]> Geophysics, a branch of Earth sciences, is the study of the Earth by quantitative physical methods, especially by seismic, electromagnetic, and radioactivity methods. The theories and techniques of geophysics are employed extensively in the planetary sciences in general. Geodesy, also called geodetics, a branch of earth sciences, is the scientific discipline that deals with the measurement and representation of the Earth, including its gravity field, in a three-dimensional time varying space.[2] Besides the Earth's gravity field, geodesists study also geodynamical phenomena such as crustal motion, tides, and polar motion. For this they design global and national Control networks, using Space and terrestrial techniques while relying on datums and coordinate systems Mechanics is the branch of physics concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effect of the bodies on their environment. Geomorphology is the study of landforms, including their origin and evolution, and the processes that shape them. The underlying question is: Why do landscapes look the way they do? Geomorphologists seek to understand landform history and dynamics, and predict future changes through a combination of field observation, physical experiment, and numerical modeling. The discipline is practiced within geology, geodesy, geography, archaeology, and civil and environmental engineering. Early studies in geomorphology are the foundation for pedology, one of two main branches of soil science. Landforms evolve in response to a combination of natural and anthropogenic processes. The landscape is built up through tectonic uplift and volcanism. Denudation occurs by erosion and mass wasting, which produces sediment that is transported and deposited elsewhere within the landscape or off the coast. Landscapes are also lowered by subsidence, either due to tectonics or physical changes in underlying sedimentary deposits. These processes are each influenced differently by climate, ecology, and human activity. Seismology (from the Greek seismos = earthquake and λόγος,logos = knowledge ) is the scientific study of earthquakes and the propagation of elastic waves through the Earth. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic, atmospheric, and artificial processes (such as explosions). Tectonics is a field of study within geology concerned generally with the structures within the crust of the Earth (or other planets) and particularly with the forces and movements that have operated in a region to create these structures. Tectonics is concerned with the orogenies and tectonic development of cratons and tectonic terranes as well as the earthquake and volcanic belts which directly affect much of the global population. Tectonic studies are also important for understanding erosion patterns in geomorphology and as guides for the economic geologist searching for petroleum and metallic ores. A subfield of tectonics that deals with tectonic phenomena in the geologically recent period is called neotectonics. Planetary science, also known as planetology and closely related to planetary astronomy, is the science of planets, or planetary systems, and the solar system. [Wikipedia]