Scientists generally credit violent collisions between tectonic plates

Question

New Project RC Butler 2019  -  Practice 2 RC Passages Everyday   
Passage # 6, Date : 03-FEB-2019
 This post is a part of New Project RC Butler 2019 .  Click here for Details

Scientists generally credit violent collisions between tectonic plates, the mobile fragments of Earth’s rocky outer shell, with sculpting the planet’s surface, as, for example, when what is now the Indian subcontinent collided with Asia, producing the  Himalayan Mountains . However, plate tectonics cannot fully explain certain massive surface features, such as the “superswell” of southern Africa, a vast plateau over 1,000 miles across and nearly a mile high. Geologic evidence shows that southern African has been slowly rising for the past 100 million years, yet it has not experienced a tectonic collision for nearly 400 million years. The explanation may be in Earth’s mantle, the layer of rock underlying the tectonic plates and extending down over 1,800 miles to the outer edge of Earth’s iron core.

Since the early twentieth century, geophysicists have understood that the mantle churns and roils like a thick soup. The relative low density of the hottest rock makes that material buoyant, so it slowly ascends, while cooler, denser rock sinks until heat escaping the molten core warms it enough to make it rise again. While  this process of convection  was known to enable the horizontal movement of tectonic plates, until recently geophysicists were skeptical of its ability to lift or lower the planet’s surface vertically. However,  recent technological advances  have allowed geophysicists to make three-dimensional “snapshots” of the mantle by measuring vibrations, or seismic waves, set in motion by earthquakes originating in the planet’s outer shell and recording the time it takes for them to travel from an earthquake’s epicenter to a particular recording station at the surface. Because geophysicists know that seismic waves become sluggish in hot, low-density rock, and speed up in colder, denser regions, they can now infer the temperatures and densities in a given segment of the interior. By compiling a map of seismic velocities from thousands of earthquakes across the globe, they can also begin to map temperatures and densities throughout the mantle.These methods have revealed some unexpectedly immense formations in the deepest parts of the mantle; the largest of these is a buoyant mass of hot rock directly below Africa’s southern tip. Dispelling researchers’ initial doubts, computer models have confirmed that this formation is buoyant enough to rise slowly within the mantle and strong enough to push Africa upward as it rises.   1 
 1) In the highlighted text ( Himalayan Mountains ), the author mentions the Himalayan Mountains most likely in order to

(A) highlight certain similarities between the southern African superswell and other massive features on Earth's surface 
(B) identify a feature of Earth's surface that predates the origins of the southern African superswell 
(C) provide an example of a feature of Earth's surface that can be explained by plate tectonics 
(D) suggest that geophysicists are correct in attributing the sculpting of Earth's surface to violent collisions between tectonic plates 
(E) give an example of a feature of Earth's surface that scientists are unable to explain fully

OA:C 
 2 
 2) It can be Inferred from the passage that prior to the technological advances referred to in the highlighted text ( recent technological ), geophysicist were unable to 
 
(A) understand exactly how the collisions of tectonic plates created the Earth's mountains 
(B) establish that mantle material becomes more buoyant as it heats and more sluggish as it cools 
(C) start mapping the densities and temperatures of rock throughout the mantle 
(D) connect the phenomenon of convection within the mantle to the horizontal movement of tectonic plates 
(E) prove that different types of rock within the mantle have different densities

OA:C 
 3 
 3) According to the passage, the process of convection mentioned in the highlighted text ( this process of convection ) was regarded until recently by geophysicists as

(A) a process unlikely to occur deep within Earth's mantle 
(B) a probable explanation for the rising of the southern African plateau 
(C) an improbable explanation for the horizontal movement of tectonic plates 
(D) unlikely to account for the vertical rising or lowering of Earth's surface 
(E) unrelated to the creation of Earth's most massive surface features

OA: D 
 4

4) According to the passage, which of the following pieces of geological evidence makes plate tectonics an inadequate explanation for the existence of the superswell of southern Africa?

