Earth as seen from space. Both geography and geology study the Earth, although in different ways.
Two overlapping but different sciences
All the time I hear the words “geology” and “geography” mixed up. I’m pretty sure that most people don’t know what the difference is, and so I’m going to explain.
I have a geography degree, although I love many different scientific disciplines. Geology is my second-favorite. I also love zoology, paleontology, and astronomy.
After defining each one separately, I will explain how they overlap and might be confused, besides the two words being so similar in spelling and pronunciation.
This is the Tabula Rogeriana, a world map created by Arab geographer Muhammad al-Idrisi in the year 1154. It took 15 years to make, and at the time was absolutely phenomenal. This amazing scientist calculated the circumference of Earth to be 37,000 kilometers (22,900 miles), an error of less than 10 percent from the true measurement.
The definition given on Wikipedia’s article about geography is: “A field of science dedicated to the study of the lands, the features, the inhabitants, and the phenomena of the Earth.”
The Oxford dictionary says: “The study of the physical features of the earth and its atmosphere, and of human activity as it affects and is affected by these.”
The way I like to describe it is that geography is the study of the Earth, and anything that can be portrayed on a map. It seeks to understand how things work, influence one another, and interact spatially.
Maps are an important part of geography, and after graduating from college with a geography degree I worked for two different map companies for about seven years designing and creating folding map products.
A volcanologist on the Big Island of Hawaii collects a sample of molten pahoehoe lava issuing from the Kilauea shield volcano, which is the most active volcano on Earth.
For geology, Wikipedia defines it as: “An earth science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which they change.”
The Oxford dictionary says: “The science that deals with the earth's physical structure and substance, its history, and the processes that act on it.”
Geology then can also be said to be the study of the Earth, but is more interested in what our planet is composed of, and how the physical Earth works – such as the tectonic processes, volcanoes, and the chemical composition of rocks.
The locations and movements of the Earth's tectonic plates would be studied by both geologists and physical geographers.
Similarities and differences between geology and geography
Perhaps what most people might need help with is remembering which word is paired with which definition. “Geo” means Earth. For geography, the “graph” part refers to describing the Earth. For geology, the “logy” part refers to studying the Earth.
In other words, even the words are very similar in what they mean.
Think of how a “graphic” is a visual image. Geography often deals with maps, which are a visual image. If you can remember that the “graph” part refers to maps, you can perhaps remember the differences in this way.
Geography and geology overlap in their study of the physical features of the Earth. They differ however in the other components of each science.
Geography studies much more than just the physical features of our planet. It’s a very broad science that overlaps with many other scientific disciplines, not just geology. It is half an Earth science, and half a subset of the humanities. This is because geography is divided between “human geography” and “physical geography.”
Geography also studies the interactions between humans the Earth’s land surface. And it also studies and analyzes phenomena of our planet’s atmosphere.
Geology on the other hand, besides studying the Earth’s physical features, delves into the chemical composition of rocks, and the processes occurring within the Earth.
You can think of geography as studying what we can see on the outside surface of the Earth, and geology as looking within rocks and within our planet's interior.
Both sciences actually can be applied outside of Earth to other celestial bodies. It’s possible to study and geography and/or geology of moons, the sun, or other planets, for example.
Both sciences can also go back in time. Rather than studying the Earth as it is now, geography and geology of the ancient Earth can also be studied and understood. Continents shift over time, for example.
In reality all sciences can overlap to some degree. Geology studies the Earth, which can include fossils. Therefore it overlaps with paleontology, which is the study of ancient life.
Meteors strike the Earth on occasion. The resulting craters are studied by geologists. Therefore geology overlaps with astronomy, which would study meteors or asteroids and all else that is outside of Earth and its atmosphere.
If you wanted to study or map the physical locations of fossil sites or meteorite craters, you would be using geography to analyze where these are spatially. The science of maps, which is part of geography and my personal specialty, is called cartography.
Earth as seen at night. This is a composite of many space photos taken at night.
Familiarity with these sciences is the key
The more familiar you are with geology and geography, and study these subjects, the more likely you will be to never confuse to the two terms. Like most things in life, you’ll know and remember it better the more you use it, and if it’s not something you commonly think about, then confusing the two is certainly understandable!