The 'abyss of time'

Siccar Point is a rocky promontory in the county of Berwickshire on the east coast of Scotland. It is famous in the history of geology for Hutton's Unconformity found in 1788, which James Hutton regarded as conclusive proof of his uniformitarian theory of geological development.

 

 

Hutton's Unconformity 

 

In his 1803 eulogy of Scottish geologist James Hutton (1726-97), mathematician John Playfair recalled the clear day in the summer of 1788 when he, Hutton, and Sir James Hall sailed south along the Berwickshire coast in southeastern Scotland in search of evidence concerning the age of Earth. They rounded Siccar Point and landed at the base of what was to become one of the most famous sites in the history of geology. Before them, nearly vertical layers of gray slate rose up from the sea in a sheer cliff face, only to terminate abruptly against gently dipping beds of red sandstone. 

 

We felt ourselves necessarily carried back to the 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 a superincumbent ocean. An epocha still more remote presented itself, when even the most ancient of these rocks, instead of standing upright in vertical beds, lay in horizontal planes at the bottom of the sea, and was not yet disturbed by that immeasurable force which has burst asunder the solid pavement of the globe.... The mind seemed to grow giddy by looking so far into the abyss of time. (Transactions of the Royal Society of Edinburgh, vol. V, pt. III, 1805) 

 

Now known as Hutton's Unconformity, the formation reveals a missing chapter in what Hutton referred to as "the annals of the Earth." Hutton recognized that constructive geological processes, such as volcanism and mountain building, created strata of rock and sediment and that breaks, or "unconformities," in the chronology were caused by erosion or an absence of deposition over long periods of time. The gray vertical beds were originally flat-lying marine sediments that over eons hardened and were turned on end. They were slowly planed away and overlain by a horizontal layer of sand deposited at the edge of a now-vanished sea. Geologists estimate that roughly 80 million years elapsed between the deposition of the Lower Silurian gray slate and the Upper Devonian Old Red