It blows the mind..

Not venturing far - because still suffering from the dreaded coughs and sneezes. So just up the road to visit the Blackford Hill Rocks.

During a period between 417 and 354 million years ago a nearby volcano erupted. It sent out some trachyte lava, which is very fine and cools down quickly. If you look at the bottom right of the picture you will see it! A bit later a volcano got going again. In the manner of our favourite Eyjafjallajoekull - the Iceland volcano that brought big chunks of the Northern Hemisphere to a grinding halt - this ancient Edinburgh version spent a long time spewing out volcanic ash. The ash is a mixture of rock, glass and sand. It settled, and you can see it here as the layer below the big fissure that runs across the scene.

Finally, it blew its top! Andesite lava flowed across the lot, solidifying into the top layer here.

Just round the corner from here Louis Agassiz a famous Swiss naturalist paid a visit to Scotland in 1840. What he saw changed the world of geology - showing for the first time the effect on rock of glacial movement.

Sorry this is packed with detail - but the time scale has an effect on me. As the volcano blew its top, this blows my mind. Whether you believe in a Creation-based evolution or a non-created evolution (and my own vote is with the former) this is as awe-inspiring as looking at the stars.