Geology (from the Ancient Greek γῆ, gē, i.e. "earth" and -λoγία, -logia, i.e. "study of, discourse") is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer to the study of the solid features of any terrestrial planet or natural satellite, (such as Mars or the Moon).
In collecting the primary geologic data, some personal capacities of the geologist (such as strong physique, perceptive faculties, perseverance, talent for drawing) are generally of much greater importance than in any of the sister sciences, which can rely on the quality of the instruments used in collecting primary data… Hans Cloos (1949) called this way of interrogation [by geologists] "the dialogue with the earth," "das Gespraich mit der Erde."