TERRACES OF THE ITHACA LAKE. 373 



only one exception, by either the 1,000 or 1,020- foot contour. The sloi)ing 

 surfiice of the terraces could not ])e below these levels, but might be a few 

 feet higher. It will be observed tliat tliis height agrees closely wnth the 

 higher terrace in the valley of Six Mile creek, and evidently indicates the 

 water-level of the Ithaca lake while overflowing by the White Church 

 outlet. 



The manuscript map does not definitely show by the contours any 

 terraces marking the higher level of the earlier water, which must have 

 been restricted to this western valley with the overflow by the col at 

 Spencer Summit. Such evidences of water surface should be sought at 

 an elevation of about 1,060 or 1,070 feet. 



Several small terraces louver than those above described are, however, 

 found on these deltas. Three deltas show terraces at 940 feet, four at 

 820 to 810, two at 700 to 720, and four at 600 to 610. Two deltas also 

 show small terraces at 500 to 520 feet, only about 100 feet above the 

 valley bottom, and 122 feet above Cayuga lake. 



In the sketch the terraces are indicated by the dotted areas, and the 

 height of the contour-line bounding the lower edge of each area is given 

 in the comparative table. In the latter an attempt is made to represent 

 graphically the relations of the several terraces. The vertical lines indi- 

 cate the ravines which bisect each delta deposit. As the sketch is taken 

 from the Geological Survey map, the contours are 20 feet apart, and on 

 that account may not fully represent the correspondence in height of the 

 terraces. Closer contouring would not lower the higher terraces of any 

 set, but might raise the lower ones so as to produce a much nearer ap- 

 proximation to one level. 



Variation in Height of Terraces. — It is evident that the subsiding waters 

 were able to produce minor terraces upon the steep slopes of the inco- 

 herent stream deposits during relatively brief halts, but the interaction 

 of lake and stream, with varying conditions of wind, slope of shores, and 

 amount and character of material, caused the delta terraces to var}'- con- 

 siderably in height within short distances or even in the two sides of the 

 same terrace. However, notwithstanding the variation in height, the 

 sketch and table show a substantial relationship between the terraces of 

 all the streams in the Cayuga Inlet valley. 



LAKE HISTORY. 



West Danhy Lake. — In the early stages of the ice-retreat there was a 

 minor lake in each of the two southern forks of the valley, these separate 

 lakes being held up to the heiglit of tlieir respective divides, and this 

 condition continued until the ice-retreat had uncovered the point of South 

 hill. Tbe lake in the Inlet valley requires a separate name, and may be 



