554 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



uiifk-r tilt' forinev Amherst House through tlie sand stratum (2) and into 

 which tlie sewage of the house had been directed for many years, the butt" 

 cohir of the sands was wholly discharged and the sands were clotted into a 

 greenish mass, and that this effect extended southward without diminution 

 as far as the excavation continued. On the north the sands retained their 

 bufl^ color up to the well itself This well was located in the middle of sec- 

 tion 5, PI. XII, and went below the bottom of the section. It was clear that 

 the decomposing organic matter had reduced and removed the iron from the 

 sands for a long distance south, and that the sands had thus lost their power 

 of jnirifying the water which set southward. A colleague who had had 

 abundant opportunity for judging remarked to me that he ne-\-er liked the 

 flavor of the water in Mr. Burt's well, located a few rods south. 



I have now traced these sand strata along the western slope of the 

 ridge which joins College Hill and Mount Pleasant from the first section 

 northward more than a mile, with a width of 50 to 350 feet and a thick- 

 ness which for a considerable distance was fully 6 feet. They run farther 

 north and south — liow much farther can not be said. They appear with 

 undiminished thickness in the northern exposure and may be seen in the 

 Central Railroad cut on the south. They crop out in a slope produced by 

 later erosion, and the position of these sand strata between layers of till 

 seems to me to have in part determined the position of the Lincoln avenue 

 plain from the Northampton road to the Agricultural College and north- 

 ward. Vertically one can see in every section how the sand has been 

 scalped by the ice, and when one considers how exceptional a grouping 

 of favorable circumstances must have been required to shield these inco- 

 herent and exposed sand beds beneatli the ice and retain any portion of 

 them intact, one will, I think, be inclined to consider Avhat remains as but 

 a feeble remnant of the beds as originally deposited. Again, the texture 

 of the beds, the large scale of the cross-bedding, the flow-aud-plunge 

 structure, and the close resemblance to the flood deposits of the valley in 

 later times, make it probable that they were of similar origin, the one 

 being deposited in the flood waters subsequent to the first retreat of the 

 glacier, while the other and later beds were laid down by the floods which 

 accompanied the final melting of the ice. 



The sands then furnish strong evidence, if not conclusive proof, of an 

 inteiTuptiou in the continuity of the presence of the ice in the valley and of 



