The topic of the origin of landforms and the importance of denudation arose as significant problems in the 18th century because of the interplay of natural history, assumptions about the Earth’s duration, and the relation between human and natural history.  This problem was particularly acute in Britain – aligning human and natural history was not a major concern for most Continental workers.

Harris, section 9

Davies (1969)

Davies’ book is one of the few really detailed treatments of the history of the study of the earth’s landforms (geomorphology). He examines this history in Britian over the time period 1578-1878. Unfortunately we do not have comparable studies for other areas. Fortunately for our purposes, the religious-scientific isses raised by denudation will lead us into Hutton’s work; in fact, they are essential to understanding the origins of his theory.

By the late eighteenth century, scientific concern about the “denudation dilemma” was greatest in Britian. The Enlightenment had made the tensions between science and religion less of a issue for scientists in Continental Europe; many of the institutional supports were governmental agencies (technical schools, mining institutes, etc.). The situation in Britian was quite different; the leading positions were at universities that remained under church control, and the tradition of Biblical literalism persisted longer. Some individuals were supported by their own incomes (Hutton is a good example). The “practical” workers (who came out of what we would think of as largely engineering fields such as canal surveyors, coal miners) only appeared in the middle and late eighteenth century and their numbers were limited.

Davies’ chapter covers most of the eighteenth century from the death of Ray (recall the fossil debates) to around the time Hutton began to publish his theories. I find it a nicely written presentation that lays out the major issues, the influx of Continental ideas, and the sociological context in which British geology was set. The opening section provides an overview that includes a forecast of the major points of the chapter (bottom of p. 97- top of pl. 98). Subsequent sections deal with ideas about the terrestrial time-scale (note DeLuc’s “natural chronometers”), the processes responsible for the Earth’s surface (primitive condition, Diluvial, or post-Deluvial processes), the significance of earthquakes. The last part deals with the “denudation dilemma” and its impact on the perception of denudation (p. 110 onward).

One notable feature of this account is the importance of sociological factors in the general development of geological thought. Davies argues that British geomorphology fell into a “period of relapse” for nearly three-quarters of a century until it recovery in the last quarter of the eighteenth century. The reasons that he gives are closely aligned with some of the sociological factors in scientific development. Another example of sociological factors is the discussion about why the denudation dilemma arose in the eighteenth century.

Extending this idea, the topic of the origin of landforms and the importance of denudation arose as significant problems in the 18th century because of the interplay of geological knowledge and assumptions about the Earth’s duration and role in human history.  Although often presented as an argument between conservative religious sentiments and progressive scientists, I do not think that this is the most useful perspective. Instead, consider a different tension over how to integrate different lines of evidence about Earth history:

• Biblical tradition – whether Genesis was viewed as factual or allegorical is not the point.  It was generally viewed as a historical record of some type that provided information on past history.
• Records of other ancient civilizations – particularly Egyptian and Indian records with antiquity rivaling or even longer than Scripture.
• Natural history – this was viewed as another source of information.  By mid-century, the gross outline of the structure of mountains and the distribution of Primary, Secondary and Tertiary rocks were known.

As naturalists moved away from Biblical literalism, the problem was how to bring these different narratives into alignment to construct a coherent history.  Keep in mind that some observations (Deluc’s natural chronometers are a good example) provided strong evidence of a relatively short time scale that could be reconsiled with human records rather easily.

Some points you will need to consider

• Why does Davies argue that British geomorphology (and study of the earth in general) fall into a decline for much of the eighteenth century?
• Time scale
  • How did ideas change about the time scale? Why did they change?
  • DeLuc’s natural chronometers were used as arguments against the vast time scales envisioned by Hutton. What was their appeal at the time? Can you figure out the underlying geological explanation (in modern terms)?
  • How would this impact thinking about denudation?
• Origin of landscapes
  • How could natural processes (earthquakes, volcanoes, etc.) form the Earth’s topography? How would these relate to some of the 17-18th century cosmological theories?
  • What were the arguments for the counter-theory that attributed the main features of the Earth’s surface to the Deluge?
  • Can you explain the reasons why Primitive Rocks were interpreted as Primative Topography? How do Walker’s criteria (p. 105) link to the general Continental time scale and the Wernian model?
• What was the Denudation Dilemma of the eighteenth century?
  • What was the theological background to this problem?
  • What was the scientific problem?
  • What ways were available to resolve the dilemma?
• What are points of agreement and conflict between the Denudation Dilemma and geognosy?
• At the end of the chapter, Davies discusses the persistence of the concept of denudation and the general denial of its significance. How was this possible? What were the alternatives?

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