Geosites Project

During the Carboniferous and Permian periods of geological time, from 360 to 260 million years ago, central Scotland was not only the scene of widespread volcanic activity but also was the site where a rift valley was developing through an elongated block of the Earth's crust subsiding along sub-parallel cracks or faults. Time relationships between the two processes can be established at Gloom Hill where the plane of the Ochil Fault, one of the principal dislocations associated with the rift valley has been intruded by igneous rock similar in composition to the great sill which underlies much of the Central Midland Valley. The fault is thus demonstrably older than the intrusions and as it is thought these are likely channels up which the sill magma rose, is very likely also older than the sill itself. Gloom Hill thus provides critical evidence for the time relationships of two of the processes largely responsible for determining the geology of Central Scotland.