CompuServe Messages

Hi, Kamron– The geologists had worked out a basic time table before radioactivity was discovered. They had sufficient confidence in these estimates that they argued vigorously against Earth/Sun creation dates figured by the physicists near the turn of the century, led by Lord Kelvin. Assuming gravitational contraction was the major source of heat, the physicists dated both Earth and Sun as about 100 million years old. But as radioactivity was studied, it was appreciated as a heat souce that kept Earth warm more than contraction could, and as indicating an energy source for the Sun beyond contraction also. Radioactive isotope dating eventually confirmed the broad outlines of the geologists' time tables, giving them greater precision, but within the uncertainty limits of the old estimates. I am not sure of all the methods used, but I am sure observed sedimentation rates had a big play in those old datings. –Doug