The Earth and it’s Layers
The Earth’s Structure
A. Earth consists of a series of concentric layers or spheres which differ in chemical and physical properties.
B. The compositional layers of the Earth are the Crust, the Mantle, and the Core. The Core is subdivided into a
molten outer core and solid iron inner core.
C. Physical state is determined by the combined effects of pressure and temperature.
1. Increasing pressure raises the melting point of a material.
2. Increasing temperature provides additional energy to the atoms and molecules of matter allowing them
to move farther apart, causing the material to melt.
3. Both pressure and temperature increase toward the center of the Earth, but at different rates. Density
also increases as you reach the center.
4. Divisions of the Earth based upon physical state (mechanical layers) are the Lithosphere, the
Asthenosphere, the Mesosphere, the Outer core, and the Inner core.
Isostacy
Isostacy refers to the balance of an object when “floating” on a fluid. This is best seen with ice in water, or iceburgs
in the ocean.
This also happens to rocks in the Earth.
BUT ROCKS AREN’T FLUIDS!
If you put enough pressure on something, it will gradually act like a fluid.
There is A LOT of pressure in the Earth. As you move towards the center of the earth, each layer gets denser than
the last.
Layers on Earth’s Surface
Three fluid (meaning they move) spheres surround the rocky portion of the Earth.
1. Hydrosphere includes all of the "free" water of the Earth contained in the ocean, lakes, rivers, snow, ice,
water vapor, and groundwater.
2. Atmosphere is the gaseous envelope that surrounds the Earth and is mainly a mixture of nitrogen and
oxygen.
3. Biosphere refers to all living and non-living organic matter.
4. Lithosphere includes all rock and land.
(See Figures!!!)
The Ocean Floor
Bathymetry of the Earth
Bathymetry- the underwater landscape.
Any feature that you see above water you can find under the sea, however some features we find
underwater aren’t found on land.
The seafloor is divided up into 3 major provinces
Continental Margins
Abyssal plains
Mid-Ocean Ridges
Continental margins – submerged edges of the continents
Made up of deposited material from land erosion and is again divided into 3 zones: Continental shelf,
Continental slope , Continental rise
The Continental shelf
If you have ever waded out into the water at the beach you have stood on the cont. shelf
Extends out to an average depth of 130m and terminates at the shelf break
Shelf break – where the seafloor begins to get steeper 1-4 degrees
The Continental slope
1-4 degrees downward slope, Extends out until water is about 2-3 km deep (kilo- 1000)
Parts of this steep slope are cut by deep canyons (submarine canyons)
Continental rise
Vast sedimentary plane, About 1 degree slope, About 4 km deep, Joins with the Abyssal plains
Deep Ocean Providence
Located between the Continental Margins and the Mid-Ocean Ridges
Mostly flat Abyssal plains, flat plains to .5 degree slopes, 3-5 km deep, Some of the flattest places on Earth
Mid-Ocean Ridge
Normally found in the middle of the ocean where sea-floor spreading occurs
Has a rift valley (indention on the top of the mountain chain) where volcanic activity occurs
Not all oceans have a mid-ocean ridge
Other Features
Trench – very deep valley found in some oceans, where seafloor is pulled under into the mantle
Guyot – Flat topped mountain underwater
Seamount – underwater mountain
Island – Where land rises up out of the water away from the continental plate
Scientific Notation,
The solution for big and small numbers
Represents REALLY big and small numbers through powers of ten.
Powers like 102, 103, 107
5 billion = 5,000,000,000
0.000005 looks like 5 x 10-6
Examples:
450000 = 4.5 x 105
230 = 2.3 x 102
4586000 = 4.586 x 106
Examples:
0.000045 = 4.5 x 10-5
0.023 = 2.3 x 10-2
0.000004586 = 4.586 x 10-6
This has 9 places after the 5
In scientific notation, this is 5 x 109
Small numbers get negative signs!