THE GEOSPHERE minerals and rocks
SCIENCE - 1r d’ESO September 2016
introduction • We live in a planet called
EARTH
• This planet has 4 major systems that interact with each other: The Geosphere, The Hydrosphere, The Atmosphere and The Biosphere:
THE LAYERS OF THE GEOSPHERE • The Surface and Interior of the Earth (rocks, minerals and landforms) form the Geosphere: It has three layers, in order of density: Crust, mantle and the core.
CRUST
MANTLE OUTER CORE
INNER CORE
THE LAYERS OF THE GEOSPHERE • The CRUST: the outer layer of the Earth. The least dense. Is solid and varied in composition. There are two types: the continental crust and the oceanic crust.
THE LAYERS OF THE GEOSPHERE • The MANTLE: Located below the crust. A solid and very homogenous layer. Thickness: 2.999 km deep. Main component peridotite (rich in the mineral olivine). • The CORE: Located below the mantle. It extends to the Earth’s centre. Main components are: Iron (80%) and Nickel (20%). It has two parts: •
Outer Core: Liquid magma (like honey). Composition: Iron and Nickel. Thickness: from 2.999 km to 5150 km deep.
•
Inner Core: Solid part. Composition: mainly Iron.
THE LAYERS OF THE GEOSPHERE
RELIEF FETAURES OF THE Continental Crust • These are the landforms we can observe are on the continental crust.
RELIEF FETAURES OF THE Continental Crust Continental slope
Continental shelves
RELIEF FETAURES OF THE Oceanic Crust Island arcs
Abyssal plains
Oceanic trenches
Guyots
Volcanic Islands
Mid-ocean ridges
RELIEF FETAURES OF THE Oceanic Crust
RELIEF FETAURES OF THE Oceanic Crust
Minerals and Rocks • The CRUST of the Earth consists of MINERALS and ROCKS. • Characteristics of MINERALS: • Naturally occurring • Solid substances • Inorganic (not living matter)
Minerals are composed by one or more chemical elements (Iron, Silicon, Chlorine, Magnesium, Calcium, Aluminium….)
A ROCK in general is made of several types of mineral But there are also: Monomineralic rocks (made up of one type of mineral)
MARBLE (monomineralic rock)
• How to identify MINERALS: • Colour of the surface CONGLOMERATE • Lustre (how they reflect light): metallic and non-metallic (fragments of other rocks) • Hardness (how it reacts when being scratched) • Cleavage (how the mineral breaks up, for example, into cubes or thin sheets)
Minerals and Rocks • •
Naturally flat faces or sides The faces take geometric shape (cubes, prisms…)
MINERALS can be CRYSTALLINE or AMORPHOUS
• •
They don’t have naturally occurring faces They have irregular shapes and never form crystals
Classification of Minerals Minerals are can be classified in 2 groups: SILCATES and NON-SILICATES
• • •
Contain: Oxygen and silicon Example: Quartz Groups within the Silicates: CLAY MINERALS MICAS FELDSPARS
• • •
They don’t contain silicon Less abundant and less diverse than silicates Groups of Non-Silicates: OXIDES CHLORIDES CARBONATES SULPHATES SULPHIDES
Classification of ROCKS We can classify them in 3 groups depending on their origin:
IGNEOUS Layers formed by accumulated sediments
Marl
Formed by heat and pressure.
Slate
Formed from cooled magma.
Basalt