Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/211

an anvil-shaped form by the frontal resistance of the sima, and the peninsula seems as a whole to be much shortened, as is shown by a comparison with the outlines of the Gulf of California. According to Böse and Wittich,^[1] the most northerly portion has only recently been elevated out of the sea and that to an amount of as much as 2000 m. a clear sign of strong compression.
Fig. 41.—California and the earthquake fault of San Francisco. From the contours it can scarcely be doubted that the southern point actually lay in former times in the notch of the Mexican coast which is in front of it. The geological maps show that at both places post-Cambrian intrusive rocks exist, the identity of which has however not yet been demonstrated.

But besides the shortening of the peninsula itself, there appears to be a sliding towards the north^[2] in which the coastal chains immediately to the north also take part. The great bulge of the coast-line near San Francisco is explained in this manner by compression. This idea is confirmed in a striking way

1. Short communication from E. Böse. The paper is to be found in the Parergones del Instituto Geologico de Mexico.
2. Or a lag of the peninsula in respect of a southerly movement of the mainland relatively to the sima.