File:Physical and commercial geography; a study of certain controlling conditions of commerce (1910) (14582000950).jpg

Identifier: physicalcommerci01greg (find matches)
Title: Physical and commercial geography; a study of certain controlling conditions of commerce
Year: 1910 (1910s)
Authors: Gregory, Herbert E. (Herbert Ernest), 1869-1952 Keller, Albert Galloway, 1874-1956, joint author Bishop, Avard Longley, 1875-1932, joint author
Subjects: Physical geography Commercial geography
Publisher: Boston, New York, Ginn and company
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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ted on the delta itself, an additional disadvantage is present,namely, that the main current may change, shifting its position in avery capricious manner. The outlet of the Hwang-ho, in 1888, was300 miles from its present mouth, and its frequent change of positionhas caused enormous destruction of life and property (§ 45). Typicalriver harbors are the ports of New Orleans (fig. 6), Portland (Oregon),Shanghai, and Calcutta. The Mississippi at New Orleans has a depth of water ample for thelargest steamships, and its navigable water connection with fifteen statesmakes its location of great commercial importance. However, in spiteof its great length and volume, the Mississippi had, in a natural state,a navigable depth over the delta of but 8 to 13 feet, a depth alto-gether inadequate for modern commerce. To remedy this defect Cap-tain Eads contracted, in 1875, to secure 30 feet of water way by asystem of jetties, which was designed to force the stream to remove 28 THE NATURAL ENVIRONMENT
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the sediment from its own bed. In this attempt he was successful,and for thirty years South Pass has been the commercial entranceto New Orleans. The new jetties in the Southwest Pass will secureeven greater depth of water and will shorten the route to Panamaand Central America. It is desirable that a Paciiic coast port be located at some place onthe lower Columbia River, for access to the interior by way of this OCEAN, COAST LINE, AND HARBOR 29 great river and its tributaries is better than by any otiier route eastwardfrom the Pacific. Appropriations have been made for the constructionof a 40-foot channel- across the bar at the mouth of the Columbia,with the idea that further dredging and training of the stream willproduce a satisfactory harbor at Portland, no miles from the sea. 31. Coral-reef harbors. Coral reefs, built by polyps where condi-tions of temperature are satisfactory, form excellent quiet-wateranchorages, particularly when the reef has the atoll form, — a ring ofcoral

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