Stratotype Point Base of Early Devonian true IUGS Series A, 5, p. 96 109, 1977 within Bed 20 Location of Stratotype Point Base of Devonian Ratified 1972 Stratotype Point Base of Lower Devonian Stratotype Point Base of Devonian Klonk, near Prague, Czech Republic Stratotype Point Base of Lochkovian Stratotype Point Base of Lochkovian Graptolite FAD Monograptus uniformis