Asthenosphere

Introduction
The asthenosphere is the layer of the Earth that lies below the lithosphere. It is a layer of solid rock that has so much pressure and heat the rocks can flow like a liquid. The rocks are less dense than the rocks in the lithosphere. This allows the tectonic plates in the lithosphere to move around on the Earth's surface by "floating" on the rocks that are slowly flowing like a liquid.

Asthenosphere, USGS

Tectonic plate interaction with the
upper layers of the Earth
, USGS

Earthquakes
Scientists use the speed and direction of earthquakes to study parts of the Earth beneath the lithosphere. Earthquake waves traveling through the Earth change speed and direction when there is a change in density of rocks within the earth. Not only do the rocks in this layer flow like a liquid they also break apart.  Deep earthquake are caused by rocks breaking in this layer.

Rocks in upper mantle
The rocks in the upper mantle can be part of the lithosphere or the asthenosphere. Lithosphere rocks are solid and rigid. Rocks below the lithosphere flow and break apart. They also rise through the lithosphere in areas where tectonic plates are separating.

How magma chambers form
The decrease in pressure allows rocks in this part of the Earth to melt and collect in magma chambers where they erupt as pillow basalt on the ocean floors.

Boundaries of the lithosphere
The boundary with the lithosphere lies between 100 and 200 kilometers deep. Scientists do not know for certain the depth of the lower boundary but it is approximately 700 kilometers deep. Earthquake waves in this part of the Earth travel much slower than they do in the lithosphere because of the density of the rocks.

More Planet Earth Links

Polar Front Find out what happens when a cold air mass from the poles meets a warm tropical air mass!

Horse Latitudes Find out where the Horse Latitudes are located and how they got their unusual name.

Earths Crust Do you know where the youngest crust on our planet is located and how it forms?

Earths Interior Our planet is made up of many layers and scientists working as detectives are uncovering its secrets.


The Earths Mantle Is the mantle molten rock or solid rock? Find out what we know about this large layer of the Earth.

Asthenosphere Find out why scientists say the rocks in the asthenosphere has properties like silly putty.

Planet Earth Find out about our planet from the Earth's core to the outer reaches of our atmosphere.

Kids Fun Science The links on our home page include information about volcanoes, science activities, plate tectonics, the rock cycle and much more.

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