190 ELEMENTARY GEOLOGY 
Plant Deposits. — Plants also aid in lake destruction, 
particularly in the last stages. As the water becomes 
shallow, vegetation commences to encroach upon the 
lake (Fig. 98). The life and death of these plants 
permits the accumulation of vegetable deposits which 
eventually may become many feet in depth. The 
Florida lakes are being destroyed almost entirely by 
Fie. 99. 
A view in Dismal Swamp. 
this means, for no sediment enters them, and the shores 
are dense swamps, while the bottom is a muck of 
vegetable origin. Dismal Swamp (Fig. 99) is another 
illustration of an extensive swamp associated with 
lake waters, Lake Drummond being enveloped in the 
swamp. 
Peat Bogs.—In the northern states, many of the 
smaller lakes have been filled and are now transformed 
