National Geographic : 1915 Sep
Photo by C. A. Harbaugh THE WARNING The splendid work of the U. S. Life Saving Service, now known as the Coast Guard, is familiar to all. During the night, winter and summer, in calm or in hurricane, or in case of stormy or foggy weather by day, a guard walks the beach between stations, ready to warn mariners too far inshore of the dangerous reefs by burning colored signals. bay. The Susquehanna River in those times flowed to the sea between Cape Charles and Cape Henry. The subsi dence of the valley let the sea-water in and drowned the Susquehanna out up as far as its present mouth. The Potomac River was then a tributary of the Sus quehanna, as were also the James and the Rappahannock. When we remember that subsidences and elevations of the land have been the rule and not the exception in the geolog ical history of the world, and that careful studies reveal the fact that they are still taking place, and when we further recall all of the shoreline changes that are go ing on and which have been recounted above, it becomes evident that the geog raphy of the earth is not a fixed one, and that while nature may change the bound aries of nations and empires more slowly than man himself is doing and has done, yet the process is going on with such vast and unmeasurable force that man is pow erless to resist it, and at the same time unable to perceive it unless he calls his tory to his aid and measures in centuries instead of years. The particular attention of the reader is directed to the photogravure series which follow. These unusually beauti ful studies were made by Mr. H. C. Mann, who takes rank with the foremost photographic artists in the country.