Micrscpes The Beringia Landscape
During the peak f the last ice age, nrtheast Asia (Siberia) and Alaska were cnnected by a brad land mass called the Bering Land Bridge. This land bridge existed because s much f Earth’s water was frzen in the great ice sheets that sea levels were ver 100 meters lwer than they are tday. Between 25,000 and 10,000 years ag, Siberia, the Bering Land Bndge, and Alaska shared many envirnmental characteristics. These included a cmmn mammalian fauna f large mammals, a cmmn flra cmpsed f brad grasslands as well as wind-swept dunes and tundra, and a cmmn climate with cld, dry winters and smewhat wanner summers. The recgnitin that many aspects f the mdem flra and fauna were present n bth sides f the Bering Sea as remnants f the ice-age landscape led t this regin being named Beringia.
It is thrugh Beringia that small grups f large mammal hunters, slwly expanding their hunting territries, eventually clnized Nrth and Suth America. n this archaelgists generally agree, but that is where the agreement stps ne brad area f disagreement in explaining the pepling f the Americas is the dmain f paleeclgists, but it is critical t understanding human histry: what was Beringia like?
The Beringian landscape was very different frm what it is tday. Brad, windswept valleys; glaciated muntains; sparse vegetatin; and less misture created a rather frbidding land mass. This land mass supprted herds f nw-extinct species f mammth, bisn, and hrse and smewhat mdern versins f caribu, musk x, elk, and saiga antelpe. These grazers supprted in turn a number f impressive carnivres, including the giant shrt-faced bear, the saber-tth cat, and a large species f lin.
The presence f mammal species that require grassland vegetatin has led Arctic bilgist Dale Guthrie t argue that while cld and dry, there must have been brad areas f dense vegetatin t supprt herds f mammth, hrse, and bisn. Further, nearly all f the ice-age fauna had teeth that indicate an adaptatin t grasses and sedges; they culd nt have been supprted by a mdern flra f msses and lichens. Guthrie has als demnstrated that the landscape must have been subject t intense and cntinuus winds, especially in winter. He makes this argument based n the anatmy f hrse and bisn, which d nt have the ability t search fr fd thrugh deep snw cver. They need landscapes with strng winds that remve the winter snws, expsing the dry grasses beneath. Guthrie applied the term “ mammth steppe" t characterize this landscape.
In cntrast, Paul Clinvaux has ffered a cunterargument based n the analysis f pllen in lake sediments dating t the last ice age. He fund that the amunt f pllen recvered in these sediments is s lw that the Beringian landscape during the peak f the last glaciatin was mre likely t have been what he termed a "plar desert," with little r nly sparse vegetatin, in n way was it pssible that this regin culd have supprted large herds f mammals and thus, human hunters. Guthrie has argued against this view by pinting ut that radicarbn analysis f mammth, hrse, and bisn bnes frm Beringian depsits revealed that the bnes date t the perid f mst intense glaciatin.
The argument seemed t be at a standstill until a number f recent studies resulted in a spectacular suite f new finds. The first was the discvery f a 1,000-square-kilmeter preserved patch f Beringian vegetatin dating t just ver 17,000 years ag—the peak f the last ice age The plants were preserved under a thick ash fall frm a vlcanic eruptin. Investigatins f the plants fund grasses, sedges, msses, and many ther varieties in a nearly cntinuus cver, as was predicted by Guthrie. But this vegetatin had a thin rt mat with n sil frmatin, demnstrating that there was little lng-term stability in plant cver, a finding supprting sme f the arguments f Clinvaux. A mixture f cntinuus but thin vegetatin supprting herds f large mammals is ne that seems plausible and realistic with the available data.
1. The wrd "remnants" in the passage is clsest in meaning
remains
evidence
results
reminders
2. The wrd "dmain" in the passage is clsest in meaning t
field f expertise
challenge
interest
respnsibility
3. Accrding t paragraph 3, all f the fllwing are true f the Beringian landscape EXCEPT.
There was little vegetatin.
The mammal species there all survived int mdern versins.
The climate was drier than it is tday.
There were muntains with glaciers.
4. The purpse f paragraph 3 is t
cntrast tday’s Beringian landscape with ther landscapes in the American cntinent
describe the Beringian landscape during the last ice age
explain why s many Beringian species became extinct during the last ice age
summarize the infrmatin abut Beringia that histrians agree n
5. The wrd "cntinuus” in the passage is clsest in meaning t
unpredictable
very cld
dangerus
uninterrupted
6. Which f the sentences belw best expresses the essential infrmatin in the highlighted sentence in the passage? Incrrect chices change the meaning in imprtant ways r leave ut essential infrmatin.
