Glacial Landform Case Study - Nant Francon

Question 1

Where is Nant Ffrancon located?

Answer 1

Nant Ffrancon is a glaciated valley in North Wales, exhibiting both glacial and periglacial features.

Question 2

How extensive was ice coverage in Nant Ffrancon during past glaciations? (Mention 2 things)

Answer 2

• Ice may have reached altitudes of 820-860m OD.
• The area was fully glaciated around 40,000 BP, with less ice around 20,000 BP.

Question 3

How did glaciation shape the Nant Ffrancon valley? (Give 3 facts)

Answer 3

• A north-westerly flowing glacier eroded the valley.
• The glacier followed a geological fault line, leading to increased erosion.
• Resulted in a U-shaped valley with truncated spurs and steep crags.

Question 4

What 4 glacial landforms are found in Nant Ffrancon?

Answer 4

• Corries (cwms): Small glaciers formed in hollows, later merging into the valley glacier.
• Arêtes: Sharp ridges formed as corries eroded backwards.
• Rock step: A 100m-high waterfall (Rhaedr Ogwen) formed due to erosion-resistant granite.
• Terminal moraine: Formed where the glacier reached equilibrium and deposited sediment.

Question 5

What is the main river in Nant Ffrancon today? (Mention 2 facts)

Answer 5

• Afon Ogwen, a misfit stream, meanders across the valley floor.
• Previously, a ribbon lake filled the over-deepened valley but has since drained.

Question 6

What 4 periglacial processes have affected Nant Ffrancon?

Answer 6

• Patterned ground is evidence of freeze-thaw activity.
• Deep, steep-sided gorges with waterfalls mark hanging valley retreat.
• Scree slopes (from frost weathering) are found below arêtes.
• Blockfields occur near Glyder and Carneddau summits.

Question 7

How did post-glacial processes modify Nant Ffrancon? (Mention 2 facts)

Answer 7

• A former ribbon lake filled with sediments, creating a flat valley floor.
• Alluvial fans formed where streams deposited sediment from mountain slopes.