More support for a big Wolstonian glaciation

 

I have been looking again at the big article by Bennett et al (2024) on the Quaternary in Devon.  As indicated on the table above, they believe that the one glacial episode that substantially affected the North Devon coast occurred during the Late Wolstonian (MIS 6).  They consider that the glaciation of the Bristol Channel during the Late Devensian (MIS 2) was less extensive, although they accept that the evidence for that time demonstrates a local ice cap on Dartmoor. (There must, of course, also have been a Dartmoor ice cap in the Late Wolstonian, but the evidence for it is not easy to find.........)

As for the Anglian (MIS 12), the authors are cautious.  They suggest that the evidence for a big glaciation at that time is not clear in and around Devon, and therefore they prefer to stick with a "periglacial" climate label for that period. 

Commendable work, with great relevance for other parts of SW Britain. 

Quote:

The most recent research on glaciation in the Bristol
Channel was published by Gibbard et al. (2017, 2022). This
included a synthesis of new publicly available borehole and
bathymetric data, combined with a wealth of other existing
disparate data sources. Sediment boreholes throughout
the Bristol Channel confirm the area was glaciated in the
Pleistocene. Till is present below marine deposits and, in some
areas, is visible morphologically as submerged moraines (Fig.
9). In the central and eastern Bristol Channel the submerged
valley course of the palaeo-Severn is very clear in new highresolution
bathymetric surveys. This former river course and
associated tributaries cross-cut through glacial sediments in
the Bristol Channel. At least three phases of glaciation are
recorded in the Bristol Channel, one related to the southern
limits of a Late Devensian Substage (~MIS 2) Welsh Ice Cap
which reached into Swansea Bay, an earlier Devensian (MIS
4 to 3) glaciation associated with Irish Sea ice, and another
older glaciation that is associated with ice that filled the entire
outer and central Bristol Channel (Fig. 1). The age of the older
Bristol Channel glaciation is still open, although it predates
the Devensian (Late Pleistocene) and must date to the Middle
Pleistocene, and as noted above is likely to correlate with MIS
6 (i.e., the Late Wolstonian). This has implications for the age
of the glacial deposits present on land in the Barnstaple area,
which have traditionally been correlated with the Anglian Stage
(MIS 12) (e.g., Croot et al. 1996). It is more likely, however,
that these deposits correlate with the oldest glaciation of the
Bristol Channel immediately to the north, i.e., with MIS 6 and
the Late Wolstonian Substage (potentially the Moreton Stadial
of Gibson et al., 2022).

I am unconvinced about the Early Devensian  (MIS 4-3) glaciation associated with Irish Sea ice, since the evidence is just not there -- and  I suspect this idea will be dumped before too long.......