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An Introduction to Mountains


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Title: An Introduction to Mountains

An Introduction to Mountains
  • Any part of a land mass which projects
    conspicuously above its surroundings (Websters
  • Definitions of Mountains
  • Importance of Mountains
  • Attitudes Towards Mountains
  • Mountains in Physical Geography
  • The Alpine Treeline Ecotone
  • Theoretical Frameworks for Studying Mountains

Definitions of Mountains
  • Subjective Mountains should be impressive, they
    should enter into the imagination of the people
    who live within their shadow, and they should
    have individuality (e.g., Mt. Fuji is benign and
    sacred, a symbol of peace and strength Mt. Etna
    is a devil, continually sending out boiling lava
    and fire to destroy farms and villages).
  • Objective Elevation, local relief, steepness of
    slope, and the amount of land in slope, dissected
    surface, structural origin, climatic and
    vegetation characteristics (i.e., ecology and
    topography are important) horizontal distances
    between ridges and valleys that establish the
    texture and framework for slope steepness
    delimited by geologic criteria, in particular,
    faulted or folded strata, metamorphosed rocks.
  • Mountains are features of construction, they are
    built and produced by some internal force. But,
    they can also be built by destructive forces like
    erosion that gives mountainous character to a
    strongly dissected plateau.

Mountain Landscapes
  • High Mountain Landscapes Alpine refers to a
    cold and windy zone above continuous forest, with
    rocky ridges and scattered tundra vegetation.
    The upper edge of the forest (the timberline) is
    generally lowest in the polar regions and rises
    in elevation toward the equator timberline tends
    to rise from coastal areas toward the continental
  • Geoecological Approach high mountains should
    rise above the Pleistocene snowline, the zone of
    rugged and serrated topography associated with
    mountain glaciers and frost action should extend
    above the regional timberline should display
    snow and ice processes such as frost-heaving and
    solifluction. High mountains are mountains which
    reach such altitudes that they offer landforms,
    plant cover, soil processes, and landscape

Importance of Mountains
  • Mountains cover one-fifth of the Earth's land,
    and support ten percent of the Earth's
  • More than one-half of humanity relies on fresh
    water that accumulates in mountains.
  • Mountains are also globally important as a
    tourism and recreation resource.
  • Mountain peoples, with thousands of years of
    experience living and working in their rugged
    environments, are stewards of irreplaceable
    global treasures of cultural and biological
  • Especially in developing countries, they include
    some of the poorest people in the world, with
    little access to education, markets, and
    decision-making power.

  • Most of the major mountain ranges are associated
    with plate boundaries and are uplifted as a
    result of plate collisions. Volcanic and seismic
    activity is also closely connected with mountain
    ranges. The process of mountain building arises
    from the movement of the earths crustal plates.
    The convergence of two or more plates causes
    buckling up of the intervening sediments and up
    thrusting to form upstanding relief. For
    example, the Himalayan arc, that was formed
    primarily around 30 millions years ago hard
    core mountains beneath softer marine sediments
    and one the latter are stripped off by erosion I
    is these hard igneous masses which form the
    highest peaks.
  • Landscape of mountains, consisting of dissected
    and differentially eroded surfaces with abundant
    steep slopes and high absolute and relative
    relief, creates an environment of high energy
    that gives rise to high rates of erosion.
    Mountains are characterized by a preponderance of
    high magnitude, low frequency major landslides,
    earthquakes and floods.
  • Main processes consist of frost action, glaciers,
    fluvial and mass movements. Weathering is
    important, particularly in humid tropical
    environments with high temperatures and abundant
    water, and Aeolian processes tend to be
    restricted to summits and arid zones where
    vegetation cover is restricted.

Attitudes Towards Mountains
  • Today, mountains are almost universally viewed
    with admiration and affection. But that has not
    always been the case.
  • The Prehistoric Era volcanoes and attitudes
    toward the fiery and destructive peaks were
    largely negative. