The lithosphere and the
hydrosphere
THE LITHOSPHERE
The lithosphere is the hard shell of the Earth,
consisting of the crust and the topmost part of
the upper mantle.
Minerals
Minerals are solid inorganic substances with
clearly defined composition and properties.
Minerals are classified by:
a. Colour. Minerals can be idiochromatic
(colour part of their chemical composition).
Minerals can also be allochromatic and get
their colour from an impurity in their
structure.
b. Transparency. Minerals can be translucent,
transparent or opaque, depending on the
amount of light that can pass through their
structure.
c. Hardness. Minerals are also classified
according to their hardness.
The Mohs scale ranges from one to ten; the
hardest minerals, like diamonds, have a Mohs
scale rating of 10.
d. Streak. When a mineral is rubbed on a hard
surface it will leave traces of itself in
powdered form.
The colour of the powder depends on the type
of mineral.
Allochromatic minerals leave white r pale
streaks.
Idiochromatic minerals leaves brightly coloured
powders.
Mining of Minerals
To mine minerals, geologists must first locate
them and then extract them from the
lithosphere.
Quebec is known for its deposits of gold, copper,
zinc, nickel and iron.
The extraction of minerals can be done from an
open pit mine or and underground mine.
Rocks
Rocks are heterogeneous solids composed of
many minerals.
Types of Rocks:
There are threee main families of rocks:
1. Igneous rocks are made from lava cooling and
solidifying quickly.
2. Sedimentary rocks are formed from the
accumulation and compaction of debris over
long periods of time.
3. Metamorphic rocks are sedimentary of
igneous rocks that have been transformed
over time by heat or pr
Soil
When the parent rock from the Earth’s crust
erodes or disintegrates, it combines with dead
organic material to form soil.
This process can take up to 200 years.
The layers of the soil are called soil horizons.
The topmost layer of the soil is
made up of organic matter
(humus).
The second layer is a mixture of
humus and water soluble
minerals.
Soil is fertile if:
1. There are enough minerals
2. There is enough moisture
3. The pH is at an acceptable
level.
**EST
The buffering capacity of soil is its ability to
resist the changes in its pH.
Different soil textures can suggest buffering
capacities. Finer grains are usually better
buffers.
Permafrost
In northern regions, the soil remains
permanently frozen.
If the soil has been frozen (0 oC or lower) for two
years, the soil is called permafrost.
In some regions, the upper layers of the
permafrost thaws out during the summer
months and refreezes when it gets colder, this
is called the active layer.
Energy Resources
Many different energy resources are held within
the lithosphere.
A. Fossil fuels
B. Radioactive substances (uranium)
C. Geothermal energy
Each of these has its advantages and
disadvantages.
The technology used to extract fossil fuels from
beneath the lithosphere has been developed
over many years.
While fossil fuels do supply the vast majority of
the world with energy, they also produce
many byproducts that are harmful to the
environment.
Radioactive materials like uranium can provide
large quantities of energy.
This benefit is outweighed however by the
harmful effects of the waste produced by
nuclear power plants.
Geothermal energy uses the heat produced by
the Earth’s core to heat up water found
beneath the lithosphere.
Although it is considered to be “clean” energy,
these systems are expensive to set up.
Contamination
The contamination of the lithosphere can occur
through:
a. Addition of fertilizers and pesticides
b. Heavy-metal or hydrocarbon leaks onto soil
c. The effects of pollution (acid rain) can also
affect soil quality.
Hydrosphere
The hydrosphere is the Earth’s outer layer of
water and includes water in all 3 phases.
1. Inland Water consists of all the freshwater
systems.
A watershed is an area of land into which all of
the rivers, streams flow into a larger body of
water.
A watershed can be affected by:
- topography of the land (shape, slope)
- Geology (type of rock)
- Climate (drought vs. rainy season)
- Vegetation (density)
- Agricultural, industrial, urban development
2. Oceans.
Ocean waters are moved by currents that carry
them all over the world.
The properties of ocean water will determine the
way they circulate.
a. Depth.
The temperature of ocean water varies with its
depth. Deeper waters have lower temperatures.
This also affects its density. Colder waters have
greater densities.
2. Seasons. Water temperature is colder in the
cooler months.
3. Latitude. Ocean water closer to the equator
is generally warmer.
Another factor that affects ocean currents is
salinity.
The salinity of an ocean is a measure of its salt
concentration.
Salt water is more dense than fresh water.
Salinity is affected by:
a. Climate. Water evaporates at a greater rate in
warmer regions. This results in a greater salt
concentration.
b. Proximity to a fresh water source. Ocean water
can be diluted by rivers and melting ice.
Ocean Circulation
Ocean currents allow the water to circulate all
around the world.
Types of currents:
1. Surface currents are wind-driven and move
horizontally.
2. Subsurface currents occur at a depth of 800m.
These currents are caused by variations in water
density. Less dense water (warm, low salinity)
rises above more dense water (cold, high
salinity).
The ocean currents work together to circulate
warmer waters around the world; this process
is called thermohaline circulation.
Any change to the thermohaline circulation
could affect the Earth’s climate.
3. The Cryosphere
All the frozen water on the Earth makes up the
cryosphere.
Included in the cryosphere are:
a. Pack ice. Ice that floats on the ocean near
the North and South poles.
b. Glaciers. Mass of ice found on land.
Energy Resources
Hydraulic energy can be obtained by harnessing
the energy from moving water.
Waterfalls and rivers can generate energy using
a hydroelectric dam.
Turbines can also harness energy from tidal
waves and subsurface ocean currents.
Pollution and Degradation (EST)
Different causes of pollution:
1. Thermal pollution:
Discharging warm water into a body of water
affects oxygen levels.
Warm water contains less oxygen.
2. Eutrophication:
Water can also lose oxygen through the process
of eutrophication.
Excess pesticides and fertilizers can find their
way into lakes. These contaminants will
promote the growth of aquatic plants (algae).
When the plants die, organisms will break down
the dead organic matter.
This process requires much oxygen, and so the
oxygen in the lake water is depleted.