Sutton Bank

Sutton Bank is one of the most spectacular inland cliffs anywhere in Britain, and carries one of the most hair-raising main roads in the country. The near vertical drop from top to bottom is around 140 metres, and crosses at least two major geological boundaries.

The platform at the top of the bank is made of hard limey gritstone formed in the Upper Jurassic period. This same rock forms the top of the escarpment that runs all the way from here to the coast at Scarborough – it even sits on top of Scarborough’s Castle Hill. Going down the cliff you encounter softer Upper Jurassic clay and limestones, then the hard Middle Jurassic sandstone that underlie the central moorland of the North York Moors. Without pausing the cliff plunges down through the Middle Jurassic rocks and into the soft shales and mudstones of the Lower Jurassic. More than 60 million years of earth’s history is covered by the rocks of Sutton Bank.

But why is this cliff here? In the last ice age, which peaked around 20 thousand years ago, an ice sheet pushed its way down the depression that lay between the upland areas of the North York Moors and the Pennines. As it scraped along the western edge of the moors, the tremendous force of the ice gouged out the soft underlying rocks, causing the hard tops to tumble down. The result was a near-vertical escarpment, of the type usually seen at the coast.

As the ice melted it left layers of mud along the bottom edge of the cliff, in what are known as lateral moraines. These mud deposits blocked up normal drainage channels causing small lakes to form Gormire Lake, below Sutton Bank, is the last remaining glacial lake.

The edge of the bank is not a perfect straight line, and a little to the south of Sutton Bank, Hood Hill stood out above the ice sheet and became detached from the moors. A small cap of hard Upper Jurassic grit sits on top of the hill, giving it a spectacular profile.