As we head east along the M62 it's the cooling towers of Drax and Eggborough that dominate the flat landscape, which is underlain by soft Triassic rocks, dating from a time when desert conditions prevailed in Britain. However there's very little to be seen of these sandstones in this part of Yorkshire because they're almost entirely covered by clay, peat and silt. During the last glacial period, some 18,000 years ago, ice sheets filled the North Sea. Meltwaters from glaciers to the north ponded up to form Lake Humber which flooded over the Vale of York.
The power stations are a reminder of even older rocks that lie concealed beneath the Triassic desert sediments. The seams in the Selby Coalfield are the remnants of tropical forest that grew here 300 million years ago. Between the coal and the desert sandstones there's the Magnesian Limestone, dating from a time around 250 million years ago when a dying sea, the Zechstein, covered much of Yorkshire.
As we approach the Humber Bridge, the ridge of Chalk that forms the Wolds comes into view. This lies on top of those desert sandstones. Turning north off the A63 (the dual carriageway extension of the M62 motorway) we pass a large chalk quarry. This very pure, white limestone formed in clear tropical seas some 95 million years ago. That's about the time that T. Rex roamed on land.
It must be all that work at Brimham that is bringing my research on Yorkshire Rock to mind again.
Prehistoric East YorkshireJust to go over that again, in chronological order;