Milankovitch proposed in the early twentieth century that : GMAT Reading Comprehension (RC)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 20 Jan 2017, 18:42

### 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

# Milankovitch proposed in the early twentieth century that

Author Message
TAGS:

### Hide Tags

Senior Manager
Joined: 30 Jun 2011
Posts: 274
Followers: 0

Kudos [?]: 65 [0], given: 20

Milankovitch proposed in the early twentieth century that [#permalink]

### Show Tags

21 Dec 2011, 03:24
2
This post was
BOOKMARKED
Milankovitch proposed in the early twentieth
century that the ice ages were caused by variations
in the Earth’s orbit around the Sun. For some
time this theory was considered untestable,
largely because there was no sufficiently precise
chronology of the ice ages with which the orbital
variations could be matched.
To establish such a chronology it is necessary
to determine the relative amounts of land ice that
existed at various times in the Earth’s past. A recent
discovery makes such a determination possible:
relative land-ice volume for a given period can be
deduced from the ratio of two oxygen isotopes,
16 and 18, found in ocean sediments. Almost
all the oxygen in water is oxygen 16, but a few
molecules out of every thousand incorporate the
heavier isotope 18. When an ice age begins, the
continental ice sheets grow, steadily reducing the
amount of water evaporated from the ocean that
tend to be left behind when water evaporates
from the ocean surfaces, the remaining ocean
water becomes progressively enriched in oxygen
18. The degree of enrichment can be determined
by analyzing ocean sediments of the period,
because these sediments are composed of calcium
carbonate shells of marine organisms, shells that
were constructed with oxygen atoms drawn from
the surrounding ocean. The higher the ratio of
oxygen 18 to oxygen 16 in a sedimentary specimen,
the more land ice there was when the sediment
was laid down.
As an indicator of shifts in the Earth’s climate,
the isotope record has two advantages. First, it is
a global record: there is remarkably little variation
in isotope ratios in sedimentary specimens taken
from different continental locations. Second, it is
a more continuous record than that taken from
rocks on land. Because of these advantages,
sedimentary evidence can be dated with sufficient
accuracy by radiometric methods to establish a
precise chronology of the ice ages. The dated
isotope record shows that the fluctuations in
global ice volume over the past several hundred
thousand years have a pattern: an ice age occurs
roughly once every 100,000 years. These data have
established a strong connection between variations
in the Earth’s orbit and the periodicity of the ice
ages.
However, it is important to note that other
factors, such as volcanic particulates or variations
in the amount of sunlight received by the Earth,
could potentially have affected the climate. The
advantage of the Milankovitch theory is that it
is testable; changes in the Earth’s orbit can be
calculated and dated by applying Newton’s laws
of gravity to progressively earlier configurations
of the bodies in the solar system. Yet the lack of
information about other possible factors affecting
global climate does not make them unimportant.

Read the question and share what do you think "evaporated ocean water" refers to
1. Vapors
2. Water left behind after evaporation

It can be inferred from the passage that precipitation
formed from evaporated ocean water has
(A) the same isotopic ratio as ocean water
(B) less oxygen 18 than does ocean water
(C) less oxygen 18 than has the ice contained in
continental ice sheets
(D) a different isotopic composition than has
precipitation formed from water on land
(E) more oxygen 16 than has precipitation formed
from fresh water
If you have any questions
New!
Senior Manager
Joined: 19 Apr 2011
Posts: 289
Schools: Booth,NUS,St.Gallon
Followers: 5

Kudos [?]: 282 [0], given: 51

### Show Tags

22 Dec 2011, 05:09
option B .It says that the more the evaporation ,the higher is the amount of oxygen 8 left behind .The oxygen 8 because of its heaviness is not evaporated .
_________________

+1 if you like my explanation .Thanks

Senior Manager
Joined: 30 Jun 2011
Posts: 274
Followers: 0

Kudos [?]: 65 [0], given: 20

### Show Tags

22 Dec 2011, 06:34
I know that but my question was not that, my question is below :

Read the question and share what do you think "evaporated ocean water" refers to
1. Vapors
2. Water left behind after evaporation
Manager
Joined: 08 Aug 2011
Posts: 203
GPA: 3.5
Followers: 1

Kudos [?]: 13 [0], given: 51

### Show Tags

23 Dec 2011, 04:31
I would say "Evaporated ocean water" refer to vapors.But if you would have asked the full question ie.what does precipitation formed from evaporated ocean water refers to, I would have said Water left behind after evaporation,as precipitation is the term used for the water which come backs to earth after evaporation(condensation theory)
Senior Manager
Joined: 30 Jun 2011
Posts: 274
Followers: 0

Kudos [?]: 65 [0], given: 20

### Show Tags

23 Dec 2011, 05:33
Yes that exactly the point. I thought the same that "evaporated ocean water" in question refers to water left behind.

Now who can explain why the answer considers the opposite.
Manager
Joined: 08 Aug 2011
Posts: 203
GPA: 3.5
Followers: 1

Kudos [?]: 13 [1] , given: 51

### Show Tags

23 Dec 2011, 08:44
1
KUDOS
Precipitation(ie. the evaporated ocean water) in this case could not return back to the ocean as ice sheets grows between the evaporated water and the left behind ocean water due to ice age
Quote:
When an ice age begins, the
continental ice sheets grow, steadily reducing the
amount of water evaporated from the ocean that
.
As a result precipitation which is the evaporated water is rich in isotope 16 and the left over water which is below the ice sheet is rich with isotope 18 which being heavier could not evaporate hence the precipitation or the evaporated water has less oxygen 18 as compared to the ocean water.
I hope this helps.
GMAT Club Legend
Joined: 01 Oct 2013
Posts: 10534
Followers: 919

Kudos [?]: 203 [0], given: 0

Re: Milankovitch proposed in the early twentieth century that [#permalink]

### Show Tags

21 Jun 2014, 17:13
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
GMAT Club Legend
Joined: 01 Oct 2013
Posts: 10534
Followers: 919

Kudos [?]: 203 [0], given: 0

Re: Milankovitch proposed in the early twentieth century that [#permalink]

### Show Tags

21 May 2016, 08:48
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Manager
Joined: 03 Aug 2016
Posts: 90
Location: United States
Concentration: Operations, Entrepreneurship
Schools: ISB '18
GMAT 1: 690 Q50 V33
GPA: 4
WE: Design (Transportation)
Followers: 2

Kudos [?]: 3 [0], given: 44

Re: Milankovitch proposed in the early twentieth century that [#permalink]

### Show Tags

30 Aug 2016, 02:13
FOUND THE QUESTIONS IN OG
D
D
B
C
B
E
7/7
Re: Milankovitch proposed in the early twentieth century that   [#permalink] 30 Aug 2016, 02:13
Similar topics Replies Last post
Similar
Topics:
9 Milankovitch proposed inthe early twentieth century that the 9 22 Aug 2013, 10:21
Milankovitch proposed in the early twentieth century that 5 29 May 2013, 01:54
Two new commentaries on the life and work of early twentieth 17 03 Dec 2011, 20:44
Milankovitch proposed in the early twentieth century that 2 17 Nov 2011, 12:57
ilankovitch proposed in the early twentieth century that the 1 15 Jun 2009, 14:51
Display posts from previous: Sort by