1890.] PUBLIC DOCUMENT — No. 4. • 301 



it occasionally retreated a mile or two back from the wall of 

 the moraine, and then, refreshed by a larger supply of snow, 

 pushed forward, driving before it in the manner of a huo-e 

 scraper a quantity of debris which was thrust up into the 

 frontal moraine. At the same time, at various points from 

 the ice front subglacial rivers were pouring forth, which 

 scoured ways through the frontal moraine, and distributed 

 vast amounts of sand and gravel in a stratified form, partly 

 in the mass of the moraine, though in a larger measure over 

 the fields lying immediately in front of the ice line. The 

 result of this action is that the morainal masses of Massachu- 

 setts and other regions contain extremely varied soils. Here 

 and there we find them so bowldery that there is no soil 

 whatever. At other points we observe patches of soil mate- 

 rial composed entirely of waste from the bed rocks in the 

 immediate vicinity. Again, the material is ordinary till in 

 its character, — sand and gravel and clay commingled with 

 large bowlders in a perfectly confused manner. At other 

 points there may be pockets of clay formed in quiet pools 

 inclosed in the extremely compact mass of the moraine. 

 Samples of characteristic morainal soils are aflTorded by the 

 moraine of the north-western side of Martha's Vineyard, or 

 that which extends through the Elizabeth Islands, and north- 

 ward to near the village of Plymouth. 



Yet another peculiarity of New England soils, due to 

 the action of glaciation, is found in the exceeding thinness 

 of the detrital coating over considerable areas, which, under 

 the ordinary conditions of the earth, would be soil-covered. 

 Owing to a variety of circumstances, the bed rocks beneath 

 a glacier are at the end of an ice period sometimes left 

 almost bare, while in the neighboring areas the bowlder clay 

 may be extremely thick. At several points in Massachusetts 

 I have observed within the limits of a square mile consider- 

 able areas nearly bare of detritus, bordering immediately on 

 patches of the drift which were one hundred feet or more in 

 thickness. Contrasts as sharp as these are rare ; but over a 

 large part of the State — indeed, of New England in gen- 

 eral — we have a disposition of the drift so irregular as to 

 give these frequent contrasts between detrital material thick 

 enough to afi"ord the foundation of good soils, and areas 



