Formation of Himalaya

Shifting of Indian plate

Block Diagram of The Himalaya

The Nepal Himalaya

• The longest division of the Himalaya
• Extended about 800 Km
• Starts from west at the Mahakali River
• Ends at the east by the Tista River

Longitudinal Division of Himalayan Range

Terai Zone (Gangetic Plain)

• Northern Terai
(Bhabhar Zone)
• Middle Terai
(Marshy) Zone
• Southern Terai Zone

Major problems in terai zone

• Flood
• Liquifaction
• Bank cutting
• Subsidences

Himalayan Frontal Thrust (HFT) Separating Terai (S) from Siwaliks (N) at Butwal

The Sub-Himalayan Zone (Siwaliks)

• Delimited on the south by the Main Frontal Thrust (MFT) and on the
north by the Main Boundary Thrust (MBT)
• Fluvial deposits of 23 Ma to 1.6 Ma old
Siwaliks can be classified as
• Lower Siwaliks (Greenish grey fine-grained sandstone and siltstone
with mudstone)
• Middle Siwaliks (Medium to coarse-grained salt-and-pepper
sandstones with colorful mudstone)
• Upper Siwaliks (Conglomerate and boulder beds and
subordinately sand and silt beds)

Main Boundary Thrust (MBT) in Dang

Major problems in Siwaliks

• Mass movement
• Erosion
• Weathering

Lesser Himalayan Zone

This zone Mainly contains
• Unfossiliferous, sedimentary, and metasedimentary rocks:
Such as slate, phyllite, schist, quartzite, limestone, dolomite, etc of very old
age (1600 Ma to 22 Ma)
• There are also some granitic intrusions in this zone
• In Eastern Nepal, high grade metamorphic rocks (gneiss and
schist)
• In Central Nepal, Medium to high grade metamorphic rocks
• In western Nepal around Gandaki and Bheri River, Low
grade of metamorphic rocks (quartzite, slate, and phyllite)
• In Far western Nepal, again high metamorphic rocks are
reappear.

Major problems in lesser Himalaya

• Mass movement:
• Rock slide,
• Rock fall
• Rock toppling
• Debris avalanche,
• Deep gully erosion,
• Wedge failure
• Flash flood

Main Central Thrust (MCT) at Myagdi

Higher Himalayan Zone

• Mainly consists of strongly metamorphosed rocks
• Separated with Tibetan-Tethys Zone by Normal
Faults
• Gneisses, schists, quartzites and marbles and
granites

Major problems of Higher Himalaya

• Mass movement
• GLOF
• Snow avalanches

Tibetan-Tethys Himalayan Zone

• It begins from the top of the Higher Himalayan
Zone and extends to the north in Tibet
• Well-developed in Mustang, Manang and Dolpa
area
• Composed of sedimentary rocks, such as shale,
limestone, and sandstone, ranging in age from 550
Millions age to 23 Millions age