Geotechnical engineering is a branch of civil engineering that concerns the study of the interrelationship between the geologic environment and the work done by humankind. Soil mechanics and rock mechanics are fields in which the mathematical aspects of analysis for the design of engineering works are defined and described as they relate to the geologic environment. Projects involving excavations in rock bear a close relationship to mining engineering. The basis on which the knowledge structure of geotechnical engineering is built is a thorough comprehension of the elements of the geologic environment. In reality, therefore, geotechnical engineering consists of two major, but separate, disciplines: geology and civil engineering.