ROCKING YOUR WORLD What does a tiny grain of sand have in common with a giant boulder What do they both have in common with a pebble on a playground Because you grabbed this book and not one on say dinosaurs- you can probably guess They're all rocks Almost our entire planet is made up of rocks Once you take away the air water and living things from the surface of our planet what you're left with is pretty much a whole lot of rock They come in many sizes and colors and are formed in different ways You can spot them everywhere Whether you're catching some rays on a beach exploring a canyon or just strolling down a city street you're bound to come upon or sometimes trip over -rocks or something made from them And then there are the rocks we can't see like the red hot rock deep below Earth's surface and the rocky mountain ranges deep within the oceans depths And just in case you're wondering there are plenty of rocks in outer space too Some are pieces of planets or smaller space objects called asteroids The rocks break off from the planets or asteroids and hit Earth's atmosphere at speeds of up to 160,000 miles an hour 257,495 km/h The space rocks that make the journey all the way to Earth's surface are called meteorites While they land all over the planet many meteorites are found on Antarctica The icy continent is very dry so the meteorites aren't damaged by water in the air as they are in most other regions Plus since Antarctica is covered in ice the dark meteorites are easy to spot against the white surface Luckily for you you don't have to go to Antarctica to see meteorites or take a submarine ride to explore underwater mountains Keep reading as we leave no stone unturned to help you learn all about rocks wherever they're found Whoaaa PAY DIRT By one estimate Earth's deserts and beaches contain more than seven quintillion grains of sand that's a seven followed by 18 zeros
rock stars WHAT IS A GEOLOGIST Anyone can admire the rocks all around us but it takes a specially trained person to dig up the dirt on the importance of rocks A scientist who studies rocks and the minerals in them is called a geologist Geologists also investigate how volcanoes erupt where earthquakes are likely to shake things up and where valuable natural resources are located Throughout this book you’ll meet some of the rock stars who have helped uncover Earth’s structure and history 7
ROCKS what is a rock Let’s rock and roll Rocks make up every continent mountain and island on the planet But what is rock In simple terms a rock is a naturally occur ring solid object usually made from minerals Rocks are classified as one of three main types igneous sedimentary and metamorphic depending on how they’re formed A rock can also transform from one type to another over millions of years the processes of the rock cycle break it down or melt it change it and reform it into new rock MINERALS MATTER Within the three different categories of rocks what makes one rock different from another are the ways the different minerals combine together Rocks are usually made up of one or more minerals see page 100 to learn more about minerals Minerals are made up of tiny particles called atoms and these atoms are arranged in a particular particular pattern This pattern creates what are called crystals The crystals determine what a mineral looks like and they can shape how a rock looks too These crystals can affect whether a rock is rough or smooth and how hard it is Minerals also come in different different colors and that can affect a particular rock’s appearance too A mineral called hematite can make a rock red or brown It’s this mineral that gives sandstone sandstone its brown tint The mineral quartz gives rocks a range of colors though they usually tend to be light shades of gray Dacite usually bluish gray or pale gray is one rock that is often loaded with quartz 8
ROCK GLOSSARY Rocks and minerals may look simple but there’s a mountain of science that helps explain how they form and what they can do To make sure you’re on solid ground as you navigate the terrain take a minute to familiarize yourself with these important terms ATOMS Microscopic particles that are the basic unit of an element BACTERIA Single-celled microorganisms thought to be the first forms of life on Earth CONDUCTOR A material that transmits a form of energy such as heat or electricity some substances are better conductors than others CRYSTAL The arrangement of tiny parti cles called atoms and molecules found in minerals each mineral has its own crystal structure DORMANT Referring to a volcano that has not erupted in a long time but might again someday ELEMENT One of more than 100 sub stances on Earth that has a unique set of chemical and physical properties and that make up everything on the planet EROSION The natural process through which wind water and ice wears away and removes rock and soil EXTINCT In geology refers to a volcano that no longer erupts FOSSIL The remains of ancient life forms or traces or impressions of an organism which are found in rocks FRACTURE The way that minerals and rocks break apart or have a break within LANDFORM A natural feature of Earth’s surface such as a mountain LUSTER The way light reflects off a rock or mineral which indicates how dull or brilliant it is MOLTEN Turned into liquid by high heat MONOLITH A single giant stone or rock NUCLEAR Referring to the center or nucleus of an atom PROPERTIES The particular traits of a specific rock or mineral QUARRY A place from which large amounts of certain rocks are or have been removed often for use in buildings or the act of removing the rocks RADIATION A form of energy released by some elements as they naturally change that can be harmful in large doses materials with high levels of radiation are called radioactive SEDIMENT Broken pieces of rock that can move from one place to another and often settle to the bottom of bodies of water TECTONIC Relating to the structure of Earth’s crust and mantle and the activity that takes place within them VITREOUS A luster with a glassy look VOLCANOLOGIST A geologist who specializes in the study of volcanoes 9 Rocks
