INTEKGLACIAL SAIsDS. 551 



lookiiiL;- soiitli westward Tlie lowest stratum (1) present is the lowest till or 

 valley (b-ift, which forms the floor of the cellar and is seen risiuj:;- to the sur- 

 face in the south wall (fig'. 2). It forms all tlie remainder of the south, 

 all the east, and nearly all the north wall (fig. 6); and in the waterworks 

 ditches which radiated from this point it occupied the whole depth for a 

 thousand feet north, south, and east; and to the west, where the ditch ran 

 parallel to the north side of the cellar, it repeated exactly the section 

 developed in the latter (fig. 6). The ground here is 311 feet above tide, 

 and slopes away in all directions, so that the till soon sank under tlie bio-hest 

 stratified deposits of the sub.sequent flood period, which reached here nearly 

 300 feet above tide. Above this level it had never been covered, and the 

 boundary of the till traced upon the map represents only the uncovered 

 part. The bottom of the deposit is here nowhere exposed, but farther east, 

 opposite the old Amherst Bank building, the New Red sandstone comes to 

 the surface and has this till on its back, and farther north the gneiss does the 

 same at the entrance to the Agricultural College farm, and in both cases the 

 stratum has shrunk to a foot in thickness. The cellar deposit has already 

 been made the type of the detailed description of the valley drift (page 537). 

 Upon this base rests a layer of stratified sand (2) 5 feet thick, upon this a 

 bed of compact till (3) 1 to IJ feet thick, next 1 foot of sand (4), and the 

 whole is capped with a 7-foot bed of till (5). 



The lower sands (2) were deposited immediately \ipon the irregular, 

 huramocky, apparently eroded surface of the till, the lowest layers, some- 

 times gravelly, folding over smaller irregularities and projecting bowlders 

 and gradually obliterating the depression. The upper and larger portion 

 was cross-stratified on a large scale, the laminae dipping west from 5° to 40°, 

 and where the stiticture was least disturbed a high dip, about 30°, pre- 

 dominated. Here and there a delicate flow-and-plunge stiaicture could 

 be seen. The whole stratum consists of clean, well-washed sand, whitish 

 where not colored by a later infiltration of iron, varying from a fine sand 

 which retains water and has an average grain of 0.09"™ to a coarse granitic 

 sand having a grain of 0.5 to 1""". Thin seams of gravel separate the layei's 

 of sand bere and there. Comparing many samples with the ordinary sands 

 which compose the higher terraces of the valley, I found them to agree 

 quite well under the microscope, but the glacial sands had been more 

 rounded by attrition in water and were better sorted than the later flood 



