Inner Hebrides Group

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Inner Hebrides Group
Stratigraphic range: Cenomanian to Paleocene
A fenced off Adit No.7, Lochaline Sand Mine - - 3183013.jpg
Entrance to silica sand mine in Lochaline White Sandstone Formation
Type Group
Sub-units Morvern Greensand Formation, Lochaline White Sandstone Formation, Coire Riabhach Phosphatic Formation, Griburn Chalk Formation, Feorlin Sandstone Formation, Strathaird Limestone Formation, Beinn Iadain Mudstone Formation
Underlies Paleocene lavas
Overlies unconformable
Thickness 10-22m
Primary sandstones
Other mudstones, limestones
Region Inner Hebrides
Country United Kingdom
Extent Mull, Eigg, Skye, Scalpay, Soay, Raasay and the Morvern peninsula

In geology, the Inner Hebrides Group is a lithostratigraphical division containing a range of rocks mainly of Upper Cretaceous age which occur around the west coast of the Scottish Highlands. It comprises the following formations:

The Clach Alasdair Conglomerate Member and the Laig Gorge Sandstone & Limestone Members are rock units below formation level, assigned to the Strathaird Limestone Formation.

Each of these formations is of limited geographical extent, the Scottish Chalk Province being fragmented amongst the islands of Skye, Eigg and Mull and the adjacent Scottish mainland district of Morvern. Each of the rock units has gone by different names in the past - the succession outlined here is based on an interpretation by the British Geological Survey reflecting more recent survey and age analysis. It is likely that the youngest of these formations, the Beinn Iadain Mudstone Formation, is largely of Paleogene age. The Group as a whole is the age equivalent of the Chalk Group of southern England. [1]


  1. ^ Hopson, P.M. 2005 A stratigraphical framework for the Upper Cretaceous Chalk of England and Scotland, with statements on the Chalk of Northern Ireland and the UK Offshore Sector. British Geological Survey Research Report RR/05/01 102pp ISBN 0-85272-517-5