510 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



non-glaciated countries, is the great bed of kaolin pi-esei'ved from the ice 

 under the lee of the great hill on which Blandford is built (see ]). 330). 

 Another area is northwest of Roaring Brook bridge, on the south line of 

 Northampton (p. 474). 



PRE-GLACIAL DRAINAGE AND EROSION. 



The above deduction concerning the age of the Deerfield notch may 

 serve as an introduction to the discussion of the other similar notches in the 

 valley and of its pre-Glacial di-ainage and erosion. (See map, PI. XI.) 

 Not only does the Connecticut pass tlu-ough a like notch in the Holyoke 

 trap range near its highest point in ii deep, short valley bordered by fine 

 rock-cut terraces (fig. 28), while it could have ^^fissed down the western 

 lateral valley (see topography of the valley, p. 8) without rising more than 

 145 feet above its present height, but the Westfield and Farmington rivers 

 also, like the Deerfield, after passing out of their gorges in the crystalline 

 rocks, run across the low sand plains of the western lateral valley, make a 



Fig. 28.— Holyoke notch from Hadley meadow; pre-Crlacial rock terraces. 



wide loop southward, and return to find in each case opposite the mouths 

 of these gorges a notch in the high trap ridge through which they join the 

 main stream, while in each case they could with a slight rise have passed 

 southwardly across the sand plains, the Deei-field to join the Connecticut 

 around the south of Sugar Loaf, the others to reach the Sound at New 

 Haven. Indeed, this peculiarity of the valley system of the Connecticut 

 early attracted the attention of President Hitchcock, who, after having 

 described it with a sketch map in the Geology of the Connecticut,^ writes 

 in the Geology of Massachusetts (1841, p. 328): 



The valleys tbrougli which the Connecticut and its tributaries flow are among 

 the most remarkable in the State. The ordinary laws of physical geography seem 

 here to be set at defiance, so much that a late ingenious writer doubted whether I 

 had correctly represented the geology of the Connecticut because the course of 

 the rivers' and the direction of the mountain ridges were described as having so 

 little correspondence with the rock formations. 



' Am. Jour. Sci., Ist series, Vol. VI, 1823, p. 1. 



