that the U.S.Soil Conservation Service planted 73 million kudzu seedlings in the southern United States to control erosion, and went on planting until 1942. By then, it was obvious that kudzu was becoming a menace in the south, and that it was moving north.Considering that kudzu requires long warm summers in order to produce its seeds, why has it successfully colonized northern areas? The ...
the fossil record is half a billion years old and has undergone enormous damage because of mountain building, land erosion, earthquakes, volcanic eruptions and so on. On top of all that, most forms of life don't die under conditions that result in fossilization. Therefore, many puzzles remain in our attempts to make sense out of the fossil record.For instance, mammals developed from reptiles ...
듯한 직벽(直壁)으로 둘러싸여 있고 해식(海蝕) 작용으로 장관을 이룬다. 해식(marine erosion)이란 파도 조류(潮流) 연안류 등이 해안선 가까이서 작용하는 침식현상. 파도의 침식으로 나타나는 지형으로는 해식애(sea cliff) 해식동(sea cave) 해식대(abrasion platform) 등이 있다. 대부분의 독도 지형은 ...
동아사이언스
디라이브러리
DS스토어
팝콘플래닛
