198 TRANSACTIONS OF THE [APR. 24 



scooped it out to a great depth in places, and then, eitber 

 carrying it forward in mass, or else pushing and squeezing it 

 ahead in a great contorted ridge*, capped by the bowlder till, 

 finally left it as part of the terminal moraine. Wherever these 

 conditions have prevailed we find the phenomena to be the 

 same, and Long Island may be considered as one of the grandest 

 object lessons in this connection. 



Just when the period of elevation ended and that of depres- 

 sion began, in fact, whether it was previous to, or subsequent 

 to that of greatest ice accumulation, is yet a matter of contro- 

 versy between authorities, but in either case on the retreat of 

 the glacier, we may picture to ourselves the terminal moraine 

 forming an elevated ridge extending through Staten Island, 

 Long Island and the islands to the eastward, forming a 

 continuous, more or less, elevated land connection to the north 

 and east, with what remained of the coastal plain sloping away 

 from it on one side and a trough filled with the water from the 

 melting glacier on the other. It is probable tbat the ridge 

 represented by Orient Point, Plum Island, Gull Islands and 

 Fisher's Island may be the remains of an independent second 

 glacial moraine, as urged by Warren Uphamj and N. S. Shaler|, 

 but the discussion of this fact need not now' concern us. 



The old river valleys had become blocked up with the debris 

 of the moraine, and the waters had to seek other outlets. These 

 would naturally be where they first began to overflow the rim 

 of the trough in which they were imprisoned. One of these 

 would probably be through the old channel of the East Eiver, 

 which was to the north of the terminal moraine, and, therefore, 

 comparatively free from obstruction. From here the waters 

 would join those of the Hudson, which had doubtless ere 

 this forced its way, through the morainal barrier and was again 

 occupying its old channel. Others are indicated to the eastward 



* Dr. Fredk. J. H. Merrill was, I believe, the first one to thus interpret this 

 phenomenon on Long Island ; for which see his paper "On the Geology of Long 

 Island." [Ann. N. Y. Acad. Sci. iii., 341-3G1.] It has been made the subject of 

 careful personal examination in the vicinity of Glen Cove, and similar effects 

 were subsequently noted by me and Dr. N. L. Britton on Staten Island. [>see 

 Proc. Nat. Sci. Assn. S. I., Nov. 8, 1884, and Trans. N. Y. Acad. Sci. xi., loi.] 

 Although so far as Long Island is concerned these views are not considered 

 tenable by Trof. J. D. Dana. [See " Phenomena of the Glacial and Champlam 

 Periods about the Mouth of the Connecticut Valley in the New Haven Region." 

 Am. Journ. Sci. xxvi., 341-3G1; xxvii., 113-130.] And they are rejected as 

 iuade(iuate on Martha's Vineyard, according to Prof. N. S. Shaler. [See 

 "Report on the Geology of Martha's Vineyard," 7th Ann. Rept- U. S. Geol. 

 Surv., 296-363.) 



t" Terminal Moraines of the North American Ice-Sheet." (Am. Journ. 

 Sci xviii., 81-92 ; 197-209.) 



t " Report on the Geology of Martha's Vineyard." ( 7 " Ann. Rept. U. S. G. S.. 

 296-363.) 



