670 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



strongly marked by iron rnst. From the north the ]lea^-y horizontal pinkish 

 sauds, underlain by equally heavy cross-bedded sands, both of mediiun 

 grain, come for a long distance, and at a the}' commence to sink down, and 

 seem to have sunk so evenly and on so smooth and regular a substratum that 

 they were stretched, and a great luimber of minute fissures, all about nor- 

 mal to the bedding, were formed — fissures so minute that the}^ would have 

 escaped attention if they had not been colored by infiltrated iron rust. A 

 few slight faults dipping inwardly Avere also formed. They are unduly 

 emphasized from their coloring with rust. Finer, pale-bufi", loamy sands 

 rest in this depression and gradually fill it, the sheets being poured over its 

 northern edge and thickened below and separatelj' cross-bedded. 



Farther s(iuth, at the south end of North Pond, the whole of a good- 

 sized kettle-hole was removed, and fig. 43 would, with small modification, 



represent any radial section through it. At the north end is seen the 

 quarter of the kettle-hole, with coarse sand and gravel beds above and fine 

 cross-bedded sands below, and both sink with a series of small faults from 

 their normal position down to form the regular bowl-shaped depression. On 

 the south the beds are cut off by erosion. An old toiTent bed runs across 

 the plain at this point, and the contrast between the two slopes is striking. 

 Interesting sections were exposed in the great cutting- of fine sand at 

 the north end of the filling of the Central Railroad south of Dwight's station 

 (called the "Big Fill" by the engineers). This cutting was in the terrace 

 connecting the sands spread through the Belchertown Pass with the great 

 delta sent out by Pelham River just north of Dwight's station. (See \). 588.) 

 When this terrace was deposited the ice formed the western bank against 

 which it rested, and when the ice had melted back a little the delta just men- 

 tioned was sent out into the temporary lake thus formed, which occupied the 

 corner of the basin in which Dwight's station now lies. The surface of this 



