As all faithful blog readers know (I was tempted to write, in homage to my guru: "... as any fule kno....") I have been banging on about the Devensian glaciation of Caldey Island for ages. Just stick "Caldey Island" into the search box and see what comes up. But on looking through some old files I came across this map, showing the nature of the sediments on the floor of Carmarthen Bay. Very interesting indeed!
As we can see, to the south of the island there is an extraordinary mixture of sediment types, ranging from mud to sandy mud to muddy sand to assorted types of sand and gravel and even "muddy sandy gravel" -- which sounds to me suspiciously like till.......... Is this all that is left of a long looped ridge that might have been a terminal moraine, marking the edge of the Late Devensian Irish Sea Ice Stream? There does not seem to be any trace of a physical feature on the sea bed today, but I like the thought......
If the ice edge was located somewhere around here, what of the other evidence? Well, we have the apparent dilemma of till at the eastern end of the island, at Ballum's Bay, very close to one of the caves which has been investigated. This is Nanna's Cave and Ogof-yr-Ychen, which I examined with Brother James and Mel Davies back in the good old days.
There are animal and human remains in the Caldey caves, mostly dating from between 20,000 and 30,000 years BP. There are doubts about the accuracy of some of these old radiocarbon dates, relating to new protocols of correction or adjustment, but broadly these dates coincide with the peak of the Late Devensian glaciation. So were all these wild animals prowling around the ice edge? Were the caves overwhelmed by glacier ice at the peak of the glaciation? Were human hunters in residence in these caves at the time that the ice advanced to its maximum extent and then started to retreat catastrophically?