QUATERNARY FORMATIONS THE DRIFT. 31 



which the land is thus being swept into the lake becomes a question 

 of importance. 



It should be understood that the lake is not advancing at all points, 

 and that the rate of its advance at different points is not uniform. 

 The encroachment seems to be most rapid in the neighborhood of Ra- 

 cine. The land at this point projects into the lake, and is thus more 

 exposed to the action of the waves. To Dr. P. R. Hoy, of that place, 

 I am indebted for data and personal assistance in investigating this 

 subject. He had previously estimated the average erosion in that 

 vicinity at four feet per year. The measurements given on a subse- 

 quent page show that for the entire shore line of the county the ave- 

 rage advance is 3.33 feet, which shows that the estimate of Dr. Hoy 

 for the more immediate vicinity of Racine, where it is greater, cannot 

 be far from the truth. 



As an example of rapid erosion, careful measurements of the cem- 

 etery lot at Racine were made and compared with previous surveys, 

 with the following results: 



Length on the lake shore 921 feet. 



Width at the south end 404 " 



Width at the north end 466 " 



Average width 435 " 



Amount of land at present date, 9.18 acres. To this is to be added 

 9 acres sold from the west side, making 18.18 acres. In 1840, there 

 were 25 acres, making a loss of 6.82 acres in 24 years, or more than a 

 quarter of an acre yearly, or, stated in an another form, the lake has 

 been advancing at that point the last 24 years at the rate of 9.73 feet 

 per year. The data for this calculation were furnished by Dr. Hoy, 

 and the measurements were made with his assistance. It is not prob- 

 able that the erosion at any point exceeds this, and it has recently 

 been checked by break- waters. 



The following carefully prepared data were furnished me by Dr. 

 Lapham, and I am glad to substitute them for the less complete meas- 

 urements made by myself. 



" Mr. S. G. Knight, of Racine, has carefully measured for the Geo- 

 logical Survey, from the nearest section corner or quarter post, to the 

 bank of Lake Michigan, along all the section lines in Racine county, 

 the results of which, compared with the government survey made in 

 1836, are given in the following table. Had these measurements been 

 made at right angles to the shore line, the result would have been a 

 trifle less ; but as some portions of the bank have been artificially pro- 

 tected, we may assume the result as a close approximation to the 



