When taking up Jan Zalasiewicz’ and Mark Williams’ Ocean Worlds; The Story of Seas on Earth and Other Planets be prepared to go deep – deep into the oceans, deep into the Earth, deep into space, and even deep into time itself. For as the authors make very clear, an understanding of the Earth’s oceans requires not just learning about their present existence but their past ones as well. And if one is to understand the history of the planet’s oceans, an understanding of not just when they came to be but how is also necessary; which in turn requires examining the existence of water itself, not just on Earth but throughout the universe.

Now by this point some who are reading this might be tempted to stop with a declaration of “this sounds far too deep for me!” However I would ask you to read on, for while the topics covered in Ocean Worlds are indeed by no means simple, the authors’ extensive expertise with them is very well paired with their exceptional writing skills to make the book both interesting and intelligible to any with a sincere interest in understanding the fascinating aspects of geoscience that it presents.

Beginning as close to The Beginning as it is reasonably possible to do, (“It was 12 billion years ago, in a far corner of the early universe…”) authors Jan Zalasiewicz, Senior Lecturer in Geology at the University of Leicester, and Mark Williams, Professor in Geology at the University of Leicester, dive right in to some of the foundational concepts that make it possible for there to be oceans on Earth today. Bouncing nimbly between astronomy, chemistry, and physics, Zalasiewicz and Williams guide the reader through what at times can admittedly seem to be a wildly tangential tour through the development of the cosmos. Yet have confidence in their guidance, for it will soon enough become very clear that in these early chapters not one word is included without purpose and not one initially seemingly unrelated explanation is put forth that is not absolutely essential to what will be presented in later ones. However a word to the wise: if you are not well versed in the terminology of geoscience – particularly that of the geologic time scale (Hadean, Archaean, etc.) – keeping a note pad close at hand and making the occasional reading note of the author’s explanations of such will make your reading of Ocean Worlds go much more smoothly.

From the foundations of the universe and subsequently that of the Earth, Zalasiewicz and Williams move rapidly into the beginnings of the seas. Many readers, even those familiar with the idea that the appearance of the Earth has not always been as it is today, may find themselves surprises at just how much the seas have changed over time as well – not just in where they are in relation to the land masses but in their chemical composition as well. Indeed, it is in just such explanations, including not only what can be known of the history of the seas but in how it can be known, that some of the most fascinating information included in Ocean Worlds is found.

Naturally, as any thorough history of the seas at some point must, Ocean Worlds contains an overview of life on Earth as it developed from its microscopic beginnings to eventually include the widely diverse range of sizes and shapes in which it is found today. As one who approaches natural history from the life sciences, I found this chapter somewhat comforting after all the geology and chemistry contained in those previous to it. Yet I must admit that by this point in the book I had become so comfortable with these former subjects that I was actually eager to continue moving forward into the book’s promised explanations of the possibilities of seas on other planets.

And it is in these examinations of the potential for seas on planets other than Earth that the reader’s eyes will likely be opened to their widest, not just because of the fascinating forms (e.g., a vast sea not of water but of liquid methane) such seas might once, presently, or some day far in the future take, but because of just how much is actually known already about many of the planets and moons in our solar system. Not being so much of an astronomy enthusiast since my school days, I had let my attention to things celestial somewhat wane over the past decades; however since reading Ocean Worlds I will happily admit to having the flame of curiosity into the things far above me in the night sky once again rekindled.

Yet it would be remiss of me prior to concluding this review not to make mention of a pair of chapters that sit between the conclusion of the one examining the myriad forms of life that have been and presently are found in the Earth’s seas, and the seas to be found beyond the Earth. These two chapters, “Oceans in Crisis” and “The End of Earthly Oceans,” very different in nature though they are, are essential to the subject and it is very much to the credit of the authors that they took the trouble to include them. “Oceans in Crisis” examines the present problems afflicting the planet’s seas in a manner that is built on all the geoscience, chemistry, and physics so careful presented in the early chapters of the book. Far from histrionics or a clarion call to “take action,” Zalasiewicz and Williams present in clear and eminently defensible language just what is happening in the planet’s seas today and what the effect of these phenomena could be. Then in “The End of Earthly Oceans” they shift their frame of inquiry far into the future and ask the question of if the planet’s seas will someday disappear, and if so how this might happen.

Anyone with an interest in learning more about both how the Earth’s seas – how they came to be, their existence both in the past as well as today, and what may someday become of them – would do well to take up Ocean Worlds. Despite its sometimes necessarily technical and advanced vocabulary (all of which is clearly explained upon first usage by the authors), it does not absolutely require a previous understanding of geoscience beyond the most basic levels. And while it goes deep quickly and delves into some admittedly complex subject matter, the skills of Zalasiewicz and Williams in explaining their points well repays with interest the working through of parts that may at first seem difficult so that by the end the reader will have a far better understanding of not only what he or she first set out to discover but of wondrous things previously unimagined as well.

Ocean Worlds coverTitle: Ocean Worlds; The Story of Seas on Earth and Other Planets

Authors: Jan Zalasiewicz and Mark Williams

Publisher: Oxford University Press

Format: Hardcover

Pages: 336 pp.

ISBN: 9780199672882

Published: January 2015

In accordance with Federal Trade Commission 16 CFR Part 255, it is disclosed that the copy of the book read in order to produce this review was provided gratis to the reviewer by the publisher.