Alecia M. Spooner

Although the early Paleozoic was ruled by invertebrates, the development of skeletal features had also begun. The evolutionary story of chordates—animals with a nerve chord (which later includes animals with a backbone, or vertebrates)—is missing in the geologic fossil record because there were no hard skeletal parts to preserve.

The beginning of the Paleozoic is marked by the sudden appearance of a wide variety of animal forms in the geologic record. In fact, the fossils from this period exhibit all the animal body plans that exist even today, 540 million years later. (A body plan is how an organism’s body parts and growth patterns are organized.

It’s easy to get distracted by the abundance and diversity of life that appears and flourishes during the Paleozoic. But life and evolution are influenced by the geologic processes that are always shaping the earth’s environments. The Paleozoic saw periods of intense mountain building, extensive glaciations, widespread shallow seas, and the continued buildup of material onto the continental cratons, building the continents into shapes resembling what you see today.

More than once in Earth’s long history, geologic events have led to the demise of multiple species. Sometimes whole families of organisms disappeared, putting an end to that particular path of evolution and leaving room for surviving animals to spread into new habitats. Each of these extinctions is well-documented by changes in the fossils preserved in the geologic record.

Here are a few of the most common ways that you use geologic resources every day. This includes in your home, in your neighborhood, and even in your computer! Burning fossil fuels One of the best known and most pervasive ways that humans use geologic resources is through the use of fossil fuels: coal, oil and natural gas, to create energy.

Living on Earth can be dangerous. Earth is a dynamic planet, geologic processes are always in motion, and while some processes take millions of years (like the formation of a sedimentary rock), others happen very quickly (like a volcanic eruption). All these processes are natural, but they become hazards when they affect human lives and the infrastructure of modern society.

Environmental science is a field of study focused on Earth’s environment and the resources it provides to every living organism, including humans. Environmental scientists focus on studying the environment and everything in it and finding sustainable solutions to environmental issues. In particular, this means meeting the needs of human beings (and other organisms) today without damaging the environment, depleting resources, or compromising the earth’s ability to meet the resource needs of the future.

Geology is the study of the earth, which begins with the study of the three types of rocks — the building blocks of the earth and its features. The unifying theory of geology is called plate tectonics, which contends that the earth's surface is separated into puzzle-like pieces that move around. Of course, earth hasn't always looked the way it does today, and geologists help tell the story of the earth's evolution by reading the rock layers.