Both physical and historical geologists use the same procedures used by scientists in other disciplines. These procedures are referred as scientific method and it is a systematic approach to reveal the answers for questions, solutions to problems, and provide evidence to prove or disprove ideas and beliefs.

A scientific investigation begins often with a question and it proceeds to data collection. Later, it developed into a hypothesis that fits all the data and is likely to account for observations in the future as well as the present. Later, a hypothesis is tested and examined critically by other scientists. As a result, it can be confirmed, modified, or subsequently discarded. A hypothesis that persists repeated challenges and is supported by accumulating favorable evidence can be elevated as a theory.