Ever wanted to learn Geology but don’t have the time?

5-minute outline on geology

Note: This analysis is by David Emery from the SciManDan Patreon Slack group, a big thanks to him for this content.

A quick primer on the science of Geology


Geology is the scientific study of rocks, earth, earth history, fossils, paleontology, volcanology, and seismology.  Yes, it is an enormous field of science covering all earth sciences. There is a lot of controversy over geology and whether it is a real science, whether the earth is a sphere or flat and whether it is a young or old earth. It is not in the scope of this post to cover all of that.


The first geologic process is uniformitarianism.  This is the fact from the earliest times on earth, geologic processes require the same amounts of time allowing scientists to estimate ages of rocks, fossils, erosion, deposition, and even catastrophic events.  Movements of glaciers and climate change are excellent studies requiring uniformitarianism.  It is only this process that allows scientists to calculate geologic ages.  Every possible age around the earth must mesh to give coordinated ages.  No single age stands by itself but is corroborated by many calculations. Denial in one event would then throw timings worldwide into question.

Rocks are classified into three broad areas: sedimentary, igneous and metamorphic.  Sedimentary are deposits of any eroded deposits of various sizes forming shale, sandstone or conglomerate depending on particle sizes.  Igneous events are those that begin with some eruption from the earth’s mantle.  Metamorphic rocks are those sedimentary or igneous that are put in extreme temperatures which fundamentally changes their structures, like shale becoming slate.

Types of rocks

There are catastrophic events such as volcanos, floods, earthquakes, meteors, lightning strikes, and fires. These are rare events, in geologic time, and all have varying impacts.

Primarily, there are these slow, incremental processes that have very long-term effects. These include sediment deposits (river deltas), weathering (Arches National Park, Grand Canyon), creation of crystals (diamonds), movement of tectonic plates (Australia, Mid-Ocean Subduction Zones), movement of glaciers and many more.  This type of event can be observed, measured across time to estimate its behavior in past Geologic time.  Around the world, similar events can be researched across time to build a picture of how the earth progressed through time.  You cannot just announce that the Grand Canyon was created in a catastrophic event in a matter of weeks.  While catastrophes do happen, they do not take over the respective geologic processes.  Continents do not zoom across oceans at breakneck speeds.  Geology is a very incremental, predictable set of processes.


Fossils are also created by slow processes.  It takes a very specific sequence of events, and fossilization.  Once again, fossilization or petrifying of plants or animals cannot happen instantaneously.  It is a rare process.  Fossils can be used as age indicators but it has to be widely identified and there is a consensus of a time range.

T-Rex Fossil


Seismology is the study of seismic waves started by geologic processes. The study of these waves helps us to understand the shape and composition of the earth.  There are only three types of waves:  p-waves, s-waves and surface waves.  Surface waves are the fastest and only propagate on the earth’s surface.  P-waves are slower and propagate through any material.  S-waves are the slowest and will not propagate through any liquid.  As with any wave, they are bent when they pass through different mediums.  All three are generated with any event (volcano, earthquake, meteor, etc). 

Seismology chart of California activity

These waves have been studied for decades and each earthquake can be detected by seismic centers all over the world. It is possible, also, to generate maps of the interior of the earth, the sphericity, and continental drift. We can see the importance of the science of geology and the results we can get from its study.  Do not allow anyone to deny what geology shows. 

What now?

Now that you have a general understanding of what the science of Geology is you can learn more by taking some free online courses at a place like Khan Academy.

Are you interested in Geology? Do you want to start a career in Geology? Let us know in the comments below!

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