Hadrian's Wall and the Whin Sill

Surely the Whin Sill was the defining feature of Borders around which Hadrian's Wall was built?

Created when two continental plates collided at least 400 millions ago the Whin Sill is just one reminder of more momentous times past.

The rock here is igneous and harder wearing the more usual limestones, shales and grits. In fact the dolerite which makes up the Sill also gives rise to other well known landscape features across the North of England...eg

High Force and Cauldron Snout.