The geology of Baton River

Abstract

The Devonian strata at Baton River, the Baton Formation, is mapped in detail and it is divided into seven members on fossil bands and lithology. So far the fossils have not provided any evidence that the age of the oldest member is significantly different from the youngest, Adjoining the Baton Formation to the north and west is the Ellis Formation containing graptolites and of Silurian or Ordovician in age. The contact between the formations is in part faulted and in part an angular unconformity. Igneous rocks intrude the eastern margin of the Baton Formation. The intrusive contact in so far as it can be defined is a fairly straight line that cuts across the bedding and the faults, and intrusion is considered to have taken place after the Baton Formation had been strongly deformed. Devonian faunas of Reefton and Baton River were supposed to be almost exactly the same age, Coblenzian, but the faunas have few species in common. The faunal difference has been attributed to facies differences but the Baton Formation includes facies similar to those at Reefton and the faunal difference is due to the probable Gedinnian age of the Baton Formation as against the Coblenzian age of the Reefton Formation.