(A) The depth of the mantle underlying the tectonic plates surrounding southern Africa
(B) The absence of any significant mountain ranges in the vicinity of the superswell 
(C) The vast size of the plateau comprising the superswell's most visible feature 
(D) The rate at whit the superswell has been rising above sea level over the past 100 million years 
(E) The absence of any tectonic collisions in southern Africa for several hundred million years prior to the origin of the superswell

OA: E

SCIENTIFIC AMERICAN  
March 2001
Volume 284, Issue 3

Sculpting the Earth from Inside Out   LINK 1 &  LINK 2 
 Powerful motions deep inside the planet do not merely shove fragments of the rocky shell horizontally around the globe–they also lift and lower entire continents
By Michael Gurnis

Difficulty Level:   600

Sajjad1994 · Accepted Answer

Explanation

1) In the highlighted text (Himalayan Mountains), the author mentions the Himalayan Mountains most likely in order to

This is an easy question   (500-Level)

Option A

Until the passages discussed Himalayan Mountains there is no mention of any other mountain ranges to compare. so it is wrong option

Option B

Himalayan Mountains may be a feature of earth but according to first 5 lines and even according to whole passage it did not prefated the origin of african superwell. This option starts from a general fact but deviates from the point to make it wrong.

Option C

If we read 3rd, 4th and half 5th line of the first para we got correct answer that this is some sort of example. To satisfy fully we need to read first six lines of the passage.   This is Correct answer

Option D

Normally we (the GMAT Test takers) attempt question after reading complete passage and in most cases we remember information in the later part of the passage more than the initial part of the passage. This option is built on human psyche. It provide something discussed in the later part but it relevant information to make this option truly Incorrect.

Option E

This option is based on 50-50 formula something correct something false. It is true (give an example of a feature of Earth's surface) but next is false (that scientists are unable to explain fully) so this option is out.

The answer is C

2) It can be Inferred from the passage that prior to the technological advances referred to in the highlighted text (recent technological), geophysicist were unable to

This is comparatively tough question   (600-Level)

It can be Inferred from the passage  - when you read these words brace yourself to be ready to find out an answer which give us information that is not explicitly mentioned in the passages but tha that MUST be true based on the facts available by passage. When GMAC think to make a question Hard they go to Critical reasoning type questions in RC.

First of all read the highlighted text  (Sometime by reading only highlighted text didn't help, we need to read 2-3 lines before and 2-3 lines after the highlighted text to understand what is being discussed) . Word "three dimensional snapshot" help us to understand that Technological Advances give us more things to understand and these three dimensions are also mentioned.

Option A

Feast of all the word  "Exactly"  seems to be extreme, always take care of such an extreme words which makes the answer incorrect. Secondly technological advances did not make us understand exactly how the collisions of tectonic plates created the Earth's mountains. It is incorrect

Option B

This is something which has been discussed in the passage but it did not belongs to Technological Advances. Hence it is incorrect.

Option C

start mapping the densities and temperatures of rock throughout the mantle

This text did not give us that three dimensioned snapshot directly rather it summarize it in the "Mapping". 
mapping the densities and temperatures of rock throughout the mantle - These were the three dimensions which geophysicist were unable to measure before Technological Advances.   This is correct Option.

Option D

connect the phenomenon of convection within the mantle to the horizontal movement of tectonic plates

This option starts with what is discussed in the passage but with the wrong angle. The correct version of information is that it make us able to measure the horizontal movement of tectonic plates to Vertical movement. It is distort the information and is wrong.

Option E

prove that different types of rock within the mantle have different densities   - No such evidence is available

The answer is C

3) According to the passage, the process of convection mentioned in the highlighted text (this process of convection) was regarded until recently by geophysicists as

This is comparatively and easy question   (550-Level)  . The question is that what scientists were unable to do before technological advances. If we read  "While this process of convection was known to enable the horizontal movement of tectonic plates, until recently geophysicists were skeptical of its ability to lift or lower the planet’s surface vertically"  we can tick the correct answer.

Option A

True but irrelevant

Option B

True but irrelevant

Option C

Opposite answer

Option D

Clearly it tells us that what scientists were unable to do before technological advances.   This is Correct

Option E

Unknown fact. Cannot be validated.

