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climax forest of the glacial plateau on which they are perched. At 

 present the outer slopes of the fixed dunes, from which the center has 

 been blown out to form the trough, are covered by a formation similar 

 to the border zone and relic patches already described. On the open 

 sand of the trough are found the usual pioneers of the region, with in 

 addition a great abundance of Anemone multifida and Lilium philadelphi- 

 cum. The sides of the earlier troughs are frequently covered witli 

 Ammophila and Calamovilfa, and in places practically form fixed grass 

 dunes. 



I). Crystal Lake Beach. The west end of Crystal Lake is bordered 

 by a sandy beacli 400 feet in widtli, with a slight slope toward the water. 

 The history and ecology of this beach are very interesting. At the 

 beginning of historic times the waters of Crystal Lake were approxi- 

 mately 15 feet above their present level, being impounded by a sand bar 

 across the mouth of the present outlet. The waters of the lake apparently 

 escaped by seepage through the sand. About 1871 certain individuals 

 formed the ambitious plan for an inland waterway from Frankfort 

 Harbor, through the Betsie River, Crystal Lake, Long and Platte Lakes, 

 and began operations by cutting through the sand bar on Crystal Lake. 

 This of course lowered the water of the lake rapidly, and laid bare 

 this imder-water shelf or sand terrace. Nothing further was done with 

 the inland waterway scheme, and the beach has remained exposed to 

 the present. As a result of this exposure of a broad sand area, the 

 formation of dunes began at the first point on the west end of the lake 

 where the southwest winds could get sufficient sweep. These dunes ex- 

 tend for nearly a mile, and increase in size toward the north. At the 

 beginning they are almost indistinguishable from the beach, and at the 

 other end have reached a height of 10 or 15 feet and a length of 50 

 feet. The vegetation on these dunes is scattered and consists chiefly 

 of Ammophila. The vegetation of the beach is interesting because a 

 definite date can be set for its beginning. At present it consists chiefly 

 of Juncus balticus in the wetter portions, some species of Aster, Solidago, 

 and stunted shrubby growths of Salix, Populus balsamifera, and Betula 

 alba. At certain points there has been a slight invasion of Thuja, 

 apparently from swamps of the high water period. At one point on the 

 beach there can be seen four stumps of trees which apparently grew on 

 the beach at a prehistoric period of low water similar to the present 

 although they may have floated there from the shore at the high water 

 stage. These stumps are about three feet in diameter, and have been 

 identified as Pinus Strobus. They were cut off level by the action of 

 the beach gravel, and the sand has been lowered around them by wind 

 action approximately eight inches. Their presence is interesting as 



