The BGS Lexicon of Named Rock Units — Result Details
Breydon Formation
| Computer Code: | BRYD | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Holocene Epoch (QH) — Holocene Epoch (QH) | ||
| Lithological Description: | This formation, which underlies much of the marshland in the Great Yarmouth district, is dominated by unconsolidated silt and clay with a shelly marine fauna. Sand is generally a minor component, though locally substantial sand bodies interrupt the argillaceous succession. Peat, of freshwater and brackish origins, is a major component adjacent to much of the marshland margin and particularly in the valleys of the River Yare and tributary streams. It also occurs as three widespread though locally inpersistent layers, at the base of the formation, within it, and at the top, mainly in the marshland fringe. | ||
| Definition of Lower Boundary: | Unconformable. Commonly overlies tills and outwash sands and gravels of the Happisburgh and Lowestoft formations and also sands, gravels and silts of the Crag Group. Also overlies gravels of the Yare Valley Formation (as in the type section). In the west of the outcrop the base of the formation locally overlies rocks of the Chalk Group and London Clay Formation (Thames Group). | ||
| Definition of Upper Boundary: | At surface. Not overlain by other deposits. | ||
| Thickness: | Up to 22 m, but thins towards the margins of the outcrop. | ||
| Geographical Limits: | Confined to the valleys of the River Bure and River Yare near Great Yarmouth. | ||
| Parent Unit: | British Coastal Deposits Group (COAS) | ||
| Previous Name(s): | Alluvium
(ALV)
Shown as alluvium of Old Series maps of area [Obsolete Name and Code: Use BRYD] (-2026) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Section | North Crains Borehole TG 50NW/417, sited on southern shore of the eastern end of Breydon Water. Arthurton et al., 1994. | ||
| Reference(s): | |||
| Blake, J H. 1890. The geology of the country near Yarmouth and Lowestoft. Memoir of the Geological Survey (England and Wales). | |||
| Coles, B P L, and Funnell, B M. 1981. Holocene palaeoenvironments of Broadland, England. International Association of Sedimentologists Special Publication, Vol.5, 123-131. | |||
| Moorlock, B S, Hamblin, R J O, Morigi, A N, Booth, S J and Jeffery, D H. 2000a. The geology of the country around Lowestoft and Saxmundham. Memoir of the British Geological Survey, sheets 176 and 191 (England and Wales). | |||
| Arthurton, R S, Booth, S J, Morigi, A N, Abbott, M A W, and Wood, C J. 1994. Geology of the country around Great Yarmouth, Sheet Memoir 162, British Geological Survey. [London: HMSO.] 138pp. | |||
| Lambert, J M and Jennings, J N. 1969. Stratigraphical and associated evidence. 1-66 in Lambert, J M, Jennings, J N, Smith, C T, Green, C and Hutchinson, J N (editors), The making of the Broads. Memoir of the Royal Geographical Society, Vol.3. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E162 E132 E148 E176 | |||