Sandusk\ Bay and Cedar Point 185 



peninsula. These have been built up by great northeast storms 

 and the approximate age of each of the principal ones has been 

 determined from the vegetation upon it. The older ones are 

 lower than those formed in the past century. By dividing the 

 difference in height between the highest aqueous deposits in two 

 ridges by the number of centuries intervening between their 

 formation I have obtained the average number of feet the water 

 has risen each century. It is about 2.14. A detailed description 

 of these ridges is given in the part of the paper dealing with 

 Cedar Point. 



EFFECT OF VARIATION IN THE RAINFALL. 



The deepening of the water produced by tilting of the lake 

 basin has not been noticeable within the past half century 

 because of greater fluctuations produced by variations in the 

 rainfall. Those who recall the high water of 1858 to 1862 know 

 that it has not been so high since. Moreover in 1894 and 1895- 

 it was lower than they had ever seen it before, unless their 

 observations began before the middle of the century. These 

 facts seemed to disprove the theory that the water is gradually 

 getting deeper. In an article in the National Geographic Mag- 

 azine for August, 1903, I showed that, since 1870, when the 

 Weather Bureau established stations about the Great Lakes, 

 there has been a very close correspondence between rainfall and 

 lake level. When the rainfall is above normal the lake rises, and 

 when below normal it falls; whether we consider particular 

 years, parts of years or periods of years. More recently I have 

 learned that at the places in this part of the country where a 

 record of rainfall was kept as early as 1857 the rain that year or 

 the next was very heavy. Bulletin C, U. S. Weather Bureau, 

 gives the rainfall of the United States from the earliest records 

 to the end of 1891. In it are twenty-two places within one 

 hundred miles of the Great Lakes that have a record for the year 

 1858. From data in this bulletin I have made the table, which 

 includes besides these, St. Louis, Peoria and Marietta, although 

 they are somewhat farther away. In fourteen of the twenty- 

 five places the maximum rainfall for the whole period of record — 

 in one instance seventy-one years — was in 1857 or 1858. In 

 most of the other places the rainfafl of 1857 or 1858 has been 

 exceeded not more than three times. No wonder there was high 

 water in 1858 with such precipitation as that. If the table were 

 brought down to 1901, the years given above would still stand 

 pre-eminent, for the rainfall from 1891 to 1901 was generally 

 light — lighter in 1895 when the lake was also lowest than in any 

 other year since the Weather Bureau was established. 



