时间:2018-12-24 作者:英语课 分类:Scientific American(八)月


英语课

 This is Scientific American’s 60-Second Science. I’m Christopher Intagliata. Got a minute? 


 
Rivers today have high muddy banks, sandbars and bends. But they didn’t always look that way because it wasn’t until the evolution of tree-like plants, some 330 million years ago that rivers were corralled into their current form. Before that, ancient waters flowed wide and shallow over the land, with little to constrain 1 them other than mountains. So says a study in the journal Nature Geoscience.
 
Researchers looked through over 400 studies of the Earth’s rock record, and visited nearly 70 field sites. And they found that channel formations in the rock—a signature of modern rivers—didn’t appear until the Carboniferous period, when tree-like plants evolved. That’s because larger plants needed deeper roots, which stabilized 2 river banks and forced rivers into narrower paths. And deep roots helped form sticky clays, which are harder to erode 3.
 
All this engineering was to the trees’ advantage, the researchers say, because river banks provide trees with easy access to water, without the constant risk of flooding. Pretty much what we humans want. Many of our greatest cities formed along river banks—for which we might have trees to thank.
 
Thanks for the minute. For Scientific American’s 60-Second Science, I’m Christopher Intagliata.

1 constrain
vt.限制,约束;克制,抑制
  • She tried to constrain herself from a cough in class.上课时她竭力忍住不咳嗽。
  • The study will examine the factors which constrain local economic growth.这项研究将考查抑制当地经济发展的因素。
2 stabilized
v.(使)稳定, (使)稳固( stabilize的过去式和过去分词 )
  • The patient's condition stabilized. 患者的病情稳定下来。
  • His blood pressure has stabilized. 他的血压已经稳定下来了。 来自《现代英汉综合大词典》
3 erode
v.侵蚀,腐蚀,使...减少、减弱或消失
  • Once exposed,soil is quickly eroded by wind and rain.一旦暴露在外,土壤很快就会被风雨侵蚀。
  • Competition in the financial marketplace has eroded profits.金融市场的竞争降低了利润。
标签: sss 托福素材
学英语单词
A.P.C. (automatic power control)
actinomucor repens
ad hoc on-demand distance vector
ammonia ash
angiulo
anomalous line condition received
autotronic system
AVRCP
Badenheim
badger dog
balmifying
beck's hydrometer
Buckley ga(u)ge
commutation of penalty
comparative feeding experiment
compositive criteria
contracted curvature tensor
croson
curator-in-charge
cyclophosphamide(CP)
deleterious substances
design transition temperature
diluent agent
distelfinks
doltons
dry blast cleaning
duodena
empurple
entertainments tax
equivalent multiply rate
Euro-farmer
exit phase
extra bright
fulminants
grip strength
gyrostabilizers
hallettsville
hamsin
hemorrhagic white eye
heteropatriarchy
high annealing
hoarsened
human factors evaluation
inductive loop detector
krashen
Lagrange-Hamilton theory
legal situation
licuala spinosa
long-period test
Loose Credit
lyncury
machinery repairman
macrophthalmus abbreviatus
magnetic amplifier type magnetic core circuit
metritic
Mount Juliet
nagal
near drowning
Negri Sembilan
oblique grooving iron
orthogonal orthomorphism
overconnected
patinoes
pennsylvanias
Pinkertonian
planty
pnictides
Politzer's plug
polyynic
preferential direction
regulation of water intake
responsible accident
rhacomitrium cucullatum broth
rhinolaryngological
roes
Roncal, V.de
Schneider Trophy
sclerotium oryzae
seeder unit
seropneumothorax
service completion time
silden
sour mushroom
sputum tubes
stimulation-escape
supress
synchronous optical transmission
taarof
taylers
telescopic belt conveyor
tend on/upon
tenthredo formosana
tetramerous flower
thiocarbazides
track start
transmarginal inhibition
triangular oscillation blade
tubular boiler
verminous abscess
vestas
wallet-size
within-participants design