of the marine invertebrate animals of the southern coast 

 of New England and adjacent waters, by Verrill, Smith, and 

 Harger,* the species represented by these fragments of shells 

 in the drumlins near Boston are noted in the following table. 



Those marked by asterisks in the first column have been col- 

 lected in Grover's cliff, the most northern section yielding these 

 fossils. In the second column are those found in Great Head, 

 mostly by Dr. Stimpson, to whose list Mr. Dodge has added, 

 somewhat doubtfully, three species. An hour's search there 

 by Mr. Q. E. Dickerman and myself was rewarded by frag- 

 ments of Venus mercenaria, abundant ; Mya arenaria and 

 Cyclocardia iorealis, frequent ; Astarte undata, rare ; and a 



* United States Fish Commission, Report of 1871-72. This work and Gould's 

 Invertebrata of Massachusetts give notes of the geographic range of our species, 

 living and fossil, and of the situations and depths at which they occur. 



