James Hutton's Deep Time

Transcript

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Hey guys, welcome back to the Cognitive Whiteboard. My name is Keegs and today we're going to be looking into the thought processes of James Hutton, the man who coined the term "deep time," and really shaped our modern understanding of geological sciences, and our understanding of how the Earth was formed. James was born in 1726. In 1749 he moved off to the University of Leiden, in the Netherlands, and obtained his medical degree. In 1750, he moved back to the Scottish Borders and inherited and worked two farms that previously belonged to his parents. It was here that he was able to witness first-hand the processes of erosion and sediment deposition and where he became interested in geology. Subsequently, in 1767, he moved back to Edinburgh where he developed and published his own geological theories.

In the 18th century, the political, social, and scientific landscape is still dominated by the theological views of the Church of England, which was a key player in what was then the Kingdom of Great Britain. Our understanding of the Earth and the processes that formed it at that point were derived from literal interpretations of the Bible. In 1658, Archbishop James Ussher boldly stated in his "Annals Of The World" that according to his most precise calculations, the beginning of time must have fallen on the 23rd of October at precisely 9 am, 4004 BC. Some fairly precise stuff coming out of the Bible there. But he was a senior member of the Church at the time, and so this date was subsequently incorporated into the English Bible, and scarily enough, later made its way into the scripture itself. 

But times were changing. Edinburgh, and Scotland as a whole, were moving into a new era we now know as the Scottish Enlightenment. Edinburgh itself was known as a hotbed of genius, and saw the rise in revolutionary ideas in the sciences and the humanities, with concepts such as empiricism and scepticism making their way into the limelight. But also crucially enough, the scientific method of observation and deductive reasoning also took a foothold, and theories of Earth, and the way it has developed, and the processes that formed the Earth, were being propounded at a rapid rate. 

In these early days, while James was formulating his own theory, there was a significant attempt, in a dominantly Christian and Western world, to reconcile biblical narratives of creationism with these new theories around the formation of the Earth. And these were convolved into bizarre theories such as Neptunism and Catastrophism, which asserted that the Earth, and the processes that formed the Earth and its materials, were sudden and were short-lived and corresponded to catastrophic global events such as global flooding. Think back to Noah's floods. But James wasn't having any of this.


James was a master of observation and deductive reasoning, and his early observations on his own lands had allowed him to see that the Earth was shaped by gradual processes of erosion, uplift, and deposition in timescales that were significantly longer than what was being posited at the time. And there must have been links somehow to the processes of Earth's heat generation in a way that no one really understood at that point. But to prove his theories, he needed to go on a journey of adventure and discovery. This trip brought him to a number of localities, one of the first of which was Holyrood Park just down the road from our office here.

What James observed there was the base of the Salisbury Crags sill intruded into carboniferous sandstones, cementstones, and shales of the Ballagan Formation.
He observed that the sandstones and cement stones were twisted and contorted as if they'd be broken and bent out of shape by the forceful intrusion of what he thought must have been some fluid-like phase. His observation of this contact supported his assertion that the dolerites were derived from magma generated by the Earth's heat internally, which was in direct opposition to the commonly accepted theory at the time of Neptunism, which suggested that dolerites and basalts were in fact sediments deposited in a marine environment, something akin to a flooded Earth situation. 

So whilst James's observations were significant, he still needed irrefutable evidence to prove his theory of deep time. And it was in 1788 that he arrived at Siccar Point and found the evidence he needed to really prove his understanding of the cycles and processes that formed the Earth and their corresponded to the principles he was describing in his theory.

What he observed there was a type locality of an angular unconformity represented by the contact between the subvertical alternating light and dark beds of the schistus that he had described at the time, erosionally overlain by deeply coloured red beds of sandstones and conglomerates. 

He inferred from the nature of the contact between these two units that there must have been an enormous interval of time and significant pressure and stress required in order to move these subvertical beds into their current orientation, and then to erode them away, and deposit over the top of them the deeply-coloured sandstones and conglomerates of what we now know to be the Devonian old red sandstone unit.

This was the crucial piece of evidence that James needed to find his concept of deep time.

He concluded at the outcrop: “we find no vestige of a beginning and no prospect of an end”.

His work was subsequently published and was later popularized by the work of Charles Lyell, who coined the term ‘Uniformitarianism’, which essentially describes the processes that have shaped earth have been in more or less a continuum since the inception of earth, and are still in operation today.

He famously stated that ‘‘the present is the key to the past!’’

Thanks for joining us, ladies and gentlemen. We hope to see you again next time at the Cognitive Whiteboard. Cheers for now.