Toarcian (early Jurassic) Ammonoids From Western North America (bulletin)

Toarcian (Early Jurassic) strata in the Queen Charlotte Islands have yielded a well-preserved and diverse ammonite fauna that provides a framework for a regional ammonite zonation for western North America described in this report. Other localities, particularly in southern Alaska and north- western British Columbia, have provided additional material contributing to the development of this zonation, which is of prime importance in determining the age of sedimentary strata and the relative timing of tectonic events. The report describes the biostratigraphy of the five western North American Toarcian ammonite zones, the occurrence and stratigraphy of Toarcian fossil occurrences in the western Cordillera, Pacific Northwest, and Queen Charlotte Islands, and biostratigraphic correlations with other areas including Europe. Systematic paleontological descriptions are provided of fossil ammonoids. The appendix includes fossil specimen locality data