The BGS Lexicon of Named Rock Units — Result Details
Loweswater Formation
| Computer Code: | LWF | Preferred Map Code: | LWF |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Arenig Series (OR) — Arenig Series (OR) | ||
| Lithological Description: | Mainly sandstone with minor mudstone and quartz-rich greywacke. Basal beds are mainly thin, fine-grained sandstones interbedded with siltstones and mudstone. Bed thickness increases towards the middle of the Formation. Bed thickness decreases through the upper part of the Formation. | ||
| Definition of Lower Boundary: | The boundary is gradational with the underlying Hope Beck Formation and crops out on the east side of Dodd (NY 171 233). Jackson (1961) used "the presence of arenites 3 inches or more in thickness" as the criterion for separating the two units. | ||
| Definition of Upper Boundary: | In a small quarry on Whiteside End [NY 1660 2169] bedding thickness reduces rapidly and the proportion of mudstone increases forming a laminated facies of sandstone and mudstone with sporadic thin beds of quartz-rich greywacke. The top of the Formation is taken at the highest thin sandstone bed in the dominantly sandstone part of the succession. | ||
| Thickness: | 900m in the northwest Lake District; 450m around Jonah's Gill [NY 190 343]; unknown in faulted inlier at Mungrisdale. | ||
| Geographical Limits: | Occurs within the western part of the Skiddaw inlier, underlain by the Hope Beck Formation and overlain by the Kirk Stile Formation. It also occurs in a small inlier at Mungrisdale [NY 164 209]. | ||
| Parent Unit: | Skiddaw Group (SKG) | ||
| Previous Name(s): | Grits in Skiddaw Slates [Obsolete Name and Code: Use SKG, LWF]
(GTSK)
Loweswater Flags [Obsolete Name and Code: Use LWF] (-1674) Redmain Formation [Obsolete Name and Code: Use LWF] (REN) Skiddaw Grits [Obsolete Name and Code: Use LWF] (-4174) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Area | The vicinity of Hope Beck on the east flank of Dodd. Cooper et al. 1995. | ||
| Reference(s): | |||
| Jackson, D E. 1978. The Skiddaw Group. 79-98 in Moseley, F (Ed.), The Geology of the Lake District. Yorkshire Geological Society, Occasional Publication, No.3. | |||
| Eastwood, T. 1933. In Summ. Prog. Geological Survey of Great Britain for 1932. Pt 1, p.59. | |||
| Waters, C N, Gillespie, M R, Smith, K, Auton, C A, Floyd, J D, Leslie, A G, Millward, D, Mitchell, W I, McMillan, A A, Stone, P, Barron, A J M, Dean, M T, Hopson, P M, Krabbendam, M, Browne, M A E, Stephenson, D, Akhurst, M C, and Barnes, R P. 2007. Stratigraphical Chart of the United Kingdom: Northern Britain. (British Geological Survey.) | |||
| Millward, D, and Stone, P. 2012. Stratigraphical framework for the Ordovician and Silurian sedimentary strata of northern England and the Isle of Man. British Geological Survey Research Report, RR/12/04. 119pp. | |||
| Jackson, D E. 1961. Stratigraphy of the Skiddaw Group in Cumberland, England. Geological Magazine, Vol.98, 515-528. | |||
| Rose, W C C. 1955. The sequence and structure of the Skiddaw Slates of the Lake District in the Keswick-Buttermere area. Proceedings of the Geological Association, Vol.65, 403-406 | |||
| Dixon, E E L. 1925. In Summ. Prog. Geological Survey of Great Britain for 1924, 70-71. | |||
| Ward, J C. 1876. The geology of the northern part of the English Lake District. Memoir of the Geological Survery of Great Britain. 132. | |||
| Cooper, A H, Rushton, A W A, Molyneux, S G, Hughes, R A, Moore, R M and Webb, B C. 1995. The stratigraphy,correlation, provenance and palaeogeography of the Skiddaw Group (Ordovician) in the English Lake District. Geological Magazine, Vol.132(2), 185-211. | |||
| Fortey, N J, 1989. Low grade metamorphism in the Lower Ordovician Skiddaw Group of the Lake District, England. Proceedings of the Yorkshire Geological Society, Vol.47(4), 325-337. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E029 E023 E028 | |||