In the picture above you can see where geologic history has been made at the west end of Horseshoe Park in Rocky Mountain National Park. A dam broke high in the mountains above this alluvial fan and the millions of gallons of water rushing down the mountain eroded out and carried rock debris to the foot of the mountain creating this alluvial fan. It is known that the history of the Earth spans a period of more than 4 billion years, although how the Earth formed is still a matter of speculation.
Some experts suggest that it originated from condensing gas and dust.
Others regard it as having developed from a cloud of meteorites and meteoric dust revolving around the Sun. Gravitational forces caused the particles to come together, or accrete , with heavier particles gravitating to the center and lighter ones collecting outside. Geologic history began when the crust first formed, about 4.6 billion years ago, as determined by radiometric age-dating of the oldest rocks and of meteorites. This event must have been preceded by a considerably longer period of astronomical history during which the Solar System and, before that, the universe were created. The first, the Precambrian Era , began 4.6 billion years ago and includes the first 4 billion years of geologic history, about 85 percent of all geologic time.