108 NORTH AMERICA 



salmon- packing industry is very active. The lower 

 Frazer and Columbia valleys are extensively cultivated 

 for wheat. 



East of the Cascades, and closed in on all sides by 

 mountains, the plain of the lower Columbia River, 

 situated at a low level, is treeless, smooth, and grassy, 

 and recalls the Great Prairies: it is well irrigated by 

 a number of large rivers, and occupies the fertile bed 

 of a former lake. Such conditions offer quite ex- 

 ceptional opportunities for agriculture, and especially 

 for wheat-growing. In easy communication with the 

 Pacific ports, the Columbia plain is one of the most 

 natural and best-defined wheat areas that can be found 

 anywhere. All around its margins the foot-slopes of 

 the mountains are covered with woodlands of cotton- 

 wood and other winter-bare trees, while in the rear rise 

 the pine-clad upper hills. 



Beyond the Blue Mountains, which limit this plain on 

 the south, is a much more arid region in southern 

 Oregon and Idaho, and here begins the great semi-desert, 

 which stretches far into Mexico, and from the Sierra 

 Nevada to the Rocky chain. Its general level above 

 3,000 feet and its rainlessness render the climate 

 extreme and arid. The northern part is largely covered 

 with lava sheets, which have dammed up a number of 

 lakes and thus caused marshes. At the foot of the 

 Cascades lies a park landscape of meadows and wet 

 moors, girdled with forests of aspen, above which rise 

 pine- clad slopes, while the broken basalt tables remain 

 barren. Farther east, dreary plains follow with thin 

 brushes of ' sage ', a name which includes several kinds 

 of bushy, hoary, and stunted artemisias or wormwood, 

 and similar plants, with small, grey, woolly leaves. The 

 sage-brush constitutes the background of the vegetation 



