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.
The Earth’s Structure
• 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.
The Earth’s Structure
– 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.
Isostacy
• 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.
Earth’s crust is dynamic (moving)
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.
Draw this figure in your notes
Make and label this model:
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 Ocean Floor
The seafloor is divided up into 3 major
provinces
• Continental Margins
• Abyssal plains
• Mid-Ocean Ridges
Continental Margins
• Continental margins – submerged edges of the
continents
– Made up of deposited material from land
erosion
– 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 MidOcean 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
Labeling Exercize
• Get into groups of 2 or 3.
• Each group needs a blue ocean floor map, a dry
erase marker, and paper towel to erase with.
Labeling Exercize
• Copy the map into your notes with labels.
• Quiz on this next class!
Mapping the Ocean Floor
• In groups of 3 or 4, get a shoe box, straw, and ruler.
• Inside the box, there is an unseen landscape you must
map.
• Make a table with one column for the hole number, and
3 others for depth.
• Gently push your straw through each hole, place your
thumb on the bottom where it stops, remove straw.
Measure from thumb to the end of straw. This is your
depth.
• Continue for all holes (3 times). Take the average of the
3 measurements and then make a graph. All group
members must copy table and make their own graph.
• You will make a line graph. Remember, bottom line =
be independent!
Mapping the Ocean Floor
Ocean Depth Sonar Data
Longitude Ocean Depth
(º W)
(m)
64
0
60
91
55
132
50
73
48
3512
45
4024
40
3805
35
4171
33
3439
30
3073
28
1756
27
2195
25
3146
20
4244
15
4610
10
4976
05
4317
04
146
01
0
Imagine you are an oceanographer traveling across the
Atlantic along the 45º N latitude line. You and your crew
are using sonar to gather data on the depth of the ocean
between Nova Scotia, Canada, and the town of Soulac on
the coast of France. In this activity, you will plot depth
data to create a profile of the ocean floor.
Lab Questions:
1. Sonar ships send down beams of sound, which bounces
off objects back to the ship. The time it takes for it to
bounce off tells how deep the ocean floor is. Can you
think of an animal that uses the same method to travel at
night?
2. Your graph contains parts of the ocean floor like the
continental shelf, slope, rise, trenches, etc. Label any sea
floor features you can see. You should find at least 11.
3. Do you think sonar is a good way to study the ocean
floor? Why?
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
– This has 9 places after the 5
– In scientific notation, this is
5 x 109
- 0.000005 looks like 5 x 10-6
- Small numbers get negative signs!
Scientific Notation
• 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
Test Yourself
1. 3,400
2. 687,000
3. 0.032
4. 0.0000983
5. 870,000,000
6. 0.0000203
7. 9,060,000
8. 200
9. 0.5
10.28,400,000,000
How did you do?
1. 3,400 = 3.4 x 103
2. 687,000 = 6.87 x 105
3. 0.032 = 3.2 x 10-2
4. 0.0000983 = 9.83 x 10-5
5. 870,000,000 = 8.7 x 108
6. 0.0000203 = 2.03 x 10-5
7. 9,060,000 = 9.06 x 106
8. 200 = 2 x 102
9. 0.5 = 5 x 10-1
10.28,400,000,000 = 2.84 x 1010
Can you go backwards?
1.
2.
3.
4.
5.
6.
7.
4.3 x 103
2.8 x 10-6
3 x 105
7.43 x 10-4
9.2 x 108
5.23 x 10-2
8.9 x 102
How did you do?
1.
2.
3.
4.
5.
6.
7.
4.3 x 103 = 4,300
2.8 x 10-6 = 0.0000028
3 x 105 = 300,000
7.43 x 10-4 = 0.000743
9.2 x 108 = 920,000,000
5.23 x 10-2 = 0.0523
8.9 x 102 = 890
One more practice…
1. 6.3 x 106
2. 4530000
3. 0.000098
-5
4. 2.45 x 10
-7
5. 7.8 x 10
One more practice…
1. 6.3 x 106 = 6300000
2. 4530000 = 4.53 x 106
3. 0.000098 = 9.8 x 10-5
-5
4. 2.45 x 10 = 0.0000245
-7
5. 7.8 x 10 = 0.00000078
Quiz on SciNot Next Class!