Mysore Plateau: Southern India’s Upland Landscape

The Mysore Plateau, also called the South Karnataka Plateau, forms the elevated interior around Mysuru, Bengaluru, Mandya, Hassan, Tumakuru, Kolar, and adjoining districts. It belongs to the wider Deccan Plateau, but its geology differs from the lava-covered plateaus farther north. Much of its surface rests on old granites, gneisses, schists, and related crystalline rocks.

This is not a level tableland. Broad plains alternate with shallow valleys, rocky ridges, isolated hills, weathered rock surfaces, and locally incised river corridors. Much of the plateau lies between about 700 and 900 metres above sea level, although lower valleys and hills above 1,000 metres create considerable local relief.

A Regional Name With Flexible Edges

The plateau does not have a surveyed boundary like a state or district. Its limits are based on changes in elevation, relief, drainage, rock type, and regional naming. This produces slightly different outlines on physical, geological, and educational maps.

Its clearest western transition is toward the Malnad, the wetter and more rugged belt beside the Western Ghats. The ground generally becomes steeper and more dissected as it approaches the Ghats. To the south, the plateau meets hill systems connected with the Nilgiris, Brahmagiri Hills, and Biligirirangan Hills.

The eastern side is less sharply enclosed. Rolling uplands continue toward the Karnataka-Tamil Nadu border, where isolated hill masses and sections of the Eastern Ghats interrupt the surface. Northward, the Mysore Plateau gradually loses its separate identity within the wider Karnataka Plateau.

A High Surface That Rolls Rather Than Lies Flat

The term plateau describes the region’s position above surrounding lowlands, not a perfectly flat surface. The dominant landform is an old, gently rolling erosional surface broken by valleys and resistant rock outcrops.

Pediplains and Pediments

Large areas consist of pediplains, broad low-relief surfaces created as weathering and erosion reduced earlier hills. Pediments form gently inclined rock surfaces near the foot of residual hills. Soil or weathered rock may cover them, making their underlying form difficult to see from ground level.

Residual Hills and Inselbergs

Rocky hills rise abruptly above the gentler terrain in many districts. These features remain where resistant granite, gneiss, or other hard rock weathered more slowly than its surroundings. Some appear as rounded domes, while others form narrow ridges or boulder-covered summits.

Chamundi Hill near Mysuru and the rocky hills around Bengaluru illustrate this contrast between resistant high ground and the surrounding planed surface. Such hills are parts of the plateau landscape rather than separate mountain systems.

An Uneven Elevation Pattern

The plateau generally stands higher in the Bengaluru area, where broad uplands commonly approach 900 metres. The Mysuru and Mandya sectors often occupy somewhat lower surfaces and river valleys. Elevation rises again toward the Western Ghats and southern hill belts.

This pattern creates local drainage divides. Water falling near Bengaluru, for example, may enter the Arkavati-Kaveri system, the South Pennar system, or smaller eastern drainage routes depending on the slope.

Ancient Crystalline Rock Beneath a Younger Landscape

The Mysore Plateau is part of the old continental crust of southern India. Its foundation includes rocks associated with the Dharwar Craton, one of the oldest preserved crustal regions on Earth. Many of its gneisses, granites, schists, and volcanic-derived metamorphic rocks formed billions of years ago.

The age of the bedrock is not the same as the age of the visible plateau surface. Today’s rolling terrain developed through long periods of chemical weathering, erosion, regional uplift, faulting, and river incision.

How the Present Upland Developed

Some fractures and shear zones in the basement influence modern valleys. Rivers may follow these weakened rock corridors, change direction along them, or cut narrow passages where a channel crosses a resistant ridge.

Kaveri Turns the Plateau Into a Drainage System

The Kaveri River provides the main drainage structure of the Mysore Plateau. It begins in the Brahmagiri Hills of Kodagu, crosses the southern Karnataka uplands, and continues east into Tamil Nadu. Most of the plateau’s best-known rivers either join the Kaveri or occupy nearby drainage divides.

Why Most Water Moves East

The Western Ghats form the high western rim of peninsular India. From this divide, much of the plateau surface slopes broadly eastward. The Bay of Bengal is farther away than the Arabian Sea, yet the regional tilt sends the Kaveri and many other peninsular rivers east.

The drainage is commonly dendritic to sub-dendritic, with tributaries branching in patterns that resemble a tree. Local channels become straighter where fractures, dykes, or structural lines control their course.

Falls, Gorges, and Rock Steps

The Kaveri does not descend across a smooth ramp. Resistant rock bands, faults, and changes in channel gradient create abrupt sections. At Shivanasamudra, the river divides and drops across rocky steps. Farther upstream from the Tamil Nadu border, the river narrows through the bedrock passage at Mekedatu.

