Principles of Geology
Jun. 15th, 2016 09:28 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
stoutfellowCharles Lyell's Principles of Geology is the other major nonfiction work I'm currently reading. In some ways, it's a window into the past; the main point of the book is to stake out and defend a position in a controversy that has been long since resolved. One of the prevailing theories of geology in Lyell's day was catastrophism, holding that the Earth had alternated between long periods of geological quiescence and brief periods of immense upheaval, in which the shape of the continents changed radically and life was virtually extinguished, to be followed by a new creation of life. Lyell argued for the uniformitarian position, that the data could be equally well explained by the assumption that the geological processes at any time in Earth's history were the same, in quality and intensity, as those now perceived; all that was needed for radical upheaval was the passage of sufficient time.
One of Lyell's biggest headaches had to do with the changing patterns of life found in the fossil record. He was at times reduced to pointing out that the record was fragmentary enough that we couldn't be sure that, e.g., there were no mammals in the Carboniferous. Darwin's work on evolution must have come as a great relief to him; he and Darwin were friends and intellectual allies, and he was an early proponent of the Darwinian position.
The only large-scale geological processes Lyell could point to were uplift and subsidence (and you can see the same ideas in, e.g., The Voyage of the Beagle); these were the source of such proposals as the existence of a lost continent of Lemuria in the Indian Ocean, to account for the presence of lemurs in Madagascar and India but nowhere in between. (Many other land bridge proposals were in vogue in the following century or so.) Plate tectonics, of course, does a much better job of explaining such things.
Uniformitarianism carried the day, eventually. It's interesting the ways that modern theory diverges from it, though. First, in the Hadean Eon, the geological processes were definitely not those of the present; it's not even clear that plate tectonics had started yet. More broadly, the study of the Great Extinctions bears a passing resemblance to catastrophism, with its continental-scale volcanic eruptions and the occasional asteroid. (Of course, the catastrophe causing the current Great Extinction is not geological in origin....)
It's an interesting read; Kindle says I'm only about 19% of the way in. I'll be interested in his discussion of the appearance of humanity, which even he had to admit was a recent phenomenon.
One of Lyell's biggest headaches had to do with the changing patterns of life found in the fossil record. He was at times reduced to pointing out that the record was fragmentary enough that we couldn't be sure that, e.g., there were no mammals in the Carboniferous. Darwin's work on evolution must have come as a great relief to him; he and Darwin were friends and intellectual allies, and he was an early proponent of the Darwinian position.
The only large-scale geological processes Lyell could point to were uplift and subsidence (and you can see the same ideas in, e.g., The Voyage of the Beagle); these were the source of such proposals as the existence of a lost continent of Lemuria in the Indian Ocean, to account for the presence of lemurs in Madagascar and India but nowhere in between. (Many other land bridge proposals were in vogue in the following century or so.) Plate tectonics, of course, does a much better job of explaining such things.
Uniformitarianism carried the day, eventually. It's interesting the ways that modern theory diverges from it, though. First, in the Hadean Eon, the geological processes were definitely not those of the present; it's not even clear that plate tectonics had started yet. More broadly, the study of the Great Extinctions bears a passing resemblance to catastrophism, with its continental-scale volcanic eruptions and the occasional asteroid. (Of course, the catastrophe causing the current Great Extinction is not geological in origin....)
It's an interesting read; Kindle says I'm only about 19% of the way in. I'll be interested in his discussion of the appearance of humanity, which even he had to admit was a recent phenomenon.
