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 MineralsTo 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 minerals2. There is enough moisture3. The pH is at an acceptable

level.

**ESTThe 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 fuelsB. 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 pesticidesb. Heavy-metal or hydrocarbon leaks onto soilc. 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.