Forces of Nature
The planet Earth is our home. It is the only planet we know of that supports life. For 4.5 billion years, forces of nature have changed the planet we live on. Towering mountain ranges form and erode. Islands rise, volcanoes erupt and earthquakes tremble. Some of these processes take millions of years, while others only take minutes. All around us the Earth is reshaped in some way everyday.
Do you know how mountains are made? Do you know how rocks form? Does dirt stay in the same place forever? Read on to find out how some of these amazing things happen!
-- Araña Pequeña
What Is a Rock?
By Haris Lefteri
If we do not look closely, all rocks appear the same. However, there are a number of different kinds of rocks, and each kind is made a different way.
All rocks are made up of one or more minerals. Minerals are inorganic (not alive) substances. (Humans, plants and animals are organic.) We are going to learn today about three types of rocks. The first type is formed when molten rock cools. Molten rock exists far below Earth’s surface where there are very high temperatures. Igneous rocks are formed when molten rock cools quickly on Earth’s surface or when molten rock slowly cools far beneath the surface. One way molten rock rises to the surface is through a volcano.
The second type of rocks is sedimentary rock that is formed when pressure (weight) is applied to layers of sediments under Earth’s surface. Sediments are fragments of rocks that are created when rocks are broken into tiny pieces by weather. On top of Earth’s surface, where extreme amounts of pressure are not present, sediments are also found in dirt and sand.
Last, but not least, are metamorphic rocks, which are formed from an older “parent” rock (either igneous or sedimentary) under intense heat and pressure beneath the Earth’s surface. The heat and pressure change the rocks so much that they look and feel different. They also then have a new name, metamorphic.
Erosion
By Wilhemina Agbemakplido
Erosion is when pieces of land, soil or rock are moved from one place to another or when large pieces of rock or land are worn into smaller pieces. There are two types of erosion: slow erosion and quick erosion.
Quick erosion happens in a short amount of time and changes Earth’s surface. Some things that cause quick erosion are landslides and earthquakes. A landslide occurs when the side of a mountain or cliff collapses. This can be caused by heavy rain or human activities. Earthquakes are a violent shaking of the Earth’s crust when the plates of the Earth’s crust push into each other. Both landslides and earthquakes move large quantities of rock and dirt. A smaller example of quick erosion is when rain on a hill carries plants and soil from the top of the hill to the bottom.
Slow erosion even affects formations as large as mountains. Do you know that the Appalachian Mountains are not as tall as they used to be? Mountains lose their height as a result of weathering. Weathering occurs over time when wind and water beat against Earth’s surface. Weathering not only moves small pebbles and dirt, it also wears formations such as mountains down by breaking up the rock that they are made of. Over thousands of years, weathering will break huge rocks, like mountains, down into small pieces that are carried away by wind and water. Eventually, mountains become noticeably smaller.
Mountain Ranges
Earth’s crust, or top layer, is divided into seven huge chunks of ocean
floor and land called plates. These plates actually move around! The study of
how these plates move is called plate tectonics. Today we know that they move at
approximately the same speed at which your fingernails grow. All the plates are constantly,
slowly shifting. Some move away from each other, and some move directly toward each other.
When two plates move slowly toward each other and push into each other, a mountain range
can form. The plates slowly push their edges up into jagged peaks as they press together.
You try it! Try gently pressing the fingertips of both of your hands together, tips against tips. See if you can make a mountain with your fingers!
Volcanic Islands
One way an island is formed is when a volcano erupts underwater. With each eruption of the volcano, lava builds up under the ocean’s surface until the top rises out of the water. Over time, more and more lava is released from the volcano and hardens on top of the previous lava. This causes the mass to continue to grow until it is so large that it rises above the sea and becomes an island, such as those that make up the state of Hawaii.
