Geomechanics (Greek prefix geo meaning earth; and mechanics) is the study of the behavior of soil and rock. The two main disciplines of geomechanics are soil mechanics and rock mechanics. The former deals with the behaviour of soil from a small scale to a landslide scale. The latter deals with issues in geosciences related to rock mass characterization and rock mass mechanics, such as applied to tunnel design, rock breakage, and rock drilling. Many aspects of geomechanics overlap with parts of geotechnical engineering. Modern developments relate to seismology, continuum mechanics, discontinuum mechanics, and transport phenomena.