Unconformities, Part II
A Brief Account of a Hero's Journey in The Scottish Enlightenment
The mind seemed to grow giddy by looking so far into the abyss of time.
- John Playfair
In the latter part of the 18th century, in a seemingly unimportant rainy corner of the world, fiery conversations were happening in pubs amongst a few educated elites with time on their hands and a common thirst for truth and innovation…
Edinburgh from 1760-1790 was the Scottish hub of ingenuity out of which came many drowsily titled publications with beginnings like An Inquiry into the Nature and Causes of…, or, An Investigation into the Laws of… and ended with meaty concepts like The Wealth of Nations, or Theory of the Earth. It is from this time and place that comes such characters as the Father of Modern Economics, Adam Smith, and the Father of Modern Geology, James Hutton. While Adam Smith’s theories would come to change the face of the modern economic landscape, James Hutton’s theories would come to explain the changing face of the physical landscape. You might wonder where on Earth one could possibly begin to attempt to make sense of such vast concepts. For James Hutton, the rich chemist turned farmer, his Theory of the Earth began by digging irrigation ditches.
“He has become very fond of studying the surface of the earth, and was looking with anxious curiosity into every pit or ditch or bed of a river that fell in his way.”
-1753, Letter of Hutton
Hutton wanted to bring the modern agricultural innovations observed from his years of academia in countries like France and Holland to Scottish farming. At the arrival of his decision to work his family’s farmland, it was in a state still much like a farm of the middle ages, soil hardened and furrowed over centuries with old rows of meager soil. Hutton went to re-enliven his lands with modern plows, draining lowland fields and carving into the landscape to create productive parcels. The chemist farmer’s mind was occupied with the soil, its composition and dispersal patterns. Surely, to better understand the nature of the soil would aid in yielding the best crops. He quickly noticed that the distribution of his soil had much to do with the rocks that surrounded it and lay underneath. It was of the same stuff, derived from erosional forces a long time in the making.
Eventually, his interest in the rocks overcame his interest in farming. He dug deeper pits and explored nearby outcrops. In 1764, he set out on a geological tour of northern Scotland with a friend. He took part in the construction of the Forth and Clyde Canal, a shipping waterway that exposed the bedrock of the entire country east-to-west.
“a vast proportion of the present rocks are composed of materials afforded by the destruction of bodies, animal, vegetable and mineral, of more ancient formation.”
- Playfair Biography of James Hutton
What struck him were the perplexities. He may have been thinking: Why were rocks of such different structure adjacent one another? How can this old red sandstone lay atop a totally dissimilar coarse greywacke? And, why did their layers meet at crooked angles and not lay in horizontal parallels the way sediments are normally deposited along rivers? If these rocks were once sands, muds and gravels, what sort of forces hardened them to rock, and what caused them to be thrust atop one another? Most bafflingly, how is there the presence of sea creatures in the rocks on land so high above the waterline of the world’s oceans?
Luckily for Hutton and anyone else who had ever become bewildered at the world’s rocks, there was an established long standing explanation for all of this. The narrative fix to every single geological enigma was called Neptunism, a scientific theory based off the Old Testament and named for the Greek God of the Sea.
Neptunism tells that the Earth is around six thousand years old and most of its formation, the continents and the seas, happened instantaneously at the moment of creation in Genesis. That explains how rocks were made. They just are. But this was not the only event that gives us our present day earth-scape. To account for all the specified complexities; faults, fossils, sedimentation, all the carved out canyons, jagged peaks and sea cliffs; this is all the result of the Great Flood. Lastly, volcanoes were explained as a manifestation of God’s awesome wrath; a reminder of his ability to punish us for our wickedness.
It honestly is a fair answer to the grand question and was utilized trans-historically beyond Abrahamic religions. Cultures across time and location have very similar creation myths. What else could the anomalies of earthquakes, volcanoes and meteor strikes be than reminders of a divine presence? Every society has seen floods rip away land and towns and noticed its aftermath looks an awful lot like the way mountains and valleys present themselves, just on a much smaller scale. The fossils up on land are the skeletal remains of all God’s animals swept away and left behind as the Great Flood waters receded. Boom! Anymore questions? Just kidding. Questioning was not allowed. God is mysterious and that is that.
Well for James Hutton, a devout christian himself, his answer was, Sorry, but this is simply not good enough. In his tiny corner of Scotland, evidences did not correlate with Neptunism. As a farmer who studied erosion and deposition he knew how unfathomably long it must take rock to become sediment and to accumulate in such expansive layers. As a chemist he knew that the fusing forces needed to turn loose sediment back into rock must take a force beyond simple compaction and drying out.
We should remember that this Substack post’s hero had the privilege of witnessing and participating in the multitude of blossoming fields of 18th century European scientific study. The central proving ground of discovery at the time was the Royal Society of London, still in existence. Their motto, which was the underlying mantra of all other scientific cradles from Bagdad to Edinburgh, is Nullius en Verba—“take nobody’s word for it. Question everything.”
