I'm adding Traeth Mawr, Newport, to my list of ancient cemented till sites in Pembrokeshire. The other three are:
1. Black Mixen, Lydstep
2. Ceibwr
3. Witches Cauldron, near Ceibwr
I have described these in other posts. The Newport exposure is on the beach, directly in front of the public car park, and for much of the year it is hidden beneath the beach sand. But in the winter, or following storms, the ancient till -- solidly cemented -- is exposed and easy to examine.
The till is so solidly cemented with iron oxide and manganese oxide cement that you cannot extract any stones from it. the erratics -- mostly less than 30 cms long -- are faceted and heavily abraded, and are of many different rock types. Sedimentary rocks (mostly sandstones and quartzites) predominate, but there are some igneous erratics as well.
I don't think these are recently cemented Devensian deposits, since there are fresh till exposures between the tide marks in the estuary on the inside of the sand dunes. There is no obvious reason why till should be cemented on the outside of the dunes and uncemented on the inside -- the obvious conclusion is that the tills must be of two different ages.
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