ABSTRACT

The Lower Palaeozoic rocks of northeastern British Columbia occurring in the Rocky Mountains between latitudes 56 and 57 degrees north include strata of Cambrian, Ordovician, Silurian and Devonian ages. Only a part of the Silurian System appears to be represented and Lower Devonian beds have not been recognized. A succession of barren, sandy dolomite lying stratigraphically above known Lower Silurian strata may be either of Silurian or Devonian age.

The strata described consist, mainly, of dolomite and limestone with lesser amounts of interbedded sandstone, siltstone and shale.

Evidence is presented which suggests that in the north-western part of the area a facies change occurs near the Ordovician-Silurian boundary from carbonate to black, graptolitic shale and that in the same general region, there is an east-west change from carbonate to shale within the Middle Devonian succession.

Unconformities probably occur between the Ordovician and Silurian successions and, also, between the fossiliferous, Lower Silurian strata and the overlying, barren dolomite beds.