Landscape by Keith Ratcliffe © 2011
A journey through timeI always like to plan some trips for early January to help kick start the New Year and this year’s treat was suggested by a book that I received as a Christmas present. “Granite & Grit” is a walkers guide to Geology and I read it avidly over the break and noted that some key ideas were formed in Edinburgh and so the trip took shape.
I joined the queue of commuters on the delayed 0807 train from Stirling to Waverley, skidded over the pavements of Prince’s Street, took the bus to the Commonwealth Pool then swam the tidal wave of students leaving Pollock Halls for the Uni down the road. So I arrived at the entrance to Holyrood Park.
Apart from the Geology book my other guide for today is the late Tom Weir whose inspiring books and TV programmes have introduced the hills to many people over the years. My first stop is Samsons Ribs which are an outcrop of columnar Basalt overlooking Duddingstone Loch. Their brooding 30m organpipes hang over a busy road and it is from Tom that I learn they are stabilised by pointing them with cement so the usual solution of netting is not required thus allowing us to appreciate their full glory.
My next location is one of the key sites in terms of ideas that formed in the early days of Geological thinking. In the late 18th Century there were two opposing views of how rocks formed – the Neptunists led by Werner believed that all rocks formed as deposits from the sea whereas Hutton’s Plutonists proposed that some rock was formed from molten lava erupting and solidifying. Here at Hutton’s Section below Salisbury Crags he found the evidence he needed – a Dolerite sill lies over layered Sandstone beds and has clearly baked and disrupted the sedimentary rock beneath. The section glows in a warm sun on this cold day and the colours illuminate the revelation of this key concept that we take for granted today.
But where did the lava flow come from? From the volcano of course, for Arthurs Seat is indeed the remains of an active efflux of molten rock from an active volcano of 300 million years ago. The summit is what remains of the plug of the main vent and as I make my way up the hill side I see outcrops of rock called tuff which is compressed ash from its eruptions with lumps of sandstone agglomerated within it.
From the summit there are fantastic views today as the cloud has moved East and clear blue skies are the norm. In that direction Bass Rock shows its white top – though not with snow. The Ochils gleam diamond white across the Forth and the Highlands are visible way out to the North & West. Looking round to the South the Pentlands sparkle below a bright but low sun that prevents photography. The city architecture is laid out before me – some of it more attractive than the rest – the castle occupies the nearest high ground. Is Edinburgh the only UK city that has a mountain within its bounds? From here also the clean sweep of Salisbury crags that dominate Holyrood Palace show clearly their sill structure and it is here that I am next headed.
I take the Radical Road from near Hutton’s section. This track was given its name after it was paved in the aftermath of the Radical War of 1820, using the labour of unemployed weavers from the west of Scotland at the suggestion of Walter Scott. It is very icy today and I resort to the grass for better footing, soon coming to Hutton’s stone that shows a vein of iron rich Hematite forced through the surrounding rock. The story here is that quarrying the crags was advancing rapidly during Hutton’s time and he appealed to the quarrymen to leave some key specimens for posterity.
I sit and watch a couple of Ravens conversing on the cliff top – I had watched their acrobatic flight from the summit – and look at the magnificent cliffs now burning red in the sunlight. My climbing past insists that I find lines of holds leading up the best faces but only in the mind – they look well past my current standard and besides climbing is restricted to a small area of quarry where falling rocks will not impale walkers on the Radical Road. Perhaps I will return on a summer evening for a spot of bouldering – having of course first requested permission of the Park rangers.
On my walk back to Waverley I pass the Holyrood Parliament building and note on one side that there is a tribute to the Geology of the area. This takes the form of a set of rock intrusions into the concrete wall with interpretive writing on the pavement edge. That outcrop will take some explaining in a few million years after the next great extinction!
© Keith Ratcliffe
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