Video Transcript
Which of the following correctly
describes the asthenosphere? (A) The asthenosphere includes all
of the mantle. (B) The asthenosphere includes all
of the crust and also includes the uppermost part of the underlying mantle. (C) The asthenosphere is the upper
layer of Earth’s mantle below the lithosphere and is partially molten. (D) The asthenosphere includes the
crust only. (E) The asthenosphere is cooler
than the lithosphere.
This question asks about the
asthenosphere. To help us answer the question,
let’s take a closer look at the outermost internal layers of Earth. The first layer of the Earth is the
crust. The crust is the thinnest internal
layer of Earth and is made of solid rocks. Below the crust is the mantle. The mantle is the thickest internal
layer of Earth and makes up approximately 80 percent of the planet’s volume. The uppermost part of the mantle is
solid rock. The crust and the uppermost part of
the mantle form the lithosphere, the solid outer part of Earth. The asthenosphere lies below the
lithosphere. The asthenosphere is subject to
higher temperatures than the lithosphere and is partially molten.
From this information, we can now
identify the statement that correctly describes the asthenosphere. The correct statement is “The
asthenosphere is the upper layer of Earth’s mantle below the lithosphere and is
partially molten.”
