618 GEOLOGY OF OLD HAMPSHIRE GOUiJTY, MASS. 



flat saud bottoms out over which peat meadow was spreading. The road 

 we have followed ends in a depression, elongated in the direction of the old 

 shore line and extending to the mountain, which has been further hollowed 

 out by the brook that now runs in it. 



The striking peculiarity in connection with the appearance and grad- 

 ual development of this system of kettle-holes is that they are excavated 

 in a quite level plain, and from a distance one would have no suspicion of 

 their existence. At first they do not interfere with the manifest levelness 

 of the surface, and as they grow deeper the ridges between them are flat- 

 topped and of the common level, and only as the depressions are crowded 

 together do the ridges become at first sharp-edged and then sink into passes 

 between the hollows, until, against and running southward parallel with the 

 mountain, there is a broad space where almost everything has sunk irregu- 

 larly below the common level. Along tliis line the surface of the plain is 

 made up of finely rounded gravel, with cobblestones 6 to 12 inches across, 

 and the exposures in the roadside Avhere the highway descends on the 

 north are of the same material for ])ei'haps 20 feet downward from the 

 surface. Farther south Bennetts Brook runs across the j^lain to the river, 

 at the bottom of a gorge 1-40 feet deep, bounded by a single steep saud 

 slope on eitlier side, without as yet cutting down to the ledge. 



Following the northern road down the slope to the ferry, one finds that 

 the gi'eat plaiu is here, on its front edge, also made up above of finely 

 I'ounded gravel of great thickness, consisting of cobblestones 6 to 12 inches 

 in length. Below a point 80 feet above the river, or 280 feet above the 

 sea, fine, horizontally laminated sands underlie the gravels, and similar 

 fine laminated claylike sands apj^ear at the same height in the road going 

 southwest up from the same meadow. The surface of the bench remains 

 unchanged to and beyond the railroad crossing. Here, just on tlie south 

 line of West Northfield, the configuration of the surface was originally 

 much modified by the great quadrangular mass of Mount Hermon, which 

 rises in the midst of the plain. The surface of the latter was depressed by 

 the sweep of the waters around this obstruction, especially on the west, 

 where they entered the naiTow passageway between this hill and the border 

 of the basin, a passage through which the road and the railroad now go, 

 and this is expressed by the sinking of the plain eastward from 375 feet at 

 the railroad crossing to about 330 feet at the eastern brow of the terrace. 



