The lithosphere rides on the asthenosphere. Improve this page Learn More. Skip to main content. Search for:. Reading: The Lithosphere and Asthenosphere Can you think of a solid that can flow? Therefore it is only logical for us to understand our environment in order to promote sustainable living. Difference Between Similar Terms and Objects. MLA 8 Reddy, Prishani. Name required. Email required. Please note: comment moderation is enabled and may delay your comment.
There is no need to resubmit your comment. Notify me of followup comments via e-mail. Written by : Prishani Reddy. Retrieved March 30, from Encyclopedia. The lithosphere-asthenosphere boundary. Annual Review of Earth and Planetary Sciences, 38, An updated digital model of plate boundaries. Geochemistry, Geophysics, Geosystems, 4 3. A global view of the lithosphere-asthenosphere boundary.
Science, , User assumes all risk of use, damage, or injury. You agree that we have no liability for any damages. Structure The lithosphere consists of the crust and uppermost mantle consisting largely of peridotite , which makes up the rigid outer layer that is divided by tectonic plates large slabs of rocky material. Chemical composition The lithosphere is divided into two types, namely: Oceanic lithosphere — a denser oceanic crust, with an average density of 2. Comparison of the Lithosphere and Asthenosphere Lithosphere Asthenosphere The lithosphere concept was proposed in The asthenosphere concept was proposed in Lithosphere is composed of the crust and upper most solid mantle Asthenosphere is composed of the upper most weaker part of the mantle Lies beneath the atmosphere and above the asthenosphere Lies beneath the lithosphere and above the mesosphere The physical structure consists of a rigid outer layer that is divided by tectonic plates.
It is regarded as rigid, brittle, and elastic. While there is some overlap in the chemical and physical designations of layers, specifically the core-mantle boundary, there are significant differences between the two systems.
Lithos is Greek for stone, and the lithosphere is the outermost physical layer of the Earth. It is grouped into two types: oceanic and continental. Oceanic lithosphere is thin and relatively rigid.
It ranges in thickness from nearly zero in new plates found around mid-ocean ridges, to an average of km in most other locations. Continental lithosphere is generally thicker and considerably more plastic, especially at the deeper levels. Its thickness ranges from 40 to km [ 35 ]. The lithosphere is not continuous.
It is broken into segments called plates. A plate boundary is where two plates meet and move relative to each other. Plate boundaries are where we see plate tectonics in action—mountain building, triggering earthquakes, and generating volcanic activity. The asthenosphere is the layer below the lithosphere. Astheno- means lacking strength, and the most distinctive property of the asthenosphere is movement.
Unlike the lithosphere that consists of multiple plates, the asthenosphere is relatively unbroken. Scientists have determined this by analyzing seismic waves that pass through the layer.
The depth at which the asthenosphere is found is temperature-dependent [ 36 ]. The mesosphere, sometimes known as the lower mantle, is more rigid and immobile than the asthenosphere.
These extreme conditions create a transition zone in the upper mesosphere where minerals continuously change into various forms or pseudomorphs [ 37 ]. Scientists identify this zone by changes in seismic velocity and sometimes physical barriers to movement [ 38 ]. Below this transitional zone, the mesosphere is relatively uniform until it reaches the core. The outer core is the only entirely liquid layer within the Earth.
It starts at a depth of 2, km and extends to 5, km, making it about 2, km thick. In , the Danish geophysicist Inge Lehmann analyzed seismic data and was the first to prove a solid inner core existed within a liquid outer core [ 39 ]. The solid inner core is about 1, km thick, and the outer core is about 2, km thick [ 40 ]. It seems like a contradiction that the hottest part of the Earth is solid, as the minerals making up the core should be liquified or vaporized at this temperature.
Immense pressure keeps the minerals of the inner core in a solid phase [ 41 ]. Other ideas are that small pools of melt are present, or that the differences in seismic properties are due to subducted slabs of lithosphere resting on the core-mantle boundary. The core is primarily composed of iron, with lesser amounts of nickel. Lighter elements such as sulfur, oxygen, or silicon may also be present. But despite the fact that the boundary between the inner and outer core is approximately as hot as the surface of the sun, only the outer core is liquid.
The inner core is solid because the pressure at that depth is so high that it keeps the core from melting. Skip to content Earth consists of three main layers: the crust , the mantle , and the core Figure 3. Figure 3. Right- crust, mantle, and outer and inner core to scale. Left- Cutaway showing continental and ocean crust, and upper mantle layers.
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