Periglis Beach and Big Pool, on St Agnes.
Some of David's notes:
Samson. There is a piece of rounded flint on the west coast of South Hill. There are also a couple of erratics in the ram (slope breccia) on the west coast of North Hill, Samson.
St Mary's. On Bar Point, the northern tip of the island, erratics embedded in horizontal ram can become exposed when sand washes away from the beach.
Annet. The west coast of the island has very little ram cliff and is mostly boulders piled up, but there is a short section of exposed ram at the southern end with middens showing, but there may not be any erratics there. There is a peat layer low in the cliff on the eastern side.
Tean. There are very good in situ glacial deposits, particularly facing Round Island.
Men a Vaur (west of Round Island). There are traces of ram containing sandstone erratics.
Little and Middle Arthur in the Eastern Isles. There are erratics in ram on the neck between the two small islands. The deposit seems to have been reworked -- and it also contains bits of broken bottle!!
Porth Killier, St Agnes. There are sandstone erratics in the really good raised beach sections exposed along the coast.
Guthers (in the sound between St Martin's and St Mary's). There are also some really good raised beach exposures here, also containing flint and sandstone.
Some of the erratics discovered are exposed in ram, close to areas of raised beach. They could have been moved around (more than once!) before becoming embedded. The flints on Samson are both near to bits of raised beach, but they do not seem to be associated with the beach exposures.
Periglis, St Agnes. At low tide in the bay, there are thick, sticky clay deposits under the sand, which are redder than the more orange ones near White Island, St. Martin’s. There is a strong chance that this is a "fresh" till related to the exposures at Chad Girt. Similar deposits are found in some of the bays of the South Pembrokeshire coast, for most of the time buried beneath beach sand.
Samson. There is a piece of rounded flint on the west coast of South Hill. There are also a couple of erratics in the ram (slope breccia) on the west coast of North Hill, Samson.
St Mary's. On Bar Point, the northern tip of the island, erratics embedded in horizontal ram can become exposed when sand washes away from the beach.
Annet. The west coast of the island has very little ram cliff and is mostly boulders piled up, but there is a short section of exposed ram at the southern end with middens showing, but there may not be any erratics there. There is a peat layer low in the cliff on the eastern side.
Tean. There are very good in situ glacial deposits, particularly facing Round Island.
Men a Vaur (west of Round Island). There are traces of ram containing sandstone erratics.
Little and Middle Arthur in the Eastern Isles. There are erratics in ram on the neck between the two small islands. The deposit seems to have been reworked -- and it also contains bits of broken bottle!!
Porth Killier, St Agnes. There are sandstone erratics in the really good raised beach sections exposed along the coast.
Guthers (in the sound between St Martin's and St Mary's). There are also some really good raised beach exposures here, also containing flint and sandstone.
Some of the erratics discovered are exposed in ram, close to areas of raised beach. They could have been moved around (more than once!) before becoming embedded. The flints on Samson are both near to bits of raised beach, but they do not seem to be associated with the beach exposures.
Periglis, St Agnes. At low tide in the bay, there are thick, sticky clay deposits under the sand, which are redder than the more orange ones near White Island, St. Martin’s. There is a strong chance that this is a "fresh" till related to the exposures at Chad Girt. Similar deposits are found in some of the bays of the South Pembrokeshire coast, for most of the time buried beneath beach sand.
If this should be confirmed, this would be the southernmost accessible glacial deposit ever found in the British Isles.
See this article:
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