60秒科学:Plants Put the Bend in Rivers
Plants Put the Bend in Rivers
Studies in the journals Geology and Earth-Science Reviews reveal that ancient rivers were broad straight sheets of water. Colonization 1 by plants changed the water flow. Adam Hinterthuer reports
What was around the bend in rivers hundreds of millions of years ago? It’s a trick question—because there weren’t any bends. Ancient rivers were typically just wide, sheetlike flows of water. New reports in the journals Geology and Earth-Science Reviews say we can thank the very first landlubbing plants for putting the turn in the river.
Researchers from Dalhousie University examined dozens of sites, from the Channel Islands off France to Death Valley. They say that well before dinosaurs 2 or, really, much of anything roamed the Earth, rivers were just vast expanses of water heeding 3 only gravity and heading straight to sea.
The first vascular 4 plants took advantage of the abundant water, and put down roots. The roots began to hold sediment 5 in place. Thus the riverbank was born and waterways began to get thinner and more defined. The communities of Paleozoic plants congregated 6 at the water’s edge and began to colonize 7 the Earth’s surface.
Over the next 50 million years this co-evolution of flora 8 and flow led to the meandering 9 rivers we know today, and a barren landscape made lush. And, also, the seven-dollar toll 10 to cross the Hudson on the George Washington Bridge.
- Colonization took place during the Habsburg dynasty. 开拓殖民地在哈布斯堡王朝就进行过。
- These countries took part in the colonization of Africa. 这些国家参与非洲殖民地的开发。
- The brontosaurus was one of the largest of all dinosaurs. 雷龙是所有恐龙中最大的一种。 来自《简明英汉词典》
- Dinosaurs have been extinct for millions of years. 恐龙绝种已有几百万年了。 来自《简明英汉词典》
- This come of heeding people who say one thing and mean another! 有些人嘴里一回事，心里又是一回事，今天这个下场都是听信了这种人的话的结果。 来自辞典例句
- Her dwarfish spouse still smoked his cigar and drank his rum without heeding her. 她那矮老公还在吸他的雪茄，喝他的蔗酒，睬也不睬她。 来自辞典例句
- The mechanism of this anomalous vascular response is unknown.此种不规则的血管反应的机制尚不清楚。
- The vascular changes interfere with diffusion of nutrients from plasma into adjacent perivascular tissue and cells.这些血管变化干扰了营养物质从血浆中向血管周围邻接的组织和细胞扩散。
- The sediment settled and the water was clear.杂质沉淀后，水变清了。
- Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。
- The crowds congregated in the town square to hear the mayor speak. 人群聚集到市镇广场上来听市长讲话。
- People quickly congregated round the speaker. 人们迅速围拢在演说者的周围。
- Around 700 Arabs began to colonize East Africa.公元700年阿拉伯人开始把东非变为殖民地。
- Japan used to colonize many countries in Asia.日本曾经殖民过许多亚洲国家。
- The subtropical island has a remarkably rich native flora.这个亚热带岛屿有相当丰富的乡土植物种类。
- All flora need water and light.一切草木都需要水和阳光。
- The village seemed deserted except for small boys and a meandering donkey. 整个村子的人都像是逃光了，只留下了几个小男孩和一头正在游游荡荡的小毛驴。 来自教父部分
- We often took a walk along the meandering river after supper. 晚饭后我们常沿着那条弯弯曲曲的小河散步。