‘The Next Supercontinent’ predicts the future of Earth’s landmasses

The Subsequent Supercontinent
Ross Mitchell
Univ. of Chicago, $30

At present, there are seven continents. Some 200 million years from now, there can be only one. In The Subsequent Supercontinent, geophysicist Ross Mitchell previews what the world would possibly appear like when Earth’s continents amalgamate right into a single landmass.

Though Mitchell’s vacation spot is the distant future, don’t be fooled. His guide is as a lot a romp via the previous as it’s a look forward, full with references distinctive to the current (like Dwayne “The Rock” Johnson helming a speedboat because it crests a extremely unbelievable tsunami that ravages the Golden Gate Bridge within the film San Andreas).

On the journey again in time, Mitchell visits how the continents got here collectively prior to now to type the earlier supercontinents. He begins about 300 million to 200 million years in the past with lush, dinosaur-laden Pangaea, which was centered on present-day Africa. He then goes again to a billion years in the past to barren Rodinia, whose heart consisted of a lot of in the present day’s North America plus Greenland. Two billion years in the past, there was what some scientists name Columbia — the Siberia-centric first supercontinent.

Monitoring the paths of in the present day’s continents via historical past takes some severe scientific sleuthing. This typically begins with fieldwork to gather samples that constrain when a rock shaped and its latitude at the moment. To offer readers a style of such (mis)adventures, Mitchell shares how he misplaced half his proper thumb within the Australian Outback whereas unearthing a few of Rodinia’s mysteries, and when he and a colleague had been practically stranded with their samples on a frigid lake in Canada’s Northwest Territories.

Clues as to why supercontinents type within the first place and what causes their repeated rending additionally reside in a wholly completely different subject of research — one by which scientists simulate how the “strong however pliable” mantle may need behaved to coax continents alongside. The mantle regulates the connection between the crust and Earth’s core, which shops primordial warmth. The supercontinent cycle, Mitchell argues, is linked to mantle motion that transfers Earth’s inside warmth upward so the crust can launch it.

As warmth rises, scientists suspect, continents drift towards areas the place the mantle is chilly. These chilly spots exist the place oceanic plates subduct, or sink under extra buoyant tectonic plates, into the mantle. Inch by inch, subducting ocean will disappear and produce continents nearer collectively, leading to a collision that may finally culminate in a brand new supercontinent. Mantle simulations counsel that after the supersized landmass has shaped, the incessant inward pull ceases as new subduction zones provoke on the coastlines of the supercontinent. Someplace within the inside of the supercontinent, scorching mantle rises, finally inflicting the supercontinent to tear, forming new oceans and starting one other cycle.

Utilizing the previous to foretell the long run and understanding the mechanics of the mantle, Mitchell presents his imaginative and prescient of Amasia — the subsequent supercontinent (SN: 1/21/17, p. 18). Some researchers have urged it’ll type from both the closing of the Pacific or Atlantic oceans. However he posits Amasia will type by way of the disappearance of the Arctic Ocean because the Americas and Eurasia meet close to the North Pole, dragging the opposite continents alongside for the journey.

All through the guide, Mitchell’s clear explanations and punctiliously chosen photos assist make sense of even probably the most sophisticated ideas (take it from a educated geologist who all the time had hassle with the particulars of the research of Earth’s previous magnetic subject — paleomagnetism — which regularly drive supercontinent reconstructions).

However whether or not Mitchell’s predictions are appropriate is one thing no reader will dwell lengthy sufficient to search out out, although perhaps our descendants will. That may require humankind to outlive far longer than another identified mammal. However given all our achievements as a species, Mitchell is hopeful we are able to beat the chances. “Whereas such longevity could seem far-fetched,” he writes, “doesn’t it additionally sound rather a lot like us?”

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