【正文】 on n. 荒漠化；沙漠化；deserter n .逃兵；背棄者；desertion n. 遺棄；開小差；逃亡；Arctic [39。kɑnt?n?nt] n. 洲，陸地 【頻】22 【例】TPO31 L2 So if an ocean floor tectonic plate meets the edge of a continent and they push against each other, the heavier one sinks down and goes under the other one. 【衍】continental adj. 大陸的；大陸性的Sediment [39。la?mston] n. [巖] 石灰?guī)r 【頻】11 【例】TPO16 L1 Sulfuric acid eats away at limestone very aggressively. So you get bigger cracks and then passageways being formed along the openings in the rock. distribute [d?39。k] vi. 破裂；n. 裂縫 【頻】9【例】TPO16 L1 You have water from the surface, streams, waterfall or whatever moving water that flows through cracks found in the limestone. It’ s the moving water itself that wears away at the rock and makes passageways. 【衍】cracker n. 爆竹；胡桃鉗crater [39。ve captured the rain right there on the top. reef [rif] n. 暗礁；[地質(zhì)] 礦脈 【頻】8 【例】TPO27 L1 Recently, researchers have used data collected by monitoring surface water temperatures to improve the ability of a reef to recover from bleaching. 【衍】 reefy adj. 多暗灘的；多暗礁的split [spl?t] vt. 分離；劈開；n. 裂縫 【頻】8 【例】TPO31 L2 Well, the seafloor is spilt. There is a ridge, a mountain range that runs north and south there. And the rock material flows up from Earth’s interior here, at the split, which forces the two sides of the ocean floor to spread apart, to make room for the new rock material.【衍】n. splitter 分離機(jī)，分流器；分解器，拆分器；core [k?r] n. 核心；地心 【頻】7 【例】TPO26 L3 Now, you remember from our previous discussion that a et’s nucleus ,its core, is made up of ice and dust, like a frozen snowball． crust [kr?st] n. 地殼；外殼 【頻】7 【例】TPO31 L2 As we’ve discussed, Earth’s crust is made up of large plates that rest on a mantle of molten rock. These plates…uh…now these tectonic plates support the continents and oceans. 【衍】crusty adj. 有殼的；crustal adj. 殼的，地殼的；mantle [39。ntl] n. 地幔；覆蓋物 【頻】7 【例】TPO31 L2 As the ocean floor plate begins to sink down into the mantle, it would drag or pull the entire plate along with it. So more and more of this plate, the ocean floor, would go down under the continent into the mantle. slide [sla?d] vi. 滑動；滑落；n. 雪崩【頻】7 【例】TPO7 L3 So ice at the base of the glacier melts. And this results in a thin layer of water between the glacier and the ground. This layer of water reduces friction is... is like a lubricant. And it allows the glacier to slide or slip over the bedrock. 【衍】n. slider 滑動器；滑雪者；滾動之物canyon [39。nj?n] n. 峽谷 【頻】6 【例】TPO1 L2 Now, we geologists thought we had a pretty good idea of how the Grand canyon in the southwestern United States was formed. We knew that it was formed from sandstone that solidified somewhere between 150 and 300 million years ago. lava [39。h?m?sf?r] n. 半球 【頻】5 【例】TPO17 L2 Which makes earth, and in particular, the northern hemisphere, warmer. And why is that important? well, because most of the planet’s glaciers are in the northern hemisphere, and if it gets too warm, then glaciers will stop forming. 【衍】hemispheric adj. 半球的，半球形狀的；mineral [39。s Hole. And by studying these clacite deposits, we can determine the climate conditions, the temperatures over the last half million years. 【衍】mine n. 礦，礦藏；礦山，礦井；mineralogy n. 礦物學(xué)；mine v. 開采，采掘；mineralize v. 使礦物化；precipitation [pr?39。te??n] n. 降水，降雨 【頻】5 【例】TPO9 L2 Second, most of the precipitation in the Arctic is in the form of snow. And the snow, which blankets the ground in the winter, actually has an insulating effect on the soil beneath it. 【衍】precipitate v. 沉淀；猛地落下；冷凝成為雨或雪等；swamp [swɑmp] n. 沼澤；濕地 【頻】5 【例】TPO11 L3 Wetlands are areas of marshy, swampy land, areas where water covers the soil, or is present either at or near the surface of the soil for a large part of the year. 【衍】swampy adj. 沼澤的；濕地的；松軟的eruption [?39。s quite possible that this is due to volcanic eruptions, because volcanic eruptions often emit gases. If that39。s thick cloud cover. 【衍】adj. eruptive 暴發(fā)的，噴出的；erupt v. 爆發(fā)，噴出；evaporate [?39。p?ret] vi. 蒸發(fā)，揮發(fā) 【頻】3 【例】TPO6 L4 Less vegetation means the soil can’t hold water as well, the soil loses its ability to retain water when it does rain. So then you have less moisture to help clouds form, nothing to evaporate for cloud formation. And then the cycle continues, less rain, drier soil, less vegetation, fewer clouds, less rain etc. etc.. 【衍】evaporable adj. 易蒸發(fā)性的，易揮發(fā)的；evaporation n. 蒸發(fā)，消失；extract [39。kt] vt. 開采,提煉 【頻】3 【例】TPO32 L3 It wasn’t the mining itself that caused such massive destruction. It was what happened after the copper ore was extracted from the mines. 【衍】extractable adj. 可抽出的，可榨出的；extraction n. 提取物；extractor n. 提取器；horizontal [39。zɑntl] adj. 水平的；地平線的；【頻】3 【例】TPO24 L3 Today we take for granted that there horizontal bands of plant munities. In the far north, it is tundra, which gives way to forest as you move southward. And even farther south, grasslands take over. But during the Ice Age, these plant munities actually grew together, mixed with one another. 【衍】horizontally adv. 水平地,地平地；horizon ,范圍latitude [39。t?tud] n. 緯度 【頻】3 【例】TPO14 L3 So the Polynesians could estimate their latitude just by looking straight up, by observing whether a certain zenith star passed directly overhead at night, they’d know if they have reached the same latitude as a particular island they were trying to get to. 【衍】latitudinal adj. 緯度的magma [39。ɡm(xù)?] n. 巖漿 【頻】3 【例】TPO14 L4 Remember, magma is hot molten rock that39。r?mn?nt] n. 殘余物 【頻】3 【例】TPO30 L3 So it’s possible that if the jarosite on Mars was also formed with the help of microorganisms, we might be able to detect remnants of them in the samples we find. slope [slop] n. 斜坡 【頻】3 【例】TPO11 L2 And look at the slope of the roof, the steep angle helps keep off all that rain and snow that accumulates in the winter. topography [t?39。n230。rod] vt. 腐蝕，侵蝕 【頻】2 【例】TPO32 L3 So the rain eroded the soil and swept it into the rivers. This is called silting, when soil particles are washed into the rivers. And the silting continued at an