220 BOULDER REVERIES. 



up for a time along the foot of a ridge or dune, 

 which is found from fifty to one hundred yards 

 from the water. If a stiff breeze be blowing, 

 the traveler over this beach is bombarded by the 

 fine, sharp edged particles of sand, many of 

 which strike against his face and produce a 

 stinging sensation. These grains are composed 

 of small angular pieces of quartz and have a 

 light brownish tint. 



Near the shore the bottom of Lake Michigan 

 is uniformly covered with sand. At the shore 

 line this sand is about ten feet deep, and it ex- 

 tends out to where the water reaches a depth of 

 thirty-five feet. Beyond this depth of water the 

 lake bottom is composed of a stiff, tenacious 

 blue clay, which is said to contain partings or 

 pockets of sand, from whence, in part, comes the 

 supply which is constantly being carried shore- 

 ward by the waves. Much of the sand is doubt- 

 less blown from the dunes by south winds back 

 over the lake and, falling on its surface, is again 

 brought to land. Moreover, by storms and by 

 ice jams in the spring, all projecting points 

 along the lake are slowly worn down and the 



