The Appalachians; The Tethys Ocean basin; Greenland
The Appalachians from the Alps are broken however from continual glaciation, a recent development -- only some two million years old. The Alps form but a small portion of a great zone of crumpling mountain ranges that stretch in a series of curves from the Atlas Mountains to the Himalayas. Within this zone the crust of the earth has been ridged up into a complex system of creases or folds out of which the great mountain chains of southern Europe and Asia have been carved by atmospheric agencies. With continuity of the zone is broken intervals by gaps of greater or lesser extent to the subsidence of portions of the folded belt and their subsequent burial by more recent accumulations- between the Alps and the Carpathians. The Carpathians are separated from the Alps by the Danube. The river also separates them from the Stara Planina, or "Balkan Mountains", at Orsova, Romania.
| The Carpathians begin on the Danube near Bratislava. They surround Transcarpathia and Transylvania in a large semicircle, sweeping towards the south-west, and end on the Danube near Orsova, in Romania. The system attains its greatest breadth in the Transylvanian plateau, and in the meridian of the Tatra group the highest range, with Gerlachovský štít, at 2,655 m (8,705 feet) above sea level in Slovak territory. The Carpathians at their highest altitude are only as high as the Middle Region of the Alps, with which they share a common appearance, climate, and flora. The Danube river also separates them from the Stara Planina, or Balkan Mountains, at Orsova, Romania. The valley of the March and Oder separates the Carpathians from the Silesian and Moravian chains, which belong to the middle wing of the great Central Mountain System of Europe. Unlike the other wings of the system, the Carpathians, which form the watershed between the northern seas and the Black Sea, are surrounded on all sides by plains, namely the Pannonian plain on the south-west, the plain of the Lower Danube (Romania) on the south, and the Galician plain on the north-east. |  |
The Alps arose as a result of the pressure exerted on sediments of the Tethys Ocean basin as its Mesozoic and early Cenozoic strata were pushed against the stable Eurasian landmass by the northward-moving African landmass the Alpine Orogeny. Most of this occurred during the Oligocene and Miocene epochs from 23 mya before the present. The Miocene follows the Oligocene Epoch and is followed by the Pliocene Epoch. The Miocene is the first epoch of the Neogene period. The Neogene Period follows the Paleogene Period. The Neogene covers roughly 23 million years. During the Neogene mammals and birds evolved considerably. Most other forms were relatively unchanged. Some continental motion took place, the most significant event being the connection of North and South America in the late Pliocene. Climates cooled somewhat over the duration of the Neogene culminating in continental glaciations in the Quaternary Era that follows, and that saw the dawn of the genus Homo.
During the Eocene, the continents continued to drift toward their present positions. At the beginning of the period, Australia and Antarctica remained connected, and warm equatorial currents mixed with colder Antarctic waters, distributing the heat around the world and keeping global temperatures high. The northern supercontinent of Laurasia began to break up, as Europe, Greenland and North America drifted apart. In western North America, mountain building started in the Eocene, and huge lakes formed in the high flat basins among uplifts. In Europe, the Tethys Sea finally vanished, while the uplift of the Alps isolated its final remnant, the Mediterranean, and created another shallow sea with island archipelagos to the north. India continued its journey away from Africa and began its collision with Asia, folding the Himalayas into existence. It is hypothesized that the Eocene hothouse world was caused by runaway global warming from released methane clathrates deep in the oceans.
Greenland may have begun to have large glaciers as early as 7 to 8 million years ago, although the climate for the most part remained warm enough to support forests there well into the Pliocene. Continents continued to drift toward their present positions. Of the modern geologic features, only the land bridge between South America and North America was absent. Mountain building took place in Western North America and Europe. Both continental and marine Miocene deposits are common worldwide with marine outcrops common near modern shorelines. Well studied continental exposures occur in the American Great Plains and in Argentina.
Crystalline rocks, which are exposed in the higher central regions, are the rocks forming Mont Blanc, the Matterhorn, and high peaks in the Pennine Alps and Hohe Tauern. Pangea the supercontinent began to break apart in the later Paleozoic (Permian) times. Two main continents, Gondwana (southern) and Laurasia (northern), were slowly formed as a new ocean, the Tethys Ocean, opened in an East-West direction. After this, the Atlantic began to open (in a North-South direction), forming the Tethys Sea. These four continents would become present day North and South America, Eurasia and Africa. The break-up history of Pangea exemplifies dispersal of supercontinents under the process of Plate Tectonics.
At the present time, an oceanic basin similar to what the early Tethys Ocean may have been like is opening below the Red Sea, continuing down through Africa, forming the Rift Valley. Eventually, a new ocean will cut through east Africa, dividing a large section of land from the main continent. As the Tethys Ocean basin continued to widen and deepen, the elements of weathering were always at work on the surrounding landmasses. The effects of wind and water were able to chemically and mechanically erode and destroy the mountain ranges which we know were present on the earlier European continent. During the approximately 100 million years of open ocean, the rivers on the surrounding landmasses transported layers of mud, sand and gravel into the depths of the Tethys Ocean and formed compacted sediment layers several thousand meters in thickness. These same processes are continuing in our present oceans.
The connection between the great mountain ranges of Europe and Asia, we find that the Alps are formed frequently arranged en echelon. folds generally run in the direction of the chain, and together they form an arc around the plain of Lombardy and Piedmont. Outside this arc lies a depression along which the waters of the upper Danube and the lower Rhone find their way towards the sea; and beyond rise the ancient crystalline masses of Bohemia, the Black Forest and the central plateau of France, together with the intervening Mesozoic beds of southern Germany and the Jura. Beyond the depression also, excepting in the Jura Mountains, there is no sign of the folding which has raised the Alpine chain. Some of the older beds indeed are crumpled, but the folding is altogether different in age and in direction from that of the Alps. Within the crust of the earth, whether by the contraction of the interior or in any other way, tangential pressures were set up.