Dorset Sediment Sources #5 Flashcards
What is mass movement and where does it occur?
Cliffs are undercut by the sea (faclillitated by marine and sub-aerial processes) added weight of buildings and disruption of natural drainage causes unstable cliffs.
Lulworth cove.
What enhances rock fall of resistant rock like limestone and chalk?
Jointing and presence of Bridport sand.
How do landslides occur at Christchurch Bay?
Cliffs are made of permeable sands and gravel overlying impermeable clay. Water seeps in but only to clay, building up and lubricating landslides.
What else are the cliffs at Christchurch susceptible to?
Mudslides, mudflows and gullying particularly on vegetated areas.
What rivers does fluvial sediment come from?
Avon and Stour flowing into the harbour.
Where are the rates of erosion the highest?
Highcliffe and Barton-on-Sea where cliffs retreat 2.9m per yr.
Where offshore act as stores and sources of sediment?
The shingles.
