Anglais scientifique (S1)

The earth sciences, also known as geosciences, are the focus of scientific understanding about this and other planets, embracing an enormous range of topics, including the evolution of the Earth, exploring the Earth‘s geologic history, fossil record, structure and motion, rocks and minerals, atmosphere, weather and water resources. Geology (Greek. "geo" – earth, "logos " –study) is one of the most important sciences about Earth. It studies the composition, structure, history of the earth‘s development and the processes occurring in its interior and on its surface. Modern geology uses up-to date achievements and methods of a number of natural sciences, such as mathematics, physics, chemistry, biology, geography. Significant progress in these fields of sciences and geology has lead to the appearance and development of important interdisciplinary sciences about Earth – geophysics, geochemistry, biogeochemistry, crystallochemistry, paleogeography which enable us to obtain data on composition, state and properties of a substance in deep parts of the Earth‘s crust and its bottom layers. A special attention should be paid to multilateral relation of geology to geography (landscape study, climatology, hydrology, glaciology, oceanography) in understanding of different geological processes occurring on the Earth‘s surface. Interrelation between geology and geography is especially important in the study of the Earth‘s surface relief and laws of its development. In its study of the Earth‘s relief, geology uses the data from geography and geography is supported by the history of geologic development and interrelation between various geologic processes. Thus, the science on relief –geomorphology – is, in fact, also an interdisciplinary science. According to geophysical data there are several covers in the Earth‘s composition: earth‘s crust, mantle and nucleus. The subject of the direct study of geology is the Earth‘s crust and underlying solid layer of the upper mantle – lithosphere (Greek "lithos " – stone). Difficulty in the object under study has led to significant differentiation between geological sciences, their unity together with interdisciplinry sciences (geophysics, geochemistry, etc) explains various aspects of its composition, history of development, the essence of the occurring processes, etc.

One of the main directions in geology is the study of elemental composition of the lithosphere: rocks, minerals, chemical elements. Some rocks are from molten magmatic silicate and are called plutonic or igneous rocks, others by sedimentation and accumulation in marine and continental conditions and are called sedimentary rocks, the third type of rocks are formed by modification of different rocks under the influence of temperature and pressure, liquid and gaseous fluids, and are called metamorphic rocks. The elemental composition of the lithosphere is studied by a number of geological sciences united under the name of geochemical sciences. Petrography (Greek "petros " – stone, rock, "grapho " – write, describe), or petrology – the science which studies magmatic and metamorphic rocks, their composition, texture, formation conditions, degree of modification under the influence of various factors and laws of their distribution in the Earth‘s crust, belongs here. Lithology (Greek "lithos " – stone) is a science which studies sedimentary rocks. Mineralogy is a science which studies minerals, i.e. natural chemical compounds or individual chemical elements making up rocks. Crystallography and crystal chemistry study crystals and crystalline state of minerals. Geochemistry is a generalizing synthesizing science about composition of the lithosphere basing on the achievements of the above sciences which studies the history of chemical elements, their laws of distribution and migration in the earth‘s entrails as well as on its surface. With the birth of isotope geochemistry, a new page was open in geology which concerns restoration of the Earth‘s historic geologic development. Elemental lithospheric composition, as well as other processes, is studied using different methods. First of all, these are direct geological methods –direct study of rocks in natural crops on the river banks, lakes, seas, mine cross-cuts, quarries, sidewall cores. All this is limited to relatively small depths. The deepest, and unique in the world today, the Kola well has reached only 12.5 km. But deeper layers of the earth‘s crust and adjoining parts of the upper mantle are also accessible for direct study. This is promoted by eruption of volcanoes, bringing us debris of upper mantle rocks embedded in the flown magma – lava flows. Similar picture can be seen in explosion diamond pipes, their depth being 150-200 km. Apart from the mentioned above direct methods of lithospheric elements study, optical methods are widely used

as well as other physical and chemical investigations - X-ray diffraction study, spectrographic study, etc. Moreover, mathematical methods on computer basis are widely used for the assessment of chemical and spectral analyses reliability, building of rational classifications of rocks and minerals, etc. A number of experimental methods, including computer methods, which model geological processes, giving us the opportunity to obtain different man-made minerals, and rocks, to reconstruct huge pressure and temperatures and to observe the substance behaviour directly under these conditions, to forecast the movement of lithospheric plates and even, to some degree, to present our planet‘s surface in millions of years ahead have been widely used for the last decades.