Main Algal Member
Main Algal Member (MAN), Carboniferous, Northern England Province
Main Algal Member is part of the Lyne Formation.
Rhythmic alternations of limestone and mudstone with 14 well developed nodular algal beds and subsidiary sandstone and siltstone.
The type section is in Birky Cleuch from (NY 5885 7540 to 5932 7538) a tributary of the Kirk Beck at Bewcastle. Here, a complete sequence from M.A.1 to M.A.14, about 87 m thick is exposed (Day, 1970).
Lower and upper boundaries
At Bewcastle, the lowermost algal bed (M.A.1 of Day, 1970) of the Main Algal Member lies conformably on the Bewcastle Member (Figure 11, Column 2), which comprises cyclical sequences of sandstone, siltstone, and mudstone, with thin limestones and ‘cementstones’.
At the top of the Main Algal Member, the top of the uppermost algal bed (M.A.14 of Day, 1970) is conformable with the overlying Lower Antiquatonia Bed of the Cambeck Member, which comprises rhythmic cycles of mainly sandstones, thin limestones and mudstones.
Some 87 m at Bewcastle.
Distribution and regional correlation
The Northumberland–Solway Basin, but described only in the Bewcastle region (Day, 1970).
- Day, J B W. 1970. Geology of the country around Bewcastle.Memoir of the Geological Survey of Great Britain, Sheet 12 (England and Wales).
- Leeder, M R. 1974. Lower Border Group (Tournaisian) fluviodeltaic sedimentation and palaeogeography of the Northumberland Basin.Proceedings of the Yorkshire Geological Society, Vol. 40, 129–180.