Page:The New International Encyclopædia 1st ed. v. 05.djvu/406

* CONTINENT. 346 CONTINENTAL SYSTEM. in common. Usually the regions of greatest elevation are found in the interior, while along the coast line there is a gentle slope outward which, continued beneath the sea, forms a slightly submerged land strip called the 'continental shelf.' On the seaward edge of the shelf the slope is very rapid down to the great depths of the sea. Tlie average altitude of the continents, according to the calculations of Lapparent, Mur- ray, Penck, Supan, and Heiderich, is shown below : Estimated Avehagb Elevations op the Continents COSTISENT 1 'Z •3 958 2,883 2,007 1,188 1,953 1,762 938 3,188 2,020 803 1,88B 2,077 918 3, 111) 2,132 918 1.968 2, 0117 931 3,084 2,034 853 2,001 2,001 1,230 3,018 frica 1,975 Australia North America.... South America.... 1.542 2.723 2,493 Between the form and distribution of the con- tinents many interesting comparisons may be drawn. The two Americas, comprising the greater part of the land area in the New World, are triangular in shape, the apex of the one lying in the Isthmus of Panama and the apex of the other being represented by Cape Horn. Both continents are bounded on the west by a long mountain system and both have a region of lower elevation in the eastern portion. The Old World, on the other hand, is composed of a sin- gle triangular land area which has its base on the Arctic Sea and its apex at the Cape of Good Hope. Here the main trend of the moim- tain chains is east and west. In general, the continents that extend into or lie within the Southern Hemisphere — South America, Africa, and Australia — are most regular, contrasting strongly in this particular with North America and Eurasia in the Northern Hemisphere. The northern continents have a wider extension from east to west than the southern, and are further characterized by a great group of islands lying along the southeastern coast. That the great land areas are not stable either as to form or elevation may be regarded as established beyond doubt by geological evidence. Moreover, certain coastal regions are known at the present time to be undergoing changes of level by which land emerges above or sinks below the sea. The extent of these oscillations in past ages can only be conjectured. Lyell's theory that there lias been a constant interchange be- tween the land and water areas lias been ob- jected to on the ground that there is no evidence that the abysmal de])ths of the ocean have ever been elevated; this objection has been weakened, however, by the discovery within continental areas of deposits abysmal in character and contain- ing a deep-sea fauna. The changes of level be- tween the land and the sea take place very slowly, and may be caused either by gradual vertical movement of the land area or bj- varia- tions in the level of the ocean itself. Geologists generally agree that the positions of the present continents were determined as far back as Archa>an times. TheLaurentian plateau of North America, the Brazilian higliUuids of South Amer- ica, and the Scandinavian peninsula and Lap- land in Europe are compo.sed of crystalline rocks, and except on the margins the} are bare of all sediments. These primitive lands were extended in area by the deposition of sedimen- tary strata on their borders, and by great up- heavals accompanied by foldings of the crust into mountain ranges. The evolution of the continental lands can be studied only tentatively, and is largely con- jectured from the evidence aft'orded by the char- acters of the fauna and flora that lived in past ages. During the Cretaceous and Tertiary times the animal and plant life of South America, South Africa, and India were strikingly similar, while there was also a uniformity between the life-forms of Europe and North America. This circumstance can best be explained by the as- sumption that in these periods the continents had an east and west trend, so that Brazil, Cen- tral Africa, and Lower India were united by one broad land-strip, and eastern Canada with Europe by another. Between the northern and southern continents an ocean basin extended from the isthmus of Central America eastward to the Indian Ocean, or nearly at right angles to the basin now occupied by the Atlantic. The changes by which the continents assumed their present form took place gradually and were accomplished by a slow depression of portions of the land and by encroachment of the sea. It is probable that certain regions for a long time remained above sea-level as large islands, the luisubmerged remnants of which still exist, for example, in the Cape Verde and Canary islands, in the British Isles, and in ^ladagascar. These changes were doubtless completed before the ap- pear.ance of mankind: at least within historical times, so far as is known, thei-e has been no marked alteration in the form of the continents. BiBLiOGRArnr. Suess. Das Aiitlitz der Erde '(Leipzig, 18S.5-1900) : Neumayr. Erdgeschichte (Leipzig, 1895) ; Mill, The Renhn of Satiire (New York, 1895) ; Mill, The International Geography (New York, 1900). See Geolocv; Geooraphy; America; Europe; Asia; Afric.v; austr.lia. CONTINENTAL CONGRESS. See United States. CONTINENTAL SYSTEM. The name given to the conunercial policy adopted by Napoleon for the purpose of shutting England out from all connection vith the Continent of Europe, and thus compelling lier to acknowledge the maritime law as established at the Peace of L'treeht. This system began with Napoleon's famous Ber- lin Decree of November 21, 180G, which declared the British Isles in a state of lilockade and prohibited all commerce nr correspondence with them ; every Englishman found in a coimtry oc- cupied by French troops or by their allies was declared a prisoner of war; all merchandise be- longing to an Englishman was made lawful prize; and all trade in English goods was entirely pro- hibited. No ship coaming directly from England, or from a British colony, was allowed to enter any port; and any ship seeking by false declara- tions to evade tliis re,gulation was confiscated with its cargo as if British property. England was not long in making reprisals. B.v an Order in Council. .Tanuary 7." 1807. all neutral vessels were prohibited from trading from port to port within France or any country in alliance with it or under its control. Every neutral ves-