corrie

Question 1

describe the look of a corrie

Answer 1

depressions shaped like an armchair with a steep backwall and rock basin. In the northern hemisphere corries are generally found at higher altitudes on North of east facing slopes

Question 2

Why are corries found at higher altitudes on north or east facing slopes

Answer 2

• Northern slopes receive less solar insulation so these glaciers last longer compared to south facing ones
• Prevailing westerly winds blow snow into east facing hollows as westerly winds tend to carry more humid air and consequently increase snow accumulation

Question 3

Are are corries formed

Answer 3

• A pre-glacial hollow is enlarged by nivation (freeze-thaw action)
• Snow accumulates in the hollow and the many layers of snow go through compression until the formation of firn (glacial ice) occurs. This firn forms by air being squeezed out, being put under pressure and meltwater percolating and freezing in crack
• Having reached a critical depth and weigh, the corrie is entrained with large amounts of debris and driven by the steep gradient, the corrie moves through rotation slip which makes ice move in a rotational manner, this erodes the back wall through plucking and abrasion which gives its steep look
• Frost shattering one the bergshrund leads to an accumulation of debris at the base which becomes entrained by the ice and is used to abraid the corrie floor
• At the front of the corrie, where pressure and thus erosion is reduces, a rock lip is formed. This may be added to later by the moraine deposition and in some corries it helps to retain a tarn e.g. Easdale tarn in the lake district