Popular Science Monthly/Volume 9/October 1876/Modern Scientific Geography
|MODERN SCIENTIFIC GEOGRAPHY.|
AMONG the various branches of natural science which have in recent times attained a high development, geography holds a prominent rank. By this, however, we must understand, not so much that vast regions of previously unexplored country have been made known to the educated world; that rivers, seas, and mountains, have been discovered, and the courses of known streams more accurately defined in maps; but rather that geotectonic data, of which a rich store has been collected, have been studied from broad and general points of view, and the individual phenomena ranged in the order of cause and effect. In earlier times geography was simply a catalogue of facts, and the earth's surface an ultimate datum; but nowadays we are beginning to regard the superficies of our planet as a result, to investigate the relations between its separate parts, and to note the changes which occur in it. In the words of Karl Patter: "Scientific geography by no means regards our planet as a lifeless, dead aggregate of an unorganized nature, or, as Herodotus expresses it, a disk turned on a lathe; but as a truly and specially organized body in steady process of development, bearing within itself the life-germs of further evolution. Herein consists its unity; and it is in virtue of this, its living principle, that it is a whole, lending itself to an orderly presentation and development of its great system. Furthermore, it is this which makes of it a science instructive to the human mind—an indispensable portion of the system of the sciences." True, even in this broad conception, Ritter conveys no adequate idea of what scientific geography is. His illustrious labors were restricted to a narrower field, and we may say that he worked only upon a part of the foundations
of the proud edifice which future ages will behold. Still, so far are we from wishing to discredit the important services rendered by this great geographer that we are free to confess that he achieved all that was possible in his day. Scientific geography is dependent upon a number of other sciences, and its progress is conditioned upon the development of these. No other science is so ill adapted as geography to advance independently and without external aid. When the astronomer aims at new applications of the theory of disturbance, or when the physicist studies the phenomena of polarization; when the chemist undertakes to break up combinations of elements, or the geologist investigates the relations subsisting between different strata, each of these investigators labors in his own province, almost entirely without reference to the progress made in other departments of science. But when, on the contrary, a traveler, like the enterprising Lieutenant Cameron, traverses broad continental regions over unexplored paths, the gain to scientific geography from such undertakings in great measure depends upon the development of astronomy, meteorology, geology, etc., inasmuch as it is by the aid of these sciences that we can discuss the observations that have been made, and turn them to account for ulterior conclusions. Then, too, we must not overlook those sciences which have to do with organic Nature and which' consider from higher points of view the distribution of living beings. Bearing all this in mind, we can readily perceive how intimate is the connection between geography and all the natural sciences. Hence it is that in earlier times the idea of scientific geography could hardly be entertained. At first geography offered little besides an imperfectly-arranged mass of descriptions of strange lands and curious things; next it gradually invaded the domain of statistical facts; then the relations of the history of man to the earth's configuration were recognized and elucidated; at last came scientific geography, which investigates the relations between the structure of the earth and the sum of all terrestrial phenomena, both organic and inorganic. The following instance will show the distinction between ordinary (descriptive) geography and scientific geography.
No inconsiderable part of the surface of terra firma consists of deserts, those vast, dry, and in part sandy regions, the type of which is the Sahara. The old descriptive geography gives the geographical situation of these wastes, their superficial extent, the number and site of their oases, the names of the mountain-regions which traverse them, and perhaps a few observations after the manner of anecdotes upon the intense heat which prevails in such regions, and the perils of a journey through the desert.
Scientific geography, on the other hand, regards these deserts as an integral part of the terrestrial organism, and shows how their occurrence is not accidental, but a necessary result of the past and present distribution of land and water, and of the position of the zone of calms. It exhibits to us the process of forming deserts still active, inasmuch as there exist centres of sand-radiation. It solves for us the enigma of the formation of springs in the oases, inasmuch as it rejects as unverified the asserted absolute rainlessness of the deserts, and in the precipitated meteoric water finds a sufficient supply for the wells of the low-lying oases. With the aid of meteorology it shows how one continent tends to reduce another to the condition of a desert; and, taking man into the sphere of its observations, it discusses the influence of the soil and the configuration of a region upon the course of culture-development therein, and even upon the development of peculiarities of speech. Scientific geography in this way vivifies the dead superficies of our planet, and gives to the conventional lines of a map the power of speaking a language that is understood by the educated mind.
