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Tuesday 3 October 2023

Glacial traces near Baggy Point, Devon

The high-level Ramson Cliff epidiorite erratic (photo:  Paul Berry, published on his blog)

Close-up showing the crystalline structure of the epidiorite erratic (photo:  Paul Berry)

Grateful thanks to Paul Madgett and Paul Berry for the following info. 

 I have published some material from PM  before, in 2019, in a post concentrating on the "high level erratic" at Ramson Cliff:

That boulder (altitude c 80m)  is not the only "high-level erratic" on Baggy Point. I know of two others, though smaller - both now on top of the stone wall to the south of Croyde Hoe Farm, and adjacent to the higher footpath/track along the south side of Baggy. Can supply images, if required. Both are tuffs/agglomerates; one a grey almost square block, the other smaller, more irregularly shaped, of a pinkish tinge. Neither were there in the 1970s, and seem to have appeared in the late 1980s or early 1990s. Formerly Croyde Hoe Farm had been mainly arable, and the fields produced regular "crops" of flint tools and waste flakes. In 1969 the farmer, a Mr Bagster, had shown us his collection after we asked permission to walk over his land, and subsequently one of his workmen has allowed me to photograph samples from his personal collection, mostly Mesolithic, but including Neolithic, Bronze Age artefacts, and even a squared-off flint from a flint-lock rifle, all found on Baggy. In the 1990s the new National Trust tenant farmer went over entirely to sheep, so the fields are ploughed only rarely nowadays.

Thus my guess is that the former farmer, knowing of the interest in his land by geologists, and recognising these cobbles / small boulders as "different", having ploughed them up, then placed them in a prominent position for others to see. Neither have the appearance of ex-beach boulders, and I would suggest that they represent the residuum of a former cover of till, now virtually all eroded, most of the boulders once emplaced higher on the coastal landscape now being incorporated into beach deposits, some incorporated in the base of the Raised Beach, as with the Saunton Red Granite (hence any putative glaciation to emplace the boulders needing to be pre-Ipswichian).

I don't have any further details from Paul M, but from the OS maps it looks as if one of these smaller erratics is at around 200 ft (60 m) and the other at around 150 ft (45 m).

Here is another quote, this time from Paul Berry (Oct 27, 2021) in an interesting blog article on the Baggy Point footpath:

About halfway along the north side of Baggy, there is another (smaller) glacial erratic sat right next to the path. It is a 500 kg block of epidiorite of Scottish origin. It is a little difficult to spot, as it is surrounded by gorse, and is slowly disappearing into the surface. Part of the surface has been chipped away, exposing the obvious crystalline structure of igneous rock. It once stood upright in the middle of a nearby pasture field and was used as rubbing post by sheep and cattle. In the early 1970s, the field was ploughed and the rock dislodged and then laid prone. It was then dragged to edge of field where it has been ever since. The erratic can be located at grid reference SS 4356 4070.

Paul B also says:
Other small erratics (tuffs/agglomerates) have been ploughed up nearby and incorporated into the stone wall by the higher path, but they are tough to spot under the dense cover of grey lichen. One is a grey almost square block, another smaller, more irregular shape of pinkish tinge.

Paul Berry was Head of Geography and Assistant Vice Principal at South Molton Community College, North Devon.

The famous Baggy Point giant erratic (photo: Paul Berry), on the rocky foreshore

See also:

Big erratics at 80 m, 60 m and 45 m altitude cannot be explained as dropstones or ice-rafted boulders, and they must represent the last remnants of ancient glacial deposits laid down by an ice incursion from the Bristol Channel during an extensive glaciation. Like the boulders at Whitesands and other locations on the Pembrokeshire coast, some of the Devon erratics on the current foreshore appear to be "sealed" beneath sandrock and Devensian slope deposits; others are "free", having been released from the coastal sediment sequence by wave action and coastal retreat.

Campbell and Gilbert, in the GCR volume for SW England in 1998, p 220, found it difficult to accept that the Ramson Cliff erratic was found originally at c 80m above sea level.  They suggested that it might have been hauled up from the shore to "act as a boundary marker."  In my view that makes no sense at all.  It's not a convenient pillar-shaped monolith suitable for use as a boundary marker -- it's a rough block.  And if the locals wanted a boundary marker stone at some point in the distant past, they could have extracted one from the rock outcrop (marked on the OS maps) on the clifftop nearby.

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