First recognized in 1951 from aerial photographs, the crater
is a circular depression about two miles in diameter formed
in Precambrian crystalline rocks. Geophysical and diamond
drilling investigations show that the crater has a present
depth . . . — — Map (db m284109) HM
Early in 1951, John A. Roberts (president of Spartan Air Services
in Ottawa) was looking at high-altitude aerial photographs taken
by his company north of Brent and noticed an almost perfectly
circular feature about 3 kilometres . . . — — Map (db m284111) HM