An investigation of the mineralogical and textural properties of channel sediments from certain selected rivers of British Honduras, Central America, indicates that the material carried by the northern rivers is distinctly different from that in the southern ones.

The northern rivers contain mainly a carbonate sediment of cryptocrystalline grains and mollusk fragments. A multiple origin for these cryptocrystalline carbonate grains is proposed. Undoubtedly, some grains are recrystallized mollusk fragments. Other grains are rock fragments, while still others appear to have been indirectly precipitated by blue-green algae. The noncarbonate grains have been derived from Pleistocene stream deposits. Abrasion of the heavy minerals and quartz grains appears to be lacking.

The southern rivers contain mainly silici-clastic sediments. The size distributions of bed-load samples plot as approximately straight lines on phi probability paper with a deviation near +2 phi. This deviation is real and has been attributed to an abrasional mechanism. The heavy mineral suites from the southern rivers indicate a more metamorphic provenance than is seen in outcrop in the source areas. The primary provenance has been interpreted to be the metamorphic belts in Guatemala. Petrographic work also indicates a more metamorphic source to the south. The river detritus, if indurated, would appear as lithic graywackes or subgraywackes, depending on the percentage of detrital matrix.

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