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ENCYCLOPEDIC ENTRY

ENCYCLOPEDIC ENTRY

sediment

sediment

Encyclopedic entry. Sediment is solid material that is moved and deposited in a new location. Sediment can consist of rocks and minerals, as well as the remains of plants and animals.

Grades

5 - 12+

Subjects

Earth Science, Geography, Physical Geography

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Morgan Stanley

Sediment is solid material that is moved and deposited in a new location. Sediment can consist of rocks and minerals, as well as the remains of plants and animals. It can be as small as a grain of sand or as large as a boulder.

Sediment moves from one place to another through the process of erosion. Erosion is the removal and transportation of rock or soil. Erosion can move sediment through water, ice, or wind.

Water can wash sediment, such as gravel or pebbles, down from a creek, into a river, and eventually to that river's delta. Deltas, river banks, and the bottom of waterfalls are common areas where sediment accumulates.

Glaciers can freeze sediment and then deposit it elsewhere as the ice carves its way through the landscape or melts. Sediment created and deposited by glaciers is called moraine.

Wind can move dirt across a plain in dust storms or sandstorms. Sand dunes are made of rocky sediment worn down by wind and collision with other sand particles.

Sediment is important because it often enriches the soil with nutrients. Areas rich in sediments are often also rich in biodiversity. Sedimentary soil is usually better for farming. Deltas and river banks, where much sediment is deposited, are often the most fertile agricultural areas in a region.

For thousands of years, the Nile River flooded yearly and brought with it 4 million metric tons (4.4 million short tons) of nutrient-rich sediment. The banks of the Nile are still Egypt's richest agricultural land.

Sedimentary Rock

Over millions of years, layers of sediment may build up and harden into sedimentary rock. Some of the many forms of sedimentary rock include sandstone, rock salt, and coal.

Sandstone forms as sand hardens. For centuries, sandstone has been mixed with sticky cement to form concrete. Concrete is an important construction material used for many buildings and roads.

Rock salt, also known as halite, forms as oceans evaporate. Oceans are made of salt water. When the water enters the atmosphere as vapor, it leaves the salt behind. The Bonneville Salt Flats, in the U.S. state of Utah, are flat desert areas covered by a layer of rock salt sediment. Lake Bonneville, the ancient sea that once covered the area, has long since evaporated.

Coal is a sediment that is made up of hardened plant debris. Coal, present on every continent except Antarctica, is found on the sites of former swamps and wetlands.

Fast Fact

Dregs
Sediment can accumulate in tea and coffee! The tiny materials left at the bottom of coffee mugs and teacupsthe remains of coffee grounds and tea leavesare a type of sediment called dregs.

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Writers
Kim Rutledge
Melissa McDaniel
Santani Teng
Hilary Hall
Tara Ramroop
Erin Sprout
Jeff Hunt
Diane Boudreau
Hilary Costa
Illustrators
Mary Crooks, National Geographic Society
Tim Gunther
Editors
Jeannie Evers, Emdash Editing, Emdash Editing
Kara West
Educator Reviewer
Nancy Wynne
Producer
National Geographic Society
other
Last Updated

May 20, 2022

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