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A short class with Sarah and her students. The other ways are under More.
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Today, we will discuss cirques, one of the primary erosional landforms created by glaciers. Can anyone describe what a cirque is?
Is it a type of valley?
Good observation! Cirques are indeed valleys, specifically deep, trough-like basins found at the heads of glacial valleys. They are formed as glaciers move down mountain slopes, eroding the landscape. Let's remember this with the acronym 'CIRCLES' \u2014 C for 'Cirque', I for 'Ice', R for 'Removal of rock', and E for 'Erosion'.
Do cirques always have lakes?
Great question! Often, after glaciers melt, these cirques can hold lakes known as tarns. So, remember, cirques can contain lakes after the glacial period.
Now let's talk about horns and serrated ridges. Who can tell me how these form?
Are they created when glaciers meet?
Exactly! Horns form when three or more glaciers erode towards each other. This creates sharp, pointed peaks. The ridges that separate these cirques are called ar\u00eates, and they have a zig-zag outline thanks to the erosion. Can anyone think of famous examples of horns?
Isn't the Matterhorn a horn?
That\u2019s correct! The Matterhorn is one of the most iconic horns, illustrating these processes perfectly. Let's recap: Cirques erode down into basins, horns arise from multiple glaciers eroding towards a point, and serrated ridges form in between.
Lastly, let\u2019s explore glacial valleys. Who can describe how a glacial valley differs from a river valley?
Is a glacial valley U-shaped?
Yes! Glacial valleys are typically U-shaped with broad floors, unlike the V-shaped cross-sections of river valleys. This is due to the deeper and more powerful erosion caused by glaciers. Can anyone suggest what might happen when some glacial valleys become submerged?
They form fjords?
Exactly! Fjords are deep glacial troughs filled with seawater. They often create dramatic coastal landscapes. So, in summary, we learned about cirques, horns, ar\u00eates, and the unique characteristics of glacial valleys and fjords.
Cirques are formed by glacier erosion and often contain lakes.
Horns form when multiple glaciers erode towards each other, creating pointed peaks.
Ar\u00eates are sharp ridges formed from headward erosion of cirque walls.
Glacial valleys are U-shaped, contrasting with V-shaped river valleys.
Fjords are submerged glacial valleys filled with seawater.
Cirques carve deep, with ice they creep; horns rise high, like mountains in the sky.
Once upon a time, glaciers roamed the mountains, carving deep bowls called cirques. As they moved, they met one another, creating sharp peaks \u2014 the horns. The valleys they left behind were U-shaped, but where the sea kissed them, there lay fjords, deep and beautiful.
Remember C.H.A.R. \u2014 Cirque, Horn, Ar\u00eate for glacial features you see. A cirque is a bowl, a horn is a peak, an ar\u00eate is a jagged ridge, unique!
C.I.R.C.L.E \u2014 Cirque, Ice, Rock removal, Carving, Lake existence.
Term
What is a cirque?
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Define the term 'horn'.
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What is an ar\u00eate?
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Describe a fjord.
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A deep, trough-like basin at the head of a glacial valley formed by glacial erosion, often containing a lake.
A sharp pointed peak that forms when glaciers erode towards each other.
A serrated ridge formed by the headward erosion of cirque walls.
A glacial valley with a U-like cross-section, characterized by broad floors and steep sides.
A deep, glacial valley that has been partially submerged by seawater.
Erosional landforms, primarily shaped by glacial activity, include features such as cirques, horns, and glacial troughs, each representing distinct processes of erosion in mountainous regions.
This section explores the various erosional landforms created by glacial processes, focusing on cirques, horns, serrated ridges, and U-shaped glacial valleys. It highlights the characteristics and formation mechanisms of these features, including cirque lakes and hanging valleys, as well as comparing glacial valleys to river valleys.