There are certain places on Earth that are quite different from the familiar hills, valleys, plains, and urban landscapes where more than half of the world’s 8.1 billion people live. One of these “otherworldly” places is the red sandstone country of Utah, where I live, but for this edition, we will visit the white continent of Antarctica, travel back in time to the Earth and its rocks many millions of years ago, and look ahead to what may be in Earth’s far off future. Let’s go!
Rasoul Sorkhabi
Editor, Core Elements
To the Ends of the Earth
Wikipedia Commons
I’ve been doing a lot of geology-focused reading this summer, and among the recent books I’ve enjoyed is an illustrated coffee-table book written by a fellow geologist Edmund Stump and entitled Otherwordly Antarctica: Ice, Rock, and Wind at the Polar Extreme.
The book combines geology with scenic photography, historical anecdotes, and field work as it walks through Stump’s five decades of research in Antarctica.
Geological highlights in Antarctica:
Antarctica is divided into East Antarctica, a Precambrian shield like Australia, and West Antarctica, a mosaic of Mesozoic blocks.
Between these two icy realms lies the Transantarctic Mountains (TAM), where geologists have access to relief and rock outcrops. Stump’s book focuses on the TAM and its rocks and glaciers.
The TAM rise as high as 14,000 feet and span 1,500 miles, revealing the important geologic events that shaped them. These events include the subduction-related Ross Orogeny (580–460 Ma), the Jurassic age volcanic intrusions (Ferrar dolerite), and Cretaceous-age extensional faulting.
Antarctica facts:
With an area of 5.5 million square miles, Antarctica is the fifth-largest continent.
Almost 61 percent of Earth’s freshwater is stored as ice sheets in Antarctica.
Thanks to its dry and cold climate, Antarctica is a repository of meteorites.
A continent for science: The 1959 Antarctic Treaty (signed by 57 countries so far) aims to preserve Antarctica for peaceful and scientific purposes and to limit the impact of tourism and other human activities. Those of us who do visit, should go with an organized group that has a permit.
If you are interested in reading more travel books about Antarctica, I recommend Sara Wheeler’s Terra Incognita and Peter Matthiessen’s End of the Earth.
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A recent article in Nature Geoscience takes us 250 million years into the future, to an Earth in which a hot dry supercontinent is largely uninhabitable to mammals. Let’s see how this is possible.
The Supercontinent Cycle:
Alfred Wegener’s idea of the Pangea supercontinent in the Permian period (some 300 million years ago) is now accepted as part of the plate tectonic theory.
Geologists have also identified other and much older supercontinents: Pannotia or Gondwana (550 million years ago), Rodina (1 billion years ago), and Columbia or Nuna (2 billion years ago).
By projecting the present motion of tectonic plates into the far future, it is possible to construct Pangea Ultima (PU)—the next supercontinent that is expected to form 250 million years from now.
Future forecast: The new study by climatologist Alexander Farnsworth and colleagues describes how the climate and environment of PU will be hostile for mammals (and humans, if they survive until then).
Farnworth predicts:
PU will be located in the Tropics. Surrounded by a single ocean, the vast inland of PU will be hot and dry.
PU will be assembled via plate-convergent volcanic eruptions on a global scale. These eruptions will elevate the atmospheric carbon dioxide levels.
The aging sun at the time of PU will shine 2.5 percent brighter.
All of the above will lead to a hothouse Earth with atmospheric carbon dioxide levels reaching up to 1,120 parts per million (compared to today’s 400 ppm) and land surface mean temperatures of 25–35 C (compared to today’s 15 C).
Considering the climatic and environmental tolerance levels of species, only 8 percent of PU will be hospitable to the world’s current mammals and some plants.
The bottom line: Constructing a supercontinent 250 million years into the future is full of uncertainties and may appeal to geologists only. It should not be our immediate concern.
However, the hot, dry, hostile climate scenario modeled for PU should motivate us to seriously think about global warming and how humans' impact may pair with geological forces.
Go deeper: Read the full article in Nature Geoscience. You can also watch this YouTube animation on how PU may one day form.
Journey Through Earth’s Extinct Worlds
Krungchingpix/ Shutterstock.com
How different was the Earth millions and millions of years ago? A recent bestseller entitled Otherlands: A Journey Through Earth’s Extinct Worlds by British paleontologist Thomas Halliday takes us to the exotic Earth of the past.
Snapshots of Earth’s history: Each of the book’s 16 chapters, equipped with a paleogeographic map and the paleontologist’s tool kit, is a stop in a certain geologic period (Pleistocene through Ediacaran) and a specific location in North and South America, Eurasia, Africa, and Australia.
First stop: Pleistocene, 20,000 years ago, Northern Plain, Alasia. This is the beginning of the end for large, North American mammals such as mammoths, due to climate change and gradual human settlements on the continent.
Last stop: Edicarian, 635–540 ma, Ediacara Hills, Australia. Life is actively experimenting to produce jelly-like, sponge-like, worm-like, and other strange marine animals. Life will eventually succeed.
Why it matters: The answer is in this line from the Aboriginal poet Oodgeroo Noonuccal: “Let no one say the past is dead / The past is all about us and within.”
Otherlandswill take you on an armchair tour of 635 million years of Earth’s history, sharing how the planet looked millions of years ago and how past worlds have shaped present life. Buckle up!
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