Life on Earth originated about 2 billion years ago, but there are no good fossil remains from periods earlier than the Cambrian, which began about 490 million years ago.
Techniques include tree rings in timbers, radiocarbon dating of wood or bones, and trapped charge dating methods such as thermoluminescence dating of glazed ceramics.
Coins found in excavations may have their production date written on them, or there may be written records describing the coin and when it was used, allowing the site to be associated with a particular calendar year.
They have been on Earth for almost 4 billion years. Melted rock is called magma when it is inside the earth, but called lava when it runs out onto the surface of the earth.
Geologists record time with the Geologic Time Table. The mineral, salt, was so valuable in ancient times that it was traded ounce for ounce for gold. Meteorites are rocks from space, and they can help scientists learn about the solar system. Some minerals are made of only one element, such as silver.
The Earth has 3 layers: the crust, the mantle and the core (which is subdivided into the outer and inner core.) Each layer is unique. Most are a combination of two or more elements, such as granite which is made of quartz, feldspar, mica. The particles of minerals are arranged in a repeating pattern called a crystal Stalactites form when mineral deposits and water seep from the walls or rocks inside caves.
You can find the interesting details of the layers at: The Structure of the Earth. This drips slowly and creates an icicle-type formation.
centuries, the dominant explanation for the sedimentary rocks and their fossilized contents was that they had been laid down in the great Flood of the days of Noah.
This was the view of Steno, the "father of stratigraphy", whose principles of stratigraphic interpretation are still followed today, and of John Woodward, Sir Isaac Newton’s hand-picked successor at Cambridge, whose studies on sedimentary processes laid the foundation for modern sedimentology and geomorphology.
In March 2004, geologists added a new time period to Earth's chronology—the Ediacaran Period.
The Ediacaran Period lasted about 50 million years, from 600 million years ago to about 542 million years ago.
It was the last period of the Precambrian's Neoproterozoic Era.