Geology is the study of Earth as a whole, its origin, structure, history and the nature of the processes which have given rise to its present state according to the Penguin Dictionary of Geology.
Science, systematic knowledge of natural or physical phenomenon can be broadly divided into three basic categories viz. Geology, Biology and Psychology. Geology can be described as the study of inert, lifeless matter. The studies of matter which do have life in them, such as animals and plants but who are unconscious of life in them form the subject matter of Biology. The study of mind, the human, who is conscious of the fact of life in it, comes under the realm of Psychology.
It is all powerful human, who because of its brain, the mind, the consciousness, rules the roost and changes circumstances to suit his requirements and convenience. What does man require to support, sustain, evolve, control and reign over life?
In the broad framework, he requires both the live and alive things such as foodstuff to sustain life and minerals and metals as support stuff for progress and prosperity and even to extend his intelligence. It is these minerals, metals and rocks which form the basic raw materials for all the industrial activity so vital for the existence of humanity. These minerals, metals and rocks (including coal, oil and water) constitute the subject matter of geology. The importance of geology can well be gauged from the extent of numerous uses these materials are put to.
Associations we keep:
The minerals just do not occur anywhere and everywhere. Their occurrence is guided by a whole lot of natural processes such as heat and pressure etc. Since time immemorial the human has been in search of minerals. The minerals are very choosy as regards to their company as us, human beings. It is just like catching your ear by bending your arm around your head and looking for their friends instead, the pathfinders to search for the mineral deposits in hiding. As particular elements can be traced through their associated elements, which have a close affinity for them. These elements are, therefore, known as pathfinders. For example mercury, arsenic and bismuth are considered useful pathfinders for locating gold.
Sometimes, the growth of particular plants over an area provides a clue as to the underlying mineral wealth. Similarly, the presence of particular elements along the particular stream when traced upstream leads you to the source deposit.
India was once known as “the golden sparrow” because of it beholding a vast mineral wealth. India is a leading producer of sheet mica in the world. It has also the largest reserves of high-grade iron ore in the world and posses large and extensive deposit of ilmenite, chromite, manganese ore, soapstone, china clay, gypsum, manganese, kyanite, sillimanite, bauxite, rutile, monazite, zircon sand and coal.
The presence of fossils in the rocks aroused the curiosity of man for all times. Any piece of evidence in the rocks which tells us about ancient life, unaltered remains, shell casts leaf imprints and footprints are called fossils. The famous theory of evolution propounded by Charles Darwin is nothing but documentation of different fossil assemblages and records throughout the world, its main plank which provided evidence in favour of the theory of organic evolution.
Changing of leg
The most destructive and dreaded among the natural phenomena, the tremors in the earth, the earthquakes take place when the proverbial oxen, lifting the earth on its horns and standing on its one leg, switches its leg according to the mythology. Like minerals, the earthquakes also do not occur uniformly throughout the world, but instead, are concentrated along specific belts. The majority of them occur in the circum–pacific belt, which overlaps the area of volcanic activity, popularly known as “the ring of fire”. Another major belt of earthquake activity runs along the Himalayas. In general, most earthquakes are associated with mountain ranges, ocean ridges, ocean trenches and island arcs. These belts form the boundaries of lithostratigraphic plates. The major earthquakes in the recent past which caused considerable damage in India are Uttarkashi earthquake (1991), Latur earthquake (1994), and Jabalpur earthquake (1997).
Although volcanic mountains comprise only a small part of the earth, landscapes of volcanic origin constitute two per cent of the total land surface in the world. Unlike other geological hazards, the volcanic areas can become exceptionally beneficial to human. Some of the most highly productive soils in the world are formed from volcanic material in warm moist climates. In such areas, fast weathering helps to provide mineral nutrients necessary for plant growth. In India, the vast cotton growing black soils in central and west central covering vast areas in Maharashtra and Madhya Pradesh are derived from Deccan traps – the flow lavas of volcanic origin.
Like earthquakes, the same belt circumscribing the Pacific Ocean, known as “the ring of fire” also locates about 80 per cent of the world’s active volcanoes. Bentonite, the weathered clay-like material composed of volcanic ash finds use in drilling of oil wells. Metals such as arsenic, bismuth and antimony occur in some volcanic regions.
If we cut along boundaries of different continents on the world map, it is interesting to notice, how easily they can fit into one another like a jig-saw puzzle. The present disposition of the continents on the globe was not like that forever but is ever changing. India once formed part of the Australian continent known as Pangea. The gradual shifting and movement of ocean basins and continental masses with respect to each other is responsible for the volcanic and earthquake activities. The various sediments of the earth’s crust are divided into a series of plates that move somewhat independently of each other, the phenomena being known as ‘Continental drift’ or ‘plate tectonics’. These plates are named as Eurasian Plate, Indian Plate, Pacific Plate, North American Plate, South American Plate, African Plate and Antarctic Plate.
During the travel, the plates may have different types of motion, such as splitting apart, colliding or grinding against each other. The inter-plate boundaries are the locale of the earthquake and volcanic activity. The major volcanic activity takes place where one lithosphere plate is being subducted under another plate. Another place of occurrence of volcanoes in specific zones is lithospheric plate divergence.
It is amusing to know that the Great Himalayan Range was not so a few million years ago but instead formed a huge sea known as Tethyan sea, as is evidenced by the presence of numerous fossil remains of marine origin. The forceful collision of Indian Plate with the Tibetan Plate upthrew the sediments of the Tethys Sea into a huge mountain range, the Himalayas, the highest mountain range in the world. And its aspirations to rise to surpass all heights as geologists say it is still rising some few millimetres per year, throwing open a challenge at those sitting in complacency, claiming to have scaled the Mount Everest, its highest peak.