10 résultats pour "crustale"
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Valley.
Except in mountainous terrain, rivers are almost always flanked by floodplains. Floodplains are flat wide deposits of alluvium, river-deposited sediment, on either side of the river channel. During floods, a river overflows its banks and spreads out the sediment near the river to form a floodplain. Floodplains of large rivers, such as thoseof the Mississippi River, can be flat areas tens of kilometers across. River channels migrate back and forth across their floodplains as alluvium is repeate...
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Valley - Geography.
Except in mountainous terrain, rivers are almost always flanked by floodplains. Floodplains are flat wide deposits of alluvium, river-deposited sediment, on either side of the river channel. During floods, a river overflows its banks and spreads out the sediment near the river to form a floodplain. Floodplains of large rivers, such as thoseof the Mississippi River, can be flat areas tens of kilometers across. River channels migrate back and forth across their floodplains as alluvium is repeate...
- Frontières divergentes Dorsale médio-Atlantique Une dorsale est une chaîne sous-marine de volcans et de bassins faillés où s'effectue l'accrétion tectonique (production de matière crustale).
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Un regard sur l'évolution de l'homme
( exemple dans une chaîne où la collision a cessée, une érosion de 25cm du relief s’accompagne d’une remontée de la racine crustale la racine crustale de 20 cm. la racine crustale de 20 cm. II. Altération et érosion des reliefs : Altération physique : agent principal est l’eau conduit à la désagrégation des roches en fragments. (exemple de l’eau qui s’infiltre dans les diaclases et alternance de période de gel et de dégel qui font éclater la roche, racine des arbres) Joue un rôle mageu...
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Géologie: TP1 : Pétrologie crustale
TP1 : Pétrologie crustale Stratégie : Problématique : Comment expliquer cette distinction bimodale de la croute terrestre par l’étude des caractéristiques pétrologiques de roches de celle-ci? Hypothèse : Nous supposons que cette distinction bimodale de la croute terrestre peut s’expliquer par une composition atomique et minérale ainsi qu’une densité différente des roches la constituant. Protocole : Nous allons par des mesures et des observations déterminer les principales caractéris...
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Africa - history.
Africa’s other major mountainous regions occur at the northern and southern fringes of the continent. The Atlas Mountains, a system of high ranges, extend for 2,200 km(1,400 mi) across Morocco, Algeria, and Tunisia, roughly parallel to the northern coast. These ranges enclose a number of broad inland basins and plateaus. In the west, theHigh (or Grand) Atlas contains Toubkal (4,165 m/ 13,665 ft), the highest peak of the system. Toward the east, the Atlas consists of two parallel ranges: the Tell...
- Etude des caractéristiques de la lithosphère continentale
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Ice Ages.
B Future Ice Ages The record of previous glacial activity is the best indicator for future ice ages. Scientists examine the evidence for the numerous 100,000-year glacial-interglacial cycleswithin the present ice age to attempt a forecast of future ice ages. Since all previous ice ages lasted tens of millions of years, our present ice age will likely continue fora considerable amount of time. Each glaciation begins slowly and may take 80,000 years or more to reach its maximum extent. A rapid me...
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Earthquake.
III CAUSES Most earthquakes are caused by the sudden slip along geologic faults. The faults slip because of movement of the Earth’s tectonic plates. This concept is called theelastic rebound theory. The rocky tectonic plates move very slowly, floating on top of a weaker rocky layer. As the plates collide with each other or slide past eachother, pressure builds up within the rocky crust. Earthquakes occur when pressure within the crust increases slowly over hundreds of years and finally exceeds...
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Mars (planet) - astronomy.
The Martian core is probably much like Earth’s, consisting mostly of iron, with a small amount of nickel. If other light elements, particularly sulfur, exist there as well, thecore may be larger than presently thought. From studying Earth’s magnetic field and core, scientists theorize that the motions of the liquid rock in Earth’s core generateits magnetic field. Mars does not have a significant magnetic field, so scientists believe that Mars’s core is probably solid. However, spacecraft data in...