Phanerozoic paleogeology

Current geochemical cycling models do not account for changes in the spatial distribution of rock exposed to weathering through time. As a step in this direction, a new method of constructing paleogeologic maps has been developed, using published, global, depositional lithofacies maps. This technique identifies areas of erosion for a given interval of time, then systematically searches back through lithofacies maps of progressively older periods to determine the most probable type of rock being weathered during the interval. The relative proportions of exposed rock types through Phanerozoic time show few abrupt changes compared to the secular changes in the areal extent of the depositional lithologies. -from Authors