ICE

About one-tenth of Earth’s dry land and one-eighth of its oceans are covered with ice. This ice is made of snow that collects and becomes compacted (pressed down). Most ice occurs in thick ICE SHEETS that cap the land in the polar regions. In the past, during long cold eras called Ice Ages, ice covered much more of the Earth’s surface than it does today. Scientists estimate that there have been over 15 Ice Ages in the last 2 million years.

ICE SHEETS

Ninety per cent of the world’s ice is found in Antarctica. The ice cap here is 4,200 m (13,000 ft) deep in places. Over thousands of years, a thick ice sheet builds up over land when more snow falls during the winter months than melts each summer. The enormous weight of the ice pushes much of this vast, high landmass down below sea level.

ICEBERG, ROTHERN POINT, ANTARCTICA

Icebergs are not formed from salty sea ice, but from land ice that calves (breaks off) from ice sheets or glaciers on the coast. Only 12 per cent of the iceberg’s mass appears above the sea surface. The rest is hidden below. A fringe of sea ice also edges the Antarctic landmass, expanding in winter and melting in summer.

RETREATING GLACIER

Glaciers are slow-moving rivers of ice that begin high on mountains. Fallen snow pressed down by new snow forms a dense ice called firn. When enough ice builds up, gravity and the glacier’s own weight set it sliding downhill at a rate of 1–2 m (3–6 1/2 ft) per day.

GLACIAL LANDSCAPE

Moving ice is a powerful erosive force. As glaciers slip downhill they carve deep, U-shaped valleys, sharp peaks, and steep ridges. The gouging power of the ice is increased by rocks and boulders carried along at the front, sides, and beneath the glacier. When the glacier reaches the warmer lowlands, it melts.

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!

7 Fun Driveway and Sidewalk Games for Kids
Looking for classic outdoor games kids can play in the driveway or on the sidewalk, just like the good ol' days? From hopscotch to bubble-blowing contests, there's something for all ages!

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!

Best Sun Safety Practices for Babies
Follow these sun safety practices for babies to ensure your little one stays safe on the beach and on sunny days all year long.