GLACIO-AQUEOUS ACTION IN NORTH AMERICA. 197 



sent some of the most remarkable examples of these moraines. 

 In North Adams, which lies in a deep and narrow trough between 

 mountains two thousand or three thousand feet high, we find 

 most striking exhibitions. About fourteen of these tumuli, some 

 of them nearly one hundred feet high, are ranged in a line on the 

 eastern side of the valley, which are represented, though imper- 

 fectly, in PL VIII, fig. 9. Half a mile further north, others give the 

 landscape a unique appearance, as is represented in Plate 3, 

 of my Final Report. That Report contains a sketch of others 

 in the south part of Berkshire county, at the foot of Monument 

 Mountain. 



I have already alluded to the rarity of moraines which are 

 nearly straight ridges. Often such ridges are found connected 

 with the irregular and conical moraines that have been described : 

 but they are usually short. Sometimes, also, I have seen gravel 

 ridges extending partly across a valley through which a river runs, 

 which I suspect once constituted a terminal moraine, (that is, of 

 ice urged forward by water,) through which the river has cut a 

 passage. We frequently also, find banks of gravel along our 

 rivers ; which, however, show a talus only towards the river. I 

 cannot doubt that these were once lateral moraines, and that the 

 talus on the side next the bank, has been concealed by the detritus 

 which has slid from the bank. Indeed, where lateral moraines 

 are produced, as I suppose these were, by ice driven forward by 

 water, we ought not to expect to find as distinct ridges of any 

 kind as those produced by glaciers ; because the water, especially 

 if deep, would do much to modify them and fill up inequalities. 

 I have, however, met with a few insulated ridges of gi-avel which 

 still retain both their slopes, though they appear more commonly 

 to be the mere ^\Tecks of moraines. 



The broad ridge of gravel extending through the town of 

 Amherst, in Massachusetts, from Mount Holyoke, six or eight 

 miles northerly, appears to me to be a case of this kind, though 

 subsequently a good deal modified. It seems to have been 

 produced mainly by the ice moving down the valley of the Con- 

 necticut; such decided marks of which, I have described as 

 occurring upon Holyoke. 



