Jack Repcheck's book is a well-written account of the career and times of James Hutton. Hutton, a well-known figure in geological circles, is the man credited with discovering so-called Deep Time. Unfortunately, Hutton's contributions to science, unlike those of Charles Lyell, remain unrecognized by the general public. Repcheck's stated task is to give Hutton his due by enlightening the general public about Hutton's seminal contribution to our understanding of earth history.
As Repcheck paints his portrait of Hutton, he takes us through the period of the Scottish Enlightenment and the history of Scotland at that time. Repcheck does a decent job at situating Hutton in his proper cultural and historical context. Hutton, as Repcheck notes, was part of the Scottish Enlightenment, one of the most astonishing periods of original thought and intellectual contribution in recorded history (earning Edinburgh the moniker of "the Athens of the North"). Other figures of this remarkable era in Scotland are the economist Adam Smith, the sociologist Adam Ferguson, the philosopher and historian David Hume, the poet Robert Burns, the novelist Sir Walter Scott, and the great chemist Joseph Black.
Beyond the general background material of Hutton's life, Repcheck also introduces the reader to Hutton's scientific contributions. First, Repcheck escorts his readers deftly through the phase of Hutton's life when he discovered the rock cycle. Hutton was the first to recognize the importance of erosion in the rock cycle, and the place of eroded sediments in producing sedimentary rocks. Hutton was also the first to recognize igneous intrusion in rocks (such as sills and dykes). At the time, many of his conclusions were quite controversial.
More importantly, though, Repcheck gives a good account of Hutton's discovery of an important geological outcrop and its implications: Siccar Point, Berwickshire, in southern Scotland. This outcrop may be called the "other Rock of Ages", for it was here that Hutton was able to convince his skeptics of the antiquity of the earth. This outcrop is composed of Silurian greywacke (known as "schistus" to Hutton) of marine origin (established by the fossils contained in the greywacke), tilted into a vertical orientation. It forms an angular unconformity (that is, two stratified rock units, with the lower one being tilted and eroded while the upper unit, deposited on the lower unit, is at a lower angle than the bottom unit) with the overlying Old Red Sandstone, also of marine origin (again established by fossils), in a normal horizontal position above it.
Hutton, using common sense and a few established principles, was able to figure out the general sequence that produced this particular rock outcrop. The Silurian greywacke had been deposited horizontally in a marine environment, which, Hutton reckoned, took thousands of years to accomplish. Thousands of years more was needed to accumulate enough sediment over this strata to cause the kind of pressure and heat necessary to lithify the graywacke. Later, heat and other additional forces caused the originally horizontal strata to be contorted and lifted up into a vertical plane. The once-submerged rock was then uplifted out of the water and erosion began immediately to wear at the graywacke. Once again the graywacke was submerged under the water (either through subsidence of the land or through a transgression from the sea) and the Old Red Sandstone, which contains a different assortment of fossilized marine life, as well as sediments derived from a different rock source,was laid down on top of the Silurian greywacke. The Old Red Sandstone and the Silurian greywacke that we see today were both covered with sufficient sediment to produce the necessary heat and pressure to lithify the Old Red Sandstone. Finally, both the Silurian greywacke and the Old Red Sandstone (which is today recognized as Devonian in age) were lifted up and exposed to the processes of erosion (for a photograph of the Siccar Point outcrop, see Doyle and others [2001: 20]).
As he worked out the sequence of events for Siccar Point, Hutton realized that this one outcrop could not have formed in the single year of the Flood, or even in the 6000 years generally believed to have transpired since the beginning of Creation. It was an astonishing conclusion! Hutton would later take those who doubted his claims to Siccar Point and use it as an incontrovertible testimony to the antiquity of the earth. It was at Siccar Point that biblical chronology fell to the observations of science, and for that reason alone, it deserves to be better known among the general public.
As for the influence of Hutton's observations, they were enormous, as Repcheck observes. In the end it was Charles Lyell who recognized the significance of Hutton's work, reserving a place of honor for Hutton in his historic textbook Principles of Geology. Lyell was taken to Siccar Point after Hutton's death by Hutton's friend James Hall — and Siccar Point worked its magic once again. Lyell became a believer of Hutton's claims. Later, a young Charles Darwin read Lyell, on his trip to the Galápagos Islands, and recognized the significance of Hutton's and Lyell's work for his own developing theory of evolution. Simply put, without Hutton's contribution, we would never have had the theory of evolution from Darwin.
It is when discussing the reception of Hutton's work, in chapters 8–10, that the book really shines. Repcheck chronicles in detail the reception of Hutton's presentation to the Royal Society of Edinburgh in March 1785 and his battle to win over his skeptics; he then progresses to the time when Darwin read Lyell's discussion of Hutton and accepted the conclusions of both men. The three chapters are really the heart of the book and make for engaging reading.
Repcheck documents the resistance to Hutton's ideas both from those still committed to biblical literalism and from the Neptunists, proponents of Abraham Gottlob Werner's idea that the rocks found in the present era were revealed when a "universal ocean" that formerly covered the whole world receded.
I must level one criticism, however. Although Repcheck discusses some of the scientific opposition to Hutton's ideas, he fails to consider the position of the Church of England or the Church of Scotland concerning Hutton. This leaves several questions unaddressed such as: Did the Church of Scotland weigh in on the controversy surrounding Hutton? What about other denominations? What about the so-called chattering classes? Did they accept Hutton's ideas, condemn them, or just ignore them? From the perspective of those interested in church/science issues, this is an unfortunate gap in Repcheck's research. Understanding the interactions with the religious authorities is vital to Hutton's story, and regrettably Repcheck has not included this dimension.