The Story of the Earth in 25 Rocks Tales of Important Geological Puzzles and the People Who Solved Them

Judging by the title of this book, you might expect it to talk of 25 remarkable kinds of rocks and minerals. But in the preface, geologist and palaeontologist Donald R. Prothero makes clear that his book looks as much at famous outcrops and geological phenomena. Bringing together 25 readable and short chapters, he gives a wide-ranging tour through the history of geology, celebrating the many researchers who contributed to this discipline.

The range of topics covered by Prothero is diverse, and seemingly not organised in any fashion. But start reading through the book, and connections are made across chapters. Some of his chapters tie in with Dartnell’s book Origins: How The Earth Made Us that I just reviewed, chronicling the discovery of economically important deposits of coal, tin or iron and how these were formed. Others will take the readers off the planet as he tackles meteorites and moon rocks. Interestingly, Prothero thinks Earth’s water has been present since the beginning, discounting the mechanism of delivery-by-comet, something which Starkey deemed a much more likely possibility (see my review of Catching Stardust).

Throughout, Prothero highlights the role of chance discoveries, such as the finding of cyanobacterial colonies in Australia that leave behind domed rocky structures called stromatolites, some of the oldest trace fossils in the fossil record, or the famed iridium layer that birthed the idea of a cosmic impact ending the reign of the dinosaurs (see T. rex and the Crater of Doom – Prothero gives a very informative overview of how the tide of opinion and evidence on how impactful that impact was sways back and forth to this day). Another famous story is how Clair Patterson’s research on dating of meteorites produced exquisitely sensitive methods to measure lead levels, resulting in the discovery of widespread lead pollution, a discovery for which he was attacked by powerful industry lobbies throughout his lifetime.

Another theme that returns time and again is how external forces and priorities provided funding and resources for important discoveries. It was the search for coal in Victorian Britain that led William Smith to produce the first map of geological strata in England in 1815, which pretty much launched the discipline of stratigraphy (see The Map that Changed the World for more). Other authors have already highlighted how the military has been instrumental in the developing discipline of oceanography, providing the material and thirst for knowledge to map the globe’s deep sea.

Prothero rightfully lavishes most attention on the cornerstones of geology; concepts such as deep time (see e.g. Earth's Deep History or Nature's Clocks) and plate tectonics. Other than the now-famous insights of Alfred Wegener (much ridiculed during his lifetime and afterwards, see my review of Four Revolutions in the Earth Sciences), he discusses all the evidence in favour, and the vindication that came with findings from amongst other palaeomagnetism (see my review of The Tectonic Plates are Moving! and The Spinning Magnet). But he also highlights subsequent insights, such as subduction zones and transform faults (e.g. the infamous San Andreas Fault).

The Story of Earth in 25 Rocks celebrates the many scientists whose names and contributions have been downplayed, such as Marie Tharp’s contribution to creating a map of the entire ocean floor (see Soundings). Or the people who are rarely mentioned, such as Scotsman James Croll’s work on variation in Earth’s orbital motion patterns well before Milutin Milankovitch. Prothero rightfully speaks of the Croll-Milankovitch cycles. Similarly, his chapter on turbidites (the product of large underwater landslides) highlighted fascinating research and characters that were all new to me.

Each chapter comes with a short recommended reading list, highlighting a selection of excellent popular science books and more academic works. A great selection of period photographs is included and many diagrams and graphs have been redrawn or slightly modified to ensure their legibility and usefulness – some photos of rock formations, on the other hand, would have been better off being reproduced in colour. There are some minor mistakes, such as submarine Alvin supposedly diving almost 4,800 kilometres beneath the waves (p. 19), which made me question the statement on page 146 that the Hull-Rust-Mahoning iron mine has produced over 650 million metric tonnes of ore, and more than 450 metric tonnes of waste (should that latter also be million metric tonnes, or is this mine particularly rich in iron ore?) Prothero furthermore reports dimensions and masses in both metric and imperial units in some chapters, but is not consistent in doing so throughout the book.

The above are but minor quibbles that take nothing away from the sheer joy and enthusiasm with which Prothero serves up these 25 chapters. Incredibly well written and insightful, there is something here for everyone with an interest in geology. Prothero distinguishes himself as an excellent science communicator and I cannot wait to get my hands on his other two books, The Story of Life in 25 Fossils, which preceded this book, and The Story of the Dinosaurs in 25 Discoveries, which is due later this year.