Which of the following does the passage imply about the "early classification of Alpine glaciation" ? A. It should not have been applied as widely as it was. B. It represents the best possible scientific practice, given the tools available at the time. C. It was a valuable tool, in its time, for measuring the length of the four periods of glaciation. D. It could be useful, but only as a general guide to the events of the Pleistocene epoch. E. It does not shed any light on the methods used at the time for investigating periods of glaciation.