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La geosfera
THE GEOSPHERE
Biology and Geology 1º ESO
La geosfera
The origin of the Earth
Accrecion ofplanetesimals
Densitydifferentiation
Biology and Geology 1.º ESO 2
Layers of the geosphereCRUST
Continental crust
• More than 1 billion years old.
• Between 10 y 70 km thick.
• Granite, clay and slate.
Oceanic crust
• 200 millions years old.
• Between 6 y 10 km thick.
• Basaltic rock.
MANTLE: Peridot
Upper mantle
• Up to 670 kmLower mantle
• Up to 2900 km.
CORE: Iron and nickel.
Outer core
• Up to 5120 km.Inner core
• Up to 6370 km.
Mohorovicicdiscontinuity
Repettidiscontinuity
Gutenbergdiscontinuity
Lehmanndiscontinuity
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Biology and Geology 1.º ESO
La geosferaMINERALS
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Rocks and minerals form part of the Earth´s crust. Minerals have somecharacteristics:
•Solid substances.
•Inorganic.
•Natural.
•Definite chemical composition.
•Crystalline structure.
Biology and Geology 1.º ESO
La geosferaPhysical properties of minerals.
Optical propertiesRelate to how a mineral reacts to light.
Habit
• Some minerals have very characteristics shapes that reflect their crystalline structures.
Colour
• Characteristic colour.
Streak
• The colour of the powder produced when a mineral is scratched.
Lustre
• Describes how the mineral reflects light.
Glassy.
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Metalic Pearly.Diamond-like. Dull.
Biology and Geology 1.º ESO
La geosfera
Hardness•Describes a mineral´sresistance to scratching.
Cleavage•Related to the way a mineral breaks (flat surfacesmaintaining crystallinestructure).
Tenacity•Describes how easily a mineral breaks.
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Physical properties of minerals:Mechanical properties
How a mineral behaves when a force is applied to its surface
Hardness Mineral Characteristics
1 Talco (Talc) Soft minerals, because theycan be scratched by anothermineral.2
Gypsum(Yeso)
3 CalciteSoft minerals that canbe scratched by the point ofa knife.
4 Fluorite
5 Apatite
6Orthoclase(Ortosa)
Hard minerals7
Quartz(cuarzo)
8Topaz(Topacio) Very hard, cannot be
scratched by any othermineral.
9Corundum(Corindón)
10 Diamond
Biology and Geology 1.º ESO
La geosfera
Physical properties of minerals:Magnetic properties
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• Some minerals, such as magnetite, behave like a magnet. Theyattract objects that contain iron or nickel.
Other properties of materials
Transparency
• Describes how a mineral reacts to light (transparent- translucent-opaque).
Density
• Relation between mass and volumeof a mineral.
ρ= m / V
Biology and Geology 1.º ESO
La geosfera
Metal ores Raw materials forindustry
• Uraninite: uraniumused as fuel in nuclear powerstations
• Quartz: manufacturing glass, computercomponents, solar panels.
• Gypsum:manufacturingplaster, alabaster, fertilisers o explosives.
The importance of minerals
Gems y preciousstones
Emerald.
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Shapphire.
Ruby.
Diamond.
Ore Metal
Bauxite Aluminium
Blende Zinc
Chalcopyrite Copper
Cassiterite Tin
Cinnabar Mercury
Galena Lead
Hematite Iron
Biology and Geology 1.º ESO
These are mineralsthat metals are extract from.
La geosferaRocks
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Rocks, like minerals, have properties that allow us to identify them, forexample:
•Composition of the rock refers to the minerals that make up the rock: homogeneous y heterogeneous.
•Texture refers to the size and arrangement of the minerals in the rock.
Types of rocks:
•Igneous: these originate when magma from the Earth´s interior cools and solidifies.
•Sedimentary: sedimentary rocks form when sediments consolidate.
•Metamorphic: Formed by the transformation of other rocks subjected to highpressure conditions and/or temperatures, without reaching a melting state.
Biology and Geology 1.º ESO
La geosferaIgneous rocks
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Volcanic igneous rocks Plutonic igneous rocks
Extrusiverocks. Intrusive rocks.
Magma rises and leaves theEarth´s crust as lava.
Magma cools slowly inside theEarth´s crust.
Lava cools quickly. They had more time to form.
No mineral crystals. Mineral crystals are easily visible.
Examples: obsidian, pumice and basalt.
Examples: granite, syenite and gabbro.
Biology and Geology 1.º ESO
La geosferaSedimentary rocks
Diagenesis or lithification
The sediments transform into
sedimentary rocks
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Detritalsedimentary rocks
Non-detritalsedimentary rocks
They are made up of other rocks.
They are made up ofsediments fromskeletons of marine life, mineral salts or alsofrom remains of livings things that have notdescomposed.
Examples: conglomerates,
sandstone and clay.
Examples: limestone, gypsum, coal y
petroleum.
Classification: we can distinguish varioustypes:
Biology and Geology 1.º ESO
water
Sediments
Sedimentary rocks
La geosfera
Metamorphic rocks
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• Classification:
Foliated metamorphic rocks Non-foliated metamorphic rocks
The minerals are arranged to formparallel layers.
The minerals are not arrangedin layers.
Examples: slate, schist, gneiss, migmatite.
Examples: marble, quartzite
Biology and Geology 1.º ESO
High temperatures and pressure cause changes in the minerals that compose a rock and a new rock forms , without reaching a melting state.
La geosfera
The rock cycleThe rock cycle is a series processes that a rock goes through to transforminto another type of rock.
13Biology and Geology 1.º ESO
Partiallymelted rock
Metamorphic rock
Magma
Sedimentary rock
Weathering
fusion
Sediments
Plutonicigneousrock
fusion
Volcanicigneousrock
Metamorphism
Lhitification
La geosfera
The use of rocks
Biología y Geología 1.º ESO 14
Building materials•Cement, concrete, ceramics and glass.
Ornamental rocks:•Marble, granite, slate are often used in decoration.
Source of fossil fuel•Coal and fuel are used because they produce a lot of energy when burnt.
Source of minerals for technological use:•Quartz are a source of silicon to make computer processors, photovoltaic solar panels. Aluminium is used to make planes, soft drink cans or kitchen utensils.
La geosfera
The extraction of rocks and minerals
Biología y Geología 1.º ESO 15
Deposit is the place where minerals are found in sufficient quantity to makeextraction economically beneficial.
To locate a deposit, drill holes are made.
Superficial extractions:
•Opencast mines•Quarries•Gravel pits
Subterranean extractions:
•Underground mines (tunnels and galleries)
