Title: Structure of Earth
Content:  The structure of Earth can be defined in two ways: by mechanical properties such as rheology, or chemically. Mechanically, it can be divided into lithosphere, asthenosphere, mesospheric mantle, outer core, and the inner core. Chemically, Earth can be divided into the crust, upper mantle, lower mantle, outer core, and inner core. The geologic component layers of Earth are at the following depths below the surface: The layering of Earth has been inferred indirectly using the time of travel of refracted and reflected seismic waves created by earthquakes. The core does not allow shear waves to pass through it, while the speed of travel (seismic velocity) is different in other layers. The changes in seismic velocity between different layers causes refraction owing to Snell's law, like light bending as it passes through a prism. Likewise, reflections are caused by a large increase in seismic velocity and are similar to light reflecting from a mirror.
Title: Structure of Earth
Content:   The internal structure of Earth, structure of the solid Earth, or simply structure of Earth refers to concentric spherical layers subdividing the Solid earth, i.e., excluding Earth's atmosphere and hydrosphere. It consists of an outer silicate solid crust, a highly viscous asthenosphere and solid mantle, a liquid outer core whose flow generates the Earth's magnetic field, and a solid inner core. Scientific understanding of the internal structure of Earth is based on observations of topography and bathymetry, observations of rock in outcrop, samples brought to the surface from greater depths by volcanoes or volcanic activity, analysis of the seismic waves that pass through Earth, measurements of the gravitational and magnetic fields of Earth, and experiments with crystalline solids at pressures and temperatures characteristic of Earth's deep interior.
Title: Earth
Content:  Earth's interior, like that of the other terrestrial planets, is divided into layers by their chemical or physical (rheological) properties. The outer layer is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by the Mohorovičić discontinuity. The thickness of the crust varies from about 6 km under the oceans to 30 - 50 km for the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as the lithosphere, which is divided into independently moving tectonic plates. Beneath the lithosphere is the asthenosphere, a relatively low-viscosity layer on 
Title: Geology
Content:   Advances in seismology, computer modeling, and mineralogy and crystallography at high temperatures and pressures give insights into the internal composition and structure of the Earth. Seismologists can use the arrival times of seismic waves in reverse to image the interior of the Earth. Early advances in this field showed the existence of a liquid outer core (where shear waves were not able to propagate) and a dense solid inner core. These advances led to the development of a layered model of the Earth, with a crust and lithosphere on top, the mantle below (separated within itself by seismic discontinuities at 410 and 660 kilometers), and the outer core and inner core below that. More recently, seismologists have been able 
Title: Earth science
Content:  Earth science generally recognizes four spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere; these correspond to rocks, water, air and life. Also included by some are the cryosphere (corresponding to ice) as a distinct portion of the hydrosphere and the pedosphere (corresponding to soil) as an active and intermixed sphere.
Title: Outline of Earth sciences
Content:  solid inner core and its mantle. ; Lehmann Discontinuity &ndash; The line between the inner core and the outer core. ; Inner core &ndash; The innermost part of the Earth, a solid ball of iron-nickel alloy.  Ecosphere &ndash; there are many subsystems that make up the natural environment (the planetary ecosystem or "ecosphere") of the Earth. Many of the subsystems are characterized as "spheres", coinciding with the shape of the planet. The four spheres (for which most of the other spheres are a subtype of) are the atmosphere, the biosphere, the hydrosphere and the geosphere. Listed roughly from outermost to innermost the named spheres of the Earth are: 
Title: Outline of Earth
Content: Structure of the Earth ; Earth's surface ; Lithosphere of Earth (solid Earth) ; Earth's crust ; Land ; Landforms  (list) ; Continents ; Africa ; Antarctica ; Asia ; Australia ; Europe ; North America ; South America ; Pedosphere ; Ocean floor ; Earth's mantle ; Earth's core ; Outer core ; Inner core 
Title: Earth
Content:  Earth's mechanically rigid outer layer, the lithosphere, is divided into tectonic plates. These plates are rigid segments that move relative to each other at one of three boundaries types: at convergent boundaries, two plates come together; at divergent boundaries, two plates are pulled apart; and at transform boundaries, two plates slide past one another laterally. Along these plate boundaries, earthquakes, volcanic activity, mountain-building, and oceanic trench formation can occur. The tectonic plates ride on top of the asthenosphere, the solid but less-viscous part of the upper mantle that can flow and move along with the plates. As the tectonic plates migrate, oceanic crust is subducted 
Title: Natural environment
Content:    Earth science generally recognizes four spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere as correspondent to rocks, water, air, and life respectively. Some scientists include as part of the spheres of the Earth, the cryosphere (corresponding to ice) as a distinct portion of the hydrosphere, as well as the pedosphere (corresponding to soil) as an active and intermixed sphere. Earth science (also known as geoscience, the geographical sciences or the Earth Sciences), is an all-embracing term for the sciences related to the planet Earth. There are four major disciplines in earth sciences, namely geography, geology, geophysics and geodesy. These major disciplines use physics, chemistry, biology, chronology and mathematics to build a qualitative and quantitative understanding of the principal areas or spheres of Earth.
Title: Outline of Earth sciences
Content:  rigid, outermost shell of a terrestrial-type planet or natural satellite that is defined by its rigid mechanical properties. ; Asthenosphere &ndash; The highly viscous, mechanically weak and ductile region of the Earth's upper mantle ; Mesozone &ndash; The part of the Earth's mantle below the lithosphere and the asthenosphere, but above the outer core. ; Gutenberg discontinuity&ndash; The line between the mantle and the Earth's core. ; Earth's core &ndash; The inner part of the planet, formed by differential buoyancy of the component materials causing the denser materials to accumulate nearer to the centre. ; Outer core &ndash; A fluid layer composed of mostly iron and nickel between 

Question: name the four major layers of the earth in order?
Answer: a liquid outer core.
an outer silicate solid crust.
a highly viscous mantle.
a solid inner core.