An Introduction to the Basics of Geology

Understand the Essential Elements That Make up the Earth

The geology of the Earth is a fascinating subject of study. Whether it is identifying rocks along the road or in your backyard or the threat of climate change, geology is a major part of our everyday lives. 

Geology includes everything from the study of rocks and minerals to Earth's history and the effects of natural disasters on society. To understand it and what geologists study, let's look at the basic elements that make up the science of geology.

Art cutaway of Earth showing interior structure
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Geology is the study of the Earth and everything that makes up the planet. In order to understand all of the smaller elements that geologists study, you must first look at the bigger picture, the makeup of the Earth itself.

Beneath the stony crust lie the rocky mantle and, at Earth's heart, the iron core. All are areas of active research and competing theories.

Among these theories is that of plate tectonics. This one attempts to explain the large-scale structure of various parts of the Earth's crust. When the tectonic plates move, mountains and volcanoes are formed, earthquakes occur, and other shifts in the planet can happen. More »

USA, Utah, Lehi, boys (6-9) in museum of dinosaurs
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All of human history is the briefest moment at the end of four billion years of geologic time. How do geologists measure and order the milestones in Earth's long history?

The geologic clock gives geologists a way to map Earth's history. Through the study of land formations and fossils, they can put together the story of the planet.

New discoveries can make drastic changes to the timeline. This is divided into a series of eons and eras that help us further understand what previously occurred on Earth. More »

Bolivia, Atacama Desert, Salvador Dali Desert
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You know what a rock is, but do you really understand what defines a rock? Rocks form the basis for geology, though they are not always hard or completely solid.

There are three types of rocks: igneous, sedimentary, and metamorphic. They differ from one another by the way in which they were formed. By learning what makes each unique, you are one step closer to being able to identify rocks.

What is even more interesting is that these rocks are related. Geologists use the "rock cycle" to explain how many rocks transform from one category to another. More »

Malachite and azurite mined from Bagdad Copper Mine, Bagdad, Arizona, USA
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Minerals are the ingredients of rocks. Just a few important minerals account for the majority of rocks and for the soil, mud, and sand of the Earth's surface.

Many of the most beautiful minerals are treasured as gemstones. It's important also to remember that most minerals have separate names when they are referred to as a gemstone. For example, the mineral quartz can be the gemstones amethyst, ametrine, citrine, or morion.

Just like rocks, there is a method you can use to identify minerals. Here, you're looking for characteristics like luster, hardness, color, streak, and the formation. More »

Monument Valley, man enjoying the view of Navajo Tribal park
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Landforms are created by the rocks and minerals found on Earth. There are three basic types of landforms and they too are defined by the way they are made.

Some landforms, such as many mountains, were created by movements in the Earth's crust. These are called tectonic landforms.

Others are built up over long periods. These depositional landforms are created by sediment left behind by rivers.

The most common, however, are erosional landforms. The western part of the United States is filled with examples, including the arches, badlands, and buttes that dot the landscape. More »

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Understanding the Geologic Processes

Lava ripples, Hawaii
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Geology is not just about rocks and minerals. It also includes the things that happen to them in the great Earth cycle.

The Earth is in a state of constant change, both on a large and small scale. Weathering, for example, can be physical and change the shapes of rocks of any size with things like water, wind, and fluctuating temperatures. Chemicals can also weather rocks and minerals, giving them a new texture and structure. Likewise, plants can cause organic weathering of the rocks they touch.

On a larger scale, we have processes like erosion that changes the shape of the Earth. Rocks can also move during landslides, because of a movement in fault lines, or as molten rock underground, which we see as lava on the surface.

Offshore Oil Platform
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Many rocks and minerals are important elements in civilization. These are the products that we take from the Earth and use for a variety of reasons, from energy to tools and even pure enjoyment in things like jewelry.

For instance, many of our energy resources come from the Earth. This includes fossil fuels like petroleum, coal, and natural gas, which power most everything we use on a daily basis. Other elements like uranium and mercury are used to make various other elements more useful, though they do have their dangers.

In our homes and businesses, we also use a variety of rocks and products that come from the Earth. Cement and concrete are very common rock-based products, and bricks are artificial stones used to build many structures. Even the mineral salt is a vital part of our lives and an essential part of the diet of humans and animals alike. More »

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The Hazards Caused by Geological Structures

Torrential Rains Bring Historic Floods To Southern Louisiana
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Hazards are ordinary geologic processes that interfere with human life. Different areas of the Earth are prone to various geologic hazards, depending on the land and water formations nearby.

Natural disasters include earthquakes, which can cause subsequent perils like a tsunami. Certain areas of the world are also in the path of erupting volcanoes.

Floods are one type of natural disaster that can strike anywhere. These are the most frequent and the damage they cause can be minor or catastrophic.