Stratigraphy of the mount potts group at Rocky Gully, Rangitata Valley, Canterbury*

Abstract

Abstract A fault‐bounded sequence of Middle and Upper Triassic rocks exposed on the east bank of the Clyde branch of the Rangitata River, Canterbury, constitutes the Mount Potts Group within the Torlesse Supergroup. Middle Triassic Kaihikuan marine fossils occur in about 5500 ft (1670 metres) of strata, Upper Triassic Oretian faunas including Halobia and Maoritrigonia occur in at least 150 ft (45 metres). The non‐marine plant beds of Tank Gully appear to underlie the marine sequence, and constitute the lowest formation of the group. Tank Gully, Nowhere, Erewhon, and Rocky Gully Formations are proposed as subdivisions of the group. Detailed stratigraphic sections are presented for some parts of the Mount Potts Group.