These features show that a plateau can contain steep river scenery even where the regional surface has gentle relief.

Rainfall Changes Across the Upland

The plateau has a tropical monsoonal climate, but elevation and distance from the Western Ghats create strong local differences. Moist air from the Arabian Sea rises over the Ghats and releases heavy rain on the western slopes. Air moving onto the interior plateau has already lost part of its moisture.

The western margins around Kodagu and Hassan are therefore wetter than the central and eastern interiors. Mandya, eastern Mysuru, Bengaluru Rural, Kolar, and nearby uplands have longer dry periods and depend more heavily on stored surface water and groundwater.

Most rain falls during the southwest monsoon, although retreating and northeast monsoon systems also contribute, especially toward the eastern and southeastern plateau. Year-to-year totals can vary widely.

Elevation Moderates Temperature

High elevation gives Bengaluru, Mysuru, and other plateau settlements milder average conditions than many nearby coastal and lowland locations at similar latitudes. Hot pre-monsoon afternoons still occur, but nights are often cooler than on the coastal plains.

Vegetation Follows the Moisture Gradient

Moist and semi-evergreen forests occur near the Western Ghats and wetter hill margins. Drier deciduous woodland, scrub, grass, farmland, and open rocky ground become more common toward the interior. River valleys and reservoirs add narrow belts of wetter habitat within otherwise seasonally dry terrain.

Hard Rock Controls Soil, Groundwater, and Farming

Crystalline rocks contain little primary pore space. Groundwater is held mainly in the weathered mantle and in connected joints, fractures, and shear zones. A borehole that intersects a productive fracture can yield useful water, while another nearby borehole may encounter relatively solid rock.

Valley floors, buried channels, fractured zones, and deeper weathered pockets often store more groundwater than exposed rocky uplands. Recharge depends on rainfall, soil thickness, slope, surface cover, and the connection between fractures.

Soils Reflect Both Rock and Relief

• Red loamy and red sandy soils are widespread over granite and gneiss terrain.
• Lateritic soils occur on some old weathered surfaces and upland caps.
• Clay-rich soils collect in valley floors, old depressions, and low-gradient basins.
• Dark soils occur locally but do not cover the entire Mysore Plateau.
• Thin, stony soils are common around residual hills and exposed bedrock.

Water Storage Reshapes Land Use

Seasonal rainfall encouraged the construction of tanks, canals, and reservoirs. Chains of tanks capture runoff from small catchments, while larger projects store water from the Kaveri and its tributaries. Krishnarajasagara, Kabini, Hemavati, and Harangi are prominent parts of this managed water system.

Ragi, pulses, oilseeds, and some hardy horticultural crops suit drier rain-fed areas. Paddy and sugarcane are concentrated where irrigation and deeper valley soils provide dependable moisture. Mulberry, coconut, vegetables, and fruit crops occur in many cultivated districts, while coffee becomes more common near the wetter western highlands.

Cities and Routes Occupy the Gentler Surface

The relatively open surface has supported dense settlement and easier overland travel compared with the steep Western Ghats. Bengaluru occupies one of the higher eastern parts of the plateau, while Mysuru stands on a lower rolling surface near the Kaveri and Kabini drainage network.

Roads and railways generally follow broad divides, pediplains, and low-gradient corridors. Routes toward the west must cross the more rugged Malnad and Western Ghats through passes and deeply cut valleys. Southward connections encounter the Nilgiri and associated hill systems.

Urban growth also changes how the plateau handles rain. Buildings and paved surfaces increase rapid runoff, while altered valleys and tank connections can redirect water from its earlier pathways. The underlying rock still controls where deeper infiltration and groundwater storage are possible.

How the Plateau Relates to Nearby Landforms

Recognizing the Mysore Plateau on a Physical Map

Elevation shading alone may not display the plateau clearly because its boundaries are gradual. Several map clues work better when used together:

1. Locate southern Karnataka between the Western Ghats and the uplands near the Tamil Nadu border.
2. Find Bengaluru and Mysuru, which occupy different elevations on the same broad interior upland.
3. Trace the Kaveri eastward and identify its branching tributary network.
4. Look for the sharp rise toward the Western Ghats and Nilgiri highlands.
5. Note the scattered hill symbols within the plateau rather than expecting an unbroken flat surface.
6. On a geological map, look for crystalline basement rocks instead of the broad basalt sheets common farther north.

Satellite images add another clue: cultivated plains and expanding urban areas are repeatedly interrupted by dark rocky hills, reservoir basins, branching valleys, and forested upland margins.