My name is Steve LeMaster, Professor Robert M. Schoch's webmaster and moderator. I am not quite sure if I am posting my query in the right place, so please forgive me if I am. Dr. Schoch is a geologist at Boston University and he has told me that geologists do not know at what rate rock erodes. Can anyone give me the various methods used in ascertaining dates of rock erosion? Or is this just pure speculation? He is a very busy man and has yet to answer my question.