IB Marine Science Standard Level (SL) Practice Exam 2026 - Free Marine Science Practice Questions and Study Guide

The idea being tested is where certain sediments form and accumulate in the ocean. Pelagic sediments describe material that settles through the water column in the open ocean, away from coastlines. These sediments are typically very fine—clay, silt, and the calcareous or siliceous shells of microscopic organisms—that sink slowly and accumulate on the deep-sea floor, far from land. Coarse material from continents tends to feed the nearshore or neritic zones, so open-ocean areas receive mostly these fine particles over long timescales. In contrast, sand is a coarser nearshore sediment, nodules are mineral/metal-rich deposits that form in place rather than by sinking through the column, and “sediment” is too general to specify the open-ocean, far-from-shore setting. Pelagic sediment is the best term for sediments that settle through the water column away from coastlines.