TOEFL IBT PRACTICE TEST 31 from Official TOEFL iBT Test

Directions: Now answer the questions.

18.Why does the student go to see her advisor, Professor Anderson?

  • She wants Professor Anderson’s help with her research.
  • She is responding to Professor Anderson’s invitation.
  • She has a complaint about another professor.
  • CD) She wants to get a letter of recommendation to law school.

19.Why does the student mention Professor Connelly’s class?

  • She was not happy with the grade she received in the class.
  • She might be able to expand the research she did in the class.
  • It was the most difficult class she ever took.
  • Professor Connelly took the class on a trip to Venezuela.

20.What does the student tell Professor Anderson she will do before their next meeting?

  • Register for Professor Connelly’s class
  • Begin to write her honors thesis
  • Turn in her honors project to Professor Connelly
  • Talk to Professor Connelly about doing an honors project

21. Listen to Track 69.

  • Very few students are asked to consider writing an honors thesis.
  • The woman has shown poor research skills in the past.
  • An honors thesis could help the woman get into law school.
  • The woman should write a proposal outlining her research skills.

22. Listen to Track 70.

  • She is uncertain about her ability to write an honors thesis.
  • She does not think an honors thesis would be useful to her.
  • She considers herself to be a good writer.
  • She has only written one research paper before.

Journalism

Directions: Listen to Track 71. 

Directions: Now answer the questions.

23.What is the lecture mainly about?

  • Why some newspapers do not improve their services
  • What newspapers can do to increase their readership
  • Why local newspapers cannot compete with major newspapers
  • How the topics that interest readers have changed over the years

24.According to the professor, what topics are newspaper readers most interested in? Choose 2 answers.

  • Political issues
  • Entertainment and weather
  • Natural disasters and accidents
  • Ordinary people

25.According to the professor, how can newspapers attract readers to serious stories?

  • By including photos that provide background information
  • By making minor revisions to the content of the story
  • By making the format more appealing to readers
  • By gradually increasing the number of serious stories

26.What does the professor imply about the use of colors in newspapers?

  • It has been greatly influenced by reader preferences.
  • It is more effective than early research indicated.
  • It has not resulted in significant increases in the number of readers.
  • It has been neglected in the study of journalism.

27. Listen to Track 72.

  • He agrees with the professor completely.
  • He is surprised by the professor’s point of view.
  • He is not familiar with the topic the professor is discussing
  • He can offer a solution to the problem being discussed.

28.Listen to Track 73.

  • He fully supports the student’s statement.
  • His experience this morning was unexpected.
  • He was not affected by what happened this morning.
  • The student should not complain.

Geology

 

Directions: Now answer the questions.

29. What aspect of the Earth 750 million years ago is the lecture mainly about?

  • The changes in locations of the continents
  • The effect of greenhouse gases on the atmosphere
  • Factors that influenced the ocean currents
  • Factors that contributed to a global freeze

30. According to the professor, how do geologists interpret the presence of erratics in the tropics?

  • It indicates that carbon-dioxide levels were once higher there.
  • It is evidence of global glaciation.
  • It indicates that the Earth may cool off at some point in the future.
  • It is evidence that some glaciers originated there.

31.What is the ice-albedo effect?

  • Global warming is balanced by carbon dioxide in the oceans.
  • Solar radiation retained in the atmosphere melts ice.
  • Large amounts of carbon dioxide are removed from the atmosphere.
  • Reflection of heat by glaciers contributes to their growth.

32.What is the relationship between carbon dioxide and silicate rocks?

  • Silicate rocks are largely composed of carbon dioxide.
  • Silicate rocks contribute to the creation of carbon dioxide.
  • The erosion of silicate rocks reduces carbon-dioxide levels in the atmosphere.
  • The formation of silicate rocks removes carbon dioxide from the oceans.

