How did the Earth form? In a nutshell their was a supernova around 5,000,000,000 (5 B.Y.A.) years ago which cuased the interstellar dust cloud to begin to spin and collapse onitself becuase of its own gravity, the heat from their collision and the intense pressure created the sun. Further out other particles started to come to gether and grew bigger and bigger and became the planets. Click the link to get a better idea.
The Hadean is the geologic eon before the Archean. It started with the formation of the Earth about 4.6 billion years ago (4,600,000,000) and ended roughly 3.8 billion years ago, The name "Hadean" derives from Hades, Greek for "Underworld", referring to the "hellish" conditions on Earth at the time.
Oldest rock on Earth: approximately 3.8 billion years ago. That means we have almost 800,000,000 years the is virtually unrecorded in the History of the Earth. On the coast of Hudson Bay in northern Quebec are dated from 3.8 to 4.28 billion years old.
Earth's Oldest Fossil: are the stromatolites consisting of rock built from layer upon layer of sediment. Stromatolites from the late Archean and through the middle Proterozoic eon were mostly formed by massive colonies of cyanobacteria (formerly known as blue-green "algae"), and that the oxygen byproduct of their photosynthetic created earth’s oxygen rich atmosphere about 2.2 billion years ago.
Theories of How Life First Evolved On Planet Earth
Panspermia: Panspermia is a Greek word that translates literally as "seeds everywhere". The panspermia hypothesis states that the "seeds" of life exist all over the Universe and can be propagated through space from one location to another. Some believe that life on Earth may have originated through these "seeds".