Variscan orogeny rifted off the north Gondwana margin in early Ordovician. By the end of the Silurian and in Early Devonian times, Baltica and Laurentia drifted towards each other, closing the Iapetus Ocean between them. They collided in the Caledonian orogeny and formed the Caledonide mountains of North America, Greenland, the British Isles and Norway. Seafloor spreading to the south of Avalonia pushed the latter into north Laurentia and thrust up the northern Appalachian Mountains in the acadian phase of the Caledonian orogeny. Contemporaneously the Tornquist Sea between Avalonia and Baltica was entirely closed. Thus Avalonia formed the southern coast of the
Kaikoura Orogeny million years ago to the present day the rate of uplift has accelerated. Oligoclase and biotite schist have also been pushed to the surface of the Earth. In total about 20 kilometres of uplift has taken place during the Kaikoura Orogeny but most of this has been eroded away. Kaikoura Orogeny The Kaikoura Orogeny is a New Zealand orogeny that has given birth to the Southern Alps. It began 25 million years ago along the Alpine Fault. In this orogeny, the Southern Alps are being formed because the Pacific Plate is colliding with the Australian Plate, with a predominant oblique