The Hyposmetric Curve

Key
Name __________________________
Percentage of the Earth's Surface within Elevation Range
From (m)
7000
6000
5000
4000
3000
2000
1000
0
-1000
-2000
To (m)
8000
7000
6000
5000
4000
3000
2000
1000
-0
-1000
Percent
0.3
0.5
0.8
1.2
1.5
5
15.5
12.5
7
4
From (m)
-3000
-4000
-5000
-6000
-7000
-8000
-9000
-10000
-11000
To (m)
-2000
-3000
-4000
-5000
-6000
-7000
-8000
-9000
-10000
Sum
Percentage
6
16.5
14.5
7.5
3
1.8
1.5
1
0.3
100.4
Hypsographic Curve
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
-1000
-2000
-3000
-4000
-5000
-6000
-7000
-8000
-9000
-10000
-11000
-12000
0
5
10
Percent of Earth's Surface
15
20
1. If the crust had uniform density and thickness what would the hypsographic
curve look like?
See graph A below...If all the crust had the same density,
then all elevation would be the same! Or at the very least,
there would only be one hump on the hypsometric curve.
2. If the crust had randomly varying density and thickness everywhere, what sort
of hypsographic curve would you expect to see?
see graph B below...If density was random,
then any elevation would be equally likely.
3. How is density calculated?
Density = Mass / Volume
4. What does the bimodality (i.e. two humps) of the hypsographic curve tell you
about the different types of crust on the earth?
The bimodality tells us that the Earth's crust is dominated by two elevations. This
occurs because the crust is composed of two distinct types of rock that have differing
densities: basalt (oceanic crust) and granite (continental crust). Because the oceanic
crust is more dense it effectively 'floats' lower than the less dense continental crust.
A
Hypsographic Curve
10000
9000
8000
7000
6000
5000
4000
3000
2000
to 100%
1000
0
-1000
-2000
-3000
-4000
-5000
-6000
-7000
-8000
-9000
-10000
-11000
-12000
B
0
5
10
Percent of Earth's Surface
15
20
0
5
10
Percent of Earth's Surface
15
20
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
-1000
-2000
-3000
-4000
-5000
-6000
-7000
-8000
-9000
-10000
-11000
-12000