In his 1954 book, “The Pebbles on the Beach”, Clarence Ellis has a chapter on “The Coastline of England and Wales”. There he writes (page 125):
In the middle of Start Bay is a bed of shingle that must not be missed. This is the extensive bar at Torcross that encloses the lagoon called Slapton Ley. There is one very unusual feature about it. Its pebbles do not come from the rocks of the Bay. Many of them are flints, yet there is no chalk or other flint-bearing rock near to Torcross. The other pebbles are quartz, including very small ones that are pear-shaped, and granite from Dartmoor.
The website of the Slapton Ley National Nature Reserve has some good information on the bar, its beach and its stones. This Reserve is managed by the Field Studies Council in partnership with the owners. Whitley Wildlife Conservation Trust, along with Natural England and South Hams District Council. Their website highlights the significance of “longshore drift” which is when waves hit the shore at an angle and will move stones and sediment in a certain direction along a stretch of coastline. The website continues: [Note: August 2019 – The website has recently been changed and no longer contains this information]
Slate is the bedrock of Start Bay and so is found in the cliffs bordering the beach. It is a metamorphic rock, changed from clays by heat and pressure, but is relatively soft and so erodes easily. You may find large pieces of slate near the cliffs that have recently been eroded but because it breaks down quickly it is hard to spot much slate on the centre of the ridge. Schist is a very resistant metamorphic rock, and forms Start Point headland jutting out to sea at the south end of Start Bay. It was formed in the Devonian around 395 million years ago. The schist and some of the slate has seams of quartz running through it. Quartz is the most abundant mineral in the Earth’s crust and you will be able to find plenty of it on the ridge. It is a milky white. You can find some igneous rock on the beach, most transported by rivers that have their source on Dartmoor. Quartzite is pinkish and forms a very smooth pebble. It can be found just offshore and was transported up onto the beach by rising sea levels. Most of the shingle making up the ridge is flint; it makes up about 80% of the material on the beach. Flint is only found about 30-40km offshore from the present day coastline which suggests that Slapton Sands originates from this area.
During the visit to Slapton Sands in mid-2016, a few handfuls of stones were collected (59 individual stones in all). Some jasper and quartz are apparent. The photos below are of dry stones followed by some photos of them wet, hinting at how they might look when polished.
See also the following Tumblestone Posts: Slapton Sands, Part One: A Visit, Mid-2016; Slapton Sands, Part Two: The Protective Significance of the Shingle Beach; Slapton Sands, Part Three: The Historical Significance of a Shingle Beach – The 1943-44 Evacuation; Slapton Sands, Part Four: The Tragedy of “Exercise Tiger”; Slapton Sands, Part Six: The Beach Stones Polished.
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