Chlorite and smectite dominate the clay-size insoluble residue of Recent carbonate sediments of Florida Bay. Illite and kaolinite also occur in very small quantities. Chlorite is derived from the Atlantic Coast and eastern Everglades provinces and is introduced by streams and by tidal channels through the northern Florida Keys. Smectite is derived from the Gulf of Mexico province to the west. In the northern part of Florida Bay, water flow is greatly impeded by a complex bank and basin system, and the clay mineral suites remain relatively segregated near their respective sources. However, in the southern part of the bay, banks are less frequent, water flow is less impeded, and the clay mineral suites mix gradually across the area.