TASK II: GAP-FILLING

TRACK 63 TRANSCRIPT

Narrator

Listen to a conversation between a student and an employee in the campus computer center.

Computer center employee

Hi, what can I help you with today?

Student

Hi, um, I wanted to—you see, the thing is, I don’t know much about computers, so I was wondering if, uh, if there’s a class or something … so I can learn how to use computers, like to write papers for my classes.

Computer center employee

Oh, I see … um, we don’t really offer a course for beginners, since most students already have

computing [……………………………. ]. But all the computers in our labs have a general […………………………. ]installed on them. You could just go there and run it.

Student

And the tutorial explains everything? I mean, it might sound [……………………………………. ]but I’ve never used a computer.

Computer center employee

Well, all the computer labs on […………………………………….. ]are staffed with student […………………………. ], and I’m sure that any one of them would be more than willing to get you started.

Student

Yeah? That sounds good. But is it expensive?

Computer center employee

No, in fact, it won’t cost anything; it’s one of the [……………………………… ]of the computer center.

Student

That’s great. How do they—I mean, how do I get in touch with the student assistants? Should I just go to a [         ] […………………………………………… ]and ask whoever’s there?

Computer center employee

Sure, you could do that, or I can let you have a list of names of the students who are assistants in the labs. You might know one of them.

Student

Actually, I think I’d prefer someone I don’t know, um, so I can ask [       ]questions .

Is there anyone you’d recommend?

Computer center employee

All of our student assistants are really [………………………………. ]about computers. I mean, they have

to be, in order to work in the computer labs … It doesn’t mean that they’re

[………………………… ]good at teaching beginners … but you probably won’t be a beginner for

very long.

Student

Hope not.

Computer center employee

And I just thought of something else. The bookstore has a lot of books on computers—there might be one for people like you, I mean, people who don’t have a lot of

[………………………… ]with computers. I actually bought one for my father so he could learn how

to use […………………………………………………………………………………………………………… ], basic word [ ], that sort of thing—and it worked

pretty well for him.

Student

OK, I’ll try that, too. And if the bookstore doesn’t have it, they can just order it for me?

Computer center employee

Right. Now is there anything else I can help you with today?

Student

Uh, just the list of names and the times they’re working. I’d like to get going on this as soon as

[…………………………. ].

Computer center employee Right. Good luck.

TRACK 64 TRANSCRIPT:

Narrator

Listen to part of a lecture in an economics class.

Professor

When [ ]to understand international trade, some things seem so

[…………………………. ]that they can hardly be [……………………………….. ], and other points that are

important are [………………………………… ]unless you’ve thought about the subject carefully.

Consider the following: if there’s an increase in imports, let’s say, um, let’s say imports of

furniture, and the […………………………………. ]producers of furniture find this new competition very

difficult and are cutting                  production and employment, then it seems obvious and            easy to

understand and many people [……………………………… from this that increasing imports will cause

generally greater […………………………… ]at home.

What is not so obvious        is that how much we import and how much we [………………………………… ]…

those are [……………………………………. ]and you can’t understand the one without the other.          But the

exports that are generated are not easily [………………………………….. ], so   most people  don’t   see them.

They see only            the imports of furniture rising and                             employment    in      domestic

[…………………………. ]production falling.

So as a result, many people argue that we ought to protect jobs by limiting imports— either by

[…………………………. ], quotas, regulations, or whatever—without [………………………………… ]that this

also has the effect of reducing [……………………………. future exports to the rest of the world, things

that we can produce   very, very … cost effectively and therefore [……………………………… ].

The [………………………….. ]proposition in international economics is          that it makes sense   to import

those things that we … that can be produced more [……………………………….. ]abroad than at home and

export things to the rest of the world that we can produce more cost [……………………………………… ]than

produced [………………………….. ]in the world. Therefore, if we limit imports we put ourselves in

danger of not being able to export.

