One hundred million years [100,000,000 years] is a small step in geological time, barely enough for mountains to 'fold' or erode, or oceans to open/close.  Yet it is possibly too great a time for the human mind to comprehend. 

By this measure, modern man evolved a mere instant ago.  Even the oldest rocks in Ireland, the schists and gneisses of Donegal and the Sperrins, have been in place for just ten of Earth’s 46 steps (it’s about 140 steps since the Universe began in the Big Bang) and the oldest rocks in our vicinity, the Ordovician and Silurian shales of the Longford-Down Inlier are a mere four/five steps old. 

Those familiar mountains that define our human horizons, the Mournes, Cooleys and Gullion emerged to the surface just a half step ago, though they formed as magmetic plutons deep within the earth some four-five steps in time ago.   The recent Ice Ages that helped to sculpt our immediate landscape happened one half of one thousandth of a step ago by our measure, and man has occupied these regions for less than one tenth of that miniscule time period. These time spans help to focus our minds.

We know about Earth’s history from our developing theories of Earth’s processes and from the evidence of the geological record.  To continue with our time scale analogy, some five steps ago most of earth’s huge tectonic plates were located in the southern hemisphere, the vast Laurentia plate that contained the modern North America as well as what we know now as Greenland, North Ireland, Scotland etc. being separated by 40° of latitude and 4000 km of Impetus Ocean from another small plate that included modern Britain and South Ireland.  From the Pre-Cambrian to the Silurian, this ocean closed to form the great land mass known as Pangea (‘all land’). 

Squeezed in this destructive plate boundary were several mid-oceanic volcanic arcs [see diagram above]. These will form the substance of the next article in this present series.

Raised in an accretionary prism from the continental shelf of the shallow seas on the edge of Laurentia that had previously eroded from even more ancient mountains, were the Ordovician and (later) Silurian shales, some of which, as yet not fully eroded in the next cycle, still blanket the tops of some Mourne peaks.  

Our rocks were all formed deep beneath ancient equatorial oceans or even deeper, several miles below the surface of the thin crust of the earth. The evidence of the erosional processes that have dominated since can be dramatically viewed from Flagstaff Hill of Fathom Mountain in beautiful South Armagh, because the mudflats that stretch from Greenbank to Narrow Water and beyond were once mountains too. 

 While you are up on Fathom (take the Upper Fathom Road just before the railway bridge at Cloghogue Chapel), enjoy the magnificent view, unparalleled in my humble opinion anywhere in the world.  Over there to your left you see the disused Narrow Water quarry that bears testimony of the geological record and now also affords walker access to the forest paths of the vicinity.  There's talk of re-opening the quarry - a step opposed by conservationists and naturists like me, especially since it's not high-quality, employment-generating materials to begin with!

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All this stuff's too serious and high-faluting!  I can't go on without a break.  It's just three kilometres from me, but, excuse me, I’m suffering withdrawal symptoms.  I’ll be back when I’ve recharged my emotional batteries by strolling through its woodland paths! 

Don’t go away.  I won’t be long! 

On the time scale we’re currently using, I’m back already!!

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