THE NORMAL CURVE 51 



4001-4200. — Continued 



variation in thickness, and several of them are 

 unusually thick; but whether they are abnormal or 

 not cannot be determined. 

 4003-4012, at locality 9, are abnormally thick and do not 

 agree with those of the other localities. The thickest 

 varves, 4004 and 4005, are each 4^ inches (6.7 

 cm.). Varves 4004 and 401 1 are also thick at 

 localities 10 and 14. 

 4123, at localities 10 and 14, is silty to sandy and 5 and 7 

 inches (13 and 18 cm.) respectively. 



4201-4249. — The curve shows rather strong fluctuations; but 

 whether the thick varves, which are often sandy, 

 are drainage varves or not cannot be made out 

 with certainty. Probably they are normal. The 

 different measurements agree well. 



4250-4330.— Good. 



4331-4338. — The varves, which register a drainage, consist of 

 quicksand and silt, and the thicknesses are of no 

 value. 



4339-4400- — Rather good. 



4357-4396, at locality 15, consist of rather coarse sand, and 

 vary in thickness from 2 inches (5 cm.) to $yi feet 

 (1.7 m.). The winter layers sometimes were eroded 

 away during the spring following their deposition. 

 At locality 16, ^ mile (1.2 km.) to the NW, varves 

 4387-4396 — the varves below 4387 not measured — 

 are sandy but 3 to 11 times thinner than those at 

 locality 15. Varve 4405, at both localities, begins a 

 long series of thin varves (see p. 15). The horizon 

 in question, at locality 15, lies at an elevation of 

 about 150 feet and, at locality 16, at a height of 

 about 100 feet. The glacial lake, according to 

 Emerson (1898, p. 657), reached the level of about 

 285 feet. Drainage and strong current evidently 

 played a prominent role in the development of the 



