Back to School at FamilyEducation.com

SEDIMENTS

The rocky material that is transported and DEPOSITED by rivers, seas, glaciers, and the wind is called sediment. Clay, sand, and gravel are all types of sediment. Sediments build up to form features such as mud banks along rivers or dunes in deserts. Sediments deposited on the seabed often build up over millions of years to form sedimentary rocks.

DEPOSITION

The laying down of sediments in water or on the ground is called deposition. Sediments are picked up by fast-flowing water, by strong, swirling winds, or by the ice in glaciers. Sediments are deposited when flowing water, wind, or glaciers cannot carry it any further – for example, when the water or wind slows down or stops, or when the glacier’s ice melts.

FORMATION OF DUNES

The shape of a sand dune depends on the strength and direction of the wind, how much sand there is, and whether plants grow on the dune or on the ground. Barchan (crescent-shaped) dunes form when the wind blows from one direction most of the time. They move forwards at up to 30 m (100 ft) a year as the wind blows sand over the crest.

SAND DUNES

A dune is a heap or hill made of sand or other small particles. Dunes are formed in sandy deserts and on coasts when loose, dry sand is picked by the wind and then deposited. In the Sahara Desert, North Africa, dunes grow up to 100 km (60 miles) long and 200 m (650 ft) high, forming an ever-changing landscape like giant ocean waves.

Copyright © 2007 Dorling Kindersley

stay connected

Sign up for our free email newsletters and receive the latest advice and information on all things parenting.

Enter your email address to sign up or manage your account.

Facebook icon Twitter icon Follow Us on Pinterest

editor’s picks

highlights

Join BIC on our mission to save handwriting and Fight For Your Write! Writing helps kids become better readers, boosts their confidence and sparks their creativity. Visit BICFightForYourWrite.com to sign our petition to save handwriting!

14 Back-to-School Fashion Trends for 2014
Send your kids back to school looking sharp! Check out 2014's hottest back-to-school fashion trends, from clothes to shoes and accessories.

Put a Stop to Bedtime Struggles
Steer clear of tears at bedtime with these helpful bedtime tips and this printable bedtime routine checklist for kids.

Kindergarten Readiness App Wins Gold
Our Kindergarten Readiness app won the Gold Award of Excellence in the educational category at the 2014 Communicator Awards. This valuable checklist comes with games and activities to help your child practice the essential skills she needs for kindergarten. Download the Kindergarten Readiness app today!