Page:Popular Science Monthly Volume 9.djvu/744

716 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