I assume that I am expected to bring forward whatever ideas will, in my opinion, help most at the present time in the development of a study of isostasy by stimulating further thinking along that line. From among the many topics which might be treated, I am selecting three:(1) I shall make some remarks on the recent paper entitled “The Chemistry of the Earth's Crust,” by H. S. Washington.(2) I shall try to emphasize the desirability of an intensive study of two small areas by observations of gravity and deflections of the vertical.(3) I shall offer some considerations that lead me to believe that the undertow involved in isostatic readjustment is above, rather than below, the depth of compensat