Introduction to Geology: Unearthing Earth's geological aspects

The Foundation of Our Planet

Photo by Christopher Burns on Unsplash

Have you ever wondered about the origin of the rocks you see during your hikes, how the beautiful landscape you see right in front of your eyes was formed or even how long it took to get to today's structure? Well, this is what Geology is for: to understand the origin and the processes that all components underwent throughout the past billions of years to become what we see today. 

Since starting geology lessons this semester, we've been paying more attention to the rocks we see while hiking. Identifying them isn’t easy—it takes a good lens (10x or 12x magnification) and a comparison to known samples. But it's a fascinating process! And geology is about so much more than just rocks. By studying them, we can learn about different eras in Earth’s history chronologically. But we’ll dive deeper into that in another post!

But what exactly is a rock?

Photo by Alireza Dashtestani on Unsplash

A rock is a solid mixture of minerals, particles, and other natural materials. Unlike minerals, rocks don’t have a fixed chemical formula because they are comprised of different substances. However, they can be grouped based on how they form, which makes them easier to classify.

Rocks are literally the foundation of our planet. They make up the Earth's crust and 

What about minerals?

Photo by Edz Norton on Unsplash

Minerals, unlike rocks, have a specific chemical composition. This means they can be identified based on their unique structure and properties, such as color, hardness, and crystal shape.

Some interesting facts are:

• Diamonds are the hardest minerals that are naturally existent, while talc is the softest!

• There are more than 3000 types of minerals known today.

Now, to just give you a general knowledge, rocks can be divided into three major groups: igneous, sedimentary, and metamorphic.

Igneous rocks are formed from cooled magma or lava that leads to the hardening (crystallization) of the rock over time. Examples include granite, basalt and obsidian.

Sedimentary rocks are created when layers of sand, mud, or organic material are compressed over time. These often contain organisms that might be alive today or extinct (fossils), which can be used to study the evolution of species by their distribution in the layers. They are considered to be most of the rocks available on the surface of our planet. As for sedimentary rocks, you can find limestone, chalk, coal, sandstone, etc.

Metamorphic rocks are formed when existing rocks are subjected to high temperatures and pressure, transforming them into new types like marble and slate. (These are my personal favorites due to the beautiful visible layers of different components. )

Diagram by TpointTech

Some of the physical properties of sedimentary rocks are:

1. Composition is essential to help determine the type of the sedimentary rock and its possible origin.

2. Texture is about grain size, shape(rounded-angular) and how sorted the grains are. Gravel is the biggest, followed by sand, silt and finally clay, which is the smallest.

3. Structure: how the rocks are composed by the sediment that has been deposed; therefore, it's the combination of size, organization, orientation, packing, shape, composition and whether it's homogeneous or inhomogeneous.

The Earth’s Structure

Beneath our feet, the Earth is made up of different layers:

• 

  Diagram from GeologyIn

  The Crust: The outermost layer where we live. It includes the continents (thicker, mostly granite) and the ocean floors (thinner, mostly basalt).

• The Mantle: A semi-solid layer beneath the crust. Its slow-moving currents drive plate tectonics, causing earthquakes, volcanoes, and mountain formation.

• The Core: The deepest layer, generating Earth’s magnetic field. The outer core is liquid, while the inner core is solid.

Geology isn’t just about studying rocks—it’s about understanding Earth’s past, present, and future. Next time you pick up a rock, think about the journey it has taken over millions of years.

Keep up with our next posts. It might be a rocky path, but we will soon be posting more about different rocks and all the chemical and physical processes they undergo to become what we can find today, especially the ones we find during our lessons and hiking. 

Thanks for reading yet another post. :)

-L.