Ben Crom () is a mountain in the

Mourne Mountains The Mourne Mountains ( ; ga, Beanna Boirche), also called the Mournes or Mountains of Mourne, are a granite mountain range in County Down in the south-east of Northern Ireland. They include the highest mountains in Northern Ireland, the high ...

County Down County Down () is one of the six counties of Northern Ireland, one of the nine counties of Ulster and one of the traditional thirty-two counties of Ireland. It covers an area of and has a population of 531,665. It borders County Antrim to the ...

Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label= Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. Nort ...

. It is situated beside

Ben Crom Reservoir Ben Crom Reservoir is a reservoir located in the Mourne Mountains near Kilkeel, County Down, Northern Ireland. Along with Silent Valley Reservoir, which is situated further down the Kilkeel River valley, it supplies water for County Down, surrou ...

, which is upstream from

Silent Valley Reservoir The Silent Valley Reservoir is a reservoir located in the Mourne Mountains near Kilkeel, County Down in Northern Ireland. It supplies most of the water for County Down, surrounding counties and most of Belfast. It is owned and maintained by Northe ...

. The mountain is composed of

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

. An exposed area on the south west of the mountain shows where the

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

aplitic granite meets the

laccolith A laccolith is a body of intrusive rock with a dome-shaped upper surface and a level base, fed by a conduit from below. A laccolith forms when magma (molten rock) rising through the Earth's crust begins to spread out horizontally, prying ap ...

top of the older

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

granite

ring dike A ring dike or ring dyke is an intrusive igneous body that is circular, oval or arcuate in plan and has steep contacts. While the widths of ring dikes differ, they can be up to several thousand meters. The most commonly accepted method of ring dik ...

. The summit of the mountain features granite crags which are crossed by basic and

feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldsp ...

porphyry

dikes Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes ...

. The mountain is used for sheep grazing and hill walking. Silent Valley and Ben Crom from Slievenaglogh - geograph.org.uk - 1205677.jpg, View of Ben Crom (centre),

(bottom) and Ben Crom Reservoir (top right) from Slievenaglogh.

Slieve Bearnagh Slieve Bearnagh () is one of the Mourne Mountains in County Down, Northern Ireland. It has a height of . Its summit is crowned by two tors with a gap between them, giving it a distinctive shape. The Mourne Wall crosses the summit of Slieve Bearn ...

is in the top left of the photo.

References

Mountains and hills of County Down Eocene magmatism Granite formations {{Down-geo-stub