The Pacific Plate originated at the triple junction of the three main oceanic plates of Panthalassa, the Farallon, Phoenix, and Izanagi Plates, around 190 million years ago.The plate formed because the triple junction had converted to an unstable form surrounded on all sides by transform faults, due to the development of a kink in one of the plate boundaries. The "Pacific Triangle", the oldest part of the Pacific Plate, created during the initial stages of plate formation, is located just east of the Mariana Trench.