702 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



The clays were grayish-blue, very fiue, "fat" clays, agreeing exactly 

 with those worked in the large brickyards a few rods south. 



When both the clay and the till were wet the sharp, curA-ed line of 

 junction was inconspicuous at a little distance, the whole surface presenting 

 a uniform dark bluish-gray color, but above the line a cane could be easily 

 thrust into the clays for its full length, while the blow of a hannner would 

 not make much more im})ression upon the till than upon the neighboring 

 sandstone. 



The section is situated far within the limits of the high terrace and is 

 exposed by the deep erosion of this terrace by the Mill River, which, in 

 cutting down to this level, has carried its gravel beds over the whole, 

 making the upper horizontal stratum in the diagram. If we restore the 

 terrace here to its condition before it was affected b)^ the erosion of the 

 rivei", we shall need 25 to 30 feet of clay resting on the till and covered 

 by 35 to 40 feet of sand to bring the level up to 200 feet above the sea, 

 which is the height of the terrace over this area. The clays are exposed 

 with this thickness in the 'face of the high terrace on both sides of the 

 stream. When the ice disappeared, however, and the deposition of the clay 

 began, this was a deep depression between the "drumlins" of till upon 

 which the hospital and Smith College stand, opening southward into the 

 main basin. 



In another section, from the Canal Railroad, exposed just west of the 

 Soutli Street bridge in Northampton, the clays rest also directly upon the 

 stony till, and although greatly disturbed by stranded ice and mixed with 

 material dropped from it, there is everywhere at least a foot of the fine clay, 

 undisturbed, intervening between the till and the horizon where coarser 

 iceberg material appears. In many of the clay pits the base of the clay is 

 reached, and it is always in contact with the till. 



In the Central Railroad cutting south of College Hill, in Amherst, the 

 following section was exposed beneath the bridge (figs. 37, 38, and 39, 

 p. 645): On the till, which appeared just above the bottom of the cutting, 

 but arose westwardly to occupy nearl}- its whole thickness, rested coarse, 

 cross-bedded sands, which had been swept from the Avest over its surface, 

 and which reached a thickness of 3 feet; upon these rested clay, reaching 

 a thickness of about 7 feet, in the lower half lianded in layers 1 inch thick, 

 with fine sand partings; many layers resting below between undisturbed 



