 During a series of geological events, the Salinic orogeny and Caledonian orogeny all three land masses began to converge upon each other slowly diminishing the ocean by subducting the oceanic crust.By the end of the Silurian period, approximately 420 million years ago, the ocean had disappeared.The geological fault zone resulting from the continental collision is known as the Iapetus Suture, named after the ocean it replaced.