DAVIS: RIVER TERRACES IN NEW ENGLAND. 327 



IV. Observations of River Terraces in New England. 



Valley of the Westfield River, Mass. Eastern Section. This 

 branch of the Connecticut rises among the hard-rock Berkshire hills 

 of western Massachusetts, the round remnants of the uplifted and 

 dissected Cretaceous peneplain of the Appalachian province, and thence 

 flows eastward part way across the broad valley lowland that has 

 been excavated in the weaker Triassic formation during later Tertiary 

 time. Between the eastern base of the crystalline uplands and the 

 ridge formed on the main sheet of extrusive trap within the Triassic 

 area, the stream has excavated a fine series of terraces in v the uncon- 

 solidated drift deposits that have been so abundantly spread over the 

 Triassic lowland by the Connecticut and its tributaries. 



The village of Westfield lies near the middle of this terrace system 

 and serves to mark the separation of its unlike eastern and western di- 

 visions. In the eastern division, Westfield river, re-enforced by Little 

 river, a branch which leaves the hills two miles south of the main 

 stream, has opened a broad basin at an elevation of about 140 feet. 

 The basin floor is nearly everywhere enclosed by the strong scarp of a 

 single high terrace whose plain stands at altitudes of 240 to 280 feet. 

 The plain is not of simple origin. On the southeast, its surface is roll- 

 ing, as if consisting of morainic and kame-like deposits. On the north, 

 it is smooth and its sands are tine enough to have been raised in occa- 

 sional dunes; here the plain falls off southwestward to the valley of 

 Powdermill brook in a series of lobes, whose intermediate depressions 

 are too large to have been excavated by local drainage : hence it is prob- 

 able that this part of the plain is a delta front in one of the areas of dep- 

 osition described by Emerson (650-653). South of the main basin, the 

 smoother part of the high plain (Poverty plains) is regarded by Diller 

 (265) as an extension of the plain on the north; the originally con- 

 tinuous surface having been formed by the flooded Connecticut. West- 

 ward up the Westfield valley, the high plain ascends towards the I11II3 

 and is of much coarser materiajs than elsewhere ; this part seems to 

 have been capped by the local outwash from the high ground during the 

 period of aggradation. As the coarse upper gravels lie on fine sands 

 and silts, this high plain is probably, like the one on the north, a delta 

 surface, built up in standing water. 



The strong scarps, B, Figure 39, by which the high drift plains 

 vol. xxxvm. — no. 7. 4 



