Influences of Geographic Environment - Ellen Churchill Semple (libby ebook reader .TXT) 📗
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Submarine reliefs have yet greater significance in their relation to the distribution of the human race over the whole earth; for what is now a shallow sea may in geologically recent times have been dry land, on which primitive man crossed from continent to continent. It is vital to the theory of the Asiatic origin of the American Indian that in Miocene times a land bridge spanned the present shallows of Bering Sea. Hence the slight depth of this basin has the same bio-geographical significance as that of the British seas, the waters of the Malay Archipelago, and the Melanesian submarine platform. The impressive fact about "Wallace's Line" is the depth of the narrow channel which it follows through Lombok and Macassar Straits and which, in recent geological times, defined the southeastern shore of Asia. In all these questions of former land connection, anthropo-geography follows the lead of bio-geography, whose deductions, based upon the dispersal of countless plant and animal forms, point to the paths of human distribution.
The mean elevation of the continents above sea level indicates the average life conditions of their populations as dependent upon relief. The 1010 meters (3313 feet) of Asia indicate its predominant highland character. The 330 meters (1080 feet) representing the average height of Europe, and the 310 meters (1016 feet) of Australia indicate the preponderance of lowlands. Nevertheless, anthropo-geography rarely lends itself to a mathematical statement of physical conditions. Such a statement only obscures the facts. The 660 meters (2164 feet) mean elevation of Africa indicates a relief higher than Europe, but gives no hint of the plateau character of the Dark Continent, in which lowlands and mountains are practically negligible features; while the almost identical figure (650 meters or 2133 feet) for both North and South America is the average derived from extensive lowlands in close juxtaposition to high plateaus capped by lofty mountain ranges. Such mathematical generalizations indicate the general mass of the continental upheaval, but not the way this mass is divided into low and high reliefs.1026
The method of anthropo-geography is essentially analytical, and therefore finds little use for general orometric statements, which may be valuable to the science of geo-morphology with its radically different standpoint. For instance, geo-morphology may calculate from all the dips and gaps in the crest of a mountain range the average height of its passes, Anthropo-geography, on the other hand, distinguishes between the various passes according as they open lines of greater or less resistance to the historical movement across the mountain barriers. It finds that one deep breach in the mountain wall, like the Mohawk Depression1027 and Cumberland Gap in the Appalachian system,1028 Truckee Pass in the Sierra Nevada1029 and the Brenner in the Alps,1030 has more far-reaching and persistent historical consequences than a dozen high-laid passes that only notch the crest. Pack-trail, road and railroad seek the former, avoid the latter; one draws from a wide radius, while the other serves a restricted local need. Therefore anthropo-geography, instead of clumping the passes, sorts them out, and notes different relations in each.
In continents and countries the anthropo-geographer looks to see not what reliefs are present, but how they are distributed; whether highlands and lowlands appear in unbroken masses as in Asia, or alternate in close succession as in western Europe; whether the transition from one to the other is abrupt as in western South America, or gradual as in the United States. A simple and massive land structure lends the same trait of the simple and massive to every kind of historical movement, because it collects the people into large groups and starts them moving in broad streams, as it were. This fact explains the historical preponderance of lowland peoples and especially of steppe nomads over the small, scattered groups inhabiting isolated mountain valleys. The island of Great Britain illustrates the same principle on a small scale in the turbid, dismembered history of independent Scotland, with its Highlanders and Lowlanders, its tribes and clans separated by mountains, gorges, straits, and fiords,1031 in contrast to the smoother, unified course of history in the more uniform England. Carl Ritter compares the dull uniformity of historical development and relief in Africa with the variegated assemblage of highlands and lowlands, nations and peoples, primitive societies and civilized states in the more stimulating environment of Asia.1032
The chief features of mountain relief reappear on a large scale in the continents, which are simply big areas of upheaval lifted above sea level. The continents show therefore homologous regions of lowlands, uplands, plateaus and mountains, each district sustaining definite relations to the natural terrace above or below it, and displaying a history corresponding to that of its counterpart in some distant part of the world, due to a similarity of relations. This appears first in a specialization of products in each tier and hence in more or less economic interdependence, especially where civilization is advanced. The tendency of conquest to unite such obviously complementary districts is persistent. Hence the Central Highland of Asia is fringed with low peripheral lands like Manchuria, China, India and Mesopotamia, into whose history it has repeatedly entered as a disturbing force. All the narrow Pacific districts of the Americas from Alaska to Patagonia are separated by the Cordilleras from the lowlands on the Atlantic face of the continents; all reveal in their history the common handicap arising from an overwhelming preponderance of plateau and mountain and a paucity of lowlands. Colombia, Ecuador and Peru have in the past century been stretching out their hands eastward to grasp sections of the bordering Amazon lowlands, where to-day is the world's great field of conflicting boundary claims. Chile would follow its geographical destiny if it should supplement its high, serrated surface by the plateaus and lowlands of Bolivia, as Cyrus the Persian married the Plateau of Iran to the plains of the Tigris and Euphrates, and Romulus joined the Alban hills to the alluvial fields of the Tiber.
