Basalt

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Basalt columns generally mean crack climbing, or bridging up steep grooves. The definitive scottish example is probably Kilt Rock on Skye. Many of the basaltic outcrops in the Lowland Outcrops guide have been quarried, which changes the nature of the climbing, although it is still usually crack-centric.

The quality of natural (unquarried) basalt for climbing is... variable! Some crags are solid, providing excellent climbing, while others can be chossy death traps! It all depends on the exact chemical composition of the rock and the kind of weathering/erosion it has undergone. Even the most solid of basalt crags have the unfortunate habit of shedding a column every now and again, particularly if they sit on top of a softer rock, or form part of a sea cliff.

Geology

Basalt is an igneous rock that is generally extrusive, but it can be intrusive, when the intrusion is shallow. In other words, it is generally formed when lava erupts from a volcano and cools, but can also be formed when a wedge of magma is injected between two layers of sedimentary rock that lie quite close to the Earth's surface. The basalts that outcrop around Arthur's Seat in Edinburgh are good examples of this intrusive type of basalt. Wherever it lies basalt is formed when the hot magma cools quickly, giving a fine grained rock. The speed of cooling and the type of eruption strongly influence the structure of the rock. Basalt that has cooled relatively slowly (either as a thick bed of lava, or sandwiched between other rocks) typically forms hexagonal columns - famous examples being the Giant's Causeway in Ireland, Staffa in the Hebrides and, of course, Samson's Ribs in Holyrood Park in Edinburgh.

Where to Climb on Basalt in Scotland

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