Ascog Member

Ascog Member (ASO), Isle of Bute, Carboniferous, Midland Valley of Scotland

The Ascog Member is part of the Clyde Sandstone Formation.

Name

From Ascog, Isle of Bute. The member was defined by Paterson and Hall (1986).

Lithology

Red-brown siltstone and sandstone with pedogenic limestone.

Stratotype

The type section occurs in the BGS Ascog Borehole (BGS Registration Number NS06SE/8) (NS 0986 6302) from 133.6 to 219.8 m depth.

Lower and upper boundaries

At the lower boundary, sandstone of the Ascog Member is interbedded with grey mudstone and dolomitic limestone (‘cementstone’) of the Ballagan Formation. The boundary is picked where beds of dolomitic limestone (‘cementstone’) are absent and sandstone becomes the predominant lithology.

At the upper boundary there is a sharp change at the probably erosional base of the overlying Birgidale Formation, which comprises mudstone, sandstone, seatrock and coal.

Thickness

Some 86.m. However, BGS (2008) gave a generalised thickness of 75.m for the member on the Isle of Bute.

Distribution and regional correlation

Isle of Bute, Strathclyde.

Age

Tournaisian