For a small country, Britain has had a big influence on the world. Like a lot of other things, modern geology started here. There are several reasons for that and one is very simple: pioneering geologists had mountains of material to work with. According to the author, “Britain has the most varied geology of any country in the world.” This is an excellent introduction to the rocks of the realm, from gneiss in the Outer Hebrides to granite on Dartmoor. I like the way Turnbull discusses not only how rocks affect your eyes – their colour, texture and contours – but also how they affect your boots. He’s a hillwalker, not a professional geologist, so he conveys a strong sense of place and of how Britain’s landscape varies. But there’s more than geological variation here: Britain isn’t just rich in rocks and its landscape is shaped by more than physics and chemistry. This is the caption to one spectacular photo of a misty mountain:
Bwlch y Saethau, where according to legend King Arthur battled his nephew Mordred; behind, Y Lliwedd stands at the centre of a far greater act of violence, the Lower Rhyolite Tuff event. (ch. 10, “Redhot Flying Avalanches: Ignimbrites in Snowdonia”, pg. 98)
Britain’s varied mountains are named in Britain’s varied languages: Welsh, English and Gaelic give different flavours to the landscapes they describe, from Carnedd Dafydd to Eskdale, from Ingleborough to Stuc a’ Chroin, from Ardnamurchan to Mynydd Mawr. But English names split into Norse and Anglo-Saxon, which have different flavours too. Underlying all these languages is a common ancestor, just as some very different rocks have common ancestors too. Heat, compression and erosion change rocks; time, separation and mutation change languages. So Turnbull is writing about two kinds of history as he discusses different parts of Britain: geological history and linguistic history.
Linguistics dwarfs geology in complexity, but geology dwarfs linguistics in time. To understand why Britain looks the way it does, you have to go back billions of years and trace its movement over many thousands of kilometres. You also have to study seemingly exotic things like volcanoes, glaciers and tropical botany, all of which are central parts of Britain’s geology. Turnbull is a relaxed but knowledgeable guide to some big events and some big transformations and because he isn’t a professional he knows how to write for a general reader. He doesn’t just inform, he re-orientates: you won’t look at Britain in the same way:
Black pointy islands of volcanic ash rise above the sea, the water around them a froth of falling ash. The shores of the new islands get washed away by tsunamis as chunks of other islands fall into the sea. Lava slides down and then runs level, to form black land made of glass. The glassy ground crackles as it cools, and then quickly weathers to orange shards and gravel. Showers of sharp-edged volcanic rubble fall into the sea, forming seabed layers 300m deep which will eventually be the summit of Snowdon itself. (ch. 10, pp. 103-4)
Geology is like cuisine in reverse: from the cooked dish you have to work out the recipe. Landscapes that seem inert can have cataclysmic pasts, full of fire and thunder or flood and frost. There are centuries of ingenious deduction and painstaking observation behind the chatty text and attractive photos in this book, but there are still mysteries to solve. More maths will be needed, because matter obeys mathematical rules in all its transformations, whether geological or culinary. And those material transformations have immaterial parallels in linguistics and sociology, where maths is the key to understanding too. And science itself has metamorphosed and mutated. Geology is an important subject not just for its contemporary research but also for its influence on other fields. It made scientists realize the vast age of the earth. Charles Darwin used that idea to transform biology. Like the pioneering geologists, he was British. That isn’t a coincidence and it’s something else that increases the power of this book. The planet starts here. So does the universe.