Coniston Limestone

Dent Group Stratigraphic range: Ordovician
Steeply-dipping calcareous mudstones of the Dent Group on Timley Knott near Coniston, Cumbria
Type	Group
Unit of	Windermere Supergroup
Underlies	Stockdale Group
Overlies	Borrowdale Volcanic Group
Thickness	ca. 100 m
Location
Region	England
Country	United Kingdom
Extent	Southern Lake District, northwest Pennines

The Dent Group is a group of Upper Ordovician sedimentary and volcanic rocks in north-west England. It is the lowermost part of the Windermere Supergroup, which was deposited in the foreland basin formed during the collision between Laurentia and Avalonia. It lies unconformably on the Borrowdale Volcanic Group. This unit was previously known as the Coniston Limestone Group or Coniston Limestone Formation and should not be confused with the significantly younger (uppermost Silurian) Coniston Group.

The Dent Group is exposed in four areas, the southern Lake District as a narrow strip across the whole width of the outcrop, in the Cautley and Dent inliers, the Cross Fell inlier and the Craven inliers.

In the main Lake District outcrop, the group consists of calcareous siltstones and mudstones of the basal Kirkley Bank Formation,micritic limestones of the Broughton Moor Formation and dark blue-gray shales of the Ashgill Formation. Locally volcanic formations are developed, including the Yarlside Volcanic Formation at the base of the Kirkley Bank Formation and the High Haume Tuff and Appletreeworth Formations at the base of the Ashgill Formations.

In the Cautley and Dent inliers, rocks of the Dent Group occur in two fault bounded strips next to the Dent Fault. In these inliers, calcareous mudstones of the Cautley Mudstone Formation are overlain by the Ashgill Formation. The Cautley Volcanic Member is a unit of volcaniclastic rocks, within the Cautley Mudstone Formation.