La Malbaie Structure,Quebec—A Palaeozoic Meteorite Impact Site

Abstract Evidence in support of an origin by meteorite impact has been found at La Malbaie structure, 105 km northeast of Quebec City on the north shore of the St. Lawrence River. The structure has a central peak (Mont des Eboulements) 2500 feet (780 meters) above sea level, surrounded by lower hills and a semicircular valley with a diameter of 35 km. The circularity is incomplete as the peripheral valley terminates to the south and east at the St. Lawrence River which obscures an estimated 40 per cent of the crater. Rocks within the crater comprise charnockitic and granitic gneisses, anorthosite and gabbro of Precambrian Grenville age, and Middle Ordovician limestone.