Glacial Lake Nevern

 

Section from the definitive BRITICE-CHRONO map of the British Isles

I have done posts before on Glacial Lake Teifi and Glacial Lake Nevern.  The former did, I think, exist at one time -- and the evidence for it is quite strong.  But Lake Nevern? (That's the smaller lake to the west of Lake Teifi, shown in the Nevern Valley to the SE of Newport. Click on the map to enlarge....)  As far as I can see, it is figment of somebody's imagination.  I think it is a hangover from Charlesworth in 1929, based, as far as I can see, on no evidence whatsoever.

I live in the area that was supposedly submerged beneath this splendid lake, but in spite of enthusiastic searching, I have never seen any laminated silts or clays, or any other evidence (such as shorelines) that might encourage me to think of a large water body.  On the map two ice edge positions are marked in 
the Newport area -- and I can see no evidence in support of them either.

There is a big (and very thick) till sheet in the lower valley of the Clydach stream, but the sediments here do not appear to have laminations, and they are best interpreted as lodgement till.

https://brian-mountainman.blogspot.com/2022/02/the-coed-y-pwll-till-sheet.html

There is a moraine, I think, in Cilgwyn, but that is not marked on the BRITICE map. The only features that might be construed as being associated with a large water body are as series of mounds of sands and gravels in the fields near Caersalem Chapel, at altitudes of 107m - 115m. Charlesworth originally proposed that water from this lake spilled over westwards through the Gwaun Channel. The channel has a humped long profile, with the hump at Llanerch, at 133m asl.   If there had been a meltwater lake here, that altitude would have set the water level.  But it is c 20m too high.  So there was no lake.

We talk often enough about myths and fantasies in archaeology.  But they exist in glacial geomorphology too...........