(WN) Geology:

• Red Crag is composed of calcium carbonate deposits, which are subject to chemical weathering by the slightly acidic seawater. The soft red crag is easily eroded by hydraulic action and abrasion, particularly at high tide and during storm conditions.
• Red Crag is permeable but London clay is impermeable and this difference means that water collects at the base of the red crag, lubricating the slope.