Glaciation Flashcards
What is an ice age?
It’s a period during which large parts of several continents are covered by ice sheets.
When was the last ice age to affect Ireland?
Roughly 12,000 years ago
What happens during an ice age?
The temperatures in the northern hemisphere were so low that snow and ice did not get a chance to melt.
How is a glacier formed?
Year after year, layers of snow and ice built up until it was compressed or compacted together to form huge masses of ice.
Where are glaciers formed?
Upland areas
What happens to glaciers formed on upland areas?
The effect of gravity eventually moved them downslope. Some glaciers melted while others joined together to form ice sheets that cover huge areas of land.
What are the processes of glacial erosion?
Plucking and Abrasion
What is the process of plucking?
As a glacier moves, there’s friction between it and the ground beneath. This friction causes the bottom of the glacier to melt. The meltwater makes its way into cracks in the rocks underneath the rocks.
What happens after meltwater enters the rocks’ cracks?
The meltwater then refreezes around the rocks. When the glacier moves, it plucks the frozen meltwater and the rocks from the ground. The rocks are then carried away the glacier.
How do striations form?
As the glacier moves, the rocks attached to it scratch and scrape the surface rock underneath and on the sides of the valley.
What do striations tell us?
The direction in which the glacier moved
What are the factors to make an ice age?
- Earth’s orbit and axis
- Earth’s atmosphere
- Ocean currents
How do Earth’s orbit and axis form an ice age?
The Earth’s orbit around the sun changes regularly from oval, or elliptical, to circular. The Earth’s axis’s angle is always changing. These changes happens over 10s of thousands of years and is thought that they’ve an important influence on the Earth’s climate.
How do Earth’s atmosphere form an ice age?
When there’s less CO₂ in the atmosphere to trap the sun’s heat, global temperatures can drop.
How do ocean currents form an ice age?
Ocean currents distribute heat. When they change course, ice sheets can build up.
