Gullet Quarry in the Malverns is a geological marvel but you can't get to it because of the fencing installed to deter swimmers. The Malverns themselves were formed as igneous rock deep underground over 600 million years ago. Later sedimentary rocks formed above them. When Africa crashed into Spain, the old igneous rocks were pushed up through the earth. There was clearly metamorphic processes at play because gneiss was formed - I didn't know it existed south of the Outer Hebrides. The sedimentary rocks eroded away more easily and that is why the Malverns stand out as a distinct range. I found out a lot from Ronald Turnbull's wonderful book, Granite and Grit. The photograph below shows pinkish rocks. This will be the pegmatite. He says "where gneiss is crushed and heated to the verge of melting down and starting all over again, the rock called pegmatite is formed". Slow cooling means even bigger crystals than in granite.
The next two pictures show the unconformity which helped geologists to work out what happened to the Malverns. The gently angled rocks in the trees are sedimentary and they are at a wildly different angle to the tilt of the igneous and metamorphic rocks.
