Customer Reviews
The Grandest Quadrille - By: Stephen A. Haines, 31 Mar 2008 
"Did the Earth move for you?", asks the voice beside you. Well, yes. Because that's what it does. All the time. The continent you live on used to be someplace else, & far away from where it is now. Your home ground has even been part of a greater landmass known as a "supercontinent" - & will be again. Hence, the title of this book. Ted Nield provides us with a fine account of how we came to learn about these movements. He has brought together the years of research tracking where the rocks have been & where they are likely to go. He likens the movement of continents to a dance of landforms - a "Grand Quadrille". A fine synopsis of the history of geology & its compelling figures - scholars who had to project what was knownin their time back into a distant past.
Earth has been a busy place for the past four billion years, & it hasn't stopped to rest. We speak of the "firmness of the Earth", but that phrase is a sham. The key figurein this story is the great supercontinent of Pangaea that began breaking up 250 million years ago. Assembled from previous continents that had once joined & also separated, Pangaea's breakup into places we live on today have been tracedin exquisite detail. The matching of rocksin places separated by wide seas provided the clues. In fact, as Nield relates, it was the vast Atlantic that bears the responsibility for Pangaea's fracturing to form the basis for the continents we know today. The author explains how the continents have been engagingin a Grand Quadrille & will continue to do so - for another five billion years, at least.
The progenitor of the idea of "drifting continents" was Alfred Wegener. Using maps to show how western Eurasia & Africa matched the east coasts of the Western Hemisphere, Wegener proposed they had once been joined, but had pulled apart. He couldn't provide a mechanism for the movement, & his idea was rejected - most notably by the geologic "establishment" of the United States. Rejection of the proposal was so strong there that one British geologist described it as "regarding the Declaration of Independence as retroactive to the Palaeozoic". Continents formed separately & remained so through time, it was thought.
However, one US dissident, Reginald Daly of Harvard, had beenin South Africa, encountering the work of Alexander du Toit, who noted similaritiesin rocks of the Great Karoo & South America. That discovery, enhanced by some detailed measurementsin Greenland, suggested that movement was occurring. It took a war & the hunt for submarines to reveal what prompted continental movement. An Irish geophysicist, John Joly had already postulated the mechanism, heat from radioactive elements deepin the Earth required escape. That venting pushed the softer areasin the Earth's crust around. Sitting atop that stirring material, the continents track the flow patterns of the heat.
In moving, the continents encounter each other, joining, fusing & establishing mighty landmasses that break up again. Nield skilfully describes the mechanisms & the people who have read the rocks to understand how they work. Beyond Pangaea, for example, the author cites the work of Mark McMenamin, who proposes a yet older supercontinent, Rodinia. Rodinia's importancein the history of the Earth is that it was probably the extant landform around which complex life, after over 3 billion years, finally emerged. Nield's skillin presenting all these complex ideas & their significance never wanes throughout the book. He's achieved a fine summary of the history of modern geology, supported by a collection of portraits & some line drawings. The emphasis on Pangaea is slightly overdone, but his pointer to Chris Scotese's web page of geologic ages more than overcomes that small limitation. An excellent overview. [stephen a. haines - Ottawa, Canada]