Well-watered lowlands invite expansion, ethnic, commercial and political. In them the whole range of historical movements meet few obstacles beyond the waters gathering in their runnels and the forests nourished in their rich soils. Limited to 200 meters (660 feet) elevation, lowlands develop no surface features beyond low hills and undulating swells of land. Uniformity of life conditions, monotony of climate as of relief, except where grades of latitude intervene to chill or heat, an absence of natural boundaries, and constant encouragement to intercourse, are the anthropo-geographic traits of lowlands, as opposed to the arresting, detaining grasp of mountains and highland valleys. Small, isolated lowlands, like the mountain-rimmed plains of Greece and the Aegean coast of Asia Minor, the Nile flood-plain, Portugal, and Andalusia in Spain, may achieve precocious and short-lived historical importance, owing to the fertility of their alluvial soils, their character as naturally defined districts, and their advantageous maritime location; but while in these restricted lowlands the telling feature has been their barrier boundaries of desert, mountains and sea, the vast level plains of the earth have found their distinctive and lasting historical importance in the fact of their large and unbounded surface.
Such plains have been both source and recipient of every form of historical movement. Owing to their prevailing fitness for agriculture, trade and intercourse, they are favored regions for the final massing of a sedentary population. The areas of greatest density of population in the world, harboring 150 or more to the square kilometer (385 to the square mile), are found in the lowlands of China, the alluvial plains of India, and similar level stretches in the Neapolitan plain and Po Valley, the lowlands of France, Germany, Holland, Belgium, England and Scotland. Such a density is found in upland districts (660 to 2000 feet, or 200 to 600 meters) bordering agricultural lowlands, only where industries based upon mineral wealth cause a concentration of population. [See maps pages 8, 9, 559.]
The level or undulating surface of extensive lowlands is not favorable to the early development of civilization. Not only do their wide extent and absence of barriers postpone the transition from nomadism to sedentary life, but their lack of contrasting environments and contrasted developments, which supplement and stimulate, puts chains upon progress. A flat, monotonous relief produces a monotonous existence, necessarily one-sided, needing a complement in upland or mountain. To the pioneer settlers in the lowlands of Missouri the Ozark Plateau was a boon, because its streams furnished water-power for much needed saw and flour mills. Treeless Egypt even before 2500 B. C. depended upon the cedars of the Lebanon Mountains for the construction of its ships; so that the conquest of Lebanon, begun by Thutmose I. and completed by Thutmose III. in about 1470 B. C., had a sound geographical basis.1033 Similarly the exploitation of the copper, malachite, turquoise and lapis-lazuli of Mount Sinai, minerals not found in the Nile plain, led the ancient Egyptians into extensive mining operations there before 3000 B. C., and resulted in the establishment of Egyptian political supremacy in 2900 B. C., as a measure to protect the mines against the depredations of the neighboring Bedouin tribes.1034 Lowlands lack the distinctive advantages of highlands found in diversity of climate, water-power, generally in more abundant forests and minerals. The latter are earlier discovered and worked in the tilted strata of mountains and uplands.
Plain countries suffer particularly from a paucity of varied geographic conditions and of resulting contrasts in their population. Their national characters tend to be less richly endowed; their possibilities for development are blighted or retarded, because even racial differences are rapidly obliterated in the uniform geographic environment, A small diversified country like Crete, Great Britain, Italy, Portugal, Saxony, or Japan, is a geographical multum in parvo. The western half of Europe bears the same stamp, endowing each country and nation with marked individuality born of partial isolation and a varied combination of environment. The larger eastern half of the continent embraced in the plains of Poland and Russia shows monotony in every aspect of human life. This comes out anthropologically in the striking similarity of head-form found everywhere north and east of the Carpathian Mountains, except in the secluded districts of Lithuania and Crimea, which shelter remnants of distinct races. Over all this vast territory the range of cephalic variation is only five units or one-third that in the restricted but diversified territory of western Europe. Italy, only one-eighteenth the size of European Russia, has a range of fifteen units, reflecting in the variety of its human types the diversity of its environment.1035
In the plains geography makes for fusion. Russia shows this marked homogeneity, despite a motley collection of race ingredients which have entered into the make-up of the Russian people. Without boundary or barrier, the country has stood wide open to invasion; but the intruders found no secluded corners where they could entrench themselves and preserve their national individuality.
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