The endeavor to meet the requirements of a higher geography is also to be seen in the better style of our modern maps. Thus, whereas in former times the seas were represented by blank spaces surrounding the land, now we have the results of soundings carefully represented, and the lines of equal depths, as they are more or less parallel to the present contours of the coast, supply to the geographer valuable data with respect to the formation of the land itself. On looking at the sketch of the Mediterranean Sea, in which various depths from fifty to five hundred fathoms are represented, the reader will perceive far more clearly than he could from the mere contour of the coasts that, not taking the Black Sea into account, the Mediterranean Sea proper consists of two great basins, viz., a western basin, extending from Gibraltar to Cape Bon and the southwestern extremity of Sicily, and an eastern basin extending thence to the coast of Syria. The shallow depth between Africa and Sicily, and especially the track of the hundred-fathom line, shown in our map by a dotted curve, prove that, at a time not very remote geologically, Africa and Europe were much nearer to one another than they are now, and that in the still remoter past the two continents were connected at this point. In all probability this union existed at a period when as yet the present southern shore of the eastern Mediterranean basin had not been upheaved, and the sea covered a portion of what is now the Sahara. French investigators have supposed that the most recent retreat of the sea was from the Syrtis Minor; nay, that even in historic times the great Algerian Chotts were directly connected with the Mediterranean as an arm of that sea. But this hypothesis is negatived by G. Stache's discovery of a stratum characterized by land and fresh-water-lulls, at the base of the Quaternary formations which constitute the coast of the Gulf of Gabes.
If we take up a geological chart, e. g., the beautiful "General Map of the Sedimentary Formations of Europe," by H. Habenicht, we find nothing that contradicts these conclusions. Thus the Eocene formations, which are widely diffused over the northern extremity of Africa, and especially in Tunis, occur again in the island of Sicily, while the southern and the southwestern portion of that island show the most recent Tertiary strata. These same strata form the coast of Syrtis Major, where yet the Mediterranean extends farthest southward, and where probably was situated the last channel through which water was supplied to the sea that once covered a portion of the Sahara. That here gradual upheavals of the land have taken place, each upheaval succeeded by a protracted season of repose, is shown by the terraces, the origin of which is so well known to the geologist. Gerhard Rohlfs found these terraces as he ascended the rising ground back of Tolmita, the ancient Ptolemais. He observes that these terraces are separated from one another by levels several miles in width.
But if, turning aside from these geological considerations, we again glance at our map of relative depths, we almost everywhere find that a flat coast accompanies a shallow sea; while, on the other hand, a mountainous coast implies a sudden and precipitous inclination of the neighboring sea-bottom. This would more plainly appear if our map were on a larger scale, and had a greater number of depth-curves for the purpose of comparison. This fact might be accounted for by supposing that the comparatively sudden upheaval of the coast-hills was connected with a considerable depression of the neighboring sea-bottom, while the slow and periodic sinking of the flatter portions gave rise to submarine terraces. But, aside from this hypothesis, the representation of graduated submarine depths has a significance not to be misunderstood in geological, zoölogical, and botanical investigations.
Turning now from the sea to the land, we find in our best modern maps a number of figures indicating, as accurately as possible, the elevations; nay, even the attempt has been made, in the magnificent atlas of Switzerland, to show the elevations by means of equidistant curves. The Lehmann method of representing the surface of a country with equidistant level-lines would be, in many respects, of the highest service for the study of the earth's surface, but as yet it can be practically employed only in individual cases, partly from the want of materials, partly also on account of technical difficulties.
Cartography is a powerful aid to scientific geography, inasmuch as it arranges in true projection a great mass of heterogeneous materials, bringing it before the eye within small space, and thus making apparent relations which else could hardly be noticed. As for political geography, viz., the description of the various empires of the world, their area, provinces, population, etc., this we would regard rather as a branch of statistics than of geography proper.—Gaea.
- Translated from the German by J. Fitzgerald, A.M.
- Relating to the earth's structure.
- "Von Tripolis nach Alexandrien," 1. Bd., S. 169.