Shannaghan Hill ASSI

Shannaghan Hill is a special place because of its earth science interest. The area provides access to exposures of a granite-like rock called granodiorite and Silurian sedimentary rocks that together with a number of other sites describe the Newry Igneous Complex.

The granodiorite was formed some 410 million years ago. This is an igneous rock type, that is, it was injected as magma (molten rock) into pre-existing older rocks – Silurian sedimentary rocks. These older rocks are known as ‘host’ rocks. The magma then cooled slowly eventually forming huge masses of solid rock deep beneath the surface. Subsequent erosion has now exposed parts of these enormous rock units.

Each of these igneous rock units is referred to as a pluton. Three of these are present which collectively make up the Newry Igneous Complex. The complex extends over an area of about 45km2 from Slieve Croob in the northeast to Forkhill in south Armagh.