The Earth’s Layers

           Human beings have always imagined what it would be like to journey to the center of the Earth. There are many books and movies about characters who have adventures that take them to the Earth’s core, or even all the way to the other side of the world! It’s fun to pretend that we can tunnel to China, but scientists have proven that humans will never be able to dig through the center of the Earth. The Earth has three very thick layers, and the center is so hot that humans could never survive there. In this lesson, you will learn about these layers from the inside out.

The Core

         The core is the innermost layer of the Earth. It is made up of two parts: the inner core and the outer core. At the very center of the Earth is the inner core. It is solid, and is made up almost entirely of iron. The inner core remains solid because it is under an extreme amount of pressure. It is about 1,200 kilometers thick.

         Have you ever heard that the Earth’s center is made up of lava? While that is not technically true, the core is partially liquid. This liquid layer is called the outer core because it surrounds the inner core. It is made up of iron and another metal called nickel. It also contains sulfur. The outer core is kept very hot by the Earth’s inner core. When elements like metal get very hot they become molten, or liquid. The outer core is about 2,300 kilometers thick.

        

The Mantle

         The middle layer of Earth is called the mantle. At 2,900 kilometers deep, it is the thickest layer of the Earth. Like the core, the mantle has two layers, the upper and lower mantle. Because of its thickness, the mantle is where most of the Earth’s heat is located. The average temperature of the Earth’s mantle is about 1,000 degrees Celsius. At this temperature, the mantle remains solid, but is flexible like plastic. When a heavy load like an ice cap pushes on the mantle, it can flex and move out of the way to make room. Once the load lessens, the mantle can return to its original position.

         The mantle retains a lot of heat, which is circulated throughout the mantle in spaces called convective cells. The movement of heat can cause the plates of the sea floor and continents to shift. Over millions of years the plates of the Earth can move quite a lot. When these shifts happen quickly), we experience earthquakes.

        

The Crust

         The top layer of the Earth is called the crust. The crust is the layer upon which we live and build our cities. The crust is the layer that can sustain life, yet it is the thinnest layer of the Earth. If you measure the thickness of the Earth’s mantle on a continent, it would be between 35 and 75 kilometers thick. If measured from the deepest basins of the ocean, the mantle is only 5 to 10 kilometers thick. It is made up of brittle minerals like calcium and sodium. Because it is very cold compared to the mantle and core, the crust is easily cracked and broken. However, the crust is also where we find valuable resources like oil, water, and gas.

         With special instruments, scientists have been able to create detailed maps of the Earth’s layers. By measuring temperature, sound waves, and other factors, Earth scientists are able to find fossil fuels, element deposits, and even underground lakes! New technologies even allow scientists to study the changes deep  in Earth’s core. We may never be able to journey to the center of the Earth, but each day scientists make discoveries that help us understand more about the planet upon which we live.

Rocks and Rock Formation

         We walk over rocks every day, build cities and roads from rocks, and even wear rocks! But what about the millions of rocks we don’t notice? If you don’t look too closely, all rocks look the same, so it’s easy to overlook most of them. But the Earth is covered with rocks of every shape and size, and each one is unique! Scientists who study the Earth and its rocks are called geologists. Today, you will become a geologist yourself as we explore the three different types of rocks and how they are formed.

         Because rocks have been here as long as we have, we may assume that they have existed just as they are since the beginning of time. In fact, it takes millions of years and many changes for rocks to form. There are three basic types of rocks: sedimentary, igneous, and metamorphic. Each type forms in a very different way.

Sedimentary Rocks Look closely at the word, “sedimentary.” You will see the word, “sediment.” Sediment is made of small particles of matter that are left over from something larger. When a large rock is crushed or ground up, the tiny specks are called “sediment.” Sand is a kind of sediment, because it is made up of very small particles of rock and shell.

         Sedimentary rock gets its name because it is made up of sediment. It is formed on the outer layer of the Earth. This layer is called the crust, and it is where all forms of life exist. Sedimentary rock is formed when sediment compresses, which most often takes place near the mouths of streams and rivers, and on beaches.

