The gravity anomaly map of Australia shows traces of a Ø 320 km Impact Crater east of the Cape-York Peninsula. This Impact Crater probably belongs to an impact crater-chain of at least three large craters in the 200–300 km diameter range. That is indicated by different gravity anomaly maps and topographic maps. The assumed crater-chain in all probability represents a secondary crater chain that was caused by the giant 1270x950 km Permian Triassic Crater around 253 million years ago. A manipulated gravity anomaly map, where New Guinea was rotated by 45 degree and moved close to the NE-coast of Australia, seems to confirm that this impact event separated New Guinea from the Australian Plate. New Zealand probably was cut-off from the Australian Plate by the same Impact Event. The impact crater chain caused the initial crack, and the later massive outflow of magma from the Cape York Crater was a driver of the separation of New Guinea and New Zealand from Australia. The traces of this assumed outflow of magma from the Cape York Crater (CYC) are clearly visible on the gravity anomaly map and topographic map. Another indication for the assumed Impact Crater-Chain comes from the triangular shape of the Gulf of Carpentaria in the North of Australia, which probably was formed by the ejecta of another 300 km crater that belongs to the CY-Impact-Crater-Chain. Proof for the impact event comes from Raman spectroscopy analyses of rock samples (Quartz) from the CYC-area. The magma flowing out of the Cape York Crater seems to have caused a large magma enclosure, which not only finalized the break-off of New Guinea and New Zealand from Australia, but in all probability also caused a gigantic flood-event when it finally collapsed. This flood event, is also indicated by traces on the gravity anomaly- and magnetic anomaly map. A chronology of the development and the collapse of the assumed magma enclosure, caused by outflow from the CYC, is shown on page 7. Different smaller secondary impact structures, probably also caused by the CY-Impact, are located along the NE-coast of Australia. Two interesting structures are the 8x7 km elliptical Warwick Impact-Crater and Mt Warning, which isn’t just a collapsed shield volcano, but rather the remain of a volcano that formed on top of the Ø30 km Mt Warning Crater, a secondary Crater of the CY-Impact Event.