Isostasy Very old rocks are at the surface in the Canadian Shield area. Up to about 3.8 or 3.96 billion years old . Multicellular life did not appear until about 1 billion years ago . Hard parts like shells don't appear until 600 million years ago. Return to Outline Scientific Method Science is a consistent body of knowledge strongly tied to experiment, and expressed in as few laws as possible.
Science relies on experimental and observational facts of nature.
We obtain these facts through experiments or observations which are repeatable by other scientists. When a hypothesis is accepted and others are rejected, it becomes a theory . A theory is a hypothesis with considerable experimental support. Many consequences of a theory may be verified, but a theory can never be proved, only disproved. Theories may have limits in certain situations.