Notes 4 – Erosion and Glaciers

Mrs. Gordon

Earth Science

Thursday, April 20, 2023

What is a glacier anyway? A glacier is a large mass of ice that FLOWS

slowly over land. About 75% of Earth’s freshwater is stored in

glaciers. Fun fact: If all land ice melted, the seas would

rise about 230 feet!

A Frozen past……..

Ice Age – A cold time period in Earth’s history, when glaciers covered vast areas.

Last one ~ 14,000 years ago.These glaciers formed many of the

land features

we see and live on

today.

Types of Glaciers1. Valley glacier – glaciers located in high mountain

valleys, leave behind U-SHAPED valleys.

2. Continental glacier – a body of ice that covers much of a continent or large island. (Greenland, Antarctica)

Seasonal surface melt extent on the Greenland Ice Sheet has been observed by satellite since 1979 and shows an increasing trend. The melt zone, where summer warmth turns snow and ice around the edges of the ice sheet into slush and ponds of meltwater, has been expanding inland and to record high elevations in recent years

Glacial Erosion

Plucking – when a glacier picks up rocks from the land it is flowing over

Abrasion – grinding surfaces with rocks that are drug underneath the glacier

Cirque – bowl shaped feature at the top of a valley

Glacial Deposition Till – mixture of unsorted,

angular sediments left behind by a retreating glacier

Moraine – a ridge formed by the till deposits at the edges of glaciers

Outwash plain – where glacial debris is deposited below the glacier

Erratic boulders, such as this north of Zug on the Swiss Plateau, transported during the last ice age, were first used by scientists such as Louis Agassiz in the early 19th Century to hypothesize that glaciers were once much more extensive than they are now.

Glacial outwash plain in Alaska.

Glacier Notes Reflection

How does a glacier act like an excavator? Give a explanation next to each labeled piece of the excavator.

Glaciers perform, in many ways, like an excavator.  Although they can push weak material, like gravel, like a bulldozer blade, they are far more likely to lift material out of place, like a backhoe, or scratch it in place, like a ripper.