Our cool planet Earth was formed about 4.6 billion years ago. Today, I will present to you how we came to the correct conclusions about how our planet was formed and when it was formed.
Zircon on the left is one of the oldest minerals found in rock from 4.5 billion years ago, this gives way through erosion and decay to uranium and then lead on the right as the mineral found in the oldest rocks.
The earth grew in mass due to constant bombardment from other celestial bodies.
The elimination of the craters and scars from impacts is due to the earths chemical makeup and the decay, erosion and reformation of rock and plate tectonics, that created and reshaped the earths crust. It is at this time that we can see the earliest chemical markers of life.
Radiometric dating is used to determine the age of rocks by measuring the radioactive elements in them. Bracketing is a way to measure different items from different layers and depths within the earth to determine their age.
We use the earths composition to compare and contrast and determine the makeup of other bodies within the solar system.