Ireland is an island in Northern Europe in the north Atlantic Ocean. The island lies on the European continental shelf, part of the Eurasian Plate. The island's main geographical features include low central plains surrounded by coastal mountains. The highest peak is Carrauntoohil (Corrán Tuathail), which is above sea level. The western coastline is rugged, with many islands, peninsulas, headlands and bays. The island is bisected by the River Shannon, which at with a estuary is the longest river in Ireland and flows south from County Cavan in Ulster to meet the Atlantic just south of Limerick. There are a number of sizeable lakes along Ireland's rivers, of which Lough Neagh is the largest.
Politically, the island consists of the Republic of Ireland, with jurisdiction over about five-sixths of the island, and Northern Ireland, a constituent country of the United Kingdom, with jurisdiction over the remaining sixth. Located west of the island of Great Britain, it lies at approximately . It has a total area of . It is separated from Great Britain by the Irish Sea and from mainland Europe by the Celtic Sea.
Ireland forms the second largest landmass in the North-West European Archipelago, together with nearby islands including Great Britain and the Isle of Man, known in the United Kingdom as the British Isles.
Geology of Ireland
The geology of Ireland is diverse. Different regions contain rocks belonging to different geological periods, dating back almost 2 billion years. The oldest known Irish rock is about 1.7 billion years old and is found on Inishtrahull Island off the north coast of Inishowen and on the mainland at Annagh Head on the Mullet Peninsula. The newer formations are the drumlins and glacial valleys as a result of the last ice age, and the sinkholes and cave formations in the limestone regions of Clare.
Ireland's geological history covers everything from volcanism and tropical seas to the last glacial period. Ireland was formed in two distinct parts and slowly joined, uniting about 440 million years ago.