Fig. 1 Upper part of the c.300m logged section from Namling indicating the stratigraphical position and ages of key dated samples. The age of deposition is determined from sanidine feldspar in a volcanogenic sediment lying immediately below locality A (MW12), and from phlogopite micas extracted from a potassic lava succession that overlies it (MW8). Since both ages are within error it is probable that the plant-bearing succession was deposited over a very short period of time at c.15 Ma. All analyses were performed on mineral separates using the 40Ar-39Ar laser step-heating technique at the Open University.