A more comprehensive definition of "sea level," one useful to

Question

A more comprehensive definition of "sea level," one useful to cartographers, requires a broad understanding of various temporal and physical factors. First, consider the history of sea level: the position at which sea and land meet, averaged over tidal stages and coastlines, has been remarkably stable over time. Current sea level measures, though having risen very slightly over the last century, are approximately the same as they were 35,000 years ago. Thus, the referent for terrestrial altitudes and oceanic depths has been largely consistent for millennia, though cartographers' ability to make accurate measurements has, of course, improved with advances in technology. Through the processes of imaginative visualization and computer generation, much knowledge has been gained regarding the predictable nature of sea level.

The oceans are governed primarily by Earth's gravity, which is strongest at the poles because of Earth's slightly ellipsoid shape, the result of billions of years of rotation. What keeps the oceans from pooling at the poles, drawn there by the greater gravitational forces, is the centrifugal force generated by Earth's rotation. This force is strong enough to cause a bulge of ocean about eight kilometers high around Earth's equator. Using sophisticated computer models, today's cartographers can postulate how the intersection of sea and land would change should the Earth ever cease to rotate on its axis. Over time, the bulge of ocean at the equator, no longer held in place by the centrifugal forces, would flatten out. Drawn by the pull of the two poles, Earth's main bodies of water would eventually become circumpolar, gathered in two massive pools around the top and bottom, so to speak, of the globe, leading to the emergence of a supercontinent around the planet's equator.   1 
 1.According to the passage, which is true of the physical forces governing sea level? 
 
A. Gravity, along with rotation, is responsible for Earth's slightly ellipsoid shape.
B. Centrifugal deterioration will eventually give rise to an enormous supercontinent.
C. The centrifugal force is the dominant influence on the shape of Earth's oceans.
D. The equatorial bulge is primarily a result of gravitational pooling at Earth's poles.
E. Gravitational forces have more influence on the oceans than does centrifugal force.

2 
 2.The author makes all of the following statements about historic sea levels EXCEPT 
 
A. Variations in them have been noted in the last 35,000 years.
B. Their consistency has allowed cartographers to improve their measurements.
C. While mutable, they have, broadly speaking, maintained stability for millennia.
D. They are measured at many times and places to obtain a useful average.
E. Measurements of depth and elevation are made relative to their height.

3 
 3.The passage is chiefly concerned with 
 
A. imparting an understanding of the effect of Earth's physical forces on sea life
B. arguing that the long-term stability of sea level assists in cartographic accuracy
C. attempting to compose an explanation of one of Earth's topographical variables
D. integrating hard data and thought experimentation to better visualize sea level
E. positing a worst-case scenario to educate readers about Earth's fragile balance

RC Butler 2021  -  Practice Two RC Questions Everyday.   
Passage # 45 Date: 02-Feb-2021
 This question is a part of RC Butler 2021 .  Click here for Details

shauryahanda · Answer

Q1 - i have a different ans so i won't be posting that
Q2 
A. Variations in them have been noted in the last 35,000 years. ->  There have been variations in a shorter term of 100 yrs 
B. Their consistency has allowed cartographers to improve their measurements. ->  This has never been mentioned 
C. While mutable, they have, broadly speaking, maintained stability for millennia.-> first psg
D. They are measured at many times and places to obtain a useful average. -> first para -  averaged over coaastlines.. 
E. Measurements of depth and elevation are made relative to their height. ->  first para

Q3 - Good que - one could miss it if in hurry 
I will not elimiate the options cause such ques are better solved by finding purpose without looking at options first and then seeing which matches it

Purpose - To explain/discuss The concept 'sea Level' and grow on that idea

Closer options 
A -> the passage is not focused on discussing the causes but the whole concept plus sea life is wrong
C-> correct - topographic variable = sea level
D-> no hard data mentioned

Kuanl · Answer

can someone explain question 1

Sajjad1994 · Answer

Official Explanation

1.According to the passage, which is true of the physical forces governing sea level?

Difficulty Level:   750

Explanation

Choice (A)  distorts the details. Only the Earth's rotation is credited with this effect. The passage states that increased polar gravitational forces are a result, not a cause, of Earth's ellipsoid shape.

Choice (B)  is also a distortion. There is nothing in the passage that states that this scenario will happen, only that it would if the Earth were to stop rotating.

Choice (C)  is a 180. It may be tempting because centrifugal force clearly has a powerful effect, but the passage explicitly states that gravity's effect is  "greater"  and  "primary."

Choice (D)  is also a 180. The equatorial bulge is a result of centrifugal forces created by Earth's rotation.

Choice (E)  matches the prediction and is correct. The first two sentences of the second paragraph say that the gravitational forces are  "greater"  and that the oceans are  "governed primarily by Earth's gravity."

Answer: E

juancruzcba · Answer

In Question #2

2.The author makes all of the following statements about historic sea levels EXCEPT

A. Variations in them have been noted in the last 35,000 years.
B. Their consistency has allowed cartographers to improve their measurements.
C. While mutable, they have, broadly speaking, maintained stability for millennia.
D. They are measured at many times and places to obtain a useful average.
E. Measurements of depth and elevation are made relative to their height.

I chose D because it says: "First, consider the history of sea level: the position at which sea and land meet, averaged over tidal stages and coastlines, has been remarkably stable over time" Averaged over tidal stages and coastlines is close to infer that is measure at many times and places. 
Instead, B, sounds to extreme to say that the consistency HAS ALLOWED cartographers to improve their measurements.

Can someone give me a explanation?

Sajjad1994 · Answer

Official Explanation

2. The author makes all of the following statements about historic sea levels EXCEPT

Difficulty Level:   700

Explanation

Choice (A)  is mentioned in the passage and may be tempting, but the prediction was not so extreme as to claim that no variation at all was possible, and choice (A) does not say that major variation has been noted. Indeed, the passage states that sea levels have been  "rising ... over the last century,"  which is clearly a  "variation."

Choice (B)  is a distortion and, therefore, is correct. The passage credits improvements in cartography to advancing technology, not to stable sea levels.

Choice (C)  is mentioned in the passage, which explicitly states that sea levels  "are approximately what they were 35,000 years ago,"  though they have changed slightly.

Choice (D)  is mentioned; the passage states that measuring sea level involves  "averag  over tidal stages and coastlines."  Clearly, sea levels are measured in multiple times and places to get an accurate assessment.

Choice (E)  is also mentioned; the passage states that they are  "the referent for terrestrial altitudes and oceanic depths,"  an idea that this answer choice almost exactly restates

Answer: B

rahulgarg02 · Answer

Hi,
Shouldn't the answer to Question 1 be 'B' instead of 'E'. The effects of Gravitational pull are countered by the centrifugal force which is keeping the oceans from becoming pools of water near the poles, which would make 'E' wrong as it implies gravity is not stronger than the centrifugal force. On the other hand, 'B' is clearly mentioned in para-2: "Over time, the bulge of ocean at the equator, no longer held in place by the centrifugal forces, would flatten out. Drawn by the pull of the two poles, Earth's main bodies of water would eventually become circumpolar, gathered in two massive pools around the top and bottom, so to speak, of the globe, leading to the emergence of a supercontinent around the planet's equator.". Can you provide any further explanation if possible please. Thanks

Sajjad1994 · Answer

Read the OE in the link below, I hope that helps.

mimishyu · Answer

para1
to introduce the topic the article intend to discuss about-sea level, in that it be influenced by lots of factors and it seems relatively consistent throughout the history, for now, we can, by the use of more advanced scientific method, to hone our prediction to its measurement

para2
to break down the mechanism behind the landscape of Earth, for gravity and centrifugal field exert its influence on equator and poles that determine the sea level on specific area and shape the Earth’s landscape we see today

1.According to the passage, which is true of the physical forces governing sea level?

A. Gravity, along with rotation, is responsible for Earth's slightly ellipsoid shape.

see sentence in para2: The oceans are governed primarily by Earth's gravity, which is strongest at the poles because of Earth's slightly ellipsoid shape, the result of billions of years of rotation.
so simplify the logic: 
Earth billions of years of rotation--> Earth's slightly ellipsoid shape--> Earth's gravity--> govern the ocean, strongest at the poles
(A)would be correct if it change its statement to “rotation is responsible for Earth's slightly ellipsoid shape, which constitute the gravity”

B. Centrifugal deterioration will eventually give rise to an enormous supercontinent.

see sentence in para2: Over time, the bulge of ocean at the equator, no longer held in place by the centrifugal forces, would flatten out. ….. of the globe, leading to the emergence of a supercontinent around the planet's equator.
--> so according to the passage, it’s the “totally disappearance” of the centrifugal, not “deterioration” give rise to the supercontinent, notice the delicacy of the use of words, also the question ask about what kind of “force” control the sea level, statement in this choice—which talks about “centrifugal deterioration”, seems irrelevant to the force we want to find

C. The centrifugal force is the dominant influence on the shape of Earth's oceans.

this choice is incorrect, as can be seen in very obvious way
see sentence:
The oceans are governed primarily by Earth's gravity, which is strongest at the poles because of Earth's slightly ellipsoid shape, the result of billions of years of rotation.
-->so its Earth’s slightly ellipsoid shape cause the gravity to perform to its greatest force at the poles

What keeps the oceans from pooling at the poles, drawn there by the greater gravitational forces, is the centrifugal force generated by Earth's rotation. …. Over time, the bulge of ocean at the equator, no longer held in place by the centrifugal forces, would flatten out.
--> it is centrifugal force that keeps the oceans from pooling at the poles and cause the bulge of ocean, whether this force affect the shape of Earth's oceans we can’t trace from the passage

D. The equatorial bulge is primarily a result of gravitational pooling at Earth's poles.

see sentence: What keeps the oceans from pooling at the poles, drawn there by the greater gravitational forces, is the centrifugal force generated by Earth's rotation. This force is strong enough to cause a bulge of ocean about eight kilometers high around Earth's equator.*
-->thus, the equatorial bulge is primarily a result of “Earth’s rotation”, which give rise to the gravitational centrifuge that made the disappearance of Earth poles’ pooling, so (D) would be correct if it rectifies as “The equatorial bulge is primarily a result of THE DISAPPEARANCE of gravitational pooling at Earth's poles

E. Gravitational forces have more influence on the oceans than does centrifugal force.

I don’t think this one be the perfect answer choice, though this one talks about “force” that respond to what the question ask, now see sentences in para2: 
The oceans are governed primarily by Earth's gravity, which is strongest at the poles because of Earth's slightly ellipsoid shape, the result of billions of years of rotation. What keeps the oceans from pooling at the poles, drawn there by the greater gravitational forces, is the centrifugal force generated by Earth's rotation. Using sophisticated computer models, today's cartographers can postulate how the intersection of sea and land would change should the Earth ever cease to rotate on its axis. Over time, the bulge of ocean at the equator, no longer held in place by the centrifugal forces, would flatten out.

….sea level in ocean is determined by Earth’s gravity force, which among them have the centrifugal force, greater in its magnitude, that keeps the oceans from pooling at the poles
….there’re no very clear comparison between gravitational and centrifugal force to the influence on the ocean, if we really want to explain we could only explain in that the range that gravity force influence is much larger than centrifugal force, which only influence the south and north pole

2.The author makes all of the following statements about historic sea levels EXCEPT

First, consider the history of sea level: the position at which sea and land meet, averaged over tidal stages and coastlines, has been remarkably stable over time. Current sea level measures, though having risen very slightly over the last century, are approximately the same as they were 35,000 years ago. Thus, the referent for terrestrial altitudes and oceanic depths has been largely consistent for millennia, though cartographers' ability to make accurate measurements has, of course, improved with advances in technology.

A. Variations in them have been noted in the last 35,000 years.

see sentence:
Current sea level measures, though having risen very slightly over the last century, are approximately the same as they were 35,000 years ago
….so we could see that variation in sea level have indeed been noted/measured throughout this 35,000 years

B. Their consistency has allowed cartographers to improve their measurements.

….correct
see sentence:
Thus, the referent for terrestrial altitudes and oceanic depths has been largely consistent for millennia, though cartographers' ability to make accurate measurements has, of course, improved with advances in technology.
consistency and the improvement of measurement are two parallel things in the original sentence, there’re no cause and effect, in that it must be one allow the another to happen, exist

C. While mutable, they have, broadly speaking, maintained stability for millennia.

this sentence correspond to choice (C):
the position at which sea and land meet, averaged over tidal stages and coastlines, has been remarkably stable over time.

D. They are measured at many times and places to obtain a useful average.

see sentence: 
consider the history of sea level: the position at which sea and land meet, averaged over tidal stages and coastlines(at many places), has been remarkably stable “over time”(at many time).

E. Measurements of depth and elevation are made relative to their height.

….history of sea level…been remarkably stable over time. “Thus” the referent for terrestrial altitudes and oceanic depths has been largely consistent for millennia….. though cartographers' ability to make accurate measurements has…… 
-->so “sea level”, or say, “sea height” are closely connected to the measurement of altitudes and depth

3.The passage is chiefly concerned with

A. imparting an understanding of the effect of Earth's physical forces on sea life
B. arguing that the long-term stability of sea level assists in cartographic accuracy
C. attempting to compose an explanation of one of Earth's topographical variables

….correct
Drawn by the pull of the two poles, Earth's main bodies of water would eventually become circumpolar, gathered in two massive pools around the top and bottom, so to speak, of the globe, leading to the emergence of a supercontinent around the planet's equator.

para2 points out the mechanism of gravitational force, with its show up and disappearance, it is in the last part of the article explain the formation of Earth's topographical map--supercontinent

D. integrating hard data and thought experimentation to better visualize sea level
E. positing a worst-case scenario to educate readers about Earth's fragile balance

shrgmat · Answer

Sorry, the passage doesnt indicate that gravitational is greater. It just says that both forces are affecting the sea level... what nonsense, Kaplan

abhishekmehra · Answer

In question 3
how is C the correct answer? i have marked A. please explain

RonTargetTestPrep · Answer

What justification did you find for choice A? That choice talks about the effect of certain physical forces on   sea life  —which doesn't describe this passage at all. This passage does not mention any type of sea life anywhere—not even once.

To see which answer choice fits the passage best, let's take brief notes on the paragraphs first:

¶1—Sea level (defined) has been the same for a long long time.

¶2—Sea level (the height of the oceans) is higher at the equator because of Earth's spin. If Earth stopped spinning, ocean water would move from the equator to the poles.

Now look at the choices...

A, B, and E have nothing to do with any of this stuff.

The second half of choice D is ok (¶2 contains a thought experiment about what would happen if Earth stopped spinning), but the first half isn't—there are no "hard data" in the passage.

The most accurate answer is C, which does describe a good chunk of the passage—and, more importantly,  DOESN'T say anything that's NOT in the passage .
Remember, the correct answer SHOULDN'T cover  everything  in the passage. (If the question contains "main", "primary", "chiefly", etc., that implies that there are also secondary themes/topics that WON'T be covered by the correct answer.)

General takeaway point—
  The correct answer to a MAIN IDEA question should...
.../1/ accurately describe stuff in the passage
.../2/ NOT describe EVERYTHING in the passage
.../3/ NOT contain anything WRONG / IRRELEVANT / NOT in the passage!

Prob2303 · Answer

Hi Sajid, Can you please help me with the official explanation for Q3?

Sajjad1994 · Answer

Explained here https://gmatclub.com/forum/a-more-compr ... l#p3062882

Prob2303 · Answer

I clicked on the link but it is just guiding me to the same page.

Sajjad1994 · Answer

Yes! It is because the explanation is posted on the same page, just a post above your initial question. You just need to find it, and I think it is not a difficult task.

Good luck!

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