large part of the Upper Cretaceous Period this region was the bottom of an inland sea which extended from the Gulf of Mexico to the Arctic Ocean, and divided eastern North America from the western portion. During the Tertiary Period the land was raised above the waters, and for a time possessed a much milder climate than at present. The Great Plains to-day form a vast barren tableland 4000 to 5000 feet in altitude, which is broken by numerous canyons, and dotted with buttes and isolated mountains. It is subject to great extremes of heat and cold, and to high winds. It is a treeless area, not because, like the prairies, it has a fine soil and a dense turf, but because of the aridity of the climate. Trees can not survive where the rainfall is less than 26 inches. Sagebrush, greasewood, and bunch grasses are the common forms of vegetation. Commercial beekeeping throughout the Great Plains is dependent on irrigated alfalfa and sweet clover. In the Dakotas, Nebraska, Kansas, and Oklahoma, alfalfa, when grown without irrigation, is only partially reliable; but the acreage of sweet clover in these states is reliable and very large, and is increasing every year. Probably 50 per cent, of the honey crop comes from this source in the Great Plains, which is destined to become a great sweet-clover belt. But in eastern Montana, Wyoming, Colorado, and New Mexico irrigated alfalfa seldom fails to yield a surplus of honey. The areas planted with alfalfa are described in detail under the different states.
6. The Rocky Mountain region comprises western Montana, eastern Idaho, western Wyoming, northeastern Utah, central Colorado, and north-central New Mexico. The summits of the mountains are bare of vegetation, but on the flanks are coniferous forests composed of pine, hemlock, and spruce. The aspen (Populus tremuloides) is a very common tree, and willows are abundant in the mountain meadows. In the northern Rocky Mountains, in the fertile valleys of western Montana and Wyoming, there are large areas under irrigation from the mountain streams, and alfalfa and sweet clover yield immense crops of honey. In the southern Rocky Mountains there is a much smaller number of colonies of bees. In the mountains the winters are long and severe and the snowfall heavy. Colonies dwindle greatly in size before spring, and a large part of the short summer has passed before they are strong enough to store a surplus. The native honey plants are not important, and large areas are covered with softwood forests. The Rocky Mountains were elevated to the height of 11,000 feet in comparatively recent times.
7. West of the Rocky Mountains and east of the towering Sierra Nevada Range is a vast desert region extending from northern Washington southward across the United States into Mexico. The northern portion of this arid area comprises the sagebrush plains of eastern Washington, the lava beds of eastern Oregon, the Snake River Desert of southern Idaho, western Colorado, Utah, and northern Nevada. There is no sod except along the streams, and probably nine-tenths of the vegetation is sagebrush. In the southern portion of this region, which includes southern Nevada, southeastern California, Arizona, New Mexico, and western Texas, as well as north-central Mexico, the heat becomes intense, and the annual rainfall decreases to a few inches, and sagebrush is replaced by cactus, yucca, and agave. The few streams vanish in the sands, or in “sinks,” or terminate in small saline lakes. There are areas of alkaline flats which are so highly charged with salts that they are bare of vegetation, or produce only greasewood and a few other plants. Except for the coniferous trees on the mountains and the mesquite forests in the south, the region is treeless. It is a desolate, forbidding country “where iron will not rust, tin tarnish, nor flesh mortify.” But millions of acres of this desert land are being reclaimed by the United States Reclamation Service and by state and private enterprises. On the great fields of irrigated alfalfa commercial beekeeping is a very reliable industry, and thousands of colonies of bees are operated by individuals or