Читать книгу Walking on Rum and the Small Isles. Rum, Eigg, Muck, Canna, Coll and Tiree онлайн

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Rum is the core of a volcano that developed on a pre-existing structure of Torridonian sandstone and shales resting on Lewisian Gneiss. Volcanic activity 65 million years ago formed a dome over a kilometre high and several kilometres across. Pressure from below caused fractures to form around the dome, which collapsed, forming a caldera. The caldera floor was gradually covered by rocks and debris, consisting largely of Torridonian sandstone and Lewisian gneiss, which was compressed, forming rocks known as breccias, found in Coire Dubh. The vestiges of the dome are evident on the slopes of the Rum Cuillin, where the Torridonian rocks incline steeply away from the adjacent igneous rocks.

Weathered Torridonian sandstone formation near Kilmory Bay, north-east Rum (Walk 3, Day 3 and Walk 7)

Magma, ash and rock erupted into the caldera, along with gas clouds known as pyroclastic flows which formed rocks known as rhyodacites, found around the margins of the Rum Cuillin and on the ridge between the summits of Ainshval and Sgùrr nan Gillean.