Coastal Features: Beer Stone and Beer Quarry Caves, The Hooken Landslide, Chalk Cliff Erosion
Beer Stone and Beer Quarry Caves
Sandwiched in these cliffs between the Upper Greensand and Middle Chalk is the 95 million year old Beer Head Limestone.
Beer Stone is a fine shelly chalk. 98 percent of chalk is composed from microscopic planktonic plant remains - coccoliths, but at Beer there was a current flowing across the seafloor and this winnowed away the coccoliths leaving a fine shelly Limestone.
The Beer Stone outcrops at Beer beach but it only forms a very thin layer. However at Beer Head, the Hooken Landslide and 1 mile (1.5 km) inland from Beer village, the band of Limestone is much thicker and the quarry caves give a fascinating insight into the stone’s importance, as well as Beer’s history and the lives of the men who worked there.
The Hooken Landslide
The Hooken Landslide is a section of cliff which collapsed overnight in March 1790.
As with the Bindon Landslide, it is thought the build up of water, this time from a blocked underground stream, flooded the permeable Greensands over a period of two years. This lubricated the Greensand/clay junction allowing a massive block of Chalk to break free and move towards the sea, creating a spectacular undercliff of greensand with Chalk pinnacles above.
Like the Bindon Landslide, this slip also pushed a reef up out to sea. Imagine the local fishermen’s surprise when they found their crab pots stranded 5 meters above sea level, when only the day before they had been set in 3 meters of water!
Chalk Cliff Erosion
Erosion of coastal Chalk cliffs is slow. Chalk is relatively hard, and only becomes unstable when the sea has carved a cave into its base, destabilising the weight of cliff above. The sea then has to wash away the cliff fall before the process can start all over again. The milky coloured seawater found at the base of Chalk cliffs, particularly around fresh falls, is evidence of coastal cliff erosion in progress.