70 R. S. TARE 



IMPORTANCE OF THESE WELLS. 



These wells have yielded three important geological results : 

 (i) They have in two cases revealed the exact depth of filling by 

 Pleistocene deposits, and have therefore given some additional 

 facts concerning the form and depth of the Cayuga Valley. (2) 

 Since samples were collected at frequent intervals in several of 

 the wells, and records kept of all, they have revealed the struc- 

 ture underlying the Ithaca delta down to the rock floor. (3) 

 They have thrown some light on the occurrence of artesian water 

 in Pleistocene deposits. 



DEPTH OF DEPOSITS. 



The wells are all located near the western margin of the delta 

 on which the main portion of the city of Ithaca is built. The 

 surface soil is clay and muck, and the region is evidently one 

 reclaimed from Lake Cayuga by the same processes of lake fill- 

 ing that are now at work on the outer edge of the delta on the 

 north side of the city. While low and swampy throughout much 

 of its area, this nearly level delta rises perceptibly toward the 

 creeks that descend through gorges cut in the valley walls. 

 These elevated sections are low, flat alluvial fans, raised above 

 the general delta level by deposits brought down by the torren- 

 tial streams that occupy the hillside gorges. 



The delta also rises gently toward the south, and at a dis- 

 tance of about two miles south of Ithaca abruptly ends against 

 the north face of the morainic complex which fills the valley 

 thence to its present divide. It is evident that this moraine 

 descends beneath the delta deposits. 



Two of the borings reached bed-rock, one (Fig. i, C) at a 

 depth of 260 feet, the other (Fig. i, 6^) still further out in the 

 valley, at a depth of 342 feet. A profile of the valley at this 

 point is shown in Fig. 2. Farther north (Fig. i, A and B^ two 

 wells, bored to the underlying salt, encountered rock at 430 and 

 401 feet respectively, the latter being 1,500 feet south of the 

 former. 



These borings are not numerous enough to warrant any con- 

 clusions further than that the maximum depth of the valley is at 



