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The Importance of Geology

Updated: Aug 4, 2022


Waves crashing on some rocks


I have stated once before in these posts the importance of geology, not only with regards to both the past and future of our planet, but also in paleontology. If you're looking for a career in any geological field, the same rules apply as the ones laid out in this post. Whether you want to take up paleontology as a hobby or a career it is important that you have a good degree of knowledge at your disposal.


But why?



Image of rocky mountains

For those that may not know, geology is the study of Earth science using rocks.

Well, as I'm sure you know, rocks are what we find fossils in. If we knew nothing about the rocks that one finds fossils, we would know absolutely nothing about the fossil, let alone any of the Earth's history. There are 3 main rock types: igneous, metamorphic and sedimentary. Sedimentary rocks make up around 70% of the Earth's surface and are the only rock type that can yield fossils. This is because igneous rocks are cooled down magma and lava and metamorphic rocks are rocks that have gone through processes of immense heat and pressure far below the Earth's surface that a bone simply wouldn't survive. Sedimentary rocks, which are other rock types that have been eroded away and gently glued back together over time (in a process called diagenesis), are the only rocks which are put together gently enough to keep a fossil intact (though even diagenesis can be too rough).


So there would be the first problem if one was struggling to find a fossil; looking at the wrong rock types!


But it goes much further than that. Paleontology is actually a science that comes under the umbrella term of geology. We simply wouldn't have paleontology without it. The study of geology yielded much knowledge about the history of the Earth, calling into question with irrefutable evidence the long accepted belief that the first testament was fact.


The age of the Earth (approximately 4.5 billion years old) wasn't simply plucked out of thin air. It was painstakingly calculated using very complicated chemical and physical procedures (of which are far too complex for a blog post of this size). It was these methods that taught us how long it truly takes to build a planet. It was also the rocks that were studied that taught us so much about what is going on beneath our feet at this very instant. It explained volcanoes, earthquakes, tsunamis, mountains, valleys, the continents and so much more.


Fossils were being unknowingly discovered for centuries before that, but nothing was taken seriously. How on Earth could the land once have been a sea? Surely these old shells that looked vaguely similar to the weird creatures of the deep were a hoax. They were believed to be until the 17th century when, during what is dubbed 'The Age of Reason', the great strides in geology were fully appreciated and studied further in tandem with fossils discovered. Georges Cuvier, an 18th century naturalist and zoologist who has been regarded as the founding father of paleontology, had used these as evidence (alongside geological discoveries) for his argument that extinction was very much a reality. If you're looking for a history in paleontology, you can find that here.


Seems silly now, but without the rock record to back all of this up, we would still be thinking these were fantasy animals and mythical beasts that only existed 4000 years ago.


The geological record also found the answer as to why marine fossils were being found on land. The Earth has always been constantly changing, especially on its surfaces. On a macroscopic scale, we have seen, in snippets, much of the history from the beginning of a lava covered planet, to the time of the dinosaurs, to the present day and pretty much everything in between (find out more about our planet's timeline here).


It is also thanks to geological knowledge that we can find information about environments that these lifeforms inhabited. Certain features can be seen with the naked eye that can tell us much about an environment, such as ripple marks or grain size. Other features can be seen using a light-polarising microscope, viewing all sorts of minerals and seeing what their morphology can tell us. Are the grains large and jagged? That means it was a high enough energy environment to carry larger grains, but they haven't travelled far as they aren't as eroded. Are they small and smooth? Vice versa.



Microscopic image of a gabbro thin section.
Microscopic image of a gabbro thin section. Image credit: https://commons.wikimedia.org/wiki/File:Gabbro_pmg_ss_2006.jpg


Chemical analysis can also tell an incredible amount about environments. Isotope analyses of rocks can tell us what the temperature was, or what the air consisted of. It was isotope analyses like this that explained how arthropods like Arthropleura got to such huge sizes during the Carboniferous. Mineral and structure analyses explained that it was in fact an asteroid impact that killed off the non-avian dinosaurs. The surrounding rocks of an organism can even tell us more directly about an animal's appearance than a fossil ever could. T-rex, for example, has hypothesised to have been a big feathery fluff-ball for the past 15 years, but a new specimen was discovered and, thanks to thorough looks at the rocks themselves, was found to have skin impressions that showed it was mostly covered in small scales!



A Fossil of a giant centipede.
Microscopic image of a gabbro thin section. Image credit: https://commons.wikimedia.org/wiki/File:Gabbro_pmg_ss_2006.jpg


Even something as important as where to find the next fossil comes down heavily to geological knowledge. Knowing how to take a strike and dip can tell you which direction to walk to find older/younger rocks. You see, two of the main principles of stratigraphy state that rock layers on the Earth's surface are laid down in a strictly chronological order as well as being laid down completely horizontally at the time of deposition. Earth movements will tilt them around and, once erosion has changed the surface, you'll then be able to walk in the direction that the rocks dip to see gradually younger rocks.



A diagram showcasing principles of stratigraphy.
Three sedimentary layers that have been tilted, showing how the rocks change on the surface.


Knowing about rocks could even save your life in certain scenarios in the field, as rock-falls, landslides and cliff-falls are very real dangers that can be mitigated by educating yourself about them.


The most applicable importance though, is that of environmentalism. Remember, geology is all about reading the rocks and the rocks have stored so much information about the planet that came before us. Not only can we see what the climate was like at most points throughout Earth's history, we can also see why the climate was like it was...and what the after effects were. Estimations of global mean temperatures, atmospheric consistency and the timings of them can be correlated against the fossil record to see just what effects certain things can have on life on our planet. It has shown us this much: that despite how resilient life is (it does, after all, 'find a way'), it is also very sensitive. One small change in an environment can have huge impacts and it is thanks to geology that we can see how big those impacts can be. Events such as the Permian mass extinction event, during which life was nearly completely wiped out (which you can read more about here), offer a scary look into what could lay ahead of us thanks to sharp changes in our atmosphere of that nature. Geology, most importantly, serves as a cautionary reminder of the delicate balance of nature.


Obviously, a post this size can only just graze the surface about how geology and paleontology are so intertwined, but if there is anything in particular you'd like to learn about in future posts, be sure to comment down below!

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