II. DEMONSTRATION
CHAPTER III
GEOPHYSICAL ARGUMENTS
The statistics of the contours of the earth’s crust lead to the remarkable result that there are two heights which occur most frequently, whilst the stages between them are quite rare. The higher stage corresponds to the continental platforms, the lower to the oceanic floor. If the whole surface of the earth be divided into square kilometres and these are arranged in a series according to their height above sea-level, the well-known diagram of the so-called hypsometric curve of the earth’s surface is obtained, which clearly shows these two steps. According to the most recent calculations of H. Wagner,[1] the frequency of the different levels is shown numerically in the following way:—
| Depth below sea. | Elevation above sea. | |||||||||||
| Below | 6 | 5–6 | 4–5 | 3–4 | 2–3 | 1–2 | 0–1 | | 0–1 | 1–2 | 2–3 | over 3 km. |
| 1.0 | 16.5 | 23.3 | 13.9 | 4.7 | 2.9 | 8.5 | 21.3 | 4.7 | 2.0 | 1.2 per cent. | ||
This series is best illustrated by another method based on the somewhat older, but only in unessentials
- ↑ H. Wagner, Lehrb. d. Geographie, vol. i., Allgemeine Erdkunde, Part 2: Physikal, p. 271. Hanover, 1922. The new survey of the oceans by Kossina (Die Tiefe des Weltmeeres, Veröff. d. Inst. f. Meereskunde, N.F.A., Part 9. Berlin, 1921) is taken into consideration in his figures. Our diagrams are taken, however, from the older but little different values of Krümmel and Trabert.
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