the Long Now Foundation, a worthy subject in itself, brought Marcia Bjornerud’s book Timefulness to my attention. I was immediately interested by the prospect of reading a contemporary work on geologic time and hoping for some poetic intersubjective understanding of what it’s like to experience deep time mapped onto physical space. I imagine looking upon the face of a cliff, with many layers of exposed rock, and wandering back in time like leafing through pages in a book.
in the prologue Bjornerud begins with by recounting the experience of a snow day in Wisconsin. this was what hooked me when investigating the book. the first person depiction of what it’s like to experience a transformed landscape: physically, visually, sonically, these are all great landmarks to set out from in the effort of building a pattern language of awe and understanding with the reader. the blanketed quietude, the distorted shapes, the freshness of the landscape, these all serve as points of focus for the unnamed emotion that is recognition of an everyday landscape in a very different context, opening the doors of perception to aspects of time that we normally elide.
the author sees geology as fitting into an uncomfortable niche in the academy. she points out that physics and chemistry are seen as more valuable, that their truths are atemporal, platonic, outside of time, fully abstracted, but that geology and biology cannot be so abstracted and are thus valued less. regardless of how valued geology is relative to physics, I appreciate the observation of the dichotomy between these four fields.
timefulness includes a feeling for distances and proximities in the geography of deep time
the story of continental drift is a strong part of this book. in 1915, Eugene Wegener proposed the theory of continental drift. at that point in time, the evidence he provided was not enough. Wegener showed the obvious but circumstantial evidence of close fit of the contours of the continents, especially south america and africa and the similar rock strata on both sides of those similar contours. while the evidence was hard to dismiss, it was even harder to convince geologists of the reality of his theory without an explanation of the mechanism that drove continental drift. so much like Mendelian genetics, this ultimately valid theory was not fully reckoned with until 50+ years after its initial proposal. not until the discovery of the mid-ocean-ridges and sea floor spreading, was there a plausible mechanism in plate techtonics to explain how continents could move around on the surface of the earth. like Mendel, Wegener was long dead by the time their respective sciences came around to the right belief.
I was able to glean two dichotomies from Timefulness.
sial vs sima
sima is the geologic term for rock that makes up oceanic crust, basalt, mostly made up of silicon and magnesium. oceanic crust is denser, and so floats lower on the surface than its opposite…
sial is the geologic term for rock that makes up continental crust, granite, mostly made up of silicates and aluminum minerals.
the process of plate techtonics, where crust is created at mid-ocean ridges and destroyed at subduction zones, is responsible for concentrating the sial rock and creating continental crust. all continents are agglomerations of exotic terranes.
the dichotomy of sima vs sial is what shapes the face of the earth. if the earth were made up entirely of oceanic crust, or entirely of continental crust, we would either have a barren moonscape planet or a fully oceanic planet. instead, we have a running dialog between continent and ocean stretching back across multiple super-continents. there can be no doubt that this complexity is one of the many and varied forces that give life on earth its richness.
uniformitarianism vs catastrophism
uniformitarianism is the assumption that natural processes operate uniformly over time and space, and as applied to geology, that the current state of the world can be sufficiently explained by the understanding of those processes as they unfold uniformly over time.
catastrophism is the belief that the earth’s current form can be best be explained by sudden events in geologic time, rather than uniform application of natural processes. floods and volcanoes are examples.
the dialectic between these two poles is a good representation of the field of geology. erosion and deposition are key parts of the story, but so are sudden changes in climate, volcanism, and even meteor and comet impacts.