UNITED STATES GEOLOGICAL SURYEY

THIRTEENTH ANNUAL REPORT OF THE

UNITED STATES GEoLOGICAL SuRVEY '1'0 THE

SECRETARY OF rrHE INTERIOR

1891-'92 BY

J. W. POWELL DIRECTOR

IN THREE PARTS

PART

II-GEOLOGY ·

WASHINGTON GOVERNMENT PRINTING OFJ!'ICE

1893

CONTENTS OF PART II. SECOND EXPEDITION TO MOUNT ST. Jy device:,; of r.m1struetion. The modem arts, informed by :,;cience, lu1ye made innumerable conquests in the domain of nature, but nowhere have these gains been more conspicuous than iu the construction and improvement of havens. Incidentally we shall have also to consider the physical conditions which favor or hinder the protection of our harbors from the attack of foreign naval forces. 'l'his is still an important, though, it is to be hoped, a diminishing clement in the economy of our ports. THE RELATION OF HARBORS TO THE DEVELOPMENT OF CIVILIZATION.

One of the most important steps which lead from the primitive savage state toward the ways of cultm·c and civilir.ation is taken when men contrive instruments of navigation. Almost all t·he peoples of the earth have accomplished this first stage of advance. Only a few inferior races are without devices in the way of boats. Although this art of navigation is itself a powerful instrument of culture, inasmuch as it teaches men to contrive and use tools, to face danger and to associate their action in a very edueative way, it was only slowly and rarely that they attained sufficient skill in the construction and management of boats to venture upon broad waters. Ships of considerable

• 6HAI.ER.)

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size, fit to undertake long voyages, appear to have been separately invented at several different points in the Old World-by the Scandinavians, by their kindred Aryans of the Mediterranea11 1 by the Chinese, and perhaps, separately, by the people of the Malay archipelago and of Hindostan. The Phrenicians and o~her Semitic people early acquired the art of constructing large boats, but whether by their own invention or by copying those of other people is uncertain. For a long time after seagoing ships were invented they were of sniall size; they an appear to have been without keel!:l and to have been propelled by oars, with only an occasional use of sails. Craft of tl1is sort were to a certain extent independent of harbors, or at least needed them only as landing-places, for it was a common custom to drag them on their flat bottoms up the surface of any smooth beach. In other words, they preserve1l the type of rowboats such as are normally used on inland waters. It was not. until about. two thousand years ago, when the use of ships for war purposes on the Mediterranean led to a great increase of their size, that vessels lost their amphibious character, became permanent denizens of the sea, and had to be sl1eltered in good harbors when they lay near land. After the invention of the keel, merchant ships gradually abandoned the use of oars for propulsion; they were increased in size, and so in time all commercial craft came to require the protection of harbors in receivjng or discharging cargoet