Hi, everyone. Let’s look at another TOEFL inference question.
Nevertheless,for archeologists concerned with the long periods of time of the Paleolithic period there are variations in coastlines of much greater magnitude to consider. The expansion and contraction of the continental glaciers caused huge and uneven rises and falls in sea levels worldwide. When the ice sheets grew,the sea level would drop as water became locked up in the glaciers;when the ice melted,the sea level would rise again. Falls in sea level often exposed a number of important land bridges,such as those linking Alaska to northeast Asia and Britain to northwest Europe,a phenomenon with far-reaching effects not only on human colonization of the globe but also on the environment as a whole-the flora and fauna of isolated or insular areas were radically and often irreversibly affected. Between Alaska and Asia today lies the Bering Strait,which is so shallow that a fall in sea level of only four meters would turn it into a land bridge. When the ice sheets were at their greatest extent some 18,000 years ago (the glacier maximum),it is thought that the fall was about 120 meters,which therefore created not merely a bridge but a vast plain,1,000 kilometers from the north to the south,which has been called Beringia. The existence of Beringia(and the extent to which it could have supported human life)is one of the crucial pieces of evidence in the continuing debate about the likely route and date of human colonization of the New World.
Which of the following can be inferred about the effects of the expansion and contraction of the continental glaciers? A. The amount of land not covered by water was greater during warmer periods. B. The glaciers’ growth and shrinkage led to uniform sea level changes. C. Land bridges became exposed during the cold periods. D. The rise of sea level occurred during periods of cold periods.
For this question, you need to find a causal chain of events. So, the question is this: Which of the following can be inferred about the effects of the expansion and contraction of the continental glaciers?
I see some students start to read the choices. Don’t! Do not read the choices when you have no idea about the effects of the expansion and contraction of the continental glaciers. You first need to have your own ideas on the effects of glaciers getting larger or smaller, and then look for the one that corresponds to your own understanding from the passage.
Now, because of the word "effect," you should know that you need to find the causal relationship relating to the expansion and contraction of glaciers. First, skim the paragraph looking for words like expansion and contraction. We find them here: ideas after "such as" are examples, so skip it. And the rest of the paragraph talks about Beringia, so this is the only place that talks about expansion and contraction. Now we are going to do close reading. It says that “The expansion and contraction of the continental glaciers caused huge and uneven rises and falls in sea levels worldwide.”
Ice expansion and contraction → uneven rises and falls in sea levels.
It then considers each case: When the ice sheets grew, the sea level would drop as water became locked up in the glaciers; when the ice melted, the sea level would rise again. Ice grows → sea level drops. Ice shrinks (=melts) → sea level rises.
It then says “Falls in sea level often exposed a number of important land bridges.” Falls in sea level means sea level drops, so sea level dropping results in land bridges being exposed.
Ice grows → sea level drops → land bridges exposed.
The rest of the paragraph did not talk about glacial expansion but about Beringia, so this is all we need to know to answer the question.
The amount of land not covered by water was greater during warmer periods. The glaciers’ growth and shrinkage led to uniform sea level changes. Land bridges became exposed during the cold periods. The rise of sea level occurred during periods of cold periods.
A states that there was more land during warmer periods. To have more land, sea level should drop. But we know that sea level drops when ice grows, and ice grows when it’s cold. So A is not true.
B: “Uniform” is the opposite of “uneven,” so B cannot be true.
C: Land bridges exposed happens when sea level drops, which happened when ice grew. When does ice grow? When it’s cold. So C is correct.
D: Sea level rises when ice melts, and ice melts in warmer periods. So D is false.
So, C is the answer.
Practice yourself how ideas are in a causal chain, that is, A leads to B, B leads to C. Being able to recognize this causal chain is critical to doing well on TOEFL integrated essays too. Thank you for listening.