Publisher Summary Based on numerous natural and social sciences, medical geography has predominantly synthesized general information on the natural conditions of some territory. The geological structure of an area affects the living conditions of the population. To live in harmony with the continually changing environment, besides geological factors, the essence and velocity of changes have to be known. For example, in California, houses, hospitals, and schools have been constructed at active faults directly. The geological environment is characterized by various factors such as principal rocks; tectonic structures; geomorphological features; loose sediments (including pedological soil); groundwater; engineering geological occurrences; deposits and occurrences of raw materials; macro- and micro-elements in rocks, soil, and water; and radioactive elements Processes changing the geological environment are discussed in this chapter.