An understanding of rates of land surface change has always been a central focus of geomorphological research. Among the questions which require a knowledge of rates of change are the following: How important is climate as a control of geomorphological processes? To what extent are humans influencing landform development? What is the potential useful life time of a particular engineering structure? How can environments be transformed by future global environmental changes? What is the relative significance of different geomorphological processes? How much time is required for a particular landform assemblage to develop? <...>

There have been two dominant models used in describing the chemical and electronic behavior of a surface. One is the atomistic model, or the “surface molecule” model; the other is the band model, often called for emphasis the “rigid band” model. The atomistic model has been preferred in general in discussions of the chemical processes at a solid surface; the rigid band model is often preferred in discussions of electron exchange between the solid (especially a semiconductor) and a surface group, where, for example, the conductivity of the solid is changed.

Brines may be generated in sedimentary, magmatic or metamorphic settings, and they change chemistry extensively as they move through rocks and interact with them. The primary constraint on their metal carrying capacity is their salinity, but they may carry very variable amounts of S in solution, depending on their source and the rocks that they have encountered. Sulphur availability and oxidation state are also major controls on which metals will be transported and which precipitated. Availability of fluid inclusion brine analyses is making possible the characterisation of a much wider range of brine types than was hitherto possible, and providing information about metal contents in a wide range of settings, as well as tracer analyses. Iron contents of brines are broadly temperature dependent, and are much higher in magmatic brines than in sedimentary ones, but basinal fluids may still carry sufficient Fe in solution to precipitate iron oxides at an oxidation front, and may be much more voluminous. Brines of different origins can often be distinguished on the basis of conservative halogen tracers unaffected by wall rock interactions: Br/CI ratios used in conjunction with I/Cl ratios or d"Cl values separate residual bittern fluids from re-dissolved evaporites, with igneous brines forming an intermediate, but somewhat distinct, grouping.

The earth is a giant system including the atmosphere, hydrosphere, lithosphere, biosphere, and the mantle, core and planetary space. Earth science is the study on the substance composition, origin, formation, evolution and the interaction of each part of the earth system. In the late 20th century, the earth science developed towards the earth system science, focusing on the lithosphere, and gradually extended to the relationship and interaction with the other layers.