Edward J. Denecke Jr. - Painless Earth Science

Copyright 2021, 2011 by Kaplan, Inc., d/b/a Barrons Educational Series

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Published by Kaplan, Inc., d/b/a Barrons Educational Series

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New York, NY 10017

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ISBN: 978-1-5062-7327-3

10 9 8 7 6 5 4 3 2 1

Painless Earth Science? Impossible, you think. Not really. Earth Science is easy or at least it can be with the help of this book!

Earth science encompasses the study of Earths land, water, air, and life, and how they interact. As you read this book, you will probably be surprised at how much of Earth science is already familiar to you. Thats because Earth science is all around you, and it affects every aspect of your life. Whether you are learning Earth science for the first time, or you are trying to remember what youve learned but have forgotten, this book is for you. Dont be afraid. Dive inits painless!

Painless Icons and Features

This book is designed with several unique features to help make learning Earth science easy.

PAINLESS TIP

You will see Painless Tips throughout the book. These include helpful tips, hints, and strategies on the surrounding topics.

CAUTIONMajor Mistake Territory!

Caution boxes will help you avoid common pitfalls or mistakes. Be sure to read them carefully.

BRAIN TICKLERS

There are Brain Ticklers throughout each chapter in the book. These quizzes are designed to make sure you understand what youve just learned and to test your progress as you move forward in the chapter. Complete all the Brain Ticklers and check your answers. If you get any wrong, make sure to go back and review the topics associated with the questions you missed.

ILLUSTRATIONS

Painless Earth Science is full of illustrations to help you better understand Earth science topics. Youll find tables, graphs, charts, and instructive science illustrations to help you along the way.

SIDEBARS

These shaded boxes contain extra information that relates to the surrounding topics. Sidebars can include more advanced topics, detailed examples, and more to help keep Earth science interesting and painless.

Spheres, spheres, spheres! The first thing you need to know about Earth is that it is made up of lots of layers and that each of those layers is shaped like a sphere. When Earth first formed it was molten, and gravity pulling toward its center caused it to form a sphere. Like a mixture of oil and water, the substances that made up Earth then separated into layers due to density differences. Gravity caused denser substances like rock to sink inward toward the center and less dense substances like gases to float outward toward the surface. Since Earth is shaped like a sphere, the layers that formed are also spheres. You can think of Earth as a whole bunch of spheres, one inside the other. Earths major layers, or spheres, include the lithosphere, hydrosphere, atmosphere, and biosphere. Lets take a closer look at each.

Cutaway of Earth showing lithosphere, hydrosphere, atmosphere, and biosphere.

Lithosphere

We often think of the entire Earth beneath our feet as solid. But think about a volcanic eruption. Clearly, liquid rock is coming up from below Earths surface. So, at least part of what lies beneath the surface is not solid. Scientific investigation has revealed that the rock inside Earth is hot enough to flow slowly like melted butter and has also separated into layers according to density. The lithosphere is Earths cold, hard, solid outer layer of soil and rock extending from the surface to a depth of about 100 kilometers. Beneath the lithosphere are more layers of hot rock reaching all the way down Earths center more than 6,300 kilometers beneath the surface. All of Earths mountains, valleys, plains, plateaus, and other surface features are part of the lithosphere.

Hydrosphere

When you dive into the water at the beach, you are diving into the hydrosphere. The hydrosphere is a thin layer of liquid water that rests upon the lithosphere. More than 70 percent of Earths surface is covered by water. The trillions of gallons of water that make up the hydrosphere cover all of the low spots in Earths lithosphere to an average depth of about 3.8 kilometers (2.4 miles). This is very thin compared to Earths diameter. If you dipped a basketball in water, the water wetting its surface would be deeper in places than the hydrosphere is on Earth.

The hydrosphere plays a key role in many geologic processes. Moving water carries loose rock from place to place and shapes Earths surface. The oceans act as heat absorbers, preventing drastic temperature changes. Water is also essential to all living things, not only as drinking water, but as the main substance in the cells of all living things.

Atmosphere

Every time you take a breath, you are breathing Earths atmosphere. The atmosphere is a thin layer of air that surrounds the whole Earth and extends out several hundred kilometers into space. Air is a mixture made up mostly of gases, but it also contains water droplets, ice, dust, and other particles. Air is about 78 percent nitrogen and 21 percent oxygen. The remaining 1 percent is mostly argon with traces of carbon dioxide and other gases. The atmosphere also contains water vapor, but the amount varies from 0 percent over deserts to as much as 4 percent over tropical jungles. All of Earths weather, from puffy little clouds to massive hurricanes, occurs in the atmosphere.

Biosphere

You and all of your friends are part of the biosphere. So is the grass in your lawn, the trees in the park, your pet dog, and the fleas and ticks on your dog. Even the bacteria and viruses that make you sick are part of the biosphere. The biosphere consists of all life on Earth. It may seem odd to think of life as a sphere, but think of what Earth would look like if you stripped away everything that is nonliving. Earth is surrounded by a thin layer of life that exists on and in its land, throughout its water, and in the lower parts of its air. The presence of a biosphere and its interaction with the other spheres makes Earth a unique planet.