The answer is D

4) According to the passage, which of the following pieces of geological evidence makes plate tectonics an inadequate explanation for the existence of the superswell of southern Africa?

This is also a Medium Level   (600-Level)   question. Subject matter and comparison starts from the first para  "Scientists generally credit violent collisions between tectonic plates"  so this something being compared and measured.

Option A

The depth of the mantle underlying the tectonic plates surrounding southern Africa

This information was also not fully explained with sub-continent condition so it is confused information. we cannot certify it.

Option B

The absence of any significant mountain ranges in the vicinity of the superswell

This is true but is not the reason of inadequate explanation for the existence of the superswell of southern Africa

Option C

The vast size of the plateau comprising the superswell's most visible feature

An information which is available in the passage but with regard to the question it is not the reason.

Option D

The rate at which the superswell has been rising above sea level over the past 100 million years

An information which is available in the passage but deviates from the point.

Option E

The absence of any tectonic collisions in southern Africa for several hundred million years prior to the origin of the superswell

Discussed in the first paragraph - Tick -   It is the Correct Answer

Hope It Helps

ankushbagwale · Answer

GMATNinja 
Can you please shed some light on question 2.

Here I was between choices A & C and have eliminate A because preceding lines clearly tell that prior to these advances, the scientists were skeptical of the vertical rise due to tectonic movement. 
 
Secondly, I thought the question is an inference one & C seems to be directly stated hence eliminated C.

Please advise on how to overcome this fallacy.

er.arun88 · Answer

check here : "after recent technology advances;scientists are able to use 3D maps .. along with some other research. which helped them to infer about temp/densities..

,recent technological advances have allowed geophysicists to make three-dimensional “snapshots” of the mantle by measuring vibrations, or seismic waves, set in motion by earthquakes originating in the planet’s outer shell and recording the time it takes for them to travel from an earthquake’s epicenter to a particular recording station at the surface. Because geophysicists know that seismic waves become sluggish in hot, low-density rock, and speed up in colder, denser regions,  they can now infer  the temperatures and densities in a given segment of the interior

aragonn · Answer

P1 - collisions between T-plates make planet’s surface. example - but it cant explain all, Earth’s mantle can. 
P2 - How Earth’s mantle works. what can be get from this movement. some predictions.

1) In the highlighted text (Himalayan Mountains), the author mentions the Himalayan Mountains most likely in order to
Pre-think - Himalayan Mountains are mentioned to attribute the example of previous sentence. C depicts it correctly.

(C) provide an example of a feature of Earth's surface that can be explained by plate tectonics

-------------------------------------------

2) It can be Inferred from the passage that prior to the technological advances referred to in the highlighted text (recent technological), geophysicist were unable to

Pre-think --- lines to read --- While this process of convection was known to enable the horizontal movement of tectonic plates, until recently geophysicists were skeptical of its ability to lift or lower the planet’s surface vertically. --------- , denser regions, they can now infer the temperatures and densities in a given segment of the interior.

(C) start mapping the densities and temperatures of rock throughout the mantle

-------------------------------------------

3) According to the passage, the process of convection mentioned in the highlighted text (this process of convection) was regarded until recently by geophysicists as

Pre-thinking - skeptical of its ability to lift or lower the planet’s surface vertically.

(D) unlikely to account for the vertical rising or lowering of Earth's surface

---------------------------------------------

4) According to the passage, which of the following pieces of geological evidence makes plate tectonics an inadequate explanation for the existence of the superswell of southern Africa?

Pre-think - However, plate tectonics cannot fully explain certain massive surface features, such as the “superswell” of southern Africa, a vast plateau over 1,000 miles across and nearly a mile high. Geologic evidence shows that southern African has been slowly rising for the past 100 million years, yet it has not experienced a tectonic collision for nearly 400 million years.

