Sediment core samples from the deeper areas (>200 meters) of the Kara Sea, composed almost entirely of terrigenous elastics, are predominantly silty clay which is very poorly sorted, near-symmetrical to coarse-skewed and mesokurtic. The clay minerals are kaolinite, chlorite, illite, an expandable component which is probably montmorillonite, and possibly some mixed layer clays. The upper layers in many cores display a color sequence from the surface downward of light brown to dark brown to yellowbrown to gray-green to brown to gray-green. No significant textural or mineralogical difference exists between brown layers and gray-green ones. In two cores non-detrital iron and manganese are greatly enriched in the brown surface layers but not at the same stratigraphic level. The highest concentration of non-detrital manganese occurs several centimeters nearer to the sediment-water interface than does the highest concentration of non-detrital iron. Beneath the surface layers the concentration of both elements is greatly reduced except in the secondary brown layers which are somewhat enriched in non-detrital iron and very slightly in non-detrital manganese. Non-detrital material isolated from the upper manganeseand iron-enriched layers gave no diagnostic X-ray diffraction patterns and is probably amorphous or crypto-crystalline. Coprolitic material from one secondary brown layer was identified as the iron phosphate, vivianite. The concentration of non-detrital iron in 98 surface samples generally increases toward the mouths of the Siberian rivers, suggesting that these are the sources of iron in the Kara Sea. The distribution of non-detrital manganese in surface sediments apparently is controlled by factors other than distance from source. The non-detrital Mn/Fe ratio generally increases away from the river mouths, suggesting that iron is deposited nearer the points of influx than manganese. The distribution of non-detrital iron and manganese with depth in the cores appears to the controlled by post-depositional processes, including dissolution, migration, and subsequent differential oxidation of iron and manganese ions, rather than by primary depositional processes or variability in the rate of influx.