Tectonic Processes and Landforms in the Lesser Himalayas
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NGJI, An International Refereed Journal, (NGSI-BHU, ISSN: 0027-9374/2016/1596), vol. 62 (4), September : 303-314 Tectonic Processes and Landforms in the Lesser Himalayas : An experimental study from Khairna Watershed Jyoti Joshi Different types of landforms and processes in different parts of the earth surface are topic of interest for the people studying geomorphology. Landforms change with time through active processes. The role of these processes becomes very significant when we are concerned with the young and dynamic mountain system like the Himalayas. The changing intensity and speed of processes that are reflected in the landforms of a Himalayan watershed is the topic of interest in this study. Analysis of the tectonically controlled landforms within the watershed further help for a better understanding of sediment mobilization and transportation of earth material down slopes and downstream. Khairna watershed, a Lesser Himalayan drainage basin is used as an experimental laboratory for continuous monitoring of the geomorphologic processes and associated landforms. Field investigations were conducted in the Khairna watershed between 2004-2007.Steep to very steep scarps, terraces, triangular facets, and waterfalls in the study area are associated with the faults and are caused by vertical displacement of rocks due to differential uplift. Apart from direct tectonic origin, debris channels, debris fans and cones, cols and knolls, sudden changes in river profiles are examples of tectonically controlled landforms modified by denudation activities. Identification, monitoring and analysis of different processes and associated landforms in the experimental drainage basin may help to understand the geomorphic processes in a systematic way which affect the region as well as the people living in the region in various ways. Similar studies in different parts of the dynamic Himalayan watersheds may be helpful for the systematic analysis of landforms and the processes associated with their origin to a great extent. Key Words: Sediment mobilization, tectonic processes, landforms, drainage basin, differential uplift. Introduction interest to the earth scientists. Though it is not Tectonic processes are related with the easy to measure the role of these processes in movements below the earth’s crust. The quantitative terms, there are sufficient processes are responsible for the evolution of evidences to prove the role of these processes different types of landforms upon the earth in a particular area. They are of special interest surface. Therefore, these processes are of for researchers working in different parts of Dr. Jyoti Joshi, Department of Geography, S. S. J. Campus, Almora-263601, Kumaun University, Uttarakhand, India. [email protected] E:\BHU\BHU.PM5 (303) 304 Jyoti Joshi the Himalayan mountain system because this processes. Changing form and type of a young orogeny has been supported by related particular landform has its effect on series of research in the last century, which prove that interconnected landforms. Description of the entire region is tectonically active. The landforms of a particular region, processes entire Lesser Himalayan belt and the Siwalik acting upon them and changes in the shape and Group are cut by a multiplicity of faults that size of the landforms due to these continuous are occupied by streams. The structure of the processes is necessary to understand the present study area is not so simple as portrayed dynamics of the earth surface in general and by earlier works (Auden, J.B., 1934;Heim and some specific area of interest in particular. Ganser, 1939; Gansser, A., 1964).The These differences can be observed in different Himalayan zone is a geosynclinal tract parts of the Lesser Himalayan region. Natural squeezed between the two large continental boundaries in the form of drainage basins can masses of Eurasia and Gondwanaland (Wadia, help to connect the link between individual 1975). A number of studies including Pande, processes and their interrelationship with the 1950, Vashi and Merh (1965) Sharma (1981), whole system. The present study is an attempt Valdiya (1988), Shastri(1989), Bartarya(1993), towards understanding different landforms of Joshi(2015) have found evidences of the the study area and the processes responsible tectonic and neotectonic processes in this for their existence. region lying in the Lesser Himalayan terrain. Starting from the top, these processes As a zone of recent folding and fracturing, large carry down the earth material in various forms. amount of sediment yield and mobilization The speed and rate of movement of every through different processes result in changing process varies with space and