blackfoot-valley

Certainly the all-time winter lows are extreme, which is why people remember them and love to talk about them. But extreme means just that - highly unusual - and most people experience record lows only once in a blue moon - in decades or a lifetime, if ever, and most cold snaps are nowhere near as severe as the all-time records. Granted, to most visitors from farther south, the Montana winter weather may seem extreme enough, but in com- parison, the Nevada / Blackfoot Valley offers sparkling clean air free of urban air pollution in all seasons, and lush green summers in which temperatures are not just agreeable, but free of oppressive hot weather. Considering the major elements shaping the character of the natural environment - climate, vegetation, soils - climate is the most basic and im- portant, because the kind of climate a region experiences basically deter- mines what kind of vegetation will prevail. The plant cover in turn largely determines what kind of soil will be formed. To be sure, underlying geologic processes such as regional uplift, subsidence, and volcanism stand apart from climate as gross shapers of landforms. They have produced the Rocky Moun- tains themselves, but even here climate plays a major role. The main agents of detail landform shaping - water and ice - which both erode material from slopes and deposit it elsewhere, are controlled by climate. We’ve already noted the conspicuous glacial moraines scattered around the Nevada / Black- foot Valley and on the Ranch which consist of material deposited by ice many thousands of years ago, not to mention the wholesale carving of the Scab- lands of eastern Washington by the repeated collapse of the ice dams that periodically held Lake Missoula. Ordinary water erosion, the slow and undra- matic wearing away of slopes, goes on continually of course, and the material taken away collects to build up lower leveler lands, a small-scale example of which we have noted in the stretch of flat land produced by the shifting chan- nels of meandering Nevada Creek and the Blackfoot River near Helmville. On a human time scale, then (rather than geologic processes that nor- mally operate much more slowly), the main shaper of the land is climate. To put the local region - and for that matter all of Montana and surrounding areas - in perspective, consider this question. Is Montana climatically unique in the world? In one sense, yes. Looked at in detail, all regions on earth are unique. But in environmental traits such as climate, vegetation, and all that derives from them that put their basic stamp on the land and human use, there are a limited number of basic types. Most climate classifications rec- ognize only twelve to fifteen or so major climatic groups in the world. Recall that the Nevada Valley area, in which the Ranch is located, is transitional in climate between humid continental and dry continental (other names have 39