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1893. | NEW YORK ACADEMY OF SCIENCES. 197 
bed of the Atlantic ocean.* On the land side this plain was 
bounded by the crystalline and Triassic rocks of Connecticut, 
southern New York, New Jersey, Pennsylvania and southward, 
as may be seen by an examination of any good geological map 
of the eastern United States. The evidence of its extension 
northward around Rhode Island and Massachusetts are now 
almost obliterated, but there seems to be every reason to believe 
that its Jand limits were approximately the coast line of the 
present day. In fact, a small isolated portion of the old coastal 
plain still exists apparently in the vicinity of Marshfield, Mass., 
as indicated by Edward Hitchcock in 18417, and recently by 
N.S. Shaler, in a paper read before the Geological Society of 
America.{ It might also be added, by way of parenthesis, that 
similar indications are to be looked for elsewhere, notably on 
Cape Cod and near Gloucester, especially in case it should be 
determined that Magnolia glauca is truly native at this latter 
locality, although Prof. Shaler does not mention any such in his 
account of the geology of Cape Ann.§ Further north than 
Massachusetts, so far as I am aware, it is not even indicated, 
and except for the presence of the well-recognized submerged 
plateau off our eastern shores all further trace of the former 
coastal plain is lost. Its eastern lmits, where it formerly met 
the waters of the Atlantic ocean, were probably where we now 
find the borders of this plateau to be, namely, at the 100 fathom 
contour. 
Shortly after the advent of the Ice Age the elevation had 
reached its maximum. The rivers had previously cut deep 
valleys through the easily eroded material forming the coastal 
plain, in their courses to the sea, and when the continental 
glacier, pushing its way southward and eastward, finally flowed 
over the edges and escarpments of the hard crystalline rocks 
onto the soft and incoherent material of the coastal plain it 
+ 
* Up to this point I believe all authorities are agreed. In regard to subse- 
quent geological changes, and the interpretation of certain recognized facts, a 
variety of views are held, many of them contradictory to one another, so that 
an impartial statement, without more or less discussion, becomes almost an 
impossibility. I shall, therefore, set forth my own views freely, with brief 
references to those of others, leaving further discussion of the subject for some 
future papers, Which are now in course of preparation. The present contribu- 
tion, so far as the geology is concerned, may therefore be considered as a pre- 
lude, and many points which are here somewhat summarily treated, it is hoped 
to consider more fully later on. 
+ “Final Rept. Geol. Mass.” ii., 427. 
+‘ Tertiary and Cretaceous Deposits of Eastern Massachusetts.” (Bull 
Geol. Soe Am. i., 443-452.) 
§ 9th Ann. Rept. U.S. Geol. Survey, 528-611. 
