. Bulletin of the Department of Geology of the University of California. 2IO University of California. [Vol. 2. On a rising coast, where the subaerial and submarine slopes are at a high angle, and the cliffs correspondingly high, the compara- tively narrow terraces formed are more rapidly obliterated through marine abrasion, after uplift, than in the case of a low angle of subaerial and submarine slope, and correspondingly low cliffs, with the resulting broader platforms, provided other factors are the same in both instances. This may be illustrated by the following example. Given two cliffs s
. Bulletin of the Department of Geology of the University of California. 2IO University of California. [Vol. 2. On a rising coast, where the subaerial and submarine slopes are at a high angle, and the cliffs correspondingly high, the compara- tively narrow terraces formed are more rapidly obliterated through marine abrasion, after uplift, than in the case of a low angle of subaerial and submarine slope, and correspondingly low cliffs, with the resulting broader platforms, provided other factors are the same in both instances. This may be illustrated by the following example. Given two cliffs such that the ratio of the volumes of the material cut in the two cases, for every horizontal foot cut back, along a given length of coast line, is as one to five. This ratio will be given by slopes with a rise of ten feet and fifty feet, respectively, in every hundred feet—corresponding to angles of 5° \2' 38" and 260 33' 54" (angles A' C D' and ACD in figure 3).. Figure 3. To simplify the conditions of the problem, the cutting may be assumed to be in homogeneous rocks, and all other factors except slope (such as character of rocks, fetch of the waves, strength and character of the off-shore currents, etc.) may be considered as the same in the two cases. Further, we may neglect the fact that the sea cliffs are not perpendicular, and also the amount of coastal detritus deposited on the submarine slopes beyond the platform cut by the waves, since neither of these factors (uncertain in any case) would materially affect the general result. Since, at the outset, with the sea-level C'B'—CB, the submarine slope CD is the steeper, the waves will be longer in making an active start in cliff cutting than on the slope A'C'D'. Although this difference is an important one, it may be set aside for the present, as it will be taken into account later. Considering, then, that in a prolonged period of wave cutting, equal volumes are removed in a given time in the two cases, it fol
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