>From memory, 35% is about the level that could be expected to result in spontaneous combustion of the biosphere. JimC Allan Edels wrote: > "Plate Techtonics and the Radiations/Extinctions of Dinosaurs, the Pele > Hypothesis" by Robert E. Sloan > Judith River Formation 75 mya 35% > Basal Hell Creek 70 mya 35% > Hell Creek (Maastrictian) 68 mya 35%