Geology of the Pacific Ocean Geology of the Pacific Ocean The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth. The tectonic plates continue to move today. The slowest spreading ridge is the Gakkel Ridge on the Arctic Ocean floor, which spreads at less than , while the fastest, the East Pacific Rise near Easter Island, has a spreading rate of over
Nansen (lunar crater) lies across the northern rim of Nansen, and a similar formation is located along the inner southern wall. A merged chain of tiny craters lies across the eastern rim. The interior floor of Nansen is more hummocky and irregular in the northern half, while the southern part of the floor is relatively level. There is a small, bowl-shaped crater in the southeastern part of the floor, and many tiny craterlets lie across the interior and along the inner walls. By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that