The details of this [……………………………………. ]will take much longer to explain than I can fully go into

now but the point of the matter is that gains—the benefits of gains—from international trade

result from being able to get things [……………………………….. ]by buying them abroad than you can

make them at home. Now there’re some things that we can make at home that are .. . that we can do more economically than they can do […………………………………………………………… ].

In the case of the United States, typically [………………………………… ]products, uh . .. are things that

Americans have [ ]in and started firms doing that sort of thing at which they do very well. Whereas goods that produce … that use a lot of relatively low skill labor, like

furniture production, cotton production, [……………………………………. ]production … those are things that

are […………………………………….. ]made more inexpensively in places where [………………………… ]rates

are low and the cost of using [……………………………. ]is very high.

However, in Florida they produce a lot of sugar, but the costs are so high, if we didn’t have

[………………………… Restrictions on imports          of sugar,     the   output of sugar would decline

[………………………… ]. But the sugar                      industry      in      the      U.S.           doesn’t produce

[………………………… ljobs, it uses resources               in [……………………… ]ways        and it blocks the

import of more cost-effectively produced sugar. It, it’s a very bad […………………………………….. ]for the

people in the United States to want to protect low-paying jobs thereby […………………………………… ]the

growth of world trading and international… uh, more international [……………………………………….. ]. It

would be better to remove [……………………………….. ]on imports and allow other countries in the

world … countries that can produce them more cheaply … let them specialize in producing those products.

Now, I agree that people who are directly [……………………………… ]by imports, what they focus on …

is, is that their […………………………… ]… their job prospects are being reduced, and their economic

[………………………… ]are getting worse. And that’s a relevant problem          and an    important problem;

what isn’t so obvious is … that by […………………………………….. ]and […………………………….. ]people to

places and industries where jobs are expanding rather than contracting, we can make the whole economy function more effectively and productively than by trying to [  ]imports.

Um, what is interesting to note is that, even if there were no international trade

[………………………… ], like imports, any changes that occur in a country’s economy—any new

technology, change in […………………………….. ], change in regulations or whatever—will lead to

“[……………………….. ]” that lead some sectors of the economy to decline and others to

[………………………… ].

And that’s what we have to figure out, and that’s a hard problem to deal with in

[………………………… ], is howto […………………………………… ]people adjusting from sectors where their

job prospects are not so good, and in particular where real wages aren’t so high, to acquire skills

that will […………………………… ]them to move into higher-paying jobs in other parts of the

economy either by retraining or relocating. Helping pay for the relocation of these people would

be very [……………………………. ], but trying to block the changes is really [……………………………….. ]. It

makes people in our country poorer, and it makes people elsewhere in the world [           ]as well.

TRACK 65 TRANSCRIPT

Narrator

Listen to part of a lecture in a marine biology class.

Professor

  • want to continue our discussion about [……………………………… ]. Specifically, today, um, I want to

talk about whale [……………………………. ]—um, why whales head south for the winter. Or really

why whales in the cold water of the Northern [………………………………….. ]head south for the winter.

Now, not all kinds of whales [……………………………. ], but most [………………………….. ] whales do.

And interestingly enough, we still don’t really know why the baleen whales migrate. We do have

several [ ], however, which I’ll discuss today. Uh, can anybody name one

reason why baleen whales might migrate south, to the warm […………………………………. ]water?

Male student

Uh, for food? You know, the whales move to warmer water in order to find a good area to feed. Professor

Good guess. That should be an obvious reason—after all, most animals that migrate do so for the

[………………………… ]of        finding food.                 But, uh, that doesn’t seem to be the         case with

[………………………… ] […………………………………. ]. To understand why, you need to know    something

about water […………………………… ]. There are a lot of technical reasons that I’m not going to go

into right now. But let’s just say that [……………………………………………………… ]don’t rise to the

[………………………… ]of tropical water like they do in other kinds of water. […………………………………… ]

water simply never gets          cold enough. So … well, what this means, uh, is that tropical water

doesn’t have much of the [……………………………. ]that most whales feed on.

