There are two main classifications for marine sediments, terrigenous and pelagic. Terrigenous sediments are derived from land and found near shore. Pelagic sediments settle slowly out of the water column and are deposited all over the ocean. Pelagic sediments are deposited at such low rates that they tend to be overwhelmed near shore by terrigenous deposits from land. So, pelagic sediments are normally associated with deep sea regions. There are four main compositional groups for marine sediments: Lithogenous sediment that is derived from rocks. Biogenous sediment that is derived from living organisms, normally planktonic organisms. Hydrogenous sediment are derived from the ions in seawater. Cosmogenous sediments, which from the Earth being continually bombarded from space by meteors and cosmic dust. Some of this material doesn’t burn up in the atmosphere and reaches the oceans, where it can settle down to the ocean floor. Cosmogenous sediment is never a dominant type of sediment — it is never more than a tiny fraction