44 SURFACE GEOLOGY. 



shore. This was the only terraced island seen by Mr. Hartwell during his voyage. 

 He says it is volcanic in part, and the terraced margin may be coral reefs. It is 

 covered with vegetation, sandalwood being abundant. 



Other Forms of Surface Geology. 



In the commencement of this paper I have enumerated other distinct forms of 

 detrital matter coming within the province of surface geology. I have not studied 

 these so carefully as the terraces and beaches, and, therefore, my descriptions will 

 be short, though I trust they may deserve the attention of observers. 



1. Sea-Bottoms. 



If we find evidence of the existence of shores of ancient seas, we .should expect 

 to discover the remains of their bottoms; and if I mistake not, New England, 

 especially in its less elevated portions, does present the gravelly and sandy plains 

 and low ridges, which can be explained only by the former presence of the ocean 

 above them, with its waves, tides, and currents. In the vicinity of Connecticut 

 river, they are less obvious, because in the lower parts of the valley drainage has, 

 in a measure, obliterated the marks of oceanic action, and the materials have been 

 converted into terraces and beaches. The sides of the valley also rise too rapidly 

 to expect many such accumulations of detritus as form sea-bottoms. But when 

 we get into the comparatively low region, within twenty or thirty miles of tlie 

 coast, in Massachusetts, Rhode Island, and Connecticut, the surface is in a great 

 measure covered with such materials, and in such forms as the ocean must have 

 produced. Though I am not prepared to mark these definitely upon a map, yet I 

 have ventured to define a few of them near the mouth of the Merrimack, and also 

 in Berkshire valleys, in Plate III; I have likewise marked a strip as of this 

 character, along the route of the New London, Palmer, and Amherst Railroads, and 

 from Merrimack river to Saco river, along the northwest side of Lake Memphre- 

 magog. 



2. Suhmarine Ridges. 



I agree with Mr. Whittlesey in the opinion that the ridges which encircle Lakes 

 Ontario and Erie, were probably formed beneath the waters. These lake ridges — 

 the lowest certainly — may not have been submarine in the strict sense of the term, 

 though as it is certain the ocean once stood above the western lakes, it is not easy 

 to say at what altitude the waters became first brackish, perhaps, and then fresh. 



I have ventured to mark one submarine ridge near the mouth of the Merrimack, on 

 its south side, and to extend it southerly along the_coast at least to Ipswich ; beyond 

 which I have not attempted to trace it. The highest part of the city of Newbury- 

 port occupies the summit of this ridge, which has a slope both towards the ocean 

 and towards the country. This ridge preserves a pretty uniform height, nearly to 

 Ipswich. 