Accrding t bilgist Dale Guthrie, mammal species require brad areas f vegetatin t survive.
Dale Guthrie is an Arctic bilgist wh argued that brad areas f dense vegetatin were surely enugh t attract mammals such as mammth, hrse, and bisn t Beringia.
Dale Guthrie argued that Beringia, thugh cld and dry, must have had enugh dense vegetatin t supprt the herds f mammth, hrse, and bisn that lived there.
As lng as Beringia was cld and dry, argued Dale Guthrie, dense vegetatin grew in rder t supprt the herds f mammth, hrse, and bisn—the mammal species present there.
7. Accrding t paragraph 4，Guthrie believes that the teeth f ice-age fauna supprt which f the fllwing cnclusins?
Large mammals wuld nt have been able t survive in the Beringian landscape.
Grasslands were part f the Beringian landscape.
Strng winds expsed dry grasses under the snw.
Hrses and bisn did nt have the ability t search fr fd thrugh deep snw cver..
8. Accrding t paragraph 4，which f the fllwing statements is true f the relatinship between ice- age Benngian animals and their envirnment?
When present in sufficient quantities, lichens and msses prvide enugh nutrients t satisfy the needs f herds f large mammals.
The anatmy f certain animals present in that envirnment prvides infrmatin abut the intensity f winds there at that time.
The structure f the teeth f mst ice-age fauna indicates that they preyed n animals such as the mammth, hrse, and bisn.
Hrses and bisn are large enugh that their feet can easily penetrate deep snw and uncver areas where they can feed n plant material.
9. In paragraph 5, the amunt f pllen in Beringian lake sediments frm the last ice age is used t explain
hw lng the ice age lasted
hw imprtant pllen is as a surce f fd
hw many different kinds f plants prduce pllen
hw little vegetatin must have been present at that time
10. Accrding t paragraph 5, hw did Dale Guthrie use the infrmatin abut radicarbn analysis f bnes frm Benngian depsits?
T suggest that Clinvaux shuld have used different methds t measure the amunt f pllen in ice-age lake sediments
T argue that the large Beringian mammals must have eaten plants that prduce little, if any, pllen
T shw that the cnclusins that Clinvaux drew frm the analysis f pllen in ice-age lake sediments cannt be crrect
T explain why s-called plar deserts are incapable f supprting such large animals as mammth, hrse, and bisn
11. The wrd "plausible" in the passage is clsest in meaning t
preferable
practical
reasnable
advantageus
12. Which f the fllwing best describes the rganizatin f paragraph 6 ?
Tw cntrasting views are presented, and a study that culd decide between them is prpsed
An argument is ffered, and reasns bth fr and against the argument are presented
A claim is made, and a study supprting the claim is described
New infrmatin is presented, and the infrmatin is used t shw that tw cmpeting explanatins can each be seen as crrect in sme way.
13. Lk at the fur squares [] that indicate where the fllwing sentence culd be added t the passage.
Nevertheless, large animals managed t survive in Beringia.
Where wuld the sentence best fit? Click n a square [] t add the sentence t the passage.
14. Directins: An intrductry sentence fr a brief summary f the passage is prvided belw. Cmplete the summary by selecting the THREE answer chices that express the mst imprtant ideas in the passage. Sme sentences d nt belng in the summary because they express ideas that are nt presented in the passage r are minr ideas in the passage. This questin is wrth 2 pints.
Drag yur answer chices t the spaces where they belng. T remve an answer chice, click n it.
T review the passage, click VIEW TEXT
During the last ice age, human hunters pursued large mammals acrss Beringia, a land whse climatic characteristics have been in dispute.
Answer Chices
Strng evidence indicates that large mammals like mammth and bisn survived in the harsh ice-age Beringian landscape.
Carnivres such as the saber-tth cat were primarily respnsible fr the disappearance f the largest f the grazing animals, but the harsh winters caused sme grazers t die f starvatin.
The discvery that grasses, sedges, and msses survived under the thick ash frm a large vlcanic eruptin prved that the ice-age Benngian plant cver was extremely resistant t climatic extremes.
Benngian mammals crssed easily frm nrtheastern Asia t Alaska acrss the Bering Land Bridge, thugh there are indicatins that they usually went back t Asia fr the brief, but warm, summers.
Analyses f ice-age sediments uncvered very small amunts f pllen, suggesting that Benngia lacked the quantity f vegetatin needed t supprt large herds f mammals.
Recent discveries suggest that shallw-rted plants created a fairly cntinuus cver ver ice-age Beringia, thugh the cver mst likely was variable and uncertain in any ne lcatin.