The Earth’s crust is made up of the continent s and the ocean basins. Oceanic crust, which consists of basaltic rock, is thinner and denser than continen tal crust, which contains granitic rock;
Nov 02, 2014
The Earth’s crust is made
up of the continents
and the ocean basins.
Oceanic crust, which consists of
basaltic rock, is
thinner and denser than continental crust, which
contains granitic
rock; because of
this, the continents rise above
the oceans.
Did You Know
• On average, continents are about 0.5 miles (0.8 kilometers) above sea level, while the ocean floor is about 2.4 miles (3.8 kilometers) below sea level. While continental crust is about 22 miles (35 kilometers) thick, oceanic crust is only about 4 miles (7 kilometers) thick.
A continental margin is a
part of ocean basin that is adjacent to continent. It includes the continental
shelf, a sloping
section of material lies
on top of continental
crust
If seawater recedes and continental
crust is exposed,
some of the continental shelf may become part of
a coastal plain.
Continental
Margin
Deep Ocean Basins
Eventually, the continental shelf or continental rise leads to a deep ocean basin. Comprising 30 percent of
the Earth’s surface, the deep ocean basins contain flat abyssal plains, deep ocean trenches and submerged volcanoes known as seamounts.
Abyssal Plains
Abyssal plains are about 2.5 miles (4 kilometers) below sea level. They are made of volcanic rock that is covered with very thick layers of sediment. Over time,
this sediment has spread out and flattened, making abyssal plains the flattest places on earth.
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