Physiography of Meghalaya and Major Physiographic Divisions
Meghalaya occupies an important position in the physical geography of Northeast India. Much of the state corresponds geographically with the Meghalaya Plateau, an ancient upland mass that forms a detached extension of the Peninsular Plateau. The plateau lies between the Brahmaputra Valley in the north and the plains of Bangladesh in the south. Its relief is characterized by plateaus, hills, escarpments, deeply dissected valleys, gorges and waterfalls.
Geological and Physiographic Background
The Meghalaya Plateau is an ancient crystalline upland. Its core is largely composed of old Precambrian rocks, including gneisses, granites and other crystalline formations. Younger sedimentary formations occur particularly along parts of its margins.
The plateau is regarded as a detached northeastern extension of the Indian Peninsular Plateau. Its present relief has been shaped by prolonged geological processes, including uplift, faulting, weathering, erosion and river incision.
A striking characteristic of the Meghalaya Plateau is the contrast between its northern and southern margins. The southern margin generally forms a steep escarpment, while the northern and western portions are comparatively more dissected by streams and valleys.
Major Physiographic Divisions
For geographical study, Meghalaya may broadly be divided into three major hill regions:
1. Garo Hills
The Garo Hills occupy the western part of Meghalaya. They are comparatively lower and more dissected than the central Khasi uplands.
The terrain consists of numerous hills, ridges and valleys. The Nokrek Peak, rising to about 1,412 metres, is the highest point of the Garo Hills.
The Garo Hills gradually descend towards the Brahmaputra Valley in the north and the plains of Bangladesh towards the south. Numerous rivers and streams have dissected the landscape, producing a highly varied relief.
2. Khasi Hills
The Khasi Hills constitute the central and most elevated part of Meghalaya. They contain some of the most spectacular plateau landscapes of the state.
The Shillong Plateau forms an important part of this region. Shillong Peak, near the state capital, reaches approximately 1,965 metres and represents the highest elevation of Meghalaya.
The Khasi Hills are characterized by:
• High plateaus and rounded hills
• Deep valleys and gorges
• Steep southern escarpments
• Numerous waterfalls
• Extensive limestone formations in several areas
The southern slopes receive exceptionally heavy monsoonal rainfall. Places such as Cherrapunji (Sohra) and Mawsynram are consequently associated with some of the world’s highest recorded rainfall.
3. Jaintia Hills
The Jaintia Hills occupy the eastern part of the Meghalaya Plateau. They form a transition between the Khasi uplands and the hills and valleys farther east.
The region has a dissected topography consisting of plateaus, hills, valleys and river gorges. Limestone is particularly important in parts of the Jaintia Hills and has contributed to the development of caves and other karst features.
The Jaintia Hills are also drained by several important rivers and streams that have deeply cut the plateau surface.
Relief and Drainage
The physiography of Meghalaya is closely related to its drainage system. Rivers have deeply dissected the plateau, producing narrow valleys, gorges and waterfalls.
The southern slope is particularly notable for its steep descent towards the plains of Bangladesh. Short but powerful rivers flowing southward have created spectacular waterfalls and deeply incised valleys.
Important rivers associated with Meghalaya include the Umiam, Myntdu, Umngot, Kynshi, Simsang, Ganol and Jadukata.
The drainage pattern therefore contributes significantly to the rugged appearance of the Meghalaya landscape.
Southern Escarpment
One of the most distinctive physiographic features of Meghalaya is its southern escarpment.
The plateau rises prominently above the plains of Bangladesh and then descends sharply towards the south. This escarpment has been modified by erosion and river action. Numerous streams flowing over the escarpment have produced waterfalls and gorges.
The steep southern face also has an important climatic influence. Moisture-laden monsoon winds from the south are forced to rise over the elevated terrain, contributing to very heavy rainfall in the southern Khasi Hills.
Valleys, Gorges and Waterfalls
Meghalaya’s rugged relief has been strongly modified by erosion. Rivers and streams have cut deep valleys and gorges through the plateau.
The combination of:
• resistant crystalline rocks,
• intense rainfall,
• steep slopes, and
• strong river erosion
has produced numerous waterfalls.
Some of the important waterfalls include Nohkalikai Falls, Nohsngithiang Falls and Langshiang Falls. These features are not only physiographic attractions but also contribute to the state’s tourism potential.
Caves and Karst Topography
Limestone formations in parts of Meghalaya have produced extensive karst landscapes. Solution of limestone by groundwater has resulted in caves, sinkholes, underground drainage and other distinctive landforms.
Meghalaya is internationally known for its extensive cave systems, particularly in the Khasi and Jaintia Hills.
The development of limestone caves demonstrates the interaction between geological structure, rock type, rainfall and groundwater processes.
Altitudinal Variation
The elevation of Meghalaya varies considerably from the low-lying peripheral areas to the high central plateau.
The Shillong Plateau and Khasi Hills contain some of the highest elevations, while the Garo Hills and surrounding valleys generally have lower elevations. This altitudinal variation influences:
• temperature,
• rainfall,
• natural vegetation,
• agriculture,
• settlement patterns, and
• transportation.
Thus, relief is an important factor in determining the geographical character of the state.
Physiographic Characteristics of Meghalaya
The major characteristics of Meghalaya’s physiography can be summarized as follows:
1. Ancient plateau region – Meghalaya forms part of an old crystalline plateau system.
2. Hilly and dissected terrain – The plateau has been extensively dissected by erosion.
3. Three major hill regions – Garo, Khasi and Jaintia Hills form the principal physiographic units.
4. High central uplands – The Khasi-Shillong region contains some of the highest elevations.
5. Steep southern escarpment – The plateau drops sharply towards the Bangladesh plains.
6. Deep valleys and gorges – Intense river erosion has produced numerous valleys and gorges.
7. Numerous waterfalls – Heavy rainfall, steep gradients and resistant rocks favour waterfall formation.
8. Limestone and karst features – Caves and other karst landforms are widespread in limestone-bearing areas.
9. Strong influence of monsoon – Relief strongly influences the distribution of rainfall.
10. Close relationship between relief and human activities – Physiography affects agriculture, settlement, transportation and economic development.
Conclusion
The physiography of Meghalaya is the product of its ancient geological foundation, tectonic movements, prolonged denudation, river erosion and exceptionally heavy monsoonal rainfall. The Meghalaya Plateau, with its Garo, Khasi and Jaintia Hills, presents a distinctive combination of uplands, escarpments, valleys, gorges, waterfalls and karst landscapes.
The Khasi-Shillong highlands, the Garo Hills in the west, the Jaintia Hills in the east, and the steep southern escarpment together form the principal elements of Meghalaya’s physical landscape. The physiography also exercises a strong control over the state’s climate, drainage, vegetation, agriculture, settlements and economic activities.
Therefore, the physical geography of Meghalaya cannot be understood merely as a system of hills and plateaus; it represents a close interaction between geological structure, relief, climate, drainage and human adaptation.