Source: National Park Service. Additional image courtesy of of Dr. Donald Sullivan, University of Denver.
Ocean basins are filled with loose sediments — the products of erosion. Most marine sediment originates inland and is fed into oceans by rivers. Debris from cliffs and other coastal landforms provides additional sediment volume, as do skeletons, shells, teeth of marine organisms, ash from volcanoes, and even asteroids. In this interactive resource adapted from the National Park Service, learn how these different parent materials influence the color and size of the materials that compose a beach, as well as other reasons why some beaches are composed entirely of fine sand, while others are a mix of pebbles and shells.
Coastal erosion occurs in areas of high energy — where wave action wears down rock and other hard material into smaller and smaller pieces. Coastal deposition, however, happens in environments where most of the energy from waves has been dissipated before it reaches the shore. This allows sand or other rock and mineral fragments suspended in the water to settle and contribute to the development of the coastline. Perhaps the most familiar depositional features of coastal environments are beaches.
Beaches are sloping bands of accumulated sediment that form at the boundary where land and sea meet. Beaches contain particles of different colors and sizes, characteristics that are largely determined by the nature of the parent, or source, material. For instance, sand — in technical terms, sediment with particle grain size of 0.0625 to 2 mm (0.0025 to 0.0787 in.) — is created by the weathering of a variety of rocks and minerals. Quartz sand may be white, pink, or yellow, while sand originating from basalt lava is gray or black.
The process by which sediments are transported by wind, waves, and currents and distributed according to grain size is called sorting. Beaches with well-sorted sediments contain particles of uniform size and shape. By contrast, beaches with poorly sorted sediments — often originally formed by glacial melt — contain particles of varying sizes and shapes.
Although many kinds of beaches exist, five beach types are most common:
Academic standards correlations on Teachers' Domain use the Achievement Standards Network (ASN) database of state and national standards, provided to NSDL projects courtesy of JES & Co.
We assign reference terms to each statement within a standards document and to each media resource, and correlations are based upon matches of these terms for a given grade band. If a particular standards document of interest to you is not displayed yet, it most likely has not yet been processed by ASN or by Teachers' Domain. We will be adding social studies and arts correlations over the coming year, and also will be increasing the specificity of alignment.