An abyssal plain is a deep undersea area created by sediments overlaying a rocky crust, and they are the flattest places on Earth. Abyssal plains cover one-third of the Earth's surface, as much as all land above water, a... More »

Octopus, fish, echinoids, worms, squid and mollusks live in the abyssal zone, which begins at about 13,000 feet below sea level. Most of the organisms there have small bones, soft bodies, big mouths and long teeth. Few a... More »

Ecosystems, or communities in which living organisms and nonliving elements interact, fall into two categories: aquatic and terrestrial. Aquatic ecosystems are found in bodies of water, either marine or freshwater. Terre... More » Science Biology

Sodium is extremely abundant, composing about 3 percent of the Earth's crust, but it is never found in its pure form as sodium metal. This is because of its extreme reactivity, with exposure to air, water and many other ... More »

According to the National Oceanographic and Atmospheric Administration, seafloor spreading is caused by the flow of plastic mantle rock beneath the Earth's oceanic crust. These flows force the seafloor apart, allowing pr... More »

The primary heat source for the Earth is the radioactive decay of uranium, thorium and potassium, found in the mantle and crust. The Earth produces more heat through phase changes, such as the freezing of liquid iron in ... More »

Silicates are the most abundant group of minerals found in Earth's crust, according to Georgia State University. The most abundant elements in the Earth's crust are oxygen at 46.6 percent and silicon at 27.7 percent. The... More »