BIOSTRATIGRAPHIC AND PALEOBIOGEOGRAPHIC SIGNIFICANCE OF SOME AERONIAN(LOWER SILURIAN) GRAPTOLITES FROM THE ARISAIG GROUP,NOVA SCOTIA,CANADA

摘要

1 INTRODUCTIONThe Arisaig Group is a succession of sedimentary strata exposed along the northern coast ofAntigonish County,Nova Scotia (Text-fig.1)that spans almost the whole of the Silurian System.Although the history of stratigraphic and paleontologic study of these strata began in the mid-1800s and has continued through the last century(see Boucot et al.,1974),there have been no thorough biostratigraphic studies of the graptolite faunas.Berry (in Boucot et al.,1974) provided identifications of graptolites collected during mapping of the strata,but these were not placed in a detailed stratigraphic context.