6i6 



ELLSWORTH HUNTINGTON 



fan where Figs, ii and 12 were seen. From below upward along 



the line xy the section is as follows: 



A. I foot of fine gravel with sand beneath it, the two forming parts of an old 

 subaerial fan or of a beach. 



I foot of lacustrine clay deposited by the lake during its expansion to the 

 60-foot level and continuing as an uninterrupted band to a height of 50 feet 

 above the lake. 



3 feet of shingle deposited on a beach at a time when the lake must have 

 retired. 



I foot of lacustrine clay soon thinning out away from the lake, but thicken- 

 ing toward it and joining B. 

 5 fett of shingle deposited on a beach. 



B. 



C. 



D. 



Fig. 15. — Section of lacustrine and shore deposits show- 

 ing alternating rise and fall of the lake. 



The section can be interpreted only on the supposition that in 

 its fall from the 60- foot level the lake fell while C was being deposited, 

 remaining at a level of less than 40 feet long enough for the formation 

 of a shingle beach 3 or more feet thick. It then rose 10 feet or more, 

 remaining high until a foot of fine clay had been deposited, and 

 finally fell again, forming the beaches which now he on the surface. 

 A similar oscillation has occurred still more recently on a smaller 

 scale. At several points along the lake-shore, especially at the north- 

 west corner, three or four httle beaches can be seen in the water 

 down to a depth of 12 feet, more or less. The head man of the 

 village of Spangmik said that when he was a boy, some 20 or 30 

 years ago, the water was 10 or 12 feet lower than now, although in his 

 grandfather's time it stood higher than now. Possibly the sub- 

 merged beaches, which are very shght, were formed at this time of 

 low water not more than thirty years ago. Whatever their date 

 may be, it is evident that the beaches, hke the deposits of Fig. 15, 

 indicate that the lake is subject to constant oscillations due to vari- 

 ations either in rainfall or evaporation. Apparently the process of 



