English: Mesozoic sediments on Rubha nan Fear The banded sedimentary rocks that form the lowest part of the cliffs of the southern tip of the Laggan peninsula, and Frank Lockwood's Island, predate the volcanic rocks which dominate most of Mull. These come from the Mesozoic era, and dip slightly northwards into the land. They had been uncovered and eroded before the great Tertiary volcanic eruptions which extended over much of the west of Scotland presaging the opening of the Atlantic Ocean. The overlying lava flows thus covered an uneven surface, basalt filling in dips and hollows in the original landscape. This unconformity sinks below sea level north of Rubha nan Fear, so all the more distant, grey, rock outcrops are basalt.