(E) The absence of any tectonic collisions in southern Africa for several hundred million years prior to the origin of the superswell

PhantomAY · Answer

Summarize the main idea and create process map:

Paragraph 1: S used to think t plates collision helps shape planet surface, but not anymore. It can't explain "superswell"

Paragraph 2: Convection of rocks might be the true cause. It remains unproved until recent tech advance, computer confirms the cause.

with above in mind, let's look at the questions:

1) In the highlighted text (Himalayan Mountains), the author mentions the Himalayan Mountains most likely in order to

(A) highlight certain similarities between the southern African superswell and other massive features on Earth's surface  author mentioned Himalayan as an example to prove t plate collision might cause planet surface changes but not similarity with counter examples "Superswell" 
(B) identify a feature of Earth's surface that predates the origins of the southern African superswell  author use it as counter-example not to identify feature predating it 
(C) provide an example of a feature of Earth's surface that can be explained by plate tectonics  it can't be explained plate tectonics 
(D) suggest that geophysicists are correct in attributing the sculpting of Earth's surface to violent collisions between tectonic plates  exactly the opposite 
(E) give an example of a feature of Earth's surface that scientists are unable to explain fully  yep that's why author introduce other causes in later sessions

2) It can be Inferred from the passage that prior to the technological advances referred to in the highlighted text (recent technological), geophysicist were unable to 
 refer to below details:
However, recent technological advances  have allowed geophysicists to make three-dimensional “snapshots”  of the mantle by measuring vibrations, or seismic waves, set in motion by earthquakes originating in the planet’s outer shell and recording the time it takes for them to travel from an earthquake’s epicenter to a particular recording station at the surface. Because geophysicists know that seismic waves become sluggish in hot, low-density rock, and speed up in colder, denser regions,  they can now infer the temperatures and densities in a given segment of the interior .

So "temperature and densities can now identified at any given part in the interior"

(A) understand exactly how the collisions of tectonic plates created the Earth's mountains  the entire 2nd paragraph is posing another cause rather than tectonic plate collisions, so this is definitively wrong 
(B) establish that mantle material becomes more buoyant as it heats and more sluggish as it cools  this is already known before  
(C) start mapping the densities and temperatures of rock throughout the mantle  this matches above details, correct answer 
(D) connect the phenomenon of convection within the mantle to the horizontal movement of tectonic plates  this is a tricky one - according to the details, this is already "known" even before technological advances 
(E) prove that different types of rock within the mantle have different densities  temperature, densities and location all matter. This answer only mentioned 1 of them

3) According to the passage, the process of convection mentioned in the highlighted text (this process of convection) was regarded until recently by geophysicists as 
 note the criteria is "until recently", so the timeline before technological advances 
(A) a process unlikely to occur deep within Earth's mantle  this is not mentioned 
(B) a probable explanation for the rising of the southern African plateau  actually the opposite, the passage mentioned geophysicists were skeptical of its ability 
(C) an improbable explanation for the horizontal movement of tectonic plates  mix-up answer, the tectonic plate movement is not related to convection process 
(D) unlikely to account for the vertical rising or lowering of Earth's surface  coincides with "skeptical of its ability" 
(E) unrelated to the creation of Earth's most massive surface features  "skeptical" doesn't mean "it is definitely false"

4) According to the passage, which of the following pieces of geological evidence makes plate tectonics an inadequate explanation for the existence of the superswell of southern Africa?

(A) The depth of the mantle underlying the tectonic plates surrounding southern Africa 
(B) The absence of any significant mountain ranges in the vicinity of the superswell 
(C) The vast size of the plateau comprising the superswell's most visible feature 
(D) The rate at whit the superswell has been rising above sea level over the past 100 million years 
(E) The absence of any tectonic collisions in southern Africa for several hundred million years prior to the origin of the superswell  this coincides with "yet it has not experienced a tectonic collision for nearly 400 million years", correct answer

carouselambra · Answer

Sajjad1994 
What are the odds of getting an easy passage like this in the exam?
So far I have see some really tough/dense passages. Not sure if the occurrence of such passages is related to how we perform during the initial questions. Could you please shed some light on this?

Sajjad1994 · Answer

This is not a very easy passage in general, If a test taker falling in the score range of 600-650 he or she might came across a passage like this one.

Thank you

VerbalBot · Answer

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Scientists generally credit violent collisions between tectonic plates

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Scientists generally credit violent collisions between tectonic plates

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