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April 3, 2011

The visual language of geology

Reading Martin J.S. Rudwick's "The Emergence of a Visual Language for Geological Science 1760-1840" and Susan B. Keller's "Sections and Views: Visual Representation in Eighteenth-Century Earthquake Studies" while re-hashing the field work I did two weeks ago was a strange self-reflective experience for me. I was reading about the production of the very first "geologic" images at the same time I was grappling with how to produce my own images that convey what I learned in the field. Reading these texts reinforced the absolute importance and also power of visual representation in geology, but it also forced me to look at some of the caveats that have persisted in geologic images despite the incredible improvements in geologic sections and imagery since the eighteenth century.

A wise graduate student at Lamont-Doherty Earth Observatory once told me that, if I didn't have the time to read a geology paper, I could get the main points and conclusions of the paper by examining the figures and reading the figure captions. This advice fueled my thinking as I read Rudwick's text on the origins of geologic images. "During the period in which 'geology' emerged as a self-conscious new discipline with clearly defined intellectual goals and well established institutional forms," Rudwick argues, "there was thus a comparable emergence of what I shall call a visual language for the science, which is reflected not only in a broadening range of kinds of illustration but also in a great increase in their sheer quantity" (150). I cannot imagine a geology paper that does not contain images; it would be impossible, in my mind, to communicate geologic observations, inferences, and conclusions with text alone. I can, however, imagine reading a chemistry or physics paper and understanding the key concepts without needing crucial figures.

Why are interpretive images so essential to the geological sciences? The goal of classical geology has been to understand the complex, three dimensional nature of the solid earth by using surface (and some subsurface) evidence to infer relationships at depth. I believe it is this three-dimensional, spatial relationship at the center of geological endeavors that necessitates the image; text is often inadequate in explanation or obscuring in nature to the type of information a geologic image, such as a section, imparts. Indeed, this is what Rudwick suggests, although I think the importance I place on geologic images is stronger, as a student of geology, than that of Rudwick, a historian. As I work on my maps and think about the cross sections and stratigraphic sections I will be producing for my senior thesis, I am keenly aware of the power of how I choose to translate what I have learned in the field into a visual interpretation.

That being said, my maps and sections will be an interpretation, and it is important to recognize and respect the limits of geologic images despite their immense communicative powers. Reading Rudiwck and especially Keller's text highlighted this for me. Keller discusses how the Lisbon earthquake of 1755 and the Calabrian earthquake of 1783 inspired the documentation of earthquakes, both theoretically in cross sections and pictorially in images of the earthquakes' effects. "By translating their theoretical considerations into the abstract form of geological sections," Keller writes, "these natural philosophers moulded a new visual language for seismology and earth history" (130). In contrast to geologic sections constructed from surface outcrop evidence, the sections produced after the Lisbon earthquake were pure theory; these philosophers had little idea of what happened at depth. In reality, all geologic sections that project to depth, despite how convincing the surface evidence, are hypotheses, well-informed conjectures. In the case of these early seismologic images, the presence of hypothesis, of unproven theory, was central to the goal of the images. Occasionally, however, geologists obscure the interpretive nature of their images. In my Crustal Deformation class, Professor Mark Anders has repeatedly shown our class examples of geologic cross sections that show what happens at great depths within the crust when often there is little evidence to make such inferences. 

This brings up both a fundamental difference between more theoretical disciplines within the earth sciences, whom the philosophers Keller discusses were precursors to, and what is considered more classical geology. As our understanding of the solid earth has expanded since the eighteenth century, the questions of theoreticians and more field-based geologists have increasingly overlapped, causing an inherently deeper tension between what we can observe, what we have concrete evidence to explain, and what we have less evidence for but inherently want to understand. This tension is transcribed in geologic images as what I described in an earlier post as construction lines. Geologists may not often demarcate with a bold line between what they know from evidence and what is more so conjecture on their geologic images (although in some cases they do). I believe figuring out where this line would have been drawn, and how its position has been modified throughout the history of geologic imagery, is a unique way to trace the growth of knowledge within the geologic sciences. Indeed, this is what Rudwick and Keller have done in their examination of the earliest geologic maps, sections, and pictorial renderings when geology was first emerging as a stand-alone science.

As both Rudwick and Keller point out, these early interpretations are made within the new visual language of geology that emerged in the eighteenth century. Perhaps another way to think about "construction lines" is to think about the evolution of this language. Maps and sections are still integral components of the visual language of geology today. The vocabulary of geologic images has also greatly expanded with technological advances in imagery: seismic images, SONAR, and LIDAR are all integral components of the expanded visual language. Geologic images like maps and sections have also been infused with a much greater significance or meaning with the advent of other fields in the geologic sciences, such as geochemistry. As a geology student, I can attest to the challenges of learning this new language that Rudwick and Keller suggest. A geology student's visual vocabulary is constantly expanding to incorporate new types of images and to comprehend how different types of geologic images can be used in concert.

Keller and Rudwick suggest that early geologic images borrowed from the language of art in the eighteenth century. Rudwick discusses crucial links between documentary landscape painting and early geologic images: "In early nineteenth century landscapes of geological interest, such implicit theoretical contents began to become more explicit. Offshore views of coastal cliffs were particularly common, simply because cliffs provide some of the most extensive and continuous natural exposures [of rock] to be found anywhere" (Rudwick 175). Keller likewise discusses how the documentation project of the effects of the 1783 Calabrian Earthquake, the Istoria de' fenomeni del tremoto avvenuto nelle Calabrie, drew from the formal artistic traditions of landscape art (152-156). Both Keller and Rudwick suggest that as geology became a more formalized science, the influence of art faded from geologic imagery. I wonder: can the language of art still be traced in modern geologic images? Have the visual languages of other disciplines have been incorporated into geologic images? How has the visual language of geology impacted the field of knowledge outside of geology? I am intensely curious as to how different types  of images, different visual languages, communicate with one another, and particularly how scientific images, geologic images, exist outside the scientific space. 

Works Cited

Keller, Susan B. "Sections and Views: Visual Representation in Eighteenth-Century Earthquake Studies." Science and the Visual in The British Journal for the History of Science. v. 31, no. 2, p. 129-159: 1998.

Rudwick, Martin J.S. "The Emergence of a Visual Language for Geological Science 1760-1840." History of Science. v. 14, no. 3, p. 149-195: 1976.

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