         Imagine a stream running through a mountain. As the water flows, it picks up sediment, carries it downstream, and deposits it at the end of the stream. Many kinds of sediment get picked up, including particles from large rocks, animal bones, and shells. This process goes on for millions of years, and the sediment is piled up in layer upon layer. Soon, all of that weight begins to put pressure on the lowest layers of sediment. They compact and become sedimentary rock. Sandstone and limestone are two examples of sedimentary rock.

Igneous Rock

         Igneous rock is unique because it comes from deep inside the Earth. It is the only kind of rock that begins as a liquid. This liquid is actually rock matter that is so hot, it is molten. It is called magma, and it can only be found close to the Earth’s center and flowing from volcanoes. When magma cools, it hardens and becomes rock.

         Sometimes this cooling process occurs on the Earth’s surface. For example, when lava flows from a volcano, it cools and becomes igneous rock. Igneous rocks that are formed on the surface are called “extrusive.” They cool very quickly, so they are made up of very fine crystals. Volcanic glass is an example of an extrusive igneous rock. When igneous rocks form beneath the Earth’s surface, they cool much more slowly. They are coarser, because they are made up of larger crystals. These igneous rocks are called “intrusive.” Granite is an example of this kind of igneous rock.

Metamorphic Rock

        

         The third type of rock actually begins as igneous or sedimentary rock! With plenty of time, heat, or pressure, igneous and sedimentary rock can be transformed into metamorphic rock. The word, “metamorphosis” means transformation or change. This kind of rock is usually found beneath the surface of the Earth. Transforming a rock requires an amount of heat or pressure that can only be found deep in the Earth.

         Metamorphic rock can also change again, into a new kind of metamorphic rock. Sometimes these rocks are under so much pressure that their molecules can be rearranged to create new minerals! These rocks often have stripes or bands of color that help scientists understand what kind of changes took place when they were being formed. Examples of metamorphic rock include: slate, jade, and marble.

Summing Up

         Some rocks, like sedimentary and extrusive igneous rocks, are right on the surface of the Earth. We can pick them up and study them anytime. But how do we learn about rock that is formed deep in the Earth? Miners and scientists often dig to find large deposits of these rocks, but you can find them in almost any park or forest. It takes millions of years, but pressure and shifts in the Earth’s deep layers bring metamorphic and intrusive igneous rocks to the surface. Take a very close look at the next rock you pick up, and remember that it was being formed millions of years before you arrived on Earth!

Google anuncia investimentos de US$ 500 milhões em parque de energia eólica

Shepherds Flat pretende ser o maior parque desse tipo de energia no mundo. Junto com o Google participam do investimento as companhias japonesas Itochu Corporation e Sumitomo Corporation Redação ÉPOCA, com Agência EFE.

 

Depois de anunciar investimentos para a construção da maior usina de energia solar, o Google anunciou que colocará US$ 500 milhões em um projeto para a construção do maior parque eólico do mundo, mais um de seus investimentos em energia sustentável. A informação foi confirmada nesta terça-feira (19) pelo grupo norte-americano General Electric (GE), que ficará responsável pelas turbinas do parque a ser construído no Estado do Oregon.

Junto com o Google participam do investimento as companhias japonesas Itochu Corporation e Sumitomo Corporation, que se tornarão, junto à gigante da internet, coproprietárias do complexo.

"Este projeto é particularmente atrativo porque usa um sistema de turbinas muito avançado, além de gerar energia limpa e renovável", disse o responsável de operações comerciais verdes do Google, Rick Needham.

O parque eólico incluirá 338 aerogeradores da GE, que ficará responsável pela manutenção destes pelos primeiros dez anos de operações. No total, as instalações foram avaliadas em US$ 2 bilhões e devem gerar cerca de 845 megawatts quando estiverem em funcionamento em 2012.

Chamado de Shepherds Flat, o parque, a ser instalado nos condados de Gilliam e Morrow, servirá quase que exclusivamente ao Estado da Califórnia, vizinho do Oregon. O abastecimento energético californiano trará à costa oeste dos EUA, enfim, uma grande usina de energia renovável.

O Google já investiu mais de US$ 350 milhões no setor das energias renováveis, incluindo o projeto da maior usina de energia solar do mundo, que está sendo construída na própria Califórnia. Já a japonesa Itochu tem investimentos em mais de 15 usinas nos EUA, e a Sumitomo possui duas usinas eólicas no Japão, uma na China e já é coproprietária de outra nos Estados Unidos junto à GE.

LH