Eduqo
Indian Geography›Ch 1: Earth & Universe›Interior of Earth and Rocks
Master Crust, Mantle, Core and Rock Types for SSC and Defence Exams
Earth is divided into Crust, Mantle, and Core based on composition. Rocks transform continuously through the rock cycle into igneous, sedimentary, and metamorphic forms.
Memory Hooks
| Layer | Depth Range | Major Elements |
|---|---|---|
| Crust | 0 - 100 km | Si, Al (Sial) |
| Mantle | 100 - 2900 km | Si, Ma (Sima) |
| Core | 2900 - 6400 km | Ni, Fe (Nife) |
Igneous
(Primary molten rock)
Primary molten rock
Basalt and granite are classic examples formed from cooling magma.
Sedimentary
(Deposited layers)
Deposited layers
Sandstone and limestone form through accumulation of sediments.
Metamorphic
(Heat and pressure)
Heat and pressure
Marble and quartzite are altered forms of limestone and sandstone.
Asthenosphere
(Plastic upper mantle)
Plastic upper mantle
Magma for volcanoes originates from this semi-fluid layer.
Core is completely in liquid stateOuter core is liquid, inner core is solid
Examiners trick students by stating the entire core is liquid due to high temperature.
Marble is an igneous rockMarble is a metamorphic rock
Limestone transforms into marble under heat and pressure, making it metamorphic.
Basalt is formed inside deep coreBasalt is an extrusive igneous rock
Basalt forms when lava cools rapidly on the Earth's surface, not deep inside.
Q1.Which layer of the Earth is responsible for generating Earth's magnetic field?
Q2.Quartzite is formed from the metamorphism of which of the following rocks?