The layers of Earth
How do scientists know what is in the center of the earth? How can we know what the core of the earth is made of, if scientists have never studied any materials from a depth below 7.5 miles? Earth is approximately 4.6 billion years old, and over this time period, many things have changed inside and out. The formation of our planet is quite amazing. Earth consists of multiple layers. The three most distinct or main layers are the core, mantle and crust. The inner portion is the core, in the middle is the mantle, and the outside is the crust. Over the course of this paper, the composition and formation of these layers will be described more specifically. According to ‘Earth: An Introduction to Physical Geology’, “The inner core did not exist early in earth’s history, when our planet was hotter. However, as the Earth cooled, iron began to crystalize at the center to form the solid inner core and even today the inner core continues to grow as the planet cools.” The idea is that the core is composed of an iron-nickel alloy with traces of oxygen, silicon, and sulfur. The average density of this iron rich substance is fourteen times the density of water. The core is split into two separate regions, inner and outer core. The inner core is spherical and has a radius of 750 miles. The iron located within the inner core is solid, despite the high temperature; this is because of the mighty pressures in the middle of earth. The outer core is about 1400 miles thick and is a layer of liquid. Earth’s magnetic field is the cause of the movement of metallic iron within this area. The mantle contains eighty two percent of the volume of Earth. It is described as a rocky, solid shell that goes 1800 miles deep. The mantle consists of an upper and lower section. From the edge of the crust to about four hundred miles deep is considered the upper mantle. The upper mantle is divided into three separate parts. The lithosphere forms the rigid outer shell of...
Earth: An Introduction to Physical Geology. Tenth edition. Tarbuck Lutgens and Tasa
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