新概念英語第四冊
Lesson 30 Exploring the sea-floor
1 . and in the course of a few hundred miles reaches the true ocean floor at 2,500-3,500 fathoms.一直延伸到幾百英里遠深達2，500至3，500的地方，
2 . it is quite reasonable to regard the sea floor as the basic form of the crust of the earth,因此完全有理由把海床看作地殼的基本模殼，
3 . with, superimposed upon, it the continents, together with the islands and other features of the oceans.上面附加著大陸以及島嶼和海洋的其他形態。
4 . From the shore line, out to a distance which may be anywhere from a few miles to a few hundred miles,從海岸線向大海延伸幾英里到幾百英里的區域是大陸架慢坡，
5 . Shortly after this the famous H. M. S. Challenger expedition established the study of the sea-floor as a subject worthy of the most qualified physicists and geologists.此後不久，英國著名的「挑戰者」號艦艇對海底的那次考察，把對海床的研究確立為一個值得一流物理學家和地質學家從事的研究課題。
6 . The open sea was deep and mysterious,無邊無際的海洋深邃而又神秘，
7 . runs the gentle slope of the continental shelf, geologically part of the continents.從地質學上來說，它是大陸的一部分。
8 . and we know something of the great variety of the sea bed's topography.而且我們對海底地形的千變萬化也有了一定的瞭解。
9 . probably vertical, cliffs, and gentle sediment-covered terraces,乃至垂直的峭壁和沉積物覆蓋的緩和的階梯地帶，
10 . Since the sea covers the greater part of the earth's surface,既然海洋覆蓋著地球的大部分表面，
11 . And anyone who gave more than a passing thought to the bottom confines of the oceans probably assumed that the sea bed was flat.凡是稍稍想過大海海底的人大概都會認為海底是平坦的。
12 . The continents form rugged tablelands which stand nearly three miles above the floor of the open ocean.大陸是崎嶇不平的高地，高出遼闊海洋海底近三英里。
13 . and near its lower reaches there is a long tailing-off which is almost certainly the result of material transported out to deep water after being eroded from the continental masses.在這個地帶的低處是很長的一段尾沙地段，基本上可以斷定這個地段是大陸塊體上侵蝕下來的物質被水沖到深水處形成的。
14 . Our knowledge of the oceans a hundred years ago was confined to the two-dimensional shape of the sea surface and the hazards of navigation presented by the irregularities in depth of the shallow water close to the land.100年前，我們只知道海洋是二維平面形的，以及靠近陸地淺水區的深淺不一能給航行帶來危險。
15 . Today, enough soundings are available to enable a relief map of the Atlantic to be drawn現在已有足夠的水深測量數據來繪製一張大西洋洋底地形圖，
16 . The real dividing line between continents and oceans occurs at the foot of a steeper slope.大陸和海洋的真正分界線是在陡坡腳大陸架慢坡
17 . that a series of deep soundings was obtained in the Atlantic and the first samples were collected by dredging the bottom.才在大西洋測得一個個海水深度，同時通過挖掘海底，取得了研究海底的首批樣品。
18 . This continental slope usually starts at a place somewhere near the 100-fathom mark一般是從差不多100英尋水深的地方開始的，
19 . and the existence of underwater features of considerable magnitude.水下特徵差異極大。
20 . when H.M.S. Porcupine was put at the disposal of the Royal Society for several cruises,皇家學會用英國"豪豬號艦艇進行了幾次巡航後，
21 . Sir James Clark Ross had obtained a sounding of over 2,400 fathoms in 1839,在1839年，詹姆斯·克拉克·羅斯爵士曾測得海水深度超過2，400英尺；
22 . The slope averages about 1 in 30, but contains steep,坡度平均約為1/30，但其中包括陡峭的，
23 . A burst of activity associated with the laying of submarine cables soon confirmed the Challenger's observation that many parts of the ocean were two to three miles deep,海洋中很多地方可深達兩三英里，