Catastrophes and Cataclysms
The discovery of the deep past in the Victorian era by geologists such James Hutton and Charles Lyell carried with it an equally deep commitment to the principle of uniformitarianism: that the Earth of the past operated in the same way as the Earth does today and, as a corolllary, that the planet was formed and is formed by gradual processes; an immortal sparrow, wiping its beak every day upon a mountain will grind even Everest down to dust, given enough time. In part this commitment was born from revulsion against Biblical catastrophism and the explanation of everything by reference to events like the Flood.
Only, it turns out, the Earth’s history is full of catastrophic events that wiped lands from the face of the planet and brought peoples to extinction. Here’s just a couple that occurred over the last few thousand years, a heartbeat in geological time.
The Storegga Slide happened 8,000 years ago, when a huge area of coastal shelf off Norway slipped into the Atlantic abyss, triggering a huge tsunami that inundated the eastern side of Britain and drowned Doggerland, the low-lying land mass that stretched into the North Sea and physically linked Britain to the continent.
Here’s a short video about the Storegga Slide.
The Earth had suffered through the long cold of the last Ice Age and, at last, the glaciers were retreating and people started moving north again. The warming seems to have been extraordinarily fast, and the glaciers melted quickly. Unfortunately, melting glaciers produce water, lots of cold water, and that has to go somewhere. Most drained into the oceans, but the geography of North America was such that an immense lake formed roughly where Lake Winnipeg lies today – only it covered a vastly greater area. Lake Agassiz contained more fresh water than all the lakes and rivers in the world today, and a chain of still unbroken glaciers held it in place, stopping the water draining into the ocean. But then, the dam broke.
Vast amounts of cold fresh water drained into the North Atlantic Ocean, reducing its salinity and stopping the Gulf Stream dead in its tracks. The Ice Age went into reverse, the glaciers started grinding south again, and the cold returned, just as quickly as it had left.