World Geography

MOUNTAINS

Overview

• A mountain is a large landform that stretches above the surrounding land in a limited area
• Mountains are sometimes referred to by the Greek name: montes or mons (singular)
• The highest mountain on earth is Mount Everest (8848 m)
• The highest mountain in the solar system is Olympus Mons on Mars (21,171 m)
• Mountains cover 24% of earth’s land mass
• The study of mountains is called Orology

Characteristics of mountains

• Mountains are colder than lower ground because the Sun heats the Earth from the ground up.
• When the Sun’s rays travel through the atmosphere and reach the ground, the earth absorbs the heat. In general air closest to the earth’s surface is warmest
• Air temperature usually decreases 1-2 C for every 300 m of altitude
• The flora and fauna in tall mountains tend to be isolated to one particular altitude zone. These isolated ecological systems are called sky islands.
• The peak shape of mountains is produced by glaciation and erosion through frost action
• As altitude increases, the atmospheric pressure decreases. Thus, although the percentage of oxygen remains constant (21%), the amount of oxygen decreases.
  
• Altitude sickness (aka Acute Mountain Sickness) is caused by lack of oxygen at high altitudes. Altitude sickness can lead to High Altitude Pulmonary Edema (HAPE) or High Altitude Cerebral Edema (HACE)
  
• Availability of oxygen decreases significantly over 3000 m (10,000 ft). for this reason, the cabin altitude in passenger aircraft is kept to 8000 ft
• Higher altitudes also mean lesser protection to UV radiation
  

Formation of mountains

• Mountains are usually produced by the movement of lithospheric plates
• Major mountains tend to occur along long linear arcs, indicating tectonic plate boundaries
• Compressional forces in continental collisions cause the compressed region to thicken and force the upper surface upwards
• Meanwhile, in order to balance the weight, much of the compressed rock is forced downwards as well, forming deep “mountain roots”. As a result, mountains form upwards as well as downwards.

Types of mountains

• Fold Mountains
  • Formed by the effects of folding on layers within the upper part of the earth’s crust
  • Fold mountains are generally formed on the less deformed areas adjacent to areas strongly affected by thrust tectonics
  • Most fold mountains are likely to relative young in geological terms since they will start to erode as soon as they are formed
  • Examples: Zagros mountains (Iran), Jura mountains (near the Alps i.e. France, Switzerland, Germany)
• Fault-block mountains
  • Formed when large areas of bedrock are broken up by faults creating large vertical displacements of continental crust
  • These mountains are formed by the crust being stretched and extended by tensional forces
  • The uplifted blocks are called block mountains or horsts. The intervening dropped blocks are called graben, and can form extensive rift valleys
  • Examples: Vosges (northeast France), Basin and Range (western USA)
• Volcanic mountains
  • Isolated mountains produced by volcanoes
  • Includes small islands that reach great heights beyond the ocean floor
  • Example: Mount Kilimanjaro (Tanzania)
• Inselberg (or Monadnock)
  • They are isolated hills or small mountains that rise abruptly from a surrounding plain
  • They arise when a rock resistant to erosion is enclosed within a softer rock like limestone. When the limestone erodes away to form the nearby plains, the resistant rock is left behind as an island-mountain
  • Example: sugarloaf mountain (Brazil), Pilot Mountain (USA)

The Seven Summits

• The Seven Summits are the highest mountain peaks of each of the seven continents
• The Seven Summits are
  • Africa: Mount Kilimanjaro – Tanzania
  • Antarctica: Vinson Massif – British Antarctic Territory
  • Australia: Kosciuszko – Australia
  • Asia: Mount Everest – Nepal, Tibet
  • Europe: Elbrus – Russia
  • North America: Mount McKinley (Denali) – Alaska
  • South America: Aconcagua – Argentina

Important Mountain ranges in the world

Mountain Range	Location	Length (km)	Notes
Mid ocean ridge		65,000	Underwater mountain range Longest mountain range in the world Demarcates boundary b/w tectonic plates Consists of seven ridges connected together: Gakkel Ridge, Mid Atlantic, Southwest Indian, Central Indian, Southeast Indian, Pacific Antarctic, East Pacific Rise
Andes	South America	7000	Longest continental mountain range Highest mountain range outside Asia
Rocky	North America	4800
Himalayas	Asia	3800	Highest mountain range on earth Includes Karakoram, Hindu Kush Separates Indian subcontinent from Tibetan plateau
Great Dividing Range	Australia	3700
Transantarctic Mountains	Antarctica	3500	Serve as division b/w East Antarctica from West Antarctica

Important Mountain peaks in the world

Mountain peak	Height (m)	Mountain Range	Location	Notes
Mount Everest	8848	Himalayas	Nepal/ Tibet	Highest mountain on earth
K2 (Mt. Godwen-Austen)	8611	Karakoram	Pakistan/China	Second highest mountain Second highest fatality rate (25%)
Kangchenjunga	8586	Himalayas	Nepal/India	Highest in India
Annapurna	8091	Himalayas	Nepal	Highest fatality rate (40%)
Aconcagua	6961	Andes	Argentina	Highest mountain outside Asia
Mt. Kilimanjaro	5895	Kilimanjaro	Tanzania	Highest volcanic mountain Highest in Africa
Mt Erebus	3794		Antarctica (Ross Island)	Southernmost active volcano
Mt Chimborazo	6268	Andes	Ecuador	Point on surface most distant from earth’s centre

Important Mountain ranges in India

Mountain range	Location	Notes
Himalayas
Aravalli	Rajasthan, Haryana, Gujarat	Were extremely tall in ancient times, now completely worn down due to weathering
Vindhyas	Gujarat, Madhya Pradesh	Earliest known fossil of eukaryotes discovered here (1.6 billion years)
Satpura	Gujarat, Maharashtra, Madhra Pradesh, Chattisgarh
Sivalik Hills	Sikkim, Nepal, Uttarakhand, Kashmir, Pakistan	Southernmost and geologically youngest of the Himalayan system
Eastern Ghats	West Bengal, Orissa, Andhra Pradesh, Tamil Nadu	Discontinuous range of mountains Older than Western Ghats
Western Ghats	Gujarat, Maharashtra, Karnataka, Kerala, Tamil Nadu	60% of Western Ghats located in Karnataka Rivers from Western Ghats drain 40% of India One of world’s ten “Hottest Biodiversity Spots”
Nilgiri Hills	Tamil Nadu	UNESCO World Heritage Site
Anamalai Hills (Western Ghats)	Kerala, Tamil Nadu	Under consideration for UNESCO World Heritage Site
Cardamom Hills (Western Ghats)	Kerala, Tamil Nadu	Under consideration for UNESCO WHS
Southwest Indian Ridge	Indian Ocean	Separates African Plate from Antarctic Plate
Central Indian Ridge	Indian Ocean	Boundary between African Plate and Indo-Australian Plate
Southeast Indian Ridge	Indian Ocean	Separates Indo-Australian Plate from Antarctic Plate

Important Mountain peaks in India

Mountain peak	Mountain range	Location	Notes
Kangchenjunga	Himalayas	Sikkim	Highest peak in India Third highest in the world
Nanda Devi	Himalayas	Uttarakhand	Highest peak entirely within India
Anamudi	Anaimalai Hills (Western Ghats)	Kerala	Highest peak in India outside the Himalayas
Mount Abu	Aravalli Hills	Rajasthan	Highest peak in the Aravallis