Mourne Mountains The Great Mourne Mountains are those which are formed around 65 million years ago. The structure encompasses great wealthy ingredients of hard granite. The site is very much packed for tourism promotion. The granite mostly came under the criterion of igneous rocks. Granite is a hardest form of rock which were in most cases found beneath the earth's crust. The mountains contain around 12 peaks of around 2000 feet high and probably higher. The Mournes are usually came to be have a breadth of around 5 to 7 miles. These are very much site seeing locations of tourism. They are mostly found in Northern Ireland and nearby regions.