Discovery of staurolite zone Caradoc age brachiopods in the summer of 1970 on the west side of Penobscot Bay, Maine, is the third occurrence in the world of staurolite or higher grade, identifiable fossils.
These fossils are the first discovered from the lengthy belt of highly metamorphosed rocks belonging to the Penobscot Formation and will help to thoroughly revise the geology of a large region where age relations have previously been very uncertain. Age determination of rocks associated with the fossiliferous strata by the Rb-Sr whole rock method yields a 460 ± 10 m.y. isochron which is in good agreement with the paleontologic evidence.
The brachiopods belong to the Old World Province and are of European rather than North American aspect, thus having great biogeographic as well as paleogeographic significance.