歌词
Lesson 30
第30课
Exploring the sea-floor
海底勘探
How did people probably imagine the sea-floor before it was investigated?
在海底探索之前，人们是如何想象海底世界的？
Our knowledge of the oceans a hundred years ago
100年前，
was confined to the two-dimensional shape of the sea surface
我们只知道海洋是二维平面形的，
and the hazards of navigation presented by the irregularities in depth
以及靠近陆地浅水区的深浅
of the shallow water close to the land.
不一定能给航行带来危险。
The open sea was deep and mysterious,
无边无际的海洋深邃而又神秘，
and anyone who gave more than a passing thought to the bottom confines of the oceans
凡是稍稍想过大海海底的人
probably assumed that the sea bed was flat.
大概都会认为海底是平坦的。
Sir James Clark Ross had obtained a sounding of over 2, 400 fathoms in 1839,
1839年，詹姆斯·克拉克·罗斯爵士曾测得海水深度超过2，400英寻；
but it was not until 1869,
但直到1869年，
when H.M.S.Porcupine was put at the disposal of the Royal Society for several cruises
皇家学会用英国“豪猪”号舰艇进行了几次巡航后，
that a series of deep soundings was obtained in the Atlantic
才在大西洋测得一个海水深度，
and the first samples were collected by dredging the bottom.
同时通过挖掘海底，取得了研究海底的首批样品。
Shortly after this the famous H.M.S.Challenger expedition
此后不久，英国著名的“挑战者”号舰艇对海底的那次考察，
established the study of the sea-floor
把对海床的研究
as a subject worthy of the most qualified physicists and geologists.
确立为一个值得一流物理学家和地质学家从事的研究课题。
A burst of activity associated with the laying of submarine cables
铺设海底电缆的热潮
soon confirmed the Challenger's observation
很快证实了“挑战者”号的观察结果：
that many parts of the ocean were two to three miles deep,
海洋中很多地方可深达两三英里，
and the existence of underwater features of considerable magnitude.
水下特征差异极大。
Today, enough soundings are available to enable a relief map of the Atlantic to be drawn
现在已有足够的水深测量数据来绘制一张大西洋洋底地形图，
and we know something of the great variety of the sea bed's topography.
而且我们对海底地形的千变万化也有了一定的了解。
Since the sea covers the greater part of the earth's surface,
既然海洋覆盖着地球的大部分表面，
it is quite reasonable to regard the sea floor
因此完全有理由把海床
as the basic form of the crust of the earth,
看作地壳的基本模壳，
with superimposed upon it the continents,
上面附加着大陆
together with the islands and other features of the oceans.
以及岛屿和海洋的其他形态。
The continents form rugged tablelands
大陆是崎岖不平的高地，
which stand nearly three miles above the floor of the open ocean.
高出辽阔的海洋海底近三英里。
From the shore line,
从海岸线
out to a distance which may be anywhere from a few miles to a few hundred miles,
向大海延伸几英里到几百英里的区域，
runs the gentle slope of the continental shelf, geologically part of the continents.
是大陆架慢坡，从地质学上来说，它是大陆的一部分。
The real dividing line between continents and oceans
大陆和海洋的真正分界线
occurs at the foot of a steeper slope.
是在陡破脚下。
This continental slope usually starts at a place somewhere near the 100-fathom mark
大陆架慢坡一般是从差不多100英寻水深的地方开始的，
and in the course of a few hundred miles
一直延伸到几百英里远
reaches the true ocean floor at 2, 500-3, 500 fathoms.
深达2，500至3，500的地方，那里才是真正的海底。
The slope averages about 1 in 30, but contains steep,
坡度平均约为1/30，但其中包括陡峭的、
probably vertical, cliffs, and gentle sediment-covered terraces,
乃至垂直的峭壁和沉积物覆盖的缓和的阶梯地带，
and near its lower reaches there is a long tailing-off
在这个地带的低处是很长的一段尾沙地段，
which is almost certainly the result of
基本上可以断定这个地段是
material transported out to deep water after being eroded from the continental masses.
大陆块体上侵蚀下来的物质被水冲到深水处形成的。
专辑信息