
38 GEOGNOSY. | [Boox II. — 
general features. In elevations of the third or true mountain type, 
there may be either one line or range of heights, or a series of — 
parallel and often coalescent ranges. In the Western Territories 
of the United States, the vast plateau has been as it were wrinkled — 
by the uprise of long intermittent ridges, with broad plains and basins 
between them. Each of these forms an independent mountain range. — 
In the heart of Europe, the Bernese Oberland, the Pennine, Lepontine, © 
Rhaetic, and other ranges form one great Alpine chain or system. 
In a great mountain chain such as the Alps, Himalayas, or Andes, — 
there is one general persistent trend for the successive ridges. Here 
and there lateral offshoots may diverge, but the dominant direction of 
the axis of the main chain is generally observed by its component ridges 
until they disappear. Yet while the general parallelism is preserved, 
no single range may be traceable for more than a comparatively 
short distance ; it may be found to pass insensibly into another, while 
a third may be seen to begin on a slightly different line, and to 
continue with the same dominant trend until it in turn becomes 
confluent. ‘The various ranges are thus apt to assume an arrange- 
ment en échelon. | 
The ranges are separated by longitudinal valleys, that is, de- 
pressions coincident with the general direction of the chain. These, 
though sometimes of great length, are relatively of narrow width. 
The valley of the Rhéne, from the source of the river down to 
Martigny, offers an excellent example. By a second series of valleys 
the ranges are trenched, often to a great depth, and in a direction 
transverse to the general trend. The Rhéne furnishes also an example 
of one of these transverse valleys, in its course from Martigny to the 
Lake of Geneva. In most mountain regions the heads of two adjacent 
transverse valleys are connected by a depression or pass (col, joch). 
A large block of mountain ground, rising into one or more dominant 
summits, and more or less distinctly defined by longitudinal and trans- 
verse valleys, is termed in French a massif—a word for which there is 
no good English equivalent. Thus in the Swiss Alps we have the 
massifs of the Glarnisch, the Tédi, the Matterhorn, the J ungfrau, &e. 
Very exaggerated notions are common regarding the angle of 
declivity in mountains. Sections drawn across any mountain or 
mountain-chain on a true scale, that is, with the length and height on 
the same scale, bring out the fact that even in the loftiest mountains 
the breadth of base is always very much greater than the height. 
Actual vertical precipices are less frequent than is usually supposed, 
and even when they do occur, form but incidents in the general 
declivity of mountains. Angles of slope more than 30° are likewise 
far less abundant than casual tourists believe. yen such steep 
declivities as those of 38° or 40° are most frequently found as 
talus-slopes at the foot of crumbling cliffs, and represent the angle 
of repose of the disintegrated débris. Here and there, where the~ 
blocks loosened by weathering are of large size, they may accumulate 
upon each other in such a manner that for short distances the 
