reading comp practise 2 : GMAT Verbal Section
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 22 Jan 2017, 04:58

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

Author Message
Manager
Joined: 05 Oct 2005
Posts: 200
Followers: 1

Kudos [?]: 7 [0], given: 0

### Show Tags

13 Nov 2005, 15:17
hello
here it is ! A long one!
thanks

No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional view supposes that the upper mantle of the earth behaves as a liquid when it is subjected to small forces for long periods and that differences in temperature under oceans and continents are sufficient to produce convection in the mantle of the earth with rising convection currents under the mid-ocean ridges and sinking currents under the continents. Theoretically, this convection would carry the continental plates along as though they were on a conveyor belt and would provide the forces needed to produce the split that occurs along the ridge. This view may be correct: it has the advantage that the currents are driven by temperature differences that themselves depend on the position of the continents. Such a back-coupling, in which the position of the moving plate has an impact on the forces that move it, could produce complicated and varying motions.
On the other hand, the theory is implausible because convection does not normally occur along lines, and it certainly does not occur along lines broken by frequent offsets or changes in direction, as the ridge is. Also it is difficult to see how the theory applies to the plate between the Mid-Atlantic Ridge and the ridge in the Indian Ocean. This plate is growing on both sides, and since there is no intermediate trench, the two ridges must be moving apart. It would be odd if the rising convection currents kept exact pace with them. An alternative theory is that the sinking part of the plate, which is denser than the hotter surrounding mantle, pulls the rest of the plate after it. Again it is difficult to see how this applies to the ridge in the South Atlantic, where neither the African nor the American plate has a sinking part.
Another possibility is that the sinking plate cools the neighboring mantle and produces convection currents that move the plates. This last theory is attractive because it gives some hope of explaining the enclosed seas, such as the Sea of Japan. These seas have a typical oceanic floor, except that the floor is overlaid by several kilometers of sediment. Their floors have probably been sinking for long periods. It seems possible that a sinking current of cooled mantle material on the upper side of the plate might be the cause of such deep basins. The enclosed seas are an important feature of the earthâ€™s surface, and seriously require explanation because, in addition to the enclosed seas that are developing at present behind island arcs, there are a number of older ones of possibly similar origin, such as the Gulf of Mexico, the Black Sea, and perhaps the North Sea.

1.According to the traditional view of the origin of the ocean basins, which of the following is sufficient to move the continental plates?
(A) Increases in sedimentation on ocean floors
(C) Movement of mid-ocean ridges
(D) Sinking of ocean basins
(E) Differences in temperature under oceans and continents

2.It can be inferred from the passage that, of the following, the deepest sediments would be found in the
(A) Indian Ocean
(B) Black Sea
(C) Mid-Atlantic
(D) South Atlantic
(E) Pacific

3.The author refers to a â€œconveyor beltâ€
_________________

when there is a will there is a way

best regards

If you have any questions
New!
Manager
Joined: 05 Oct 2005
Posts: 200
Followers: 1

Kudos [?]: 7 [0], given: 0

### Show Tags

15 Nov 2005, 15:39
no taker ?
_________________

when there is a will there is a way

best regards

15 Nov 2005, 15:39
Similar topics Replies Last post
Similar
Topics:
18 Verbal Advantage - LEARN TO DESTROY READING COMP & BOOST VERBAL PACING 3 27 Jul 2015, 14:54
3 Reading Comprehension Concepts Must Read (part2) 0 28 May 2015, 03:19
Getting Excited about Reading Comp, Gangnam Style 0 29 Aug 2012, 16:01
GMATPrep: Reading Comp Short ONe. 4 20 Aug 2008, 12:38
Reading Comp Software 0 18 Jul 2007, 06:39
Display posts from previous: Sort by