Based off the volume of rock, there must not have been just one Great Flood, but multitudes of them. Based off the varieties of rock types and layers, there must have been not one ancient world, but many, made of forgotten mountains and rivers that had been created and erased again and again. As for faults and the confusing angular intersections and vertical protrusions of layers across one another, there must have been some inertial force that pushed rocks around and brought sea fossils all the way up from the bottom of the ocean to the tops of mountains.
The earth-forming conundrum generally revolves around two unknown phenomena: rock-making, and the force which causes the movement of rocks from low to high—uplift. His Neptunism-denying synthesis of information gathered from his observations of correlations in the irregular Scottish landscape relied on three revolutionary concepts. One, that erosion is an ever-present land-carving force that happens on a slow and unimaginably epic scale. Two, that there must be a massive heat source from below our feet made evident by volcanism that creates propulsion like the convection currents observed in simple chemistry which can move around landmasses. Three, that the beautifully harmonious presentation of our complex Earth is the result of these two forces continually acting against each other.
It took twenty-five years for James Hutton to produce his first publication of Theory of the Earth which he presented to the Royal Society of Edinburgh in 1785. Their reception was something along the lines of, …very interesting. Now go prove it. So, for a few years more he ran around Scotland marking sites of unquestionable evidences to demonstrate his point. Like any theory to describe everything, Hutton’s was based on one particular occurrence which would become known as Hutton’s Unconformity. Interestingly enough, this particular geologic irregularity was not just the one that showed itself in the many rock outcrops he observed on his geologic tours, or the one found in the canal he helped carve across the British Isle, but it consisted of the same rocks he found when digging his irrigation ditches on his farm. It was that weird collision of old red sandstone and coarse greywacke—the chunks of which he built his farmhouse walls out of.
In 1788, Hutton, his mathematician-artist friend John Playfair, and Scottish geologist Sir James Hall of Dunglass took a boat trip along the east coast of Scotland where the North Sea had carved out great cliffs exposing the underlying stratigraphy better than anywhere else. Along the voyage they came across a jut of land which Hutton described as, “a beautiful picture of this junction (his unconformity) washed bare by the sea.” This spot was called Siccar Point.
Here, more clearly than anywhere else was seen the Devonian Old Red Sandstone (a 370 million year old sedimentary rock laid down by an ancient coastal river system) atop an irregular surface of the vertical-tilted Silurian Grewacke (a 435 million year old coarse sandstone formed by crumbling continental shelves into the sea). Just further along the coast they found strong evidence of ripple-marks in the exposed layers of vertically tilted rocks, the same which you find in flat tide pools and sandy river bottoms. This provided irrefutable evidence that these sediments were deposited horizontally in river systems a very long time ago atop an exposed bedrock formed of an ancient seabed that had at some point been solidified, tilted and uplifted onto the land. Confused or overloaded? If so, you are not alone, and that is the point. The processes of earth-making are hard to wrap the head around. This simple extravagant instance alone made it clear that the time it takes to create such stratigraphy is beyond any previous comprehension. That singular acknowledgment of this natural process prescribed to every other unique unconformity exposed across all seven continents opens the door to such profundity that it strikes one dumb.
Describing their moment of discovery at Siccar Point standing on the edge of the sea, John Playfair wrote:
“We felt necessarily carried back to a time when the schistus on which we stood was yet at the bottom of the sea, and when the sandstone before us was only beginning to be deposited, in the shape of sand or mud, from the waters of the supercontinent ocean ... The mind seemed to grow giddy by looking so far back into the abyss of time; and whilst we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events, we became sensible how much further reason may sometimes go than imagination may venture to follow.”
James Hutton published the complete version of Theory of the Earth in 1788 and went on to do other things such as continue his writings on reason, philosophy and his forty years in the making treatise on agriculture. He died in 1797 at the age of 70. The significance of his work was not fully appreciated until years after. It should be noted that Hutton remained a christian throughout all his explorations and realizations of geologic time. He saw the rock record as God’s books wrote upon by God’s own finger. The vastness and complexity of nature exemplified his appreciation for the creator’s mysterious performance.
His ultimate conclusion to Theory of the Earth ends with this:
“The result therefore of our present inquiry is that we find no vestige of a beginning – no prospect of an end.”
As I write this and consider the geological concepts, I cannot help but find greater correlations. The sustained harmonic forces that reveal the perpetual sublimity of our physical existence are manifest in so many ways. Nature in all its forms, from the stars to a bumblebee; art in all its forms, from Rembrandt to the cave painters; humanity, individuals and communities across time at our best, relating, celebrating, creating and synthesizing with the world around us. There is no finality to it. But, there is an endless wonderment to the mysterious energy. It is felt in the form of awe which is kindled by our power to love.
Note: This is the second part of a several part series on art, nature, humanity and geology. In Part III, I will tie together Parts I and II so that in the slimmest of chances you may appreciate why I am asking you to read all of this.
Sources:
Hutton, James. (1785). Theory of the earth or an investigation of the laws observable in the composition, dissolution, and restoration of land upon the globe. (From the Transaction of Royal Society of Edinburgh, Volume 1, Part II, pp209-304).
Playfair J. (1805) Biography of James Hutton. Volume 5, Transactions the Royal Society of Edinburgh
Bassett, Douglas A. (1970). James Hutton, The founder of modern geology: an anthology