Geology
Ulva's interior is moorland, while the spectacular geological formations of the south coast, have been somewhat overshadowed by those of its neighbour Staffa. Nonetheless, they are still renowned in their own right. Around 60 million years ago, the region was volcanically active, with Ben More on Mull being the remnant of a volcano, and it was in this period that the famous rock formations of Staffa and the basaltic columns of "The Castles" on Ulva came into being. The lava flows are known as the "Staffa Magma Type member" and can also be seen on Mull at Carsaig, Ardtum, and near Tobermory on its east coast. They are particularly rich in silica. These were formed when the cooling surface of the mass of hot lava cracked in a hexagonal pattern in a similar way to drying mud cracking as it shrinks, and these cracks gradually extended down into the mass of lava as it cooled and shrank to form the columns which were subsequently exposed by erosion.
Much more recently, Ulva was subjected to glaciation, which dug out the fjords/sea lochs on its north and south east sides - Loch Tuath (meaning simply "north loch") and Loch na Keal, as well as softening some of its sharper edges.
The Hebridean coastline has been subject to significant post-glacial changes in sea level and the area is rising up at about 2 millimetres per annum as isostatic equilibrium is regained. The relative drop in sea-level has left the highest raised sea cave in the British Isles on Ulva at A' Chrannag. At some point, Ulva was probably a west pointing headland of Mull, connected to Gometra and Eilean Dioghlum off the latter's west coast.
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