2/6 SURFACE GEOLOGY. 



is a fill of 120 feet. Then follows the cut figured in our heliotype, with 

 the title Ice-drift over sand printed on a railroad tie. It is a compact, 

 unstratified mass of rubbish, the stones consisting mainly of the Mont- 

 alban granites and schists common in the neighborhood, overlying layers 

 of sand, as shown in the illustration. The material appears to conform 

 to the surface of the ground, being just as thick in the depression as over 

 the elevations. This earth is evidently some form of ice accumulation; 

 it is not water-worn gravel, nor does it correspond to either of the tills. 

 It approaches nearer to the coarse gravel at the Crawford house than to 

 any other class of deposits known in the state, but is unlike that, in the 

 common absence of stratification and the angularity of the fragments. 

 Its association with the sand about to be described may intimate the 

 presence of a mass of ice in the neighborhood in the time of local gla- 

 ciation. 



The rest of the cut just entered into extends for 336 feet. It is com- 

 posed of sand, with some large stones in it, underlying the angular drift, 

 as seen in the illustration. The strata dip southerly underneath the ice 

 drift, and at the north end of the cut they dip northerly to correspond 

 with the depression of the surface, 120 feet wide, crossed by the railroad 

 upon an embankment. Next is another cut in the sand 264 feet long, 

 showing boulders in it, and depressions to correspond with the surface 

 of the ground. After an embankment 528 feet long, succeeds another 

 cut in the sand of 384 feet length. From a point in this excavation, 

 about 4,300 feet north of the Crawford station, was taken the hehotype 

 illustration entitled Boulder in sand. The fragment may be six feet 

 through, composed of bright granite as fresh as if uncovered yesterday, 

 and of the same character with the adjacent ledges. Horizontal strata 

 of sand underlie it, while the layers are slightly irregular about it, as 

 would naturally result from the varying velocity of the current striking 

 against the stone. The layers above are regular, and conformable with 

 those beneath. This is therefore a clear case of a mass of stone too large 

 to have been pushed by the current of water, nevertheless brought to 

 this spot by some agent and dropped as readily as if it were a grain of 

 sand. There must have been water deep enough to float ice carrying 

 this stone upon it; and owing to a change in the equilibrium of the berg 

 at this point, the granite fell to the bottom, and lies in a condition of 



