Goraghwood Quarry ASSI

Goraghwood Quarry is a special place because of its earth science interest. The area provides access to exposures of granite-like rocks called granodiorite, as well as Silurian sedimentary rocks that together with a number of other designated 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.

The rocks at Goraghwood Quarry form part of the central pluton and are of great importance as they show the relationship between the igneous rocks and the ‘host’ rocks into which they were intruded.

The older Silurian sedimentary rocks that formed in this ocean are exposed at Goraghwood Quarry. These near vertical layers (or beds) of sedimentary rocks have been altered by the heat of the igneous intrusion; a process known as contact metamorphism. This has caused the rocks to change composition and colour resulting in a different appearance from the rest of the Silurian sedimentary rocks that are widespread across Co. Down.