Physiography of Meghalaya
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.