Page:Popular Science Monthly Volume 69.djvu/79

Rh Summing up, the evidence seems to warrant the following statements:

1. Since the beginning of Quaternary time there have been differential movements of uplift along fault planes on the San Francisco peninsula amounting in several cases to nearly or quite a mile and one half.

2. That these movements have been followed by subsidence and subsequent uplifts, involving sliding of several hundred feet along the older fault planes.

3. That these last movements are geologically of extremely recent date, that possibly a considerable part of these movements have come since the occupation by the Indians, and probably have continued to the present.

4. That some of the movements along the fault planes, geologically, in fairly recent times, seem to have produced more striking physiographic results than any produced the past spring.

5. That while the recent movement may have relieved the stress which the rocks were under to such an extent that it will be many years, or possibly centuries, before another such a disturbance will take place, on the other hand, a comparison of the few feet of motion in April with the hundreds of feet of movement that have taken place in very recent time suggests that fault adjustments of equal or greater violence are liable to occur at any time in the future. And since similar conditions are known to occur all over the Pacific Coast region, no place in that whole district can claim immunity.