Anyway, after brief introductions, it was off on a short walk to the first stop – a limestone quarry, where Don Cameron, the group leader, described the ‘Derbyshire Dome’. Around 300 million years ago, the sea floor was lifted and a gentle anticline formed across what is now the Peak District, giving the area the characteristic 'dome' shape, hence the name. Folding of the rocks caused cracks (faults) to appear, particularly so within the limestone.
From the top down, the sequence of rocks present are coal measures; millstone grit; shale and limestone. The coal measures and millstone grit were then subject to erosion and at the most exposed upper part of the dome the gritstone was completely removed thus exposing the limestone in the centre of the Peak District.