time. Thornbury landscapes and landforms in the mountainous (1993) has stated that geologic structure is a region. In the tectonically active areas, the dominant control factor in the evolution of mass wasting processes are more active. landforms and is reflected in them. The term Majority of the third, fourth and fifth order structure includes all the ways in which the streams flow along these lineaments and the earth materials differ from one another in their faults that are more susceptible to weathering, physical and chemical attributes. Attitude of slope failures and erosion. specific rocks, presence or absence of joints, Different levels of terraces, shifting of bedding planes, folds, faults, rock massiveness, streams, steep scarps are some of the very the physical hardness of the constituent common features of the Himalayan region. The minerals, the permeability of rocks and various landforms and the processes directly affect the other ways by which the rocks of the earth people living in the study area and indirectly crust differ from one another. These the entire country. Throughout the history of differences can be observed in different parts the evolution of the mighty Himalayas, these of the Lesser Himalayan region. Flowing in their processes have been active, have reshaped, youthful stage, the Himalayan streams differ and resized the landforms. Landforms from each other and; of course their drainage (particularly the landforms of tectonic origin) systems too. The drainage basin as a unit for have evolved through complex geomorphic studying the complex geomorphic processes E:\BHU\BHU.PM5 (304) Tectonic Processes and Landforms in the Lesser Himalayas : An experimental.... 305 Fig.1. Location of the study area may be helpful in quantitative geomorphologic and two fifth order streams. The area of the studies. Therefore, identification, location, drainage basin is about 125 km2.The area measurements and understanding different enjoys cool temperate climatic conditions. The types of landforms associated with tectonic stream flows from south to north and joins river activities in a lesser Himalayan drainage basin Kosi at Khairna . The basin area lies in Nainital are the objectives of the present study. district in the hill state of Uttarakhand. Most of The Study Area the southern part of the drainage basin is surrounded by Gagar Ninglat reserve forest. To study the complexities in landforms of Mukteshwer, a tourist destination is located in a particular area, drainage basin is the most the southeastern part of the drainage basin. practical unit, which is specifically helpful in Along the southwestern boundary lies Nainital, quantitative geomorphologic studies. In this famous tourist centre of Kumaun hills. The study, the selected area includes the drainage western boundary is formed by Naina Reserve basin of Khairna stream. The drainage basin forest. More than half of the drainage basin lies between 290 23' to 29031' North latitudes area is covered with forest. Agriculture is not and 790 25' to 79039' East longitudes in the a very profitable job in the steep hill slopes. Kumaun Lesser Himalayas (Fig. 1). All the Some patches of terraces are good to grow streams flowing within the Khairna stream are fruits and vegetables. Bhowali-Ramgarh and structurally controlled (Valdiya, K. S. 1988).The Khairna Garampani are the places growing Khairna river is a sixth order stream comprising fruits (apples, plums, peaches, khubani pears as many as 380 first,76 second 19 third 5 fourth etc.) and vegetables (capsicum, beans, brinjals E:\BHU\BHU.PM5 (305) 306 Jyoti Joshi peas, tomatoes, potatoes etc.). Two tributaries this deformation so commonly recorded in the of the Khairna stream namely Ninglat stream study area, mark the dominant lineation and and the Jakh gadhera are south-north flowing generally plunge at various angles due N to streams while the Ramgarh stream flows in NE.The eastern part of the study area is said east-west direction. The area is experiencing to be the lower part of Almora synform which serious environmental hazards related to the is constituted of two thrust sheets. Pande, instability of the hill slopes (Valdiya, K. S. 1988). (1950) recognized this as Ramgarh Nappe. The Khairna river basin has unique geologic and area constitutes of five major stratigraphcal geomorphic setting. groups namely Krol formation, Blaini formation, The Khairna stream and all its tributaries Upper Jaunsar formation, Lower Jaunsar are structurally controlled. The region is formation and the Ramgarh formation. Nine characterised by numerous mountain ranges, sub groups have been identified within these dissected valleys and undulating steep slopes. groups (Valdiya 1988). These groups have The deposition of terraces of different levels varied rock types ranging from volcanic, and