Additional Notes

18 July 2010

Chapter 5: The North–South Divide

The Tertiary period - from 2.5 to 65 million years ago - marks the time that the continents gradually moved into their current configuration. A map of our world from around that time would start to show the familiar modern outlines of the continents as they continued their gradual do-si-do around the globe. If you are a fan of paleogeography and want to know just where various bits of the Earth’s crust have been for the last 600 million years or so, there’s an excellent website by Christopher R Scotese here and an, I believe, unrelated downloadable Google Earth file here.

A lot was going on in Britain at this point in time. London Clay was being laid down in the south east of Britain while, in the North West, all hell was breaking loose during a short and brutal volcanic period which saw the creation of a 700,000 square mile plateau of lava., the product of the birthing pains of the Atlantic Ocean. The remains of that lava plateau - the Thulean Plateau - can be seen today as the Isle of Staffa and the Giant’s Causeway.

Part of that former plateau covered the Ardnamurchan peninsula in Scotland. As time went on, as various minerals precipitated out of the lava and others were melted from the surrounding rock, the consistency and recipe of the lava changed. Thicker lavas began to form more “traditionally-shaped” volcanic cones - shield volcanoes - and the remains of one such cone which collapsed to form a caldera is clearly visible from the air.

View The North-South Divide in a larger map