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Features
The Earth's surface, or its crust, includes both the continental crust that is mostly made from granite, and the oceanic crust that is mostly made from basalt. It is the outer layer of the Earth and it has an average thickness of about 19 miles. As you might expect, the mountainous areas are the highest points and the ocean basins are the lowest points.
Function
The continental crust is formed from tectonic plates, which float on top of the upper mantle--the next layer of the Earth beneath the surface. The crust and the upper mantle together make up a region called the lithosphere. Sometimes these tectonic plates collide. When this happens, mountains may push up higher. Sometimes the plates slide behind each other. This can cause the formation of new valleys and rifts.
Types
The Earth's surface is composed of many elements. Oxygen makes up nearly half of the content. Silicon accounts for nearly a third of it. Aluminum, iron, calcium, sodium, potassium and magnesium together make up nearly a fifth of the chemical composition of the Earth's surface.
Effects
The temperature in the deepest part of the Earth's mantle is 7950 degrees Fahrenheit. This is much hotter than anywhere on the Earth's surface, which is somewhat brittle as well as cool. The surface of the Earth cracks open during earthquakes, which can be caused by shifts in the positions of the tectonic plates. These shifts can also cause volcanoes, forcing the molten rocks from the hotter mantle to flow up to the surface through rifts and openings. There is an area around the Pacific Basin known as the Ring of Fire because of the large number of volcanoes.
Size
The Earth's surface stretches over an area of 196,800,000 square miles, of which one-third is land and two-thirds is water. The earth weighs six sextillion metric tons. This number is a six followed by 21 zeros. The entire earth has a circumference at the equator of 24901.55 miles and a diameter at the equator of 7926.41 miles.