Density Layers Inside Earth We are surrounded by

Density Layers Inside Earth We are surrounded by materials arranged by density!

Due to gravity, the earth system is arranged in layers by density. Using average densities: Atmosphere =. 0012 g/cm 3 Ocean = 1. 03 g/cm 3 (Hydrosphere) Solid Earth = 5. 5 g/cm 3 (Geosphere) And there are layers within each of these systems as well…

The density of the atmosphere varies continuously from less dense at high altitudes to most dense at the surface: Density of the earth's atmosphere Elevation - meters 30000 Humans need an air density of at least this much, so cannot live permanently above about 5000 m (17, 000 ft) elevation. 25000 20000 15000 10000 5000 So we need to take care of this thin layer. 0 0 0. 2 0. 4 0. 6 0. 8 1 1. 2 1. 4 Kg per cubic meter = milligrams per cubic centimeter This logarithmic curve shows the density near the surface (1. 2) is over 70 times the density at 30, 000 meters elevation (. 017) – this is a large variation.

Most of the water on the Earth is in the oceans, also known as the hydrosphere. The density of sea water varies from about 1. 023 g/cm 3 at the surface of the ocean to about 1. 0275 g/cm 3 at the deepest places. This is very little variation compared to the variation in the atmosphere, because water is not as compressible as air. And most of the density variation in the sea with depth is caused by temperature differences (colder at the bottom, so more dense).

Finally, the Earth itself is in layers based on density: Crust = about 2. 9 g/cm 3 Mantle = 5 to 6 g/cm 3 Liquid core = 9 to 10 g/cm 3 Solid core = about 13 g/cm 3 Unlike the atmosphere and hydrosphere (which are nearly the same composition throughout), the density differences in the layers of the Earth are caused in part by composition differences – from rock on the outside to metals in the cores.

Where do other things fit in with these average densities? Hydrogen (least dense element) =. 00009 g/cm 3 Atmosphere =. 0012 g/cm 3 Average human body = 1. 01 g/cm 3 Ocean = 1. 03 g/cm 3 Average granite = 2. 7 g/cm 3 And this results in. . . Average basalt = 3. 0 g/cm 3 Solid Earth = 5. 5 g/cm 3 Common core elements: Iron = 7. 87 g/cm 3 , Nickel = 8. 91 g/cm 3 Osmium (most dense element, not common) = 22. 59 g/cm 3

Density (& Thickness) of Crust Determine Average Elevations for the Earth's Surface Granitic crust Thicker and less dense crust "floats" high. Basaltic crust Mantle - more dense than crust; solid but deformable. thinner and more dense crust, "floats" lower. This creates 2 major elevation areas on the Earth. Then when it rains, the water collects over the lower crust, creating the oceans. leaving the higher crust dry. This gives us the usual names for these crusts: granitic crust is continental, and basaltic crust is oceanic. Note the oceans don't cause oceanic crust - the basaltic crust just happens to create the low places on the Earth where the water collects to make oceans.

Resulting solid Earth layers These layers together make a "plate" in plate tectonics. Source: https: //commons. wikimedia. org/wiki/File: Earth-cutaway-schematic-english. svg