Structure and Material of the Earth Flashcards
Minerals
A mineral is a naturally occurring deposit in the earth’s crust consisting of one or more elements. It has definite chemical and physical properties.
Rocks
Rocks are solid material which make up the Earth’s crust.
Ores
Rocks containing Metal compounds in large quantities which can e obtained economically.
Sill
A flat, horizontal, sheet-like igneous intrusion between old layers of sedimentary rocks or beds of volcanic lava.
Batholith
It is the largest body of an intrusive igneous rock. It is irregularly shaped and covers more than 100 m²
Lithification
The process that turns loose sediments into rocks.
GR: The density of rocks increases with depth.
Due to the process of planetary differentiation, our planet has solidified from molten material. In the molten state the denser materials moved down while the lighter material began to float on top. Thus when the earth solidified we find lower density in the crust and highest density in the core.
GR: In spite of high temperatures in the interior of the Earth, rocks act as solid.
The great pressure in the inner core keeps this layer firm and solid in spite of high temperatures.
GR: Igneous rocks are primary rocks.
Igneous rocks are formed by cooling and solidification of magma. All rocks are directly or indirectly formed from igneous rocks.
GR: Extrusive igneous rocks have small crystals.
When the magma erupts and flows on the surface, it is called lava. When the lava cools on the surface, the cooling process takes place rapidly leading to the formation of small crystals and may contain gas bubbles.
GR: Intrusive igneous rocks have large crystals.
When magma cools below the surface of the earth, the cooling process takes place slowly leading to the formation of large crystals.
GR: Sedimentary rocks are called stratified rocks.
Sedimentary rocks are formed in layers and these layers are distinctly found on the rocks.
GR: Sedimentary rocks help us to know about life in the past.
Sedimentary rocks are formed organically. Fossils are found in layers of sedimentary rocks. Fossils are once living organisms (plants/animals) which can be preserved completely or in the form of an imprint.
GR: Sedimentary rocks are economically important.
Sedimentary rocks are formed organically. Coal, oil and natural gas are formed when vast forests in the ancient past were submerged underground and underwent change.
GR: Metamorphic rocks are called so.
Metamorphic rocks are formed when igneous or sedimentary rocks are is completely different in its physical appearance and chemical composition from the original. Thus the word ‘metamorphosis’ which means ‘to change’ is applicable to them.
Differentiate between core and Mantle
Mantle
1. Average thickness is 2900 kms
2. Temperature ranges from
870⁰ c to 2200⁰c.
Core
1. Average thickness is 7000 kms.
2. Temperature ranges from
2200⁰c to 5000⁰c
Differentiate between Extrusive Igneous
and Intrusive Igneous
**Extrusive Igneous **
1. Formed by cooling and solidification of lava on the surface of the Earth.
2. Fine grains or small crystals.
3. They are also called volcanic rocks.
Intrusive Igneous
1. Formed due to cooling and solidification of magma inside the surface of the Earth.
2. Coarse grains or large crystals
3. They are also called plutonic rocks.
Differentiate between Igneous and sedimentary rock
**Igneous Rocks **
1. Formed by cooling and solidification . of lava and magma,
2. Formed of crystals.
3. Primary rocks.
Sedimentary Rocks
1. Formed by weathering, and erosion, transportation, magma, deposition and Lithification of sediments.
2. Formed of layers or stratus.
3. Secondary rocks ( derived
from pre-existing rocks)
Differentiate between Hyberbyssal and Plutonic Rocks
**Hypabyssal Rocks **
* These are formed just below the Earth’s surface.
* They are narrow horizontal or vertical intrusions.
Plutonic Rocks
* These are formed deep beneath the ground.
* They are irregular gigantic intrusions.
