Last Updated September 5, 2023.
Rachel Carson explains in the first chapter some of her reasons for writing a historical overview of the sea's importance. While she suspects that most people have some appreciation of the ocean's multiple roles, she wanted to offer a wealth of information in accessible prose and to encourage people to take an active role in protecting these vast resources.
The book was published in 1951 in the midst of the Atomic Age, when a large number of tests were being conducted. Thus, she cautions this practice:
Although man's record as a steward of the natural resources of the earth has been a discouraging one, there has long been a certain comfort in the belief that the sea, at least, was inviolate, beyond man's ability to change and to despoil. But this belief, unfortunately, has proved to be naïve. In unlocking the secrets of the atom, modern man has found himself confronted with a frightening problem—what to do with the most dangerous materials that have ever existed in all the earth's history, the byproducts of atomic fission.
One point that Carson emphasizes is the continued dependence of humans and other animals on the sea. This dependence is based in the important role that the sea played in helping develop all animal life on shore.
She offers information about the initial development of plant life as the continents emerged, which in turn facilitated animal occupation:
The lakes, the shores of the coastal rivers, and the swamps . . . were the testing grounds in which plants and animals either became adapted to the new conditions or perished.
As the lands rose and the seas receded, a strange fishlike creature emerged on the land, and over the thousands of years its fins became legs, and instead of gills it developed lungs.
The author considers the differences between the knowledge of events at sea (such as severe storms and the subsequent height of waves) that are recent and instrumentally recorded in relation to the tales and lore of earlier eras. Because the technological bases for recording such phenomena were developed only in the last few centuries, we cannot know if these weather events have actually changed or if the earlier reports were hyperbole.
She notes that the water in the southern hemisphere tends to have much longer waves than those of the northern hemisphere, but length does not necessarily correlate with height:
The greatest possible height of storm waves at sea is a much debated question, with most textbooks citing a conservative 60 feet and mariners stubbornly describing much higher waves. Throughout the century that has followed the report of Dumont d'Urville that he encountered a wave 100 feet high off the Cape of Good Hope, science generally has viewed such figures with skepticism.
She then provides a 1933 report from the USS Ramapo, en route from the Philippines to California, that sailed through a fierce storm that lasted for several days. The exact measurement was calculated by comparison to the height of the mast because the ship was on an even keel when the high wave was sighted.
Winds of 68 knots came in gusts and squalls, and the seas reached mountainous height. While standing watch on the bridge . . . one of the officers . . . saw . . . a great sea rising astern to a level above an iron strap on the crow's nest of the mainmast. . . . [S]imple mathematical calculations based on the dimensions of the ship gave the height of the wave. It was 112 feet.
Looking below the surface, Carson reviews the...
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state of knowledge about the ocean floor. She points to significant phases that advanced our understanding, including the early experiments that reached the ocean floor and the knowledge that is still incomplete.
Even though the geological features that define the ocean's floor are covered by water, they exhibit tremendous variety:
Little by little, like the details of a huge map being filled in by an artist, the hidden contours of the ocean are emerging. . . . The general bottom topography is, however, well established. Once we have passed the tide lines, the three great geographic provinces are the continental shelves, the continental slopes, and the floor of the deep sea. Each of these regions is as different from the others as an arctic tundra from a range of the Rocky Mountains.