GEOGRAPHY OF CENTRAL FLORIDA 1 65 



The larger lakes have sandy beach ridges on their more exposed 

 shores, and sand-bars forming across their embayments, as in lakes 

 with sandy shores the world over, but none of our lakes are large 

 enough to have any perceptible development of dunes around them. 

 Wave-cut cliffs are exhibited on a small scale in the clay bluffs 

 on the southeast side of Lake Weir, and perhaps on other lakes. 



Minor topographic forms. In many places close to the Indian 

 River, St. John's River, Tampa Bay, and other navigable waters 

 there are shell mounds several to many feet high and usually an 

 acre or less in extent, which are commonly supposed to be Indian 

 "kitchen middens," though the possibility of some of them having 

 been partly built up by raccoons or other four-footed animals does 

 not seem to have been wholly eliminated. Some are composed 

 chiefly of oysters and others of other mollusks, especially along 

 rivers, where there are no oysters. One on the east side of the 

 Indian River about opposite Melbourne (fig. 34), which is being 

 excavated for road material (a fate shared by many others), shows 

 about ten feet of shells, nearly all Chione cancellata, a small clam- 

 like bivalve, resting on yellowish sand. There are thin layers of hu- 

 mus among the shells every few inches, presumably indicating that 

 the growth of the mound was frecjuently interrupted long enough 

 for a little vegetation to grow on it. Some of the mounds have 

 more sand than shells in them, and must have been formed in a 

 somewhat different manner; but the subject has not been suf- 

 ficiently investigated. 



Terraces (?). The boundary between flatwoods and uplands 

 is sometimes gradual and sometimes rather abrupt, as for example 

 at or near Bronson, DteLand and Lake Helen. In recent years 

 these abrupt scarps have been regarded by some geologists as Pleis- 

 tocene shore lines, or terraces,* but they do not appear to be contin- 

 uous for any great distance, as terraces should be, and they lack 

 some of the characteristic features of shore-lines, such as dunes. 



*See Matson & Sanford, U. S. Geol. Surv. Water Supply Paper 319 (1914), 

 PP- 31-35, 210-21 r, and map (plate 5) ; and comment on same in Geog. Rcvica- 

 4:224-225. 1917. 



