# 第四册 Lesson 30 Exploring the sea-floor 海底探索

## 一、课文原文

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. The open sea was deep and mysterious, and anyone who gave more than a passing thought to the bottom confines of the oceans probably assumed that the sea bed was flat. Sir James Clark Ross had obtained a sounding of over 2,400 fathoms in 1839, but it was not until 1869, when H.M.S. Porcupine was put at the disposal of the Royal Society for several cruises, that a series of deep soundings was obtained in the Atlantic and the first samples were collected by dredging the bottom. 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. 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, and the existence of underwater features of considerable magnitude.

Today, enough soundings are available to enable a relief map of the Atlantic to be drawn and we know something of the great variety of the sea bed's topography. Since the sea covers the greater part of the earth's surface, it is quite reasonable to regard the sea floor as the basic form of the crust of the earth, with, superimposed upon it, the continents, together with the islands and other features of the oceans. The continents form rugged tablelands which stand nearly three miles above the floor of the open ocean. From the shore line, out a distance which may be anywhere from a few miles to a few hundred miles, runs the gentle slope of the continental shelf, geologically part of the continents. The real dividing line between continents and oceans occurs at the foot of a steeper slope.

This continental slope usually starts at a place somewhere near the 100-fathom mark and in the course of a few hundred miles reaches the true ocean floor at 2,500-3,500 fathoms. The slope averages about 1 in 30, but contains steep, probably vertical, cliffs, and gentle sediment-covered terraces, 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.

— T.F. GASKELL, *Exploring the Sea-floor* from Science Survey

## 二、重点词汇详解

| 单词 | 音标 | 词性 | 释义 | 用法说明 |
|------|------|------|------|----------|
| confine | /kənˈfaɪn/ | v. | 限制，局限 | be confined to 局限于 |
| irregularity | /ɪˌreɡjuˈlærəti/ | n. | 不规则，凹凸不平 | irregular adj. 不规则的 |
| sounding | /ˈsaʊndɪŋ/ | n. | 测深 | sound v. 测深；sounding 测得的水深 |
| fathom | /ˈfæðəm/ | n. | 英寻（水深单位=1.8米） | 2,400 fathoms 约4,380米 |
| disposal | /dɪˈspəʊzl/ | n. | 处理，支配 | at the disposal of 由……支配 |
| dredge | /dredʒ/ | v. | 挖掘，疏浚 | dredge the bottom 挖掘海底 |
| expedition | /ˌekspəˈdɪʃn/ | n. | 探险，远征 | the Challenger expedition 挑战者号探险 |
| submarine | /ˌsʌbməˈriːn/ | adj./n. | 海底的；潜水艇 | submarine cables 海底电缆 |
| magnitude | /ˈmæɡnɪtjuːd/ | n. | 巨大，规模 | features of considerable magnitude 相当大的地貌 |
| topography | /təˈpɒɡrəfi/ | n. | 地形，地貌 | sea bed's topography 海底地形 |
| superimpose | /ˌsuːpərɪmˈpəʊz/ | v. | 叠加，覆于……之上 | superimposed upon 叠加在……之上 |
| rugged | /ˈrʌɡɪd/ | adj. | 崎岖的，粗犷的 | rugged tablelands 崎岖的高地 |
| terrace | /ˈterəs/ | n. | 阶地，台地 | sediment-covered terraces 沉积物覆盖的阶地 |
| erode | /ɪˈrəʊd/ | v. | 侵蚀，腐蚀 | eroded from the continental masses 从大陆侵蚀下来 |

**专有名词：**
- **Sir James Clark Ross**：詹姆斯·克拉克·罗斯爵士（英国探险家）
- **H.M.S. Porcupine**：豪猪号（英国军舰）
- **H.M.S. Challenger**：挑战者号（英国海洋调查船）
- **Royal Society**：英国皇家学会

## 三、语法知识点

### 1. It was not until...that... 强调句

> **It was not until** 1869, **when** H.M.S. Porcupine was put at the disposal of the Royal Society, **that** a series of deep soundings was obtained

not until 的强调句型，意为"直到……才"。

| 结构 | 例句 | 翻译 |
|------|------|------|
| It was not until + 时间 + that | It was not until midnight that he returned. | 直到午夜他才回来 |
| Not until + 时间 + 倒装 | Not until midnight did he return. | 直到午夜他才回来 |

### 2. with + 宾语 + 宾补（独立主格变体）

> with, **superimposed upon it**, the continents

with + 名词 + 过去分词，作伴随状语。superimposed upon it 修饰 the continents。

### 3. 倒装句

> From the shore line, out a distance..., **runs** the gentle slope of the continental shelf

