Structure of the earth. and the age of the earth
4.5 billion years – Earth’s age
Formation – how Earth was made
Dust and gas cloud – where Earth began
Accretion – small pieces joining to form Earth
Solar system – Sun + planets
Radiometric dating – method to find age
Fossils – remains of old life
Rocks – hold Earth’s history
Geology – study of Earth
Ancient Earth – very early Earth
Structure of Earth
Crust – outer layer of Earth
Continental crust – land crust
Oceanic crust – crust under oceans
Mantle – thick middle layer
Lithosphere – crust + upper mantle
Asthenosphere – soft, flowing mantle
Core – centre of Earth
Outer core – liquid metal
Inner core – solid metal ball
Earth Processes
Magma – melted rock inside Earth
Lava – magma that comes out
Pressure – force inside Earth
Temperature – how hot Earth is
Tectonic plates – big pieces of the crust
Earthquake – shaking of Earth
Volcano – opening where lava comes out
Interesting points:
The Earth formed 4.5 billion years ago from a cloud of dust and gas.
When Earth was young, it was a red-hot ball of melted rock.
As Earth cooled, the crust formed first, like a skin on hot soup.
The mantle is still hot and moves slowly — this movement pushes tectonic plates.
The inner core is a solid metal ball even though it is as hot as the Sun’s surface!
The outer core is liquid metal and creates Earth’s magnetic field, which protects us from harmful space radiation.
Continental crust is older than oceanic crust — some continents are billions of years old.
Rocks and fossils help scientists measure Earth’s age using radiometric dating.
Earth’s layers (crust, mantle, core) were formed because heavy metals sank and lighter rocks floated.
The Earth is always changing — mountains rise, oceans form, and continents move slowly over millions of years.
Main points:
The Earth is 4.5 billion years old.
The Earth formed from a cloud of dust and gas in space.
The Earth has three main layers — crust, mantle, and core.
The crust is the thin outer layer where we live.
The mantle is a thick, hot layer of soft rock.
The core has two parts: liquid outer core and solid inner core.
Tectonic plates are big pieces of the crust that move slowly.
Magma (melted rock) comes up during volcanoes and becomes lava.
Pressure and temperature increase as we go deeper into the Earth.
Scientists use radiometric dating, rocks, and fossils to find Earth’s age.
Fun Fact:
The Earth is about 4.5 billion years old—older than the moon!