The Fremington erratics

The till sheet (light blue) in the Fremington - Bickington - West Yelland area, on the south side of the Taw estuary.  The area is littered with old clay pits.

This is a key record of some of the erratics found in the Fremington clay pits. Whether or not much of the clay was laid down in a lacustrine environment, the presence of ice here on the Devon coast is no longer a matter of dispute.  The question is -- which glacial episode are we talking about?

SIR,—Erratics associated with the Fremington Clay of North Devon have been described by Maw (1864), Dewey (1910), Taylor (1956, 1958), Vachell (1963), and others. The object of this letter is to put on record what I have learnt locally concerning the stratigraphical position at which some of these erratics were excavated. I wish to express my gratitude for this information, and for all their help, to Mr. A. Hobbs, Mr. W. Prust and the late Mr. C. Green, and a!so to the late Mr. C. W. Taylor.

The Fremington Clay (Maw, 1864) occupies part of a valley west of Barnstaple and opening into the Taw estuary at Fremington Pill; it is generally considered to be of glacial origin, although Balchin (1952) suggested that it was an alluvial infilling of reworked Keuper Marl. Zeuner (1959) believed that it was the bottom-moraine of an ice-sheet which approached Barnstaple Bay from the Irish Sea, so that its existence is the only evidence at present known of an ice-sheet having actually penetrated inland on the south shore of the Bristol Channel. Near Fremington, the Culm Measures are overlain by a bed of gravel above which is clay with stones, and then comes the smooth brown potting clay of variable thickness, up to 21 feet being found in the present pits at Bickington. Above the smooth clay are about 2 feet or more of clay known as " horseflesh ", with small stones and grit and decayed wood; and finally at the surface there is a layer of gravel ranging from a few feet up to 16 feet or more in thickness, from which erratics have also been recorded.

At Combrew Farm (SS(21)524323) near Fremington, the boulder described by Dewey (1910) as a vesicular granophyre and catalogued by Taylor (1956) as erratic No. 6, appears to be the same boulder which Maw (1864) recorded as having been found in isolation in the middle of the clay-bed at Combrew. At Chilcotts Farm (523323), the erratic No. 7 of Taylor (1956), on the gate- post to the right as one faces the house, is evidently the hypersthene-andesite discussed by Dewey (1910), although he described it as having been placed on the garden-wall of Combrew Farm house. Mr. A. Hobbs, of Chilcotts Farm, has told me that this boulder was found by his grandfather about the year 1870, in the clay near by, some 22 feet below the surface of the ground.

I am indebted to Messrs. C. H. Brannam, Ltd., of Barnstaple, for permission to study their pits (SS(21)531318) in Tews Lane at Bickington near Fremington. The late Mr. C. Green, who had worked there since 1920, showed me in 1948 a quartz-dolerite boulder (No. 9 of Taylor, 1956), which he had found many years before in the very middle of the brown clay. In 1957, the present foreman, Mr. W. Prust, showed me a smooth rounded boulder, some 19 inches long, which he had excavated 10 feet below the upper surface of the clay, and in 1957 he found another boulder 16 feet below the upper surface of the clay. Neither of these boulders has hitherto been recorded, nor have they (so far as I know) been identified. In 1962, Mr. Prust excavated another quartz-dolerite erratic, No. 13 of Taylor (Vachell, 1963), about 10 feet from the top of the clay. Since 1956, Mr. Prust has also collected over fifty miscellaneous small pebbles, the majority of which were found at or near the base or the top of the clay; a number, however, were embedded in the clay itself at depths ranging from approximately 5 feet to 11 feet above the base of the clay. Two pebbles found in 1955 about 2 or 3 feet above the base of the clay were described by Taylor (1956) who identified one as an olivine-dolerite.

There is thus first-hand evidence that erratics are actually included in the heart of the Fremington Clay itself. This supports the theory of its glacial origin.


REFERENCES

BALCHIN, W. G. V., 1952. The Erosion Surfaces of Exmoor and Adjacent Areas. Geogr. J., 118, 453-76.

DEWEY, H., 1910. Notes on some Igneous Rocks from North Devon. Proc. Geol. Ass., Lond., 21, 429-434.

MAW, G., 1864. On a Supposed Deposit of Boulder-Clay in North Devon. Quart. J. geol. Soc. Lond., 20, 445-451.

TAYLOR, C. W., 1956. Erratics of the Saunton and Fremington Areas. Rep. Devon. Ass. Adv. Sci., 88, 52-64.

1958. Some Supplementary Notes on Saunton Erratics. Ibid., 90, 187-191.

VACHELL, E. T., 1963. 5th Report on Geology. Rep. Devon. Ass. Adv. Sci., 95, 100-7.

ZEUNER, F. E., 1959. The Pleistocene Period. London.

18 SHERLOCK CLOSE, CAMBRIDGE.

8th March, 1964.


MURIEL A. ARBER.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/B34A6E72966498B37FB95BE11B3CB6B5/S0016756800049517a.pdf/erratic_boulders_within_the_fremington_clay_of_north_devon.pdf 

From Wikipedia:

The clay may have formed in varve lakes, near an ice deposit which lay over Fremington during the Last Glacial Maximum or previous glaciations such as the Anglian (MIS12) or the Wolstonian glaciation (MIS6).  Unusually, glacial deposits are found here in the county of Devon. Two patches of boulder clay lie over the centre of the parish's bedrock. The next nearest boulder clay deposits are in the Gower Peninsula, South Wales, approximately 45 miles (72 km) due north of Fremington across the Bristol Channel. The nearest deposit of boulder clay in England is in the central Cotswolds, 6 miles (10 km) due east of Bourton-on-the-Water and approximately 140 miles (225 km) north-east of Fremington. The existence of the boulder clay is puzzling as the southernmost limit of the Devensian glaciation is believed to have been located over South Wales. There are few other signs of glaciation in North Devon to support this.  However this does not fully explain the presence of the nearly co-located varve clay beds.

That Wikipedia entry is somewhat dated. There is of course till or boulder clay much closer than the central Cotswolds -- in the Gordano Valley and other sites in the Bristol - Bath area.    And the idea of an ice mass that "drifted across the Bristol Channel" is rather charming in its naivety!

Never mind -- the Fremington area ids now quite well studied, and there is a sizeable entry in the Geol Cons Review book on  The Quaternary of SW England (1998) (pp 193-246) by Prof Nick Stephens that leaves us in no doubt that we are dealing here with glacial features in abundance that cannot be dressed up as anything else.  And if -- as seems likely from some of the more recent dating work -- they are not of Devensian age,  they must be Anglian or older.  

https://brian-mountainman.blogspot.com/2020/04/the-fremington-enigma.html