- 介词短语前置，完全倒装
- 正常语序：the gentle slope runs from the shore line

### 4. which 引导定语从句

> a long tailing-off **which** is almost certainly the result of material transported out to deep water

which 引导定语从句修饰 tailing-off。

## 四、重点句型分析

### 句型1：长难句——强调句中嵌时间状语从句

> It was not until 1869, **when** H.M.S. Porcupine was put at the disposal of the Royal Society for several cruises, **that** a series of deep soundings was obtained

- 主干：It was not until 1869 that...
- when 引出非限制性定语从句修饰 1869
- that 从句为强调句的主要部分

### 句型2：with 独立主格

> it is quite reasonable to regard the sea floor as the basic form of the crust of the earth, **with, superimposed upon it, the continents**, together with the islands

- with + n. + V-ed 结构
- superimposed upon it 为过去分词短语作 continents 的后置定语
- 语序倒置：normal order = with the continents superimposed upon it

### 句型3：被动结构的专业表达

> the first samples were collected **by dredging** the bottom

- by + V-ing 表示方式
- 被动语态体现科学论文的客观性

## 五、课文翻译

一百年前我们对海洋的了解仅限于海面的二维形状和近岸浅水区深度不规则所带来的航海危险。公海深邃而神秘，任何对海洋底部有过些许思考的人大概都认为海底是平坦的。詹姆斯·克拉克·罗斯爵士在1839年获得了超过2,400英寻的测深数据，但直到1869年，当"豪猪"号被交由皇家学会支配进行数次巡航时，才在大西洋获得了一系列深水测深数据，并通过挖掘海底采集了第一批样品。此后不久，著名的"挑战者"号探险确立了海底研究作为最优秀物理学家和地质学家值得研究的课题的地位。与铺设海底电缆相关的一系列活动很快证实了"挑战者"号的观察：海洋的许多部分有两到三英里深，还存在相当大的水下地貌。

今天，已有足够的测深数据可以绘制大西洋的立体地图，我们对海底地貌的多样性也有了些了解。既然海洋覆盖了地球表面的大部分，那么把海底看作地壳的基本形态，而大陆连同岛屿和海洋的其他特征叠加在上面，是非常合理的。大陆形成崎岖的高地，几乎比公洋海底高出三英里。从海岸线向外延伸一段距离——可能是几英里也可能是几百英里——是大陆架的平缓斜坡，在地质学上属于大陆的一部分。大陆与海洋的真正分界线位于一个更陡峭的斜坡的底部。

这个大陆坡通常从大约100英寻的地方开始，在几百英里的距离内下降到2,500-3,500英寻的真正洋底。斜坡平均约为1:30，但包含陡峭的——可能是垂直的——悬崖和平缓的沉积物覆盖的阶地，在其下部附近有一个长长的渐变带，几乎可以肯定是大陆物质被侵蚀后搬运到深水中的结果。

## 六、语言点精讲

### 1. 写作手法：历史叙事与科学说明结合

- 第一段：人类认识海底的历史进程
- 第二段：海底地形的基本认识
- 第三段：大陆坡的详细地质特征

### 2. 逻辑结构

| 段落 | 主题 | 论述方式 |
|------|------|----------|
| 第一段 | 从无知到认知 | 时间线索（1839→1869→此后） |
| 第二段 | 海底地貌概览 | 空间线索（海底→大陆→大陆架） |
| 第三段 | 大陆坡细节 | 数据说明（100→2,500-3,500英寻） |

### 3. 文化背景

- H.M.S. Challenger（1872-1876）：人类首次大规模海洋科学考察
- 大陆架（continental shelf）概念是20世纪海洋地质学的基础
- fathom（英寻）：传统水深单位，1 fathom = 6英尺 ≈ 1.8米

### 4. 修辞分析

- 科学术语使用准确（sounding、dredging、topography、terraces）
- 数据支撑论述（2,400 fathoms、1 in 30、2,500-3,500 fathoms）
- with 独立主格使句子紧凑而信息丰富

## 七、课后练习要点

1. **词汇练习**：掌握 sounding、fathom、dredge、topography、erode 等地质学词汇
2. **语法练习**：It was not until...that... 强调句；with 独立主格；倒装句
3. **翻译练习**：注意科技术语和被动语态的翻译
4. **写作练习**：模仿课文的科学说明文风格，描述一种自然现象

## 八、本课小结

本课介绍人类探索海底的历史与海底地貌知识。核心内容：**从对海底一无所知到逐步认识海底地形的多样性**。文章按时间→空间→细节的逻辑展开。语法重点为 It was not until...that... 强调句、with 独立主格结构和倒装句。词汇方面需掌握海洋地质学专业术语。