225 



usual formation, but this beach continues along the shore for one-fourth of a mile 

 beyond the blufif as a very sandy beacli a foot or more above the water's level and 

 50 feet wide; then the beach grows narrower and is on the level of the water, the 

 sand becomes less plentiful, and the beach is composed of a small amount of 

 coarse gravel and then merges into the marsh, where the shore line of Ogden 

 Point turns north. The same formation is found running a short distance north 

 of the bluffs on the east side of Johnson's Bay. 



Between the two bluffs on the east side of Johnson's Bay is a beach 1,000 feet 

 in length, with the lake on one side and a marsh containing pond lilies on the 

 other. This beach is from 20 feet to 80 feet wide, 3 feet above the water's level, 

 and composed of sand and coarse gravel. The margin of the beach further 

 from the lake is the higher, and is covered with a growth of willows, cedar and 

 other small trees. Along the lowlands of Crow's Bay is a broad beach composed 

 of coarse gravel about three feet high and on a level with the land back of it. 

 Along the south end of the west side of Morrison's Island, which is lowland, the 

 beach is from 15 feet to 25 feet wide, three feet high, and composed of coarse 

 gravel. The beaches along marshes and lowland are broader and higher, and 

 contain much more material than those along bluffs. 



The action of the ice is an important factor in the formation of these beaches. 

 For the explanation of the action of ice on beaches as well as the formation of 

 ice cracks, I am indebted to I. C. Ku- sell's excellent book, "Lakes of North 

 America." The lake freezes over and by expansion the ice is pushed up along 

 the shore carrying sand, gravel and stones with it. Numerous ice cracks form 

 during the winter and fill with water. This water freezes and pushes the ice still 

 further up the shore carrying the beach forming material still higher. These ice 

 cracks are very numerous and may be as much as three inches wide. The amount 

 of lateral pressure brought to bear on the shores by this means is very great, and 

 beach ridges are begun and added to each year. The action of the ice informing 

 beaches along marshes is very great, while along bluffs it is small. In the first 

 case no great resistance is met with in expansion, and the material for building- 

 the beach will be carried up to the full extent of the expansion of the ice, while 

 along the bluffs the ice crowds against the shore and is itself broken at every ex- 

 pansion. A recent ice formation is evident at the northwest end of the Gordo- 

 niere Marsh, between the marsh and the Channel. In 1891 this marsh was under 

 water, but since that time the water of the lake has receded and left the marsh 

 dry. Separating the marsh from the Channel is a ridge of earth more than one 

 foot high running parallel with the water's edge. This ridge can be accounted 



(15) 



