165 



Eev. George F. Wright, of Antlover, read the paper 

 of the evening, an abstract of which is here inserted.- 



INDIAN RIDGE AND ITS CONTINUATIONS. 



The so-called "Indian Ridge" of Andover, Mass., has 

 long been an object of curiosity to citizens, and of inter- 

 est to geologists. In the "Transactions of the Association 

 of American Geologists and Naturalists," for 1841 and 

 1842, Pres. Edward Hitchcock, of Amherst College, gave 

 a detailed account of the formation so far as it had then 

 been observed.^ This distinguished observer character- 

 ized it as "decidedly the most interesting and instructive 

 case [of moraine ridges] which he had met with." A 

 map of it is given in the same paper, taken from a survey 

 of Professor Alonzo Gray, then of Andover, now of 

 Brooklyn, N. Y. This map, in reduced dimensions, 

 reappears in Hitchcock's Elementary Geology,^ as an il- 

 lustration of "Submarine Ridges." 



The formation is described as a series of narrow, par- 

 tially parallel and interlacing ridges, composed of sand, 

 gravel and boulders intermixed. These ridges are said 

 to be from fifteen to thirty feet high and four or five rods 

 through at the base, extending a mile and a half or more, 

 in a line nearly north and south. Similar ridges two or 

 three miles south are alluded to ; and at South Reading, 

 now Wakefield, twelve miles south of Andover, still other 

 and higher ridges of a like nature were observed. At 

 the close of his remarks upon the subject, Dr. Hitchcock 

 writes, "I presume that still further careful examination 

 of the region above described may show other similar 

 ridges, or a continuation of those on the map. 

 I would gladly resurvcy all the moraines with which I am 

 acquainted, in the confident belief that now 'I have learnt 



iSee page 198. 2 see page 260 (30th edition). 



ESSEX INST. BULLETIN VII. 13 



