Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/53

Rh different, figures of Trabert, given in Fig. 5. It is applied to stages of 100 m., so that the percentages are naturally only about one-tenth of those given above. According to this, the maxima lie at a depth of about 4,700 m. and at an elevation of about 100 m.

These figures draw attention to the fact that the increase of the number of soundings always shows an increase in the steepness of the declivity from the margin of the continent or shelf. This is emphasized

by any comparison of older ocean charts with the most recent one taken from Groll. For example, whilst Trabert gives, even in 1911, 4.0 per cent. for the stage 1 to 2 km., and for the 2 to 3 km. 6.5 per cent., we find that Wagner, whose figures are based ultimately on Groll’s chart, gives for the same distances only 2.9 and 4.7 per cent. respectively. Thus it is