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AMERICA

undermined by anxiety in Spain, died on 3rd November 1890) he died at Turin in the arms of his elder brother, 1876. Not until llth September 1888 did Amedeo con- King Humbert L, leaving four children—the duke of tract his second marriage with his niece, Princess Letitia Aosta, the count of Turin, the duke of the Abruzzi, and the Bonaparte. Less than two years later (18th January duke of Salemi. (h. w. s.)

AMERICA. THE historical accident that resulted in the use of a single name, America, for the pair of continents that has a greater extension from north to south than formation any other continuous land area of the globe, has had some justification in recent years, since geological opinion has begun to turn in favour of the theory of the tetrahedral deformation of the earth’s crust as affording explanation of the grouping of continents and oceans. America, broadening in the north as if to span the oceans by reaching to its neighbours on the east and west, tapering between vast oceans far to the south where the nearest land is in the little-known Antarctic regions, roughly presents the triangular outline that is to be expected from tetrahedral warping; and although greatly broken in the middle, and standing with the northern and southern parts out of a meridian line, America is nevertheless the best witness among the continents of to-day to the tetrahedral theory. There seems to be, however, not a unity but a duality in its plan of construction, for the two parts, North and South America, resemble each other not only in outline but, roughly speaking, in geological evolution also; and the resemblances thus discovered are the more remarkable when it is considered how extremely small is the probability that among all the possible combinations of ancient mountain systems, modern mountain systems, and plains, two continents out of five should present so many points of correspondence. Thus regarded, it becomes reasonable to suppose that North and South America have in a broad way been developed under a succession of somewhat similar strains in the earth’s crust, and that they are, in so far, favourable witnesses to the theory that there is something individual in the plan of continental growth. The chief points of correspondence between these two great land masses, besides the southward tapering, are as follows:—(1) The areas oi ancient fundamental rocks of the north-east (Laurentian highlands of North America, uplands of Guiana in South America), which have remained without significant deformation, although suffering various oscillations of level, since ancient geological times; (2) the highlands of the south-east (Appalachians and Brazilian highlands) with a north-east south-west crystalline axis near the ocean, followed by a belt of deformed and metamorphosed early Palaeozoic strata, and adjoined farther inland by a dissected plateau of nearly horizontal later Palaeozoic formations—all greatly denuded since the ancient deformation of the mountain axis, and seeming to owe their present altitude to broad uplifts of comparatively modern geological date; (3) the complex of younger mountains along the western side of the continents ( Western highlands, or Cordilleras, of North America: Andean Coi dilleras of South. America) of geologically modern deformation. and upheaval, with enclosed basins and abundant volcanic action, but each a system in itself, disconnected and not standing in alignment; (4) confluent lower lands between the highlands, giving river drainage to the north (Mackenzie, Orinoco), east (St Lawrence, Amazon), and south (Mississippi, La Plata). Differences of dimension and detail are numerous, but they do not suffice to mask what seems to be a resemblance in general plan. Indeed, some of the chief contrasts of the

two continents arise not so much from geological unlikeness as from their unsymmetrical situation with respect to the equator, whereby the northern one lies mostly in the temperate zone, while the southern one lies mostly in the torrid zone. North America is bathed in frigid waters around its broad northern shores; its mountains bear huge glaciers in the north-west; the outlying area of Greenland in the north-east is shrouded Avith ice; and in geologically recent times a vast ice-sheet has sjiread over its north-eastern third; while warm waters bring corals to its southern shores. South America has warm waters and corals on the north-east, and cold waters and glaciers only on its narrowing southern end. If the symmetry that is so noticeable in geological history had extended to climate as well, many geographical features might now present likenesses instead of contrasts. When America is compared with the continents of the Old World, an important correspondence is found between its northern member and the greater part of Eurasia ; but here the corresponding parts are reversed, right and left, like the two hands. The Laurentian highlands agree with Scandinavia and Finland, both having escaped deformation since very ancient times. A series of water bodies (the Great lakes in North America, the southern Baltic, with Onega, Ladoga, &c., in Europe) occupy depressions that are associated with the boundary between the very ancient lands and their less ancient covering strata. The old worn-down and re-eleated Appalachian mountains of south-eastern North America agree well with the Hercynian mountains of similar history in middle Europe (Ardennes, Slate mountains of the middle Bhine, Ac.), each range entering the Atlantic at one end (in Nova Scotia and Newfoundland; in Brittany, Wales, and Ireland), and dipping under younger formations at the other. Certain younger ranges—seldom recognized as mountains because they are mostly submerged in the American mediterraneans (Gulf of Mexico and Caribbean Sea), but of great absolute relief and with crests rising in the larger West Indian islands—may be compared with the younger ranges of southern Europe (Pyrenees, Alps, Caucasus) bordering the classic Mediterranean and the seas farther east. The. central plains of North America correspond well with the plains of Russia and western Siberia; both stretch from great enclosed water bodies on the south to the Arctic Ocean, and both are built of undisturbed Palaeozoic strata toAvard the axis of symmetry and of younger strata away from it. Finally, the Western highlands of North America may be compared with the great mountain complex of central and eastern Asia. In this remarkable succession of resemblances, we find one of the best proofs of the continental unity of Eurasia, however independently Europe and Asia should have been developed on a tetrahedral earth, and hoAvever fully the separation of these two grand divisions is demanded on historical and political grounds. Moreover, the resemblances thus described controvert the idea, prevalent Avhen geology was less advanced than to-day, that the New World of civilised discovery is an “old world” geologically, and that the Old World of history is geologically “ new.” Both worlds are so old, and both share so well the effects of successive geological changes from the most ancient to