Male student

don t understand—if there’s no plankton, how do the whales [……………………………………. ]through the

winter?

Professor

Right. How do they survive? You see, they don’t have to eat anything, because they’ve stored up

so much fat during the summer [………………………………….. ] season that they can just survive off of that.

So if they don’t need to eat anything, we’re back to our [………………………………….. ]question. Why do

baleen whales migrate? Any theories? No?

Well, there’s one idea out there that a lot of people believe. In fact, uh, you could say it’s the most

popular theory we have about whale migration. Basically, the [……………………………………. ]is that for

baleen whales, migration is a kind of […………………………………. ]act. Let me explain. On one hand,

whales need to take [……………………………. ]of the summer months by eating as much food as they

can. And that’s what they can do best in the northern seas. This allows them to build up a lot of fat. But in the winter, food is [………………………………………………………………… ]even in the north, so what the whales need to

do is save […………………………… ]. And that’s what migrating south can help them do Amanda,

you have a question?

Female student

Yes. Um, the […………………………….. ]theory doesn’t make [……………………………… ]to me. Maybe

whales might need to save energy during the winter, but wouldn’t moving all the way down to tropics make them lose energy?

Professor

That’s a good point, and it’s one reason why this isn’t a […………………………………. ]theory. It does cost

the whales energy to migrate, but it’s [……………………………….. ]for whales to save energy in warm

water than it is to save energy in cold water, so there might still be, you know, a good reason to move south for the winter. OK?

Now, before moving on to the next [………………………………….. ], I want to briefly discuss how the

baleen whale […………………………….. ]to navigate. It’s pretty […………………………………… ], because the

whales manage to return to the same places year after year, and have to travel over an

[……………………………………. ]area of ocean in order to do it. I mean, it’s not like whales can just look at a

map right? So exactly how do they do it?

Well, a lot of [………………………………………………. ]work still needs to be done, but we have been able to

[…………………………. ] […………………………… ]at least three ways       the     baleen   whale navigates

without getting lost. The first is the                                          [………………………. ]to use Earth’s

[…………………………………….. ]field like it was a map. That sounds strange, but we know that many birds

use that method, use the magnetic field, and it’s possible that whales have the [    ]ability to do the same thing.

Another theory is that if they stay close to the [………………………………….. ], whales might be able to

find familiar [……………………………………. ]and use those as guides. But we don’t really know if a whale’s

[…………………………. ]is good enough to be able to    do that, so that’s  not   a perfect theory.

And finally, we know that many whales                     make very loud            sounds   that can         travel

[………………. ]hundreds of miles [………………………………………………………. ]. Through a process called

[ ], it’s possible that these whales hear the sounds [……………………………………………………………… ]off of

islands or other pieces of land and use those [……………………………….. ]as clues to help them find their

way.

TRACK 68 TRANSCRIPT.

Narrator

Listen to a conversation between a student and a professor.

Student

Hi, uh … Professor Anderson … wondering if you had a [……………………………….. ]minutes …

Professor Of course, Paula …

Student

Thanks … uh, you sent me a letter [……………………………………………. ]about doing, uh, an honors

[…………………………. ]—inviting me to come in and talk about…

Professor

Right, right, well, as your academic [ ], it’s my job to look out for your

academic interests, and based on your [………………………………………. ], and some very positive

[…………………………. ]I’ve heard from your professors, I wanted to formally invite you to

[…………………………. ] doing an honors project…

Yeah … well, thanks … uh, actually I kinda wanted to ask you … quite […………………………………….. ]—

like how much work it would probably be? I mean, I’m gonna be spending a lot of time applying to law schools next [………………………………………………………. ]and …

Professor

Well, let me tell you how it works … and then you can decide from there.

Student

OK.

