The Geology of H Ingham. 23 



of a second advance of the glacier on the American continent, 

 though there is abundant proof of great refrigeration in tempera- 

 ture, which was probably the principal cause of the extinction of 

 most of the large animals, the elephants, mastodons, horses, and 

 other species before mentioned, that roamed over the northern 

 plains. 



The modern era of the period, that of the reign of Man, shows 

 that the same causes that have produced changes of level of the 

 surface and of temperature are yet active. There is evidence of 

 the gradual subsidence of Greenland, and that it has been sinking 

 slowly for centuries, and that a like change has been going on 

 along a great part of the eastern coast of the United States. On 

 the other hand it is shown that in other regions there has been a 

 gradual elevation. The formation of rocks still goes on as in 

 former times ; the ocean depths receive as in past periods the 

 remains of siliceous and calcareous shells from the multitudinous 

 forms that live in its waters ; the coral animals yet build up their 

 reefs to become part of the strata of the dry land of the future ; 

 volcanic action continues as of old to add to the surface its lavas, 

 and vegetable life as in earlier ages of the earth's history, by ac- 

 cumulation of peat and other plant structure, contributes some- 

 thing towards future formations. 



Having thus by a rather elaborate preliminary essay presented 

 what the writer has deemed essential to an understanding of the 

 Geology of Hingham, by those who have not made the earth's 

 history a study, he proceeds to remark upon the phenomena 

 observable within the town limits, referring to what is exterior 

 only as far as may be necessary for a clearer idea of the subject. 



