The Holleford meteorite crater is about 20 miles northwest of Kingston, Ontario. It forms a circular structural depression 1.46 miles in diameter and about 950 ft deep. It is filled by sedimentary rocks of Late Proterozoic and Early Paleozoic age with a maximum thickness of 850 ft.The rocks of this section and the polymictic breccia underlying them have been divided into seven lithic units. The bulk of the sequence consists of microlaminated calcareous quartz arenites with lesser amounts of argillaceous and carbonaceous material. These arenites are unlike any rocks found locally outside the crater. They are overlain by carbonates and shales of the Black River Group with apparent unconformity.The origin postulated for the arenite sequence in the crater is a Late Proterozoic or Early Paleozoic fresh-water lake. This lake existed in a subtropical to temperate climate and only rarely froze over. It is probable that it was meromictic for part of its existence, but later became holomictic.Later compaction of the underlying breccias and the paleolacustrine arenites formed a shallow structural basin in the Black River carbonates.