166 



to see,' I should find many of them continuous ridges 

 where I have supposed a confused group of moraines to 

 exist." Acting upon this hint I have given my spare 

 time for many months baclv, in attempting to add to our 

 stock of knowledge upon the subject. I herewith furnish 

 a brief survey of the results. 



1. Measurements. Takino; them in order, o-oiuGf west- 

 ward about half a mile from Andover depot, and meas- 

 uring from their base, the East ridge is 41 feet high, the 

 Middle or Indian ridge is 49 feet, and the West ridge 91 

 feet. The base is 40 feet above the Shawshin river, and 

 90 feet above the sea level. So that the summits of these 

 ridges at this point are, respectively, 131, 139, and 181 

 feet above the ocean. The west ridge at the place of 

 measurement is 250 feet broad at the base. I am in- 

 debted to various members of the scientific class of 1875, 

 in Phillip's Academy, for assistance in securing these 

 measurements. 



2. Composition. These ridges were not primarily 

 stratified, and so differ in an important respect (if their 

 observations were sufficiently accurate) from the "Horse- 

 backs" of Maine, described by Professor C. H. Hitch- 

 cock,^ and the "Kames" of Scotland, described by James 

 Geihie.* There is, however, usually a secondary stratifi- 

 cation along the flanks of the ridge, and around the rim 

 of the numberless basins that are enclosed by its inter- 

 lacing branches, and in some places the entire ridge is 

 stratified. But ordinarily, sand, gravel, pebbles and 

 boulders are indiscriminately mingled. Boulders from a 

 few inches to two or three feet in diameter are found in 

 the higher portions of the Ridge as well as in the lower. 



3. Character of the Stones. The stones of the 



ridge are uniformly rounded and polished, but I have 



f- 



3 See Maine Agricultural Reports, 1861, 1862. * See The Great Ice Age, pp. 210-237. 



