As the cooling continued, water vapor began to escape and condense in the earth's early atmosphere.
Clouds formed and storms raged, raining more and more water down on the primitive earth, cooling the surface further until it was flooded with water, forming the seas.
The continual changing and reshaping of the earth's surface that involves the melting down and reconstructing of old rock has pretty much eliminated most of the original rocks that came with earth when it was newly formed. It is estimated that That's pretty much all there was for about the next two billion years.
acquired trait: A phenotypic characteristic, acquired during growth and development, that is not genetically based and therefore cannot be passed on to the next generation (for example, the large muscles of a weightlifter).
In the infancy of our home planet the entire earth was molten rock - a magma ocean.
Fossils are important for working out the relative ages of sedimentary rocks.
Throughout the history of life, different organisms have appeared, flourished and become extinct.
The method of reading the order is called stratigraphy (layers of rock are called strata).
Relative dating does not provide actual numerical dates for the rocks.