Clay-with-Flints

In geology, Clay-with-Flints describes a series of mineral deposits distributed throughout southern England. While the composition of each deposit varies in mineral types and concentrations, they typically contain mixtures of red clay with flints. Similar deposits have also been identified in northern France, referred to as "Argile à silex." ^[1]

Nomenclature and Definitions

The name Clay-with-Flints was first proposed by William Whitaker in 1861 to describe a particular deposit located at Chiltern Hills. ^[2] Over the years the name was adopted to refer to a variety of formations throughout southern England thought to be of common origin. To clear up the ambiguity several definitions have been proposed. J. Loveday proposed defined it as yellowish red or red-brown clay with up to 50% of flints, a few flint and quartzitic pebbles, and small amounts of sand, that rests in the plateau areas on an irregular, solution affected chalk surface. ^[3]

Occurrence

The Formation is associated with deposits of the Chalk Group, subsequent Palaeogene and Neogene strata, and occasionally Upper Greensand. ^[4] It occurs in sheets or patches of various sizes over a large area in the south of England, from Hertfordshire on the north to Sussex on the south, and from Kent on the east to Devon on the west. It almost always lies on the surface of the Upper Chalk, but in Dorset, it passes on to the Middle and Lower Chalk, and in Devon, it is found on the Chert-Beds of the Selbornian group. ^{[5] [6]}

Origin

The formation is now considered to be a combination of residual and cryoturbated strata, and to be of a variety of ages. ^{[7] [8]}

References

1. Gallois, R.W. "The origin of the Clay-with-flints: the missing link". Geoscience in South-West England. 12: 153–161 – via The Ussher Society.
2. Hull, E.; Whitaker, W. (1861). "The Geology of Parts of Oxfordshire and Berkshire". Memoir of the Geological Survey of Great Britain.
3. Loveday, J. (1962-01-01). "Plateau deposits of the southern Chiltern Hills". Proceedings of the Geologists' Association. 73 (1): 83–IN5. doi:10.1016/S0016-7878(62)80019-4. ISSN   0016-7878.
4. Cooper, Mark R.; Troll, Valentin R.; Lemon, Kirstin (November 2018). "The 'Clay-with-Flints' deposit in Northern Ireland: reassessment of the evidence for an early Paleocene ignimbrite" . Geological Magazine. 155 (8): 1811–1820. Bibcode:2018GeoM..155.1811C. doi:10.1017/S0016756817000760. ISSN   0016-7568. S2CID   54505871.
5. Howe 1911, p. 475.
6. A. J. Jukes-Browne, "The Clay-with-Flints, its Origin and Distribution,” Q.J.G.S., vol. lxii., 1906, p. 132
7. Anon. "Clay-with-flints Formation". The BGS Lexicon of Named Rock Units. BGS. Retrieved 3 May 2017.
8. Gallois, R. W. (2009). "The origin of the Clay-with-flints: the missing link". Geoscience in South-West England. 12: 153–161.

•  This article incorporates text from a publication now in the public domain : Howe, John Allen (1911). "Clay-with-Flints". In Chisholm, Hugh (ed.). Encyclopædia Britannica . Vol. 6 (11th ed.). Cambridge University Press. pp. 475–476.

External links

• Clay-with-Flints in the British Geological Survey lexicon.