Head on up Hollowstone but just after Dancin' International (a shop selling dancing clothes and shoes) turn left and left again. This is Chardlace Walk.

The area is home to modern flats and offices but is built upon sandstone that dates back 80 million years. It's amazing to think how old this material is because, to the touch, it is quite fragile and flaky.

Vegetation that has established itself in the sandstone

Believe it or not this whole area would once have been covered by sea. When the ice age came the level would have risen causing the sandstone bedding planes.

Today, this seemingly barren rock is actually a haven to a host of lichens and mosses. You'll also notice a number of plants which have colonised the rock over the years.

Look also for holes in the rock. These show the different resistance of the sandstone and other materials. Freeze thaw action over the years - where ice melts then freezes again - would have weakened the rock structure leading to the formation of the holes.