A PRELIMINARY REPORT ON CLAYS OF VLORIDA 119

Material resulting from the decomposition and disintegration of this igneous and metamorphic rock may have been deposited in central Georgia and Alabama as Paleozoic, Mesozoic or Cenozoic sediments and a second time weathered and eroded away or it may have been transported directly by southward-flowing streams to the Florida area. Probably both conditions may be found. In any event, this material was carried in solution, in suspension in a finely-divided state, or mechanically rolled along by the stream currents. The quartz sand and gravel found in many of the clays was rolled along by mechanical processes, the mica and much of the colloidal matter was transported in suspension, and much of the lime, magnesia, iron, etc., was probably carried in solution. The prevailing drainage has been southward in the Southern States, hence most of the sediments in Florida have been derived from the northern areas. In the case of limestone residual clay the parent rock was deposited by precipitation of the calcium carbonate and the deposition of much of the impurities from suspension where it was being held in a finely divided condition. In the weathering, of a pure limestone no clay would result, but as practically all limestones are more or less impure these insoluble impurities remain as clay when the calcium carbonate is dissolved out. Some of the Florida limestones are high in impurities, hence the resulting clay is quantitatively great.