Book review- “The Next Supercontinent”

Book review- “The Next Supercontinent – solving the puzzle of a future Pangea” by Ross Mitchell is a hard back book of 260 pages. It is an easy read that would suit geologists more than most popular science readers. Ross outlines the science and the scientists that developed what we now accept as plate tectonics & continental drift, and the popular concept of heat blooms and cold sinks in the mantle as the main principal driving force. Other factors mention the rotating the Earth may come into play. Back tracking on today’s continental drift brings the continents into one supercontinent called Pangea. Fast forward the continental drift will see the next supercontinent [Amasia] in around 200 million years. Various theories about oceans closing, or not closing, and continents rotating are outlined to speculate on the formation of this next super continent.

Continental drift is the principal cause of mountain building, such as the India plate colliding with Eurasia to form the Himalayas, or subduction zones producing volcanic chains. Upon weathering, such mountains now reveal their deep roots as metamorphosed sequences, and it is these rocks that point to earlier super continents. Geoscience techniques including age dating zircons, paleomagnetic and isotopes reflecting paleo oxygen content from ancient rocks help understand the nature and impact of the older super continents of Gondwana (about 500 million years ago) and the earlier Rodinia (perhaps 2 billion years old).

A couple of points that I was surprised to discover included.

1.????? As continents collide to form the earlier Gondwana, they form mountains that are then weathered releasing minerals (carbonates, phosphorous etc) into the ocean and so provide the stimulus for the Cambrian explosion of life. As the continents break apart, they stimulate evolution diversity (Darwin on Galapagos Island), and upon reforming a super continent of Pangea the species compete contributing to mass extinctions.

2.????? One concept Ross considers is that the Earth has two major deep mantel upwellings, one under Africa and the other under the Pacific Ocean. Could the thermal upwelling under the Pacific Ocean uplift the vast Pacific Ocean floor? Certainly, this would be a significant factor in raising global ocean levels. I wonder if we can measure if the Pacific Ocean floor is bulging upwards at a rate of centimeter/ year scale today?

3.????? Some explorationists theorize that major mineral deposits are found on old continental boundaries. Perhaps this could stimulate conceptual exploration to look at the boundary where north and south Australia crashed into one another.