Sediment Provenance and Properties

Thickness, depths, ages, and structural features of sedimentary strata on the ocean floor were presented in the previous chapter on the basis of geophysical measurements and drill holes. This chapter is intended to provide information on physical, chemical, and biological compositions of the sediments and inferences about sources, pathways, and rates of deposition of the sediments and their components. Most of this information is better obtained from surface sediments, because vastly more surface samples and short cores are available than samples from deeper and older sediments that are obtained from drill holes and at places where tectonic movements or ocean-floor erosion has exposed older strata in outcrop. Finally, a knowledge of modern surface sediments is needed in order to be able to recognize abnormal properties of older sediments that may indicate changes in sources and depositional conditions.