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

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
West of59°. With the exception of the higher mountain tops, no part of theUnited States is permanently too cold for vegetation; on the otherhand, there is no state which has not been visited by frost. So far as agriculture is concerned, it is important to know the timeof the first and last killing frosts of the year, for this gives the lengthof the growing season; and since every plant species requires a certainsum total of heat in order to complete its growth, the length of theseason will determine the type of product for each section. A studyof the map ^ (fig. 14) will show that the length of the growing seasonvaries considerably in different parts of the country. Thus the lastfrost to be expected at Phoenix, Arizona, is February 23, and the firstfrost of the fall is on December 3, making a growing season of almost 1 This map, as well as other climatic data used in this chapter, is based uponClimatology of the United States, issued by the Weather Bureau. 6o THE NATURAL ENVIRONMENT
Text Appearing After Image:
TOPOGRAPHY 6l ten months; while Augusta, Georgia, has a growing season of eightmonths (March 15 to November 15), central Vermont five months(May 15 to October 15), and North Dakota only four months (May 15to September 15). The mean annual rainfall varies from 2 inches to 105 inches, withextremes varying from 138 inches in Oregon to a mere trace of rainin the Salton desert. All of the region east of the looth meridianhas a good rainfall, and one which is favorably distributed throughoutthe year (§§ 121, 217). The great western-highland districts are de-ficient in precipitation, having less than 20 inches, an amount whichdecreases to 6—10 inches in Nevada, Utah, northern Arizona, andwestern Colorado, and reaches the extreme of 2 inches at the headof the Gulf of California. The soils of the United States include the great alluvial plains ofCalifornia and the Mississippi valley, the drained lake beds of Minne-sota (§ 43), the loess deposits of the Missouri valley (§ 72), and thearea

Note About Images