The BGS Lexicon of Named Rock Units — Result Details

Hailes Lava Member

Computer Code: HSLA Preferred Map Code: notEntered
Status Code: Full
Age range: Visean Stage (CV) — Visean Stage (CV)
Lithological Description: The Hailes Lava Member consists of dark grey, feldspar-phyric olivine-basalts ("Markle type") with sparse to abundant, large or small feldspar phenocrysts, non-porphyritic basalts and pale purple-grey, platy jointed mugearites. Thicknesses of flows are up to 17m. The feldspar-phyric basalts characterize this unit of about six flows.
Definition of Lower Boundary: The base is conformable or locally unconformable on the East Linton Lava Member (olivine, clinopyroxene and locally plagioclase-phyric basaltic lavas; ankaramites and basaltic hawaiites) or locally unconformable on the North Berwick Pyroclastic Member.
Definition of Upper Boundary: The Member is overlain by the Bangley Trachytic Member. The contact is conformable and locally unconformable. The change is from olivine-basalt and mugearite lava flows to trachytic lava flows with trachytic tuff and lapilli tuffs.
Thickness: 0 to 70m
Geographical Limits: East Lothian, outcrop of the Garleton Hills Volcanic Formation around North Berwick, East Linton, Garleton Hills, Hailes and in the subcrop farther west in the BGS Spilmersford Borehole near Pencaitland, but absent south of Hailes adjacent to the Dunbar-Gifford Fault.
Parent Unit: Garleton Hills Volcanic Formation (GHV)
Previous Name(s): Hailes Member (-2855)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  East Lothian around North Berwick, East Linton, Garleton Hills, Hailes and in the Spilmersford Borehole (Davies et al.,. 1986, Figure 10; McAdam and Tulloch, 1985, Figure 17). McAdam and Tulloch. 1985. 
Reference(s):
McAdam, A D and Tulloch, W, 1985. Geology of the Haddington district. Memoir of the Geological Survey, sheet 33W (Scotland). 
Davies, A, McAdam, A D and Cameron, I B. 1986. Geology of the Dunbar district. Memoir of the British Geological Survey, Sheet 33E and part of Sheet 41 (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S033 S033