Sediments of the Panama Basin contain >90% nonbiogenous components adjacent to Central and South America, but <5% in the area west of the Galapagos Islands. The nearshore deposits are quartz rich, with clay fractions consisting of roughly equal amounts of chlorite, illite, and kaolinite. These sediments are dispersed over distances of several hundred kilometers by currents in waters of intermediate depth (below the photic zone, but not deep enough to be affected by bottom topography), and to a lesser extent by bottom currents that flow through the deepest parts of the Basin. In the outer parts of the basin, the nonbiogenous deposits are quartz poor, with clay fractions dominated by authigenic montmorillonite. Winnowing and lateral reworking at the sea floor, which strongly affect the distribution of biogenous components, have little effect on the patterns of occurrence of the clay minerals.