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: Part Of SKG Or SKGM] (GTSK)
Skiddaw Grits (-4174)
Loweswater Flags (-1674)
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):
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. 
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. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E029 E023 E028