Professor

Basically, the honors project is an [………………………………………. ]to do … some in-depth work on a topic

you’re interested in before graduating college. You register for the class, but it doesn’t work the same way a regular class does—you find a professor who you want to work with—you ask the

professor—a sort of mentor who’s […………………………………. ]on the topic you’re interested in—the

topic you’re gonna write your [……………………………… ]thesis on …

Student

Writing a thesis? That’s part of the [………………………………… ]? Ah, like how many pages are we

talking?

Professor

Usually about 50 … but it’s a valuable experience, writing a [………………………………. ]paper.

Student

So, basically, after I register for the class, I need to ask a professor who’ll [          ]help me…

Professor

Actually, you need to do that—a professor needs to agree to [……………………………………. ]your honors

project—before you register.

Student

Oh, OK . ..

Professor

  • mean, I know it sounds kinda [………………………………. ], but that’s what the professor’s there for—

to help guide you through the different steps of the [………………………………………. ]and … uh … most

stu-dents are very pleased with the experience … they’re able to [……………………………………. ]advanced

research skills, which is important; [………………………………. ]in your case, writing an honors thesis

would be a big plus …

Student

You think so?

Professor

Absolutely. Especially considering your plans, since         you’re applying to law        schools. It shows

[………………………… ], that you’ve done well as an [………………………………….. ]—to  be allowed to do

the honors project… that you’re able to work […………………………………… ]and, of course, you would

graduate with honors …

Student

Yeah, it does sound good—it’s just, you know, I’ve never written something like that before, so Professor

Well,     you choose something you’re interested in—maybe             you   can    even  expand a shorter

[………………………… ]paper from another class or …

Student

So, like, maybe … You know, I took this course from Professor […………………………………………. ]—his

course on Comparative […………………………….. ]last semester and, uh … did pretty well I wrote a

paper actually, on political parties in [………………………………….. ]and—and he seemed to like my

research. Anyway, he, uh, I got an A in the course.

Professor

Good, so it sounds like you do have a [……………………………… ]idea for a topic, and you might know

what professor you want to work with … and look, it’s still a couple weeks before [          ], maybe you should talk to Professor Connelly and then get back to me.

Student

Yeah, I will—thanks. I’ll come by again sometime next week.

Professor

That’s fine. Good luck.

TRACK 71 TRANSCRIPT

Narrator

Listen to part of a lecture in a journalism class. The professor has been discussing newspapers. Professor

About 40 years ago, half of all Americans felt they’d be lost without a daily

[……………………………….. ]. But today, only one in ten […………………………… ]say they’d be lost without

a paper.    In fact,          today, half of all Americans say  they don’t need         a newspaper at all. And so

people in the newspaper [………………………………… ]are trying to figure            out how they can get more

people      reading                 the newspaper more often.    They’re   trying to crack journalism’s

[…………………………. ]for the ages: what makes people read newspapers? OK, well, let me ask

you—as a [……………………………. ]stu-dent, what do you think is the answer to this question?

Elizabeth?

Female student

Um, I would probably try to [……………………………. ]the content of the newspaper.

Professor

Better content. Hmm. You mean like [………………………………… ]editorials and articles?

Female student

Well, I mean [………………………………………… ]more interesting content, like, I would first try to find out

what readers really want to read … and then put that into the paper.

Professor

Yes, in fact, not too long ago, there was an [………………………………… ] study conducted to investigate

what [………………………….. ]people to newspapers. Uh, they found out that there’s a clear, strong

link between [………………………………………. ]with content and overall readership. Those newspapers that

[……………………………………………….. ]what the readers wanted most brought in the most readers. No big

[………………………………………. ]there, right? So, what kind of content brings in readers? The study found

that people- centered local news ranks at the top of the list… stories about

[……………………………………… ]people. For example, you could write about the experiences of those who

were […………………………………….. ]in a news story, and their friends and relatives … The vantage points

would be those of ordinary people, not of police or other [………………………………….. ]… OK? Now the

study also […………………………… ]that people want more stories about movies, TV, and weather,

and fewer stories and photos about natural [………………………………. ]and […………………………. ]… So,

to get reader satisfaction, you need to select the right topics, and within those topics, the right news events or stories to cover. Yes, James?

