while no theory has been found that will replace it and is capable of explaining all the facts.”[1]
But in my opinion it is chiefly in regard to another problem that the contraction theory is forced to declare its complete bankruptcy, namely, the problem of the ocean basins and the continental blocks. A. Heim had already thrown a little light on this problem in the statement, “that until accurate observations on the continental oscillations of the past are made, … and until we have more complete measurements of the amounts of the average contraction of the majority of mountain ranges, scarcely any essential and certain progress in our knowledge of the causal connection between mountains and continents and the form of the latter in relation to one another can be expected.”[2] The problem becomes increasingly more urgent as the soundings of the seas of the earth become more numerous and the contrast between the extensive smooth surfaces of the oceans and the similar level surfaces of the continents, about 5 km. higher, becomes more sharply marked. E. Kayser[3] wrote in 1918:—
“Contrasted with the volume of these stone colossi (the continental blocks), all the elevations of the mainlands appear to be small and trifling. Even such high ranges as the Himalayas are only ripples, insignificant in altitude, on the surface of those pedestals. This fact already makes the old view, according to which the mountain chains form the constructive framework of the continents, appear nowadays as untenable. … The converse rather must be assumed, that the continents are the older and the determining factors, the
