What rocks are on the Mourne mountains Co Down N Ireland?

The Mourne Mountains in County Down, Northern Ireland, are primarily composed of granite. This granite was formed approximately 60 million years ago during the Tertiary Period when magma from deep within the Earth's crust rose and solidified. The magma cooled slowly, allowing large crystals to form, resulting in the characteristic coarse-grained texture of Mourne granite. Erosion and glaciation have since shaped the mountains and exposed the granite, making it a prominent geological feature in the region.