Male student

It seems to me that a lot of what you just [………………………………………… ] doesn’t line up with the

[………………………… ]of good journalism. Catering to readers’ tastes may improve overall

[………………………… ]but what about the social [………………………………………. ]that newspapers have? I

mean, there are some topics that newspapers need to write about in order to serve the public

interest. Those topics may not always be fun and interesting for the […………………………………… ]reader,

but it’s still the newspaper’s [………………………………… ]to make that information available to the

public.

Professor

That’s a good point. You need a good mix of [………………. ]. You can’t just rush towards

an […………………………………… ]topic and forget about the reporting role of newspapers. There’s a danger

of going soft newspapers do have to perform their […………………………………… ]to citizens. So what

newspapers sometimes do is to combine serious [……………………………………… ]with a reader-friendly

presentation. Um, let me give you an example: When the justice department opened an

[………………………… ]on the local police—some pretty [………………………. ]stuff that could be

boring to some readers—well, one local newspaper ran a lead story on their front page, but they

also [………………………………………………………………………………………. ]the format by including small [ ]boxes that

presented in a [………………………………………. ]the highlights of the story. That way, they could report the

serious stories they needed to report, and, and still hold their […………………………………. ] attention. OK?

Uh, going back to the research on [………………………………. ]growth we were talking about… Uh, the

most [………………………….. ]step of all, the study shows, may be making the paper easier to use.

How can we make the paper “easier to use”? Well, it means stories need to include information,

such as phone numbers, times, dates, […………………………………. ], Web sites and the like, so that

readers can “go and do” things based on what they’ve read.

Female student

Professor Ellington? Um, when you said we need to make the paper “easier to use,” I thought

you were [……………………………….. ]say something about use of graphics, colors, and

[………………………… ]like that.

Professor

Well, I guess those things do help in a way, but it turned out that those […….. ]touches, uh, such as more [ ]designs, extensive use of

color, and informational [……………………………… ]matter much less than you’d expect. Surprising,

isn’t it?

Female student

Yeah, it is … Um, how about [……………………………………. ]? Does the study say anything about

improving service? I don’t think people are gonna [……………………………………… ]if the paper doesn’t

arrive, or shows up late …

Professor

Or shows up wet, which by the way, happened to me this morning. Oh, [……………………………………….. ].

Service affects readership. In fact, improving your service is much more likely to increase your

readership than making changes in your [……………………………………… ]content… Not only on-time

[…. ]in good condition, but also things like [……………………………………………………………………. ]billing,

affordability, um … Yes?

Female student

They could also, like, increase the number of sites where they sell single copies.

Professor

Certainly that’s one way to improve service.

TRACK74 TRANSCRIPT

Narrator

Listen to part of a lecture in a geology class.

Professor

Um, beginning in the late [……………………………………….. ], geologists began to uncover some

[………………………… ]of a rather surprising kind when they looked … um … at

[………………………… ]places around the world. What they found out when they

[………………………… ]rocks from about a … the period from about [………………………………….. ] million

years ago to about [……………………………… ] million years ago, they found that… it seemed that

[………………………… ]covered the entire surface of the Earth—from pole to pole, including the

[………………………… ].

Um … how did they come to this [………………………………. ]conclusion? What was the evidence for

this? Especially when glaciers today are found only at the poles … or in the mountains.

Well, uh … basically when glaciers grow and move they leave behind a

[………………………… ]deposit consisting of primarily … of, at least on the top level, of ground up

little bits of rock … almost… they almost look like [……………………………….. ]that have been deposited

by [………………………….. ], if you’ve ever seen those. And that’s caused because, although the

glacier is ice, it is actually flowing very slowly and as it moves it [……………………………………. ]the top

layer of rock, it breaks off pieces and [……………………………………………. ]them away. So when you have

[ ]you have a distinctive pattern of these pieces of rock which are called

“[……………………………. ].”

