A Crack in the Edge of the World
Northern Appalachian mountains in Pennsylvania (Google Earth placemark
)
Schoolroom memories
It was always those heavy multi-coloured pieces of felt that where supposed to teach us how mountains were formed. On more than one occasion my geography teacher would grab both ends of those layers of felt and push them inwards causing it to flex and bend. That was how close I got to geology at school and it all came back to me while reading a passage in the following book.
North America and the 1906 quake
“A Crack in the Edge of the World” is fascinating read by Simon Winchester and it talks much about the geology of America in general and the devastation of San Francisco in the 1906 earthquake in particular. The narrative on the geological basics of North America is a eulogy to the early explorers and the breathtaking natural monuments they found as well as providing a captivating insights into plate tectonics and other aspects of the often ignored and fairly recent science of geology. Winchester has the rare talent to research little-known facts and put them into elegant prose one never tires to read.
“There is so much time in geology”
In one of his stories he takes the reader back to 1969 when the grey-bearded world of hammer, lens and acid bottle was finally coming round to the notion of plate tectonics. During a scientific conference on the subject “[...] the full import of the plate tectonic revolution burst on the participants like a dam failure.” Notably it was Eldridge Moores who had a “blinding flash of insight” while musing over the presentations of his colleagues. It was a realization that would make him famous.
Moores grasped that certain rocks which today form the tops of mountains are the remnants of ocean floors. In turn he deduced that the great mountain chains of the West are …
“[...] the result, time and time again, of neighbouring plates bumping into each other. [...] The plates bang into each other, and, where they do so, large amounts of material are dislodged and stay put, being heated and compressed by the enormous forces of the collision. Then the collision abates [...] and the foreign material that is left behind [...] is already or becomes in time a mountain chain. [...] Most of these bodies or sequences trend north and south in great elongated ranges of mountain peaks [...] that etch the land below when you are flying across America toward the Pacific Ocean.”
The last phrase of this excerpt brought an aerial photo back to mind which I had taken on a chilly snow-dusted March morning on a flight from Newark to St. Louis. The plane crossed Pennsylvania and the uniform undulations of the Appalachian mountains were spread out below the plane like a page from a geography school book. There were the bulging felt layers of the class room in all their timeless geological glory.

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