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Geologists have long known that the Earth's mantle is hetero
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24 Apr 2020, 10:24
24 Apr 2020, 10:24
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Geologists have long known that the Earth's mantle is heterogeneous, but its spatial arrangement remains unresolved -is the mantle essentially layered or irregularly heterogeneous? The best evidence for the layered mantle thesis is the well-established fact that volcanic rocks found on oceanic islands, islands believed to result from mantle plumes arising from the lower mantle, are composed of material fundamentally different from that of the midocean ridge system, whose source, most geologists contend, is the upper mantle.
Some geologists, however, on the basis of observations concerning mantle xenoliths, argue that the mantle is not layered, but that heterogeneity is created by fluids rich in "incompatible elements" (elements tending toward liquid rather than solid-state) percolatIng upward and transforming portions of .the upper mantle irregularly, according to the vagaries of the fluids' pathways. We believe, perhaps unimaginatively, that this debate can be resolved through further study, and that the underexplored midocean ridge system is the key.
Some geologists, however, on the basis of observations concerning mantle xenoliths, argue that the mantle is not layered, but that heterogeneity is created by fluids rich in "incompatible elements" (elements tending toward liquid rather than solid-state) percolatIng upward and transforming portions of .the upper mantle irregularly, according to the vagaries of the fluids' pathways. We believe, perhaps unimaginatively, that this debate can be resolved through further study, and that the underexplored midocean ridge system is the key.
Question 1
00:00
A
B
C
D
E
Question Stats:
45% (02:54) correct
55% (02:14) wrong based on 117 sessions
Show timer Statistics
17. Which of the following best expresses the main idea of the. passage?
(A) Current theories regarding the structure of the Earth's mantle cannot account for new discoveries regarding the composition of mantle xenoliths.
(B) There are conflicting hypotheses about the heterogeneity of the Earth's mantle because few mantle elements have been thoroughly studied.
(C) Further research is needed to resolve the debate among geologists over the composition of the midocean ridge system.
(D) There is clear-cut disagreement within the geological community over the structure of the Earth's mantle.
(E) There has recently been a strong and exciting challenge to geologists' long-standing belief in the heterogeneity of the Earth's mantle.
Question 2
00:00
A
B
C
D
E
Question Stats:
89% (00:42) correct
11% (00:57) wrong based on 107 sessions
Show timer Statistics
18. According to the passage, it is believed that oceanic islands are fonned from
(A) the same material as mantle xenoliths
(B) the same material as the mid-ocean ridge system
(C) volcanic rocks from the upper mantle
(D) incompatible elements percolating up from the lower mantle
(E) mantle plumes arising from the lower mantle
Question 3
00:00
A
B
C
D
E
Question Stats:
49% (01:28) correct
51% (01:42) wrong based on 97 sessions
Show timer Statistics
19. It can be inferred from the passage that the supporters of the "layered-mantle" theory believe which of the following?
I. The volcanic rocks on oceanic islands are composed of material derived from the lower part of the mantle.
II. The materials of which volcanic rocks on oceanic islands and mid-ocean ridges are composed are typical of the layers from which they are thought to originate.
III. The differences in composition between volcanic rocks on oceanic islands and the midocean ridges are a result of different concentrations of incompatible elements.
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III
Question 4
00:00
A
B
C
D
E
Question Stats:
39% (00:51) correct
61% (01:06) wrong based on 94 sessions
Show timer Statistics
20. The authors suggest that their proposal for determining the nature of the mantle's heterogeneity might be considered by many to be
(A) pedestrian
(B) controversial
(C) unrealistic
(D) novel
(E) paradoxical
Re: Geologists have long known that the Earth's mantle is hetero
[#permalink]
02 May 2020, 21:09
02 May 2020, 21:09
16
Passage summary
mental notes
I) The author starts with a question. Then a theory is cited and explained.
II)A contending theory is explained. Author's opinion - Q's answer is uncertain, suggests more Research.
