The Silurian period

Abstract

SummaryRadiometric dates for the Silurian at present depend upon determinations on sediments. Available data suggest a time-span of up to about 50 m.y. for the Silurian period, with upper and lower limits of bout 390 m.y. and 440 m.y. Relations between graptolite zones and the time-scale imply a stratigraphical precision of about 1 m.y. Problems of international correlation are mentioned. The world maximum thickness of the system is estimated at about 70000 ft.