ON THE CHOICE OF TIMESCALE IN GLACIAL REBOUND MODELING - MANTLE VISCOSITY ESTIMATES AND THE RADIOCARBON TIMESCALE

Most glacial rebound studies have been carried out with respect to the radiocarbon timescale, whose departures from the calendar timescale a re becoming increasingly well established, In consequence, it has some times been argued that the choice of the radiocarbon timescale may inv alidate some of the conclusions drawn from rebound and sea-level analy ses. The purpose of this note is to compare rebound model results base d on both timescales, using the British Isles data for the test. The r esults indicate that the choice of timescale is unimportant provided t hat the time dimension of viscosity is appropriately defined. The resu lts confirm that the radiocarbon viscosities are about 15 per cent les s than the corresponding calendar-time viscosities. Also, provided tha t consistency of timescales is maintained in the analysis, and that th e time-accuracy estimates of the radiocarbon data reflect the departur es from a linear timescale, the use of the radiocarbon timescale does not impinge on inferences drawn about the timing of melting of ice she ets or eustatic sea-level change.