William Smith's Bitchin' Map

Getting an area mapped is a pretty satisfying feeling, and gives me the absurd sense that I have really mastered the landscape in front of me. If I have explored an area thoroughly enough to map it in detail, I know that I have really nailed the stratigraphy...or at least that I probably nailed it as well (or better) than anyone else ever has, and conceivably as well as it is possible to. It is an awesome feeling to walk through an area that I have been mapping, wandering back and forth and all around to see it from all different angles until I really understood the physical relationship between different layers, and have the whole landscape before me make sense as a structure, as a story.

As I have argued elsewhere, my experiences both in my dissertation area and in PEFO have convinced me that a detailed map is not just a nice supplement to stratigraphic work, but is absolutely essential for a stratigraphic model to be considered reliable. A map ideally serves as evidence that you explored the distribution of rock units personally, and that you could trace these distributions in a way consistent with your understanding of their superpositonal relationships. If you trace two units you think are the same layer into the same area, and one turns out to dive underneath the other, your lithostratigraphic model is in need of modification...and as a direct consequence, so is the biostratigraphic model you built on it. In stratigraphy, geography is everything. Stratigraphy is a three-dimensional endeavor, not a two-dimensional one.

This often tragically under appreciated fact goes back to the founding of geology as a real science in the early 19th century. Lithostratigraphy, biostratigraphy, and geologic mapping were the inventions of the same man, a British canal surveyor named William Smith. Smith's critical insights and methods are beautifully explained in Simon Winchester's book, "The Map That Changed The World." However, although Winchester alludes early on to the importance of Smith's work in reshaping our understanding of Earth history away from Genesis and Ussher, he seems to have forgotten to talk about it later. The book ends with Smith's death, and does not really go into the fundamental importance of Smith's work to historical geology and paleontology.

Smith had two major insights. First, that rock strata can be traced geographically, and maintain their superpositional relationships wherever they are traced. Second, that the fossils vary between different strata, and likewise maintain consistent superpositional relationships in different geographic areas. Although in the almost 200 years since Smith we have found numerous complications and exceptions to these principles, their basic significance can hardly be understated. Only the introduction of radioisotopic dates had comparable importance in understanding the history of life as a narrative.

Consider the following list of statements, all made possible due to Smith's insights:

-Human beings lived after dinosaurs.

-The first fish showing a superficially tetrapod-like fin structure appear before the first fish-like tetrapods, which appear before less fish-like tetrapods, which appear before the first amniotes.

-Permian and Triassic synapsids showed an increasing number of mammal-like characters over time, with mammals appearing after the most mammal-like non-mammalian therapsids.

-Australopithecines appear before the earliest members of the genus Homo, which appear before more advanced members of the genus Homo, which appear before the first anatomically modern humans.

Smith didn't just allow us to make a the history of life into a story, in which events could be ordered, and cause and effect inferred based on the ordering of these events. His observations made it possible to determine that the fossil record supported evolution, by showing that forms appeared in a particular order consistent with evolutionary change. Consequently, I would argue that William Smith's contribution to understanding the history of life is on par with that of Charles Darwin. Darwin demonstrated that evolutionary change was a reality, and gave us a mechanism for that change, but it was Smith who gave us the tools for figuring out how the history of life actually unfolded.

Smith also made another brilliant innovation: he figured out how to document stratigraphy geographically, by plotting the exposures of rock strata on a map. Moreover, he illustrated the effectiveness and importance of geologic mapping as a way of testing stratigraphic models in the most dramatic way possible: by helping people make money off it. Smith's explorations were originally a way of finding the best routes for canals, but also applied to helping people figure out if economic commodities like coal and building stone could be found on their land. It is worth pointing out to creationists that the effectiveness of lithostratigraphy and biostratigraphy, the tools used for deriving evolutionary history, can be demonstrated by the fact that they have electricity and gas. Millions of dollars are staked on the effectiveness of these geologic tools, and it pays off. The money says historical geology is on a solid foundation.

Smith's first geologic map was of the area around Bath. Unfortunately it is (I am told) in Nottingham, so I didn't get a chance to see it. However, his completed geological map of England, published in 1815, is justifiably more famous. It is a monumental piece of work, and comparisons of the outcrop patterns with modern geologic maps of Great Britain shows that Smith really nailed it.

I had the privilege of seeing two copies. One is mounted in the lounge of the Geology Department in the University of Bristol, framed but not behind glass, and a little ragged at the seams. Unfortunately, my pictures came out a little blurry:


The other copy hangs at the home of the British Geological Society in Burlington House, a few blocks from Piccadilly Circus in London. This copy is framed behind glass, and is in absolutely magnificent condition. It looks like it was printed yesterday. The somewhat confused and long-suffering girl at the reception desk, who had only been working there about six days, could not understand why I wanted her to photograph me in front of a pair of green curtains (I couldn't photograph the actual map due to "copyright issues"), but did her best.


I still got more hair than him, hee hee.

LNJ