GLACIATION Flashcards
What is a ‘glacial’ period?
A glacial period is an interval of time within an ice age that is marked by colder temperatures and glacier advances.
What is an ‘interglacial’ period?
An interglacial period is a period of warmer global average temperature lasting thousands of years.
How does snow turn into ice?
Snow-Firn-Ice
Over time snow falls and becomes compact into a denser layer. After at least one year it is called firn. After another 25-40 years the firn turns into ice and the process repeats.
What is ‘abrasion’?
As a glacier flows downslope, it drags the rock, sediment, and debris in its base over the rock beneath it creating striations and other features.
What is ‘plucking’?
As the glacier moves down the slope of mountains the ice at the bottom plucks away loose rocks from the surface of slopes.
What is ‘freeze thaw’?
Freeze-thaw is when water fills a crack in the rock and freezes to make the crack wider. The process repeats until the rock completely breaks apart.
What is a corrie?
A corrie is an armchair-shaped hollow high on a mountain with steep back and side walls.
How is a corrie formed?
Snow gathers in north-facing mountain hollows. This snow builds up and compacts to ice and the ice move downhill due to gravity leaving a hollow called a corrie.
What is an arête?
An arête is a narrow ridge of rock that separates two valleys.
How is an arête formed?
An arête forms when two corries form back to back or side by side. The rock between them is plucked away to form a narrow ridge.
How is a pyrmid peak formed?
A pyramidal peak forms when three or more corries are next to each other. The rock between them was plucked and weathered into a sharp point.
Where are ribbon lakes found?
Ribbon lakes are found in U-shaped valleys.
How are ribbon lakes formed?
Ribbon lakes are formed when glaciers were able to erode more deeply elsewhere. When this happens the ice leaves a hollow which becomes a lake.
