P1 Glacial Landscapes Flashcards
How long does a quaternary period last?
2 million years
What are the two types of periods?
Glacial and interglacial periods
How long ago was the last ice age?
22,000 years ago
How thick was the ice in the last ice age?
3km thick
What is a glacial period?
When global temperatures drop to an average below 15C. When glaciers can build up into big ice sheets which cover mountain ranges and move to lowland areas.
What is an interglacial period?
A period of time when temperatures around the world are above 15C for extended periods of time
What evidence do we have for the last ice age in the uk?
.steep sided mountains
.shore lines on mountains formed by glaciers
.erratics
.loch ness - the depth gets very deep very quickly
-drumlins
What caused the last ice age in the uk?
Orbital cycles of the earth around the sun, changes every 100,000 years
What is a glacier?
A thick moving mass of ice that usually forms in mountainous areas and moved downhill causing the processes erosion, deposition,and transportation.
Describe the process of freeze thaw-weathering
.water seeps into cracks in the rock face
.temperature falls at night causing the water to freeze
. Water expands 10% when it freezes
.the water melts again and seeps further into the crack and the process repeats until eventually the rock face cracks
What is glacial erosion?
The wearing a way and removal of the land by flowing water, ice or wind
What are the two main erosional processes?
Plucking and abrasion
What is plucking?
When a glacier moves over an area of rock and due to friction, the glacier melts ad water seeps into cracks around the rocks below. The water re freezes and the rock effectively becomes a part of the glacier nd is ripped out when the glacier continues to ove forward.
What is abrasion?
Where rocks at the bottom of the glacier act like sandpaper grinding over the bedrock. This can polish the rocks or create sharp grooves called striations.
What is glacial transport?
As glaciers move they transport debris(till) along with them in various ways.
What three ways is till carried with a glacier?
.subglacial material : plucking/abrasion , underneath or inside the ife
.englacial material: material that has fallen into crevices (cracks in the ice)
.supraglacial material: material that has fallen onto the ice
What does glacial till form when in it deposited?
Moraine
What is bulldozing?
When a glacier moves forward it can avt like a giant earth wormer bulldozing piles of rock and debris in front of it to create a high ridge called moraine.
Why do glaciers deposit material?
Because they loose energy
What is a Corrie?
A bowl shaped hollow with a steep back wall and ridges, forming an armchair around the hollow, sometimes containing a small round lake called a tarn
How is a Corrie formed?
- snow accumulates in a depression or in a hollow high up in a mountain area
- over time the snow compresses into ice which then starts moving
- plucking occurs on the back wall of the glacier making it steeper
- freeze-thaw weathering occurs which produces scree which then gets trapped in the ice
- the mass slides downhill, scree in the glacier causes abrasion scrapes away the floor, making it deeper
- there is less arrosions at the front of the glacier which causes a rock lip to form as a result of less powerful erosion.
- when all the ice has melted a tarn forms