The release of the book, The Mountain Mystery, coincides with the 50th Anniversary of the discovery of how the Earth’s mountains were formed. It’s fascinating to think about – in our parents’ and grandparents’ lifetimes, geologists finally figured out why the planet has mountains.

Getting Smaller.  Before plate tectonics, mountains were indeed a mystery. For a long while – a few hundred years, actually, the prevailing notion was the mountains are the scabby remnants of a shrinking, contracting world. Sometimes called the Apple-Earth Theory, advocates championed the idea that the planet is cooling, ridges are forming (“Just like a dry old apple,” they said) and mountains were the result. Not as silly as it sounds – almost everything shrinks as it cools, the Earth is undoubtedly cooling – and has been for billions of years. It would take only a millimeter or two each thousand years. In four billion years, you’ve got mountains.

Getting Bigger.  Then there were the geologists who figured that the planet wasn’t shrinking – it was expanding. Growing a few millimeters each several hundred years. Ripping itself apart at the seams. Advocates described elaborate (and perhaps accurate) schemes in which various inner earth materials crystallized in ways that expanded our old ball of iron and stone. By the way, the fruit for these scientists was the orange – theirs is the Orange-Peel Theory.

Bouncing.  Still others figured mountains rose along the edges of seas where continental erosion filled enormously deep geosynclines which became pressurized and hot. Eventually, a great rebound occurred and the mountains rose as if they were on a trampoline. Alas, this theory has no known fruits.

Just 50 years ago, scientists supporting the improbable idea of mobile continents were in a minority – a rejected, ridiculed minority. They held a counter-intuitive solution: big cumbersome landmasses sailing the oceans. Put that way, it does sound a bit ridiculous. But a newly constructed model – plate tectonics – was being developed to supplant continental drift. The older image of continents plowing through the open seas was being refined. Over the next few months, this blog will look at how that revolution developed and will look at some of the new ideas – and still unresolved issues – that are part of this solution to the mountain mystery.