Introduction to Geomorphology
Geomorphology derives from the Greek words Geomorphology [Geo-Earth (Earth), morphi-form (form), and logos-discourse (description)], which literally means ‘study of landforms’. Under this, the reliefs of the globe’s terraces, their constructional processes, and the interrelations between them and humans are studied.
The following three types of reliefs are included under this science
1. First class relief – It covers the continent and oceanic basin.
2. Second class relief – It includes the study of mountains, plateaus, plains, and lakes.
3. Third-class relief – Under this, the topography generated due to sarita, ocean water, groundwater, wind, glaciers, etc. is studied.
The present form of geomorphology has become possible as a result of gradual systematic developments in the last centuries. A preliminary study of topographies in Greece, Greece, and Egypt 500 B.C. It has started with but some basic concepts of geomorphology have been given to geomorphology, which is as follows
Basic concepts of Geomorphology
Several fundamental concepts related to the development of topographies have been presented in geomorphology, which has made the gradual development of geomorphology possible. Professor Thornthvette has beautifully described these concepts in his book ‘Principles of Geomorphology‘.
Geomorphology fundamental concepts
In the construction of topography, the geological processes, and rules which are active at the present time, they have been employed in the entire geological history even though their intensity has not been the same.
It is also called the principle of uniformity. It is a fundamental theory of geomorphology, first proposed by James Hutton in 1785, and later John Playfair and Sir Charles Loyal carried this concept forward. Hatten formulated the concept of uniformism by criticizing the theory of contingency prevalent in his time. He told that the history of gradual development is hidden behind the external form of nature we see today. It is not that that external form is suddenly attained. Every process that works in the land is used in the past, is also working in the present time, and will be employed in the future. By looking at the functions of the current processes or the current forms of the present, one can get information about the topography of the past.
These processes of erosion have always been active, they were active in the past, they will also be in the future, although the area and intensity of their work may vary. It may be that the process that is working fast today would have been less effective in the past.
The geological structure is an important controlling factor in the development of topography and is reflected in topography. The above concept implies that structure remains an important contributor to the construction of topographies.
Davis also considered structure to be an important factor in the evolution of topography along with process and condition. According to Polridge and Morgan, “The rocks, whether igneous or sedimentary, present on the one hand the handwriting of the history of the earth, on the other hand, provide the basis for contemporary scenery.” Variations in the composition and nature of rocks have a significant effect on the rate of erosion and erosion of the terrain, due to which there is a local and regional difference in the intensity of processes in different rock areas, which leads to variations in topography. For example, sandstone is a highly inaccessible rock. In contrast, the rock is an inaccessible rock. In the area of sandstone rock, most of the rainwater goes underground, so rivers are less in such areas, their tributaries are also less The valleys of the rivers are shallow. In contrast, the water flows more on the surface in the rock zone and the valleys are also deep and well-defined. Cart topography is formed due to the action of water in the limestone areas.
Metamorphic rocks are often harder and more compact than other types of rocks, due to which they do not erode easily, hence rocks like slate, nees, quercite, schist, etc. form hills, mountains, and high plateaus. Granite and fine rocks often form the dome. It is thus clear that the effect of the structure is clearly reflected in the topographies.
In the development of the landscape, there are more complexities than simple ones. It is generally believed that a particular type of process creates a specific topographic set, but in reality, it does not occur because only one process is not active in a landmass but more than one process is employed, although One process can be most effective, for example in dry or semi-arid regions, although wind erosion is a major factor, flowing rain also becomes an active factor here. In addition, the development of topography is not related to a single erosion cycle but is a byproduct of several erosion cycles. Due to the disruption caused by geomagnetic movements, more cyclic and mixed topographies are seen more than simple and single cyclic topographies.
Therefore, complexities are more common than simplifications in the development of topographies and there are two reasons for these complications – one is the operation of more than one process and the other is more than one development cycle.
On the basis of these facts, Harburg has divided the topographies into the following five major classes.
(i) Simple topography
(ii) Mixed topography
(iii) Acyclic topography
(iv) Multi-cyclic topography
(v) Exposed or regenerated topography
Specific landscape process
Geomorphic processes leave their own distinct mark on topography and each process forms a distinct set of topographies.
According to this concept, each process creates different topographies and has clear characteristics of topography created by a particular process and with the help of these specifications, the topography generated by one process can be distinguished from the topologies developed by other processes. . Examples
For delta, Gokhur lakes are the byproduct of flowing water, while Barkhan, Inselvarg, etc. are related to the winding process. Similarly, the Moren, Drumlin escar, U shaped valleys are topography generated by Himani.
Since each process generates distinct topographies, genetic classification of topographies can be made based on these characteristics. Keeping this fact in mind, Davis presented a genetic classification of the topographies.
By classifying various topographies in terms of their respective processes, their construction method, the sequence of development and geographical history, etc. can be easily understood. Considering the significance of the process in the development of the landscape, it emphasizes that the development of landforms does not happen in an irregular manner. Rather, there is a definite correlation of other topographies with some topographies, that is, if some topographies are found in an area, it can be estimated with the help of the relevant process which other topographies are likely to be found there.
History of rocks
Rocks are geological history books and fossils are its pages. By studying the present form of rocks, its history can be traced to how old this rock is and how it was built.
Wallbridge and Morgan have clarified that “rocks, whether igneous or flaky, form the handwriting of the history of the earth on one side, providing the basis for contemporary scenery on the other hand. Hatton also learned about geological history by using rocks. Have tried to do.
Similarly, the study of fossils gives an understanding of the cycle of rock development, climatic conditions, and physical conditions at the time of construction, such as the formation of coal in humid and hot climatic conditions due to vegetation being buried in deep river valleys.
Stages of evolution
As various erosive factors are employed on the ground floor, gradual landforms, which have distinct characteristics in successive stages of development, are formed.
The topography created by any process has different characteristics at different stages of its development. Thus each stage has its own specific characteristics.
Davis has also emphasized in his concept of the landscape shape that topographies have successive stages of development and each stage has its own characteristic features. Davis has described three stages of development of topographies as puberty, maturity, and old age. Through which an elevation attains the base plane (peneplain). Although many geoscientists currently do not consider the cyclical development of topography in young, adult, and old age as suggested by Davis, Hank has emphasized the concept of timeless development of topographies.