Geology is a vast field of science that encompasses the physical, historical, and environmental areas of study. These three areas of the study are the principal subdivisions of geology, which somehow overlap, but they also differ in significant ways overall. Therefore, we divide geology into three fundamental branches; i.e Physical Geology, Historical Geology, and Environmental […]
The age of the earth as determined by current methods of radiometric dating is about 4600 million years. Before the discovery of radiometric dating, several attempts were made to determine the age of the earth. The important one’s are as follows.
From the history of organic evolution.
From the rate of sedimentation.
From salinity of seawater.
From the rate of Cooling.
There are dozens of theories about the origin of the Earth. In general the theories of origin of the Solar System or earth can be divided into two groups: (i) Evolutionary theories (ii) Catastrophic Theories.
Evolutionary Theories: The theories which suggest that planets are formed during the evolution of the sun, are called ”Evolutionary Theories“. Nebular Hypothesis is an example of these theories.
Catastrophic Theories: ”Catastrophic Theories” are those which imagine that planets are formed by some special accident or catastrophe, such as the close approach of two stars or by collision of two stars. However, as the stars are so far apart in the galaxy, the possibility of such a catastrophe is extremely rare. the examples of Catastrophic Theories are the planetesimal and gaseous tidal hypothesis.
Solar System The Earth is a planet. It is a member of the solar system. Nine planets and the sun are the main bodies of the ”Solar System”. The planets in the order of increasing distance from the sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Each planet moves around the […]
Geology is a Science, which is devoted to the study of the Earth. It deals with all the features of the earth’s surface, its origin, composition, structure, history, inhabitants, and processes of change in its features. An important part of geology is the study of how Earth’s materials, structures, processes, and organisms have changed over time.
Composition The composition of almost all lava of the Earth’s crust is dominated by silicate minerals: mostly feldspars, feldspathoids, olivine, pyroxenes, amphiboles, micas and quartz. Rare nonsilicate lavas can form by local melting of nonsilicate mineral deposits or by separation of a magma into separate immiscible silicate and nonsilicate liquid phases. Silicate lavas Silicate lavas are molten mixtures dominated by oxygen and silicon, the Earth’s most abundant chemical elements, with smaller quantities of aluminium, calcium, magnesium, iron, sodium, […]
Diagnosis of Amethyst, This post is incomplete, it will be composed soon Chemical composition and properties of Amethyst, Physical Properties of Amethyst, Structure of Amethyst, Colours and tone of Amethys, Occurrence of Amethyst, Historical Importance of Amethyst, Metaphysical Importance of Amethyst, Artificial Synthesis of Amethyst, Cultural Association of […]
“Metamorphic Rocks” are formed from the older rocks when they are subjected to increased temperature, pressure, and shearing stresses at considerable depth in the earth’s crust. The older rocks may be either sedimentary, igneous, or other metamorphic rocks. During metamorphism, recrystallization takes place essentially in the solid-state and new minerals and new textures are produced. […]
Some important sedimentary rocks are as under; (1). Conglomerate Nature: Consolidated gravels. Colour variable. Mineral Composition: Rounded pebbles are set in a fine-grained matrix. The matrix commonly consists of sand and silt and it is cemented by silica, calcium carbonate, or iron oxide. The individual pebbles may be entirely composed of quartz or maybe rock […]
The composition of sedimentary rocks is of two types; chemical composition and mineral composition. The chemical composition of a substance means the aggregate chemicals that constitute that substance, while the presence of different types of minerals illustrates the mineral composition of that substance. Here we will discuss the two types of compositions separately. (1). Chemical […]