TOPOGRAPHY. 9 



Of the longitudinal valleys the most peculiar is the basin in Greenwich 

 and Enfield, in the eastern portion of the region, in which the branches of 

 the Swift River join and move southward. It is a bi'oad, low, sand plain, 

 studded Avith isolated, high, rocky islands and stretching from north to 

 south through these towns. The streams enter and leave it by narrow 

 channels, while the plain continues south through Ware, and was once, I 

 suspect, continuous with the deep, straight valley which extends through 

 the middle of Monson and on into the valley of the Willimantic; and it 

 was in its middle part (in Palmer) clogged up with till during the Glacial 

 period, so that the Swift River, which on this supposition formerly ran 

 southward across Palmer and Monson into the Housatonic, has in post- 

 Glacial time found its way westward, breaking through the side of the 

 basin to join the Connecticut. If this be so it explains at once why the 

 basin is so disproportionate to the size of the i^resent river, and wliy it is 

 on all sides walled in by liigh ground, except the narrow gorge by which 

 the Swift River escapes from it. It also explains the very straight Monson 

 Valley, in the middle of which, just at the State line, the waters run south 

 to the Willimantic and north to the Quabaug at Palmer. 



The Comiecticut Valley stretches across the center of the area from 

 north to south, with a width of al)out 1 xV miles at the north, which increases 

 to 8 J miles opposite Greenfield, 10^ miles opposite Amherst, and averages 

 16 miles in the southern portion of the State. It is divided lengthwise into 

 two portions of about equal width by the remnants of the red sandstone 

 and the long trap ridges of Deerfield Mountain and the Holvoke range; 

 and, except the short canyons of the two western tributaries, the only 

 breaks in this dividing wall are at its north end in Bernardstou and in the 

 long distance opposite Amherst, between Sugar Loaf and Mount Holyoke. 

 Post-Glacial deposits occupy the full width of the Connecticut Vallev in 

 great complexity and beauty. 



From the northern line of the State the eastern border of the valley, 

 sloping rapidly to the bottom, runs nearly due south across the State, 

 notched sharply by the gorges of the Millers and Chicopee rivers, and 

 rarely opening out into a rounded high-lying valley, as in Pelham, opposite 

 Amhei'st, or breaking down into an elevated plateau, as in Belehertowu. 



On the west the high ground crosses the State line but a little way back 

 from the river, and for a few miles the valley preserves the same narrow limits 



