The BGS Lexicon of Named Rock Units — Result Details

Longlands Farm Tuff Member

Computer Code: LOFA Preferred Map Code: LoFa
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Vitric tuff and lapilli-tuff; massive homogeneous andesitic ignimbrite; some intercalated pyroclastic breccia.
Definition of Lower Boundary: At base of homogeneous lapilli-tuff - sharp contact on thin bed of volcaniclastic sandstone at top of reworked, underlying ignimbrite or on pyroclastic breccia of Sides Farm Member.
Definition of Upper Boundary: Not seen, but mapped at the change from densely welded tuff to a mixed sequence of lithic-rich tuff and parataxitic tuff of the Loweray Formation.
Thickness: 380m+ in type section - total thickness unproved because of eroded top. (Thickness not corrected for strutural dip or borehole deviation from the vertical).
Geographical Limits: Sellafield boreholes 2 (NY00SE/28), 4 (NY00SE/29), 5 (NY00SE/30), 8A (NY00SE/38), 10A (NY00SW/38) , RCF1 (NY00SE/35), RCF2 (NY00SE/36), RCF3 (NY00SE/37), RCM1 (NY00SE/41), RCM2 (NY00SE/40) and RCM3 (NY00SE/39).
Parent Unit: Fleming Hall Tuff Formation (FLH)
Previous Name(s): Longlands Farm Member (-1041)
Alternative Name(s): none recorded or not applicable
Partial Type Section  Sellafield borehole No 4, BGS Registered No. NY00SE/29, 411.75m - 795.90m below Rotary Table Elevation, 338.15m - 722.3m below OD. 
Beddoe-Stephens, B and Millward, D, 2000. Very densely welded, rheomorphic ignimbrites of homogeneous intermediate calc-alkaline composition from the English Lake District. Geological Magazine, Vol.137, 155-173. 
Akhurst, M C, Chadwick, R A, Holliday, D W, McCormac, M, McMillan, A A, Millward, D, Young, B, Ambrose, K, Auton, C A, Barclay, W J, Barnes, R P, Beddoe-Stephens, B, James, J C W, Johnson, H, Jones, N S, Glover, B W, Hawkins, M P, Kimbell, G S, MacPherson, K A T, Merritt, J W, Milodowski, A E, Riley, N J, Robins, N S, Stone, P and Wingfield, R T R. 1997. The geology of the west Cumbria district. Memoir of the British Geological Survey, Sheets 28, 37 and 47 (England and Wales). 138pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used: