Thick sections of kaolinitic sediments occur in the Lake Wales ridge area of peninsular Florida. These materials, usually referred to as the Citronelle formation in the published literature, consist largely of quartz sand and gravel with a binder of kaolinite. In exposures the sediments often can be divided, from the surface downward, into 3 zones: 1) loose surface sands, 2) red and yellow clayey sands, and 3) white clayey sands. In much of western Putnam County, the present mining area, the loose surface sands have resulted from weathering and erosion of the kaolinitic sediments. The color of the reddish zone is due to oxidation above the water table of Fe compounds. Throughout large areas the kaolin-bearing sands rest unconformably on the middle Miocene Hawthorne formation. On the eastern side of the Lake Wales Ridge, the kaolinitic sediments in some localities overlie shell marls of late Miocene or younger age. Present data indicate that kaolinitic clay generally is more abundant in the lower part of the formation. This portion of the formation is close to the surface in parts of Clay, Putnam, Marion, Lake, and Polk counties. In areas where the Lake Wales ridge is highest, for example in Polk County, the lower part of the formation can be found outcropping or close to the surface on the sides of the ridge and in low areas of the ridge crest. The kaolinite is believed to have been deposited as sedimentary clay in an alluvial environment rather than having been derived from the weathering in situ of feldspar sand or some clay mineral.

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