A-In the Glorious Qur'an
Universe
Earth
Plant
Animals
Human Beings
Historical
Legislative
Educational
Medical
Understanding Islam
Embracing Islam
Signs of the Greatness of Allah
Prophets of Islam
Miscellaneous
Questions &Answers
New Muslims
B- In the Sunnah
Universe
Earth
Plant
Animals
Human Beings
Historical
Legislative
Educational
Medical
Understanding Islam
Embracing Islam
Signs of the Greatness of Allah
Prophets of Islam
Miscellaneous
Questions &Answers

"And the mountains He has fixed firmly, (To be) a provision and benefit for you and your cattle." (Surat An-Nazi'at (Those Who Pull Out): 32-33)

In these two Qur’anic verses it is explicitly stated that the stabilization of the Earth by means of its mountains was a specific stage in the long process of creation of our planet and still is a very important phenomenon in making that planet suitable for living. Now, the following question arises: how can modern Earth Scientists visualize mountains as means of fixation for the Earth? As mentioned above, the rocky outer cover of the Earth (the lithosphere, which is 65-70 km thick under oceans and 100-150 km thick under continents) is broken up by deep rift systems into separate plates (major, lesser and minor plates as well as micro plates, plate fragments and plate remains). Each of these rigid, outer, rocky covers of the Earth floats on the semi-molten, plastic outermost zone of the Earth’s Mantle (the asthenosphere) and move freely away from, past or towards adjacent plates. At the diverging boundary of each plate, molten magma rises and solidifies to form strips of new ocean floor, and at the opposite boundary (the converging boundary) the plate dives underneath the adjacent plate ‘(subducts) to be gradually consumed in the underlying uppermost mantle zone (the asthenosphere) at exactly the same rate of sea-floor spreading on the opposite boundary. An ideal rectangular, lithospheric plate would thus have one edge growing at a mid-oceanic rift zone (diverging boundary), the opposite edge being consumed into he asthenosphere of the over­riding plate (converging or subduction boundary) and the other two edges sliding past the edges of adjacent plates along transform faults (transcurrent or transform fault boundaries, sliding or gliding boundaries). In this way, the lithospheric plates are constantly shifting around the Earth, despite their rigidity, and as they are carrying continents with them, such continents are also constantly drifting away or towards each other. As a plate is forced under another plate and gets gradually consumed by melting, magmatic activity is set into action. More viscous magmas are intruded, while lighter and more fluid ones are extruded to form island arcs that eventually grow into continents, are plastered to the margins of nearby continents or are squeezed between two colliding continents. Traces of what is believed to have been former island-arcs are now detected along the margins and in the interiors of many of today’s continents (e.g. the Arabian Shield). The divergence and convergence of lithospheric plates are not confined to ocean basins, but are also active within continents and along their margins. This can be demonstrated, by both the Red Sea and the Gulf of California troughs which are extensions of oceanic rifts and are currently widening at the rate of 3cm/year in the former case and 6 cm/year in the latter. Again the collision of the Indian Plate with the Eurasian Plate (which is a valid example of continent/continent collision) has resulted in the formation of the Himalayan Chain, with the highest peaks currently found on the surface of the Earth. Earthquakes are common at all plates’ boundaries, but are most abundant and most destructive along the collisional ones. Throughout the length of the divergent plate boundary, earthquakes are shallow seated, but along the subduction zones, these come from shallow, intermediate and deep foci (down to a depth of 700 kin), accompanying the downward movement of the subducting plate below the over-riding one. Seismic events also take place at the plane’s transcurrent fault boundaries where ii slides past the adjacent plates along transform faults. Plate movements along fault planes do not occur continuously, but in interrupted, sudden jerks, which release accumulated strain. Moreover, it has to be mentioned that lithospheric plates do not all travel at the same speed, but this varies from one case to another. Where the plates are rapidly diverging, the extruding lava in the plane of divergence spreads out over a wide expanse of the ocean bottom and heaps up to form a broad mid-oceanic ridge, with gradually sloping sides (e.g. the East Pacific Rise). Contrary to this, slow divergence of plates gives time for the erupting lava flows to accumulate in much higher heaps, with steep crests (e.g. the Mid-Atlantic Ridge). The rates of plate movements away from their respective spreading centers can be easily calculated by measuring the distances of each pair of magnetic anomaly strips on both sides of the plane of spreading. Such strips can be easily identified and dated, the distance of each from its spreading center can be measured, and hence the average spreading rate can be calculated .Spreading rates at mid-oceanic ridges are usually given as half-rates, while plate velocities at trenches are full rates. This is simply because the rate at which one lithospheric plate moves away from its spreading center represents half the movement at that center as the full spreading rate is the velocity differential between the two diverging plates which were separated at the spreading center (the mid-oceanic ridge). In studying the pattern of motion of plates and plate boundaries, nothing is fixed, as all velocities are relative. Spreading rates vary from about 1 cm/year in the Arctic Ocean, to about 18cm/year in the Pacific Ocean, with the average being 4-5 cm/year. Apparently, the Pacific Ocean is now spreading almost ten times faster than the Atlantic (c.f. Dott and Batten, 1988). Rates of convergence between plates at oceanic trenches and mountain belts can be computed by vector addition of known plate rotations (Cf. Le Pichon, 1968). These can be as high as 9 cm/year at oceanic trenches and 6 cm/year along mountain belts (Le Pichon, op. c.i.t) Rates of slip along the transform fault boundaries of the lithospheric plate can also be calculated, once the rates of plate rotation are known. The patterns of magnetic anomaly strips and sediment thickness suggest that spreading patterns and velocities have been different in the past, and that activity along mid-oceanic ridges varies in both time and space. Consequently such ridges appear, migrate and disappear. Spreading from the Mid-Atlantic rift zone began between 200 and 150 MYBP, from the northwestern Indian Ocean rift zone between 100 and 80 MYBP, while bothAustralia and Antarctica did not separate until 65 MYBP (cf. Dott and Batten, bc. cit.). Volcanoes also abound at divergent boundaries, whether under the sea or on land. Most of these volcanoes have been active for a period of 20-30 million years or even more (e.g. the Canary Islands). During such long periods of activity, older volcanoes were gradually carried away from the spreading zone and its constantly renewed plate edge, until they became out of reach of the magma body that used to feed them and hence gradually faded out and died. The floor of the present-dayPacific Ocean is spudded with a large number of submerged, non-eruptive volcanic cones (guyots) that are believed to have come into being by a similar process.

 

1 -
The religion of Islam is growing faster than any other religion in the world.
Yes5431
I Think so2583
Not all410
No comment486
 

Fatal error: Call to undefined function session_is_registered() in /home/workspace2/public_html/elnaggarzr.com/en/footer.php on line 8