The BGS Lexicon of Named Rock Units — Result Details
Aldeby Sand and Gravel Member
| Computer Code: | ASAG | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Anglian Stage (QA) — Anglian Stage (QA) | ||
| Lithological Description: | The Aldeby Sand and Gravel Member is lithogically very variable; it is composed predominantly of sand and gravel that also contains lenses of reworked chalky till, discrete beds of clay and silt, reconstituted chalk and masses of sand transported and apparently derived from the Happisburgh Formation. The gravel fraction is composed predominantly of clasts of angular flint with some quartz and quartzite. In places beds of well-rounded flint and quartz gravel are present. The Member is thought to have formed during wastage of the Lowestoft ice from the adjacent higher ground. | ||
| Definition of Lower Boundary: | Unconformable, most commonly overlies silt- and clay-rich chalky till (diamicton) of the Lowestoft Formation, but also locally overlies well-sorted sands and gravels of the Crag Group and Happisburgh Formation. | ||
| Definition of Upper Boundary: | The Aldeby Sand and Gravel is overlain unconformably by variable Head deposits, and peat and silt of the Breydon Formation, and locally by river terrace sand and gravel of the Britannia Catchments Group. The overlying sand and gravel is typically better sorted and more well bedded. | ||
| Thickness: | Thicknesses are imprecisely known but 18m was exposed at Oaklands Pit, Aldeby and 4m at Aldeby Quarry, (see Stratotypes). | ||
| Geographical Limits: | Restricted to the valley sides of the River Waveney and Hundred River to the west and south of Lowestoft. | ||
| Parent Unit: | Lowestoft Formation (LOFT) | ||
| Previous Name(s): | Lowestoft Gravel Member [Obsolete Name And Code: Use ASAG]
(LGRV)
Aldeby Sands and Gravels [Obsolete Name and Code: Use ASAG] (-3806) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Section | Oaklands Pit at Aldeby. Hopson, 1991. | ||
| Reference Section | Aldeby Quarry, Aldeby. Lee at al., 2004. | ||
| Reference(s): | |||
| Lee, J R, Booth, S J, Hamblin, R J O, Jarrow, A M, Kessler, H, Moorlock, B S P, Morigi, A N, Palmer, A, Riding, J B and Rose, J. 2004. A new stratigraphy for the glacial deposits around Lowestoft, Great Yarmouth, North Walsingham and Cromer, East Anglia, UK. Bulletin of the Geological Society of Norfolk, Vol.53, 3-60. | |||
| 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). | |||
| Hopson, P M. 1991. Geology of the Beccles and Burgh St. Peter district. British Geological Survey Technical Report, WA/91/53 | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E176 | |||