Erratics are rocks … they’re the stones that are often carried long distances by glaciers.

So, in the [……………………………. ]and onward up through the [………………………………….. ], we keep

finding evidence for gla-ciation, no matter what the […………………………………….. ]… even in tropical

latitudes. Now, today there are glaciers in the tropics but only at very high elevations. But

[………………………… ]million years ago, apparently there were glaciers even at sea level in the

tropics.

How could this have happened?

Well, first… the growth of glaciers, uh, [……………………………………………. ], if you will, from a kind of a

positive [………………………….. ]loop called the “[……………………………. ]effect.”

With the ice-albedo effect, glaciers—’cause they’re white—reflect light and heat more … much

more        than does                               [… ]water… or                soil and rock, which are            dark and

[………………………… ]heat. So, the more glaciers there are,                              the more                 heat is

[………………………… ], so the climate gets cooler, and glaciers grow even more.

However… normally, on a global scale, there is a major process that […………………………………. ]to curb

the growth of glaciers. And, that process [………………………………………………. ] carbon dioxide.

Now,        we’re all           familiar with the notion that             carbon dioxide is what we call a

“[…………………………… ]gas.” The more carbon dioxide           there is in the [                                 ], the

more heat the atmosphere […… ]. That’s what a greenhouse gas does. So, the

greenhouse-gas effect is kinda the opposite of the [……………………….. ] effect.

Um … now as it happens … when […………………………. ]rocks, which is a very common class of

rock, when they’re [ ]to the air and to normal weathering, they erode. Carbon

dioxide is [……………………………. ]to these [………………………………… ]rocks and binds to them, forming

calcium carbonate.

Calcium carbonate is eventually [……………………………………………………………… ]into the ocean where it

[………………………… ]to the bottom. This process, this forming of calcium carbonate, has the

effect of [……………………………………. ]the carbon dioxide out of the air and storing it at the bottom of the

ocean.

Now, follow me here. The process that’s sucking carbon dioxide out of the air, keeping the greenhouse gas levels low, cannot happen if the rock is [……………………………………………………………………. ]with ice.

So, while glaciers […………………………….. ]light and heat… cooling the Earth, they at the same time

cover rocks so there’s less calcium carbonate [………………………………. ].. . which leaves more carbon

dioxide in the atmosphere. Higher levels of carbon dioxide keep the atmosphere warm … which

slows the growth of glaciers. So, it’s a […………………………………………………….. ], and the glacier growth

[……………………………… ]pretty much under control.

Now, what happened 750 million years ago to upset that balance? It seems a relatively simple explanation actually …750 million                                                   years ago             … all the major continents are rocky, bare, and

pretty much lined up along the [………………………………………. ]; they hadn’t yet moved to where they are

today. So, what happened was, perhaps a slight cooling of … the very slight and

[………………………… ]cooling of the Sun—which still happens from time to time—and the Earth

starts to cool, the ice starts to [………………………………………………………. ]on the oceans … starting at the

[………………………… ].

Now, by the time the ice reaches about two-thirds of the way to the equator, it’s too late.

See … because the [………………………………. ]are the last things to be covered by glaciers, they

continue weathering … the rocks keep eroding and the carbon dioxide levels keep

[………………………… ]… So, the ice-[……………………………. ]effect from the glaciers is increasing in

strength while the […………………………………… ] continues to lose its ability to retain heat making glacier

growth [………………………….. ]. Now      you                                                                                 have what’s called a “runaway […………………….. ].”

And for perhaps as long as [……………………………………… ] million years, possibly with some interludes,

the Earth was […………………………… from pole to pole, like a giant [……………………………… ].