Main Idea of the passage Question
Prethinking
The author wants to point out the heated up argument of arrangement of earth's mantle
lets see if we can find something similar
(A) Current theories regarding the structure of the Earth's mantle cannot account for new discoveries regarding the composition of mantle xenoliths.
wrong it's never mentioned about current theory vs new discoveries. OUT
(B) There are conflicting hypotheses about the heterogeneity of the Earth's mantle because few mantle elements have been thoroughly studied.
looked good until "because few mantle elements have been thoroughly studied." what? not mentioned. OUT
(C) Further research is needed to resolve the debate among geologists over the composition of the midocean ridge system.
Trap answer, the debate is mantle layer is layered or mix of all the stuff. not for heterogeneity of midocean ridge system.
(D) There is clear-cut disagreement within the geological community over the structure of the Earth's mantle.
looks good skip
(E) There has recently been a strong and exciting challenge to geologists' long-standing belief in the heterogeneity of the Earth's mantle.
there's no doubt in heterogeneity of the soil. it's the arrangement.
Going back to passage
Breaking it down
1)Island formed from manle plumes arising from lower mantle
2) mid ocean ridge is diff from island forming substance which is formed from Upper
A,B and C are crap. OUT
(D) incompatible elements percolating up from the lower mantleIts formed so that the reader might go to 2nd paragraph and tick this because of same wordings.
E) is exact match
I)Yup, thats right, we just read for previous question.
II) we can infer this, from the same excerpt- last line of 1st paragraph. there's a lower layer, and then there's middle layer.
III)"are a result of different concentrations of incompatible elements." what? no that's said by the folks who hate the layers theory.
choose C
PRETHINKING
So. reading carefully it says determining nature of Mantle's HETEROGENEITY ...not if they are layered or not
going to first line, author basically says, everyone knows its heterogeneous, the earth's mantle. Geologists know it since long time.
pedestrian is - dull or boring.
since they already know this, it will be *YAWNS* boring. A) seems right
B) controversial
If you read or you get confused for reading this for layered or not. you might choose B.
C) unrealistic? what no .
D)novel is unusual or never seen before. OUT
E) paradoxical. hmm. no
mental notes
I) The author starts with a question. Then a theory is cited and explained.
II)A contending theory is explained. Author's opinion - Q's answer is uncertain, suggests more Research.
Quote:
17. Which of the following best expresses the main idea of the. passage?
(A) Current theories regarding the structure of the Earth's mantle cannot account for new discoveries regarding the composition of mantle xenoliths.
(B) There are conflicting hypotheses about the heterogeneity of the Earth's mantle because few mantle elements have been thoroughly studied.
(C) Further research is needed to resolve the debate among geologists over the composition of the midocean ridge system.
(D) There is clear-cut disagreement within the geological community over the structure of the Earth's mantle.
(E) There has recently been a strong and exciting challenge to geologists' long-standing belief in the heterogeneity of the Earth's mantle.
(A) Current theories regarding the structure of the Earth's mantle cannot account for new discoveries regarding the composition of mantle xenoliths.
(B) There are conflicting hypotheses about the heterogeneity of the Earth's mantle because few mantle elements have been thoroughly studied.
(C) Further research is needed to resolve the debate among geologists over the composition of the midocean ridge system.
(D) There is clear-cut disagreement within the geological community over the structure of the Earth's mantle.
(E) There has recently been a strong and exciting challenge to geologists' long-standing belief in the heterogeneity of the Earth's mantle.
Main Idea of the passage Question
Prethinking
The author wants to point out the heated up argument of arrangement of earth's mantle
lets see if we can find something similar
(A) Current theories regarding the structure of the Earth's mantle cannot account for new discoveries regarding the composition of mantle xenoliths.
wrong it's never mentioned about current theory vs new discoveries. OUT
(B) There are conflicting hypotheses about the heterogeneity of the Earth's mantle because few mantle elements have been thoroughly studied.
looked good until "because few mantle elements have been thoroughly studied." what? not mentioned. OUT
(C) Further research is needed to resolve the debate among geologists over the composition of the midocean ridge system.
Trap answer, the debate is mantle layer is layered or mix of all the stuff. not for heterogeneity of midocean ridge system.
(D) There is clear-cut disagreement within the geological community over the structure of the Earth's mantle.
looks good skip
(E) There has recently been a strong and exciting challenge to geologists' long-standing belief in the heterogeneity of the Earth's mantle.
there's no doubt in heterogeneity of the soil. it's the arrangement.
Quote:
18. According to the passage, it is believed that oceanic islands are fonned from
(A) the same material as mantle xenoliths
(B) the same material as the mid-ocean ridge system
(C) volcanic rocks from the upper mantle
(D) incompatible elements percolating up from the lower mantle
(E) mantle plumes arising from the lower mantle
(A) the same material as mantle xenoliths
(B) the same material as the mid-ocean ridge system
(C) volcanic rocks from the upper mantle
(D) incompatible elements percolating up from the lower mantle
(E) mantle plumes arising from the lower mantle
Detail questions
Going back to passage
Quote:
The best evidence for the layered mantle thesis is the well-established fact that volcanic rocks found on oceanic islands, islands believed to result from mantle plumes arising from the lower mantle, are composed of material fundamentally different from that of the midocean ridge system, whose source, most geologists contend, is the upper mantle.
Breaking it down
1)Island formed from manle plumes arising from lower mantle
2) mid ocean ridge is diff from island forming substance which is formed from Upper
A,B and C are crap. OUT
(D) incompatible elements percolating up from the lower mantleIts formed so that the reader might go to 2nd paragraph and tick this because of same wordings.
E) is exact match
Quote:
19. It can be inferred from the passage that the supporters of the "layered-mantle" theory believe which of the following?
I. The volcanic rocks on oceanic islands are composed of material derived from the lower part of the mantle.
II. The materials of which volcanic rocks on oceanic islands and mid-ocean ridges are composed are typical of the layers from which they are thought to originate.
III. The differences in composition between volcanic rocks on oceanic islands and the midocean ridges are a result of different concentrations of incompatible elements.
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III
I. The volcanic rocks on oceanic islands are composed of material derived from the lower part of the mantle.
II. The materials of which volcanic rocks on oceanic islands and mid-ocean ridges are composed are typical of the layers from which they are thought to originate.
III. The differences in composition between volcanic rocks on oceanic islands and the midocean ridges are a result of different concentrations of incompatible elements.
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III
Infer matching
I)Yup, thats right, we just read for previous question.
II) we can infer this, from the same excerpt- last line of 1st paragraph. there's a lower layer, and then there's middle layer.
III)"are a result of different concentrations of incompatible elements." what? no that's said by the folks who hate the layers theory.
choose C
Quote:
20. The authors suggest that their proposal for determining the nature of the mantle's heterogeneity might be considered by many to be
(A) pedestrian
(B) controversial
(C) unrealistic
(D) novel
(E) paradoxical
(A) pedestrian
(B) controversial
(C) unrealistic
(D) novel
(E) paradoxical
PRETHINKING
So. reading carefully it says determining nature of Mantle's HETEROGENEITY ...not if they are layered or not
going to first line, author basically says, everyone knows its heterogeneous, the earth's mantle. Geologists know it since long time.
pedestrian is - dull or boring.
since they already know this, it will be *YAWNS* boring. A) seems right
B) controversial
If you read or you get confused for reading this for layered or not. you might choose B.
C) unrealistic? what no .
D)novel is unusual or never seen before. OUT
E) paradoxical. hmm. no
General Discussion
Re: Geologists have long known that the Earth's mantle is hetero
[#permalink]
24 Apr 2020, 12:06
24 Apr 2020, 12:06
Expert Reply
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