The Troodos mountains are known worldwide for their geology and the presence of an undisturbed ophiolite sequence, the Troodos Ophiolite. These mountains slowly rose from the sea due to the collision of the African and European tectonic plates, a process that eventually formed the island of Cyprus. The slowing and near-cessation of this process left the rock formations nearly intact, while subsequent erosion uncovered the magma chamber underneath the mountain, allowing a viewing of intact rocks and petrified pillow lava formed millions of years ago, an excellent example of ophiolite stratigraphy. The observations of the Troodos ophiolite by Ian Graham Gass and co-workers was one of the key points that led to the theory of sea floor spreading.