Books
The hills are shadows, and they f low, From form to form, and nothing stands;
They melt like mist, the solid lands, Like clouds they shape themselves and go. (Tennyson, ‘In Memoriam’)
GEOLOGY? A bit like economics, the famously boring science? I confess I suffered the prejudice—agriculture and history being my thing, both of them vital in every sense— but Robert Muir-Wood’s voyage through the past 66 million years of the making of the British landscape has biblical-level drama on almost every other page. Flood, fire, ice… or, perhaps, the formation in rock, sand, mud and lava of these isles is best conceived of as fierce poetry. There is a knowingness in the author’s dotted, select quotations from Tennyson (‘the most scientifically literate of poets’); the proper telling of the island creation story requires imagination, as well as stone-cold fact and theory.
What a geological genesis Britain had! Dr Muir-Wood takes a broadly chronological approach, beginning with the Cretaceous-era seas, submerging almost the entire place in tropical shallow water filled with coccoliths, microscopic, shelled phytoplankton. As the coccoliths died, their bodies sank; a perpetual submarine snowstorm that deposited sediment on the seabed—the chalk that dominates southern and eastern Britain (Local Distinctiveness, May 1). In Sussex, the chalk layer is 560m (1,837ft) thick— once, we were inhabitants of Albion, the white land, from the same word-root as albino.
As the chalk seas retreated, a subterranean plume of superhot (1,700°C) mantle material heaved Britain up into the air. If you ever wondered, on singing Rule Britannia, when Britain was lifted from the ‘azure main’, the answer is about 60 million years ago. Volcanoes then constructed a chain of isolated mountains down western Britain, with the one on Rum scraping the sky at 3,000m (9,842ft).
With the volcanoes came earthquakes and ‘dykes’ (splits in the earth’s surface) requiring 20 cubic km (4.8 cubic miles) worth of magma to fill them. The famous Giant’s Causeway in Co Antrim, a dried lava field consisting of hexagonal columns, is only one of the many strange geometries that creation deposited nationally. As entrancing is Alum Bay on the Isle of Wight, where a fault in the planet’s superficial tectonic plates has rotated what were once horizontal layers of sediment to display them vertically, like a shelf of books with coloured spines.
As the author writes: ‘We live with the comfortable illusion that Britain and Ireland are stable and immutable, and yet the landscape is rich in tectonic sig
