WLGS 36 Auchinoon Quarry (Proposed RIGS) [NT 0919 6175] (Figure 117), (Figure 118), (Figure 119), (Figure 120), (Figure 121)

WLC site description

Part of the Alkali-dolerite sill group of sites

Other designations: AGLV

Auchinoon Quarry is situated beside the A70 north of Harperrig Reservoir. The site is an excellent example of a dolerite sill and the best example of contact metamorphism in West Lothian. In the quarry face the sill intrudes laminated siltstones of the Gullane Formation — for approximately 2 m above the contact the siltstones have been thermally altered to calcsilicate hornfels. Unmetamorphosed siltstones can be seen above the hornfels in the east side of the quarry. The southern top of Auchinoon Hill, about 200 m north-north-west of the quarry, is a good viewpoint for Pentland Hills.

(Figure 117) Auchinoon Hill from south-east of Harperrig Reservoir. Auchinoon Quarry (WLGS 36) left of centre.

(Figure 118) Auchinoon Quarry [NT 0919 6175] (WLGS 36) with the Pentland Hills beyond. Dolerite sill in lower part of quarry with Gullane Formation laminated siltstones above.

(Figure 119) Auchinoon Quarry [NT 0919 6175] (WLGS 36). 5 m of dolerite sill in lower part of quarry face with thermally metamorphosed laminated siltstones of the Gullane Formation above.

(Figure 120) Centre section of Auchinoon Quarry [NT 0919 6175] (WLGS 36). Approximately 5 m of dolerite sill in lower part of quarry face with thermally metamorphosed laminated siltstones of the Gullane Formation above.

(Figure 121) Auchinoon Quarry [NT 0919 6175] (WLGS 36). Dolerite sill in lower part of quarry with Gullane Formation laminated siltstones above. Siltstones have been thermally metamorphosed to calc-silicate hornfels by contact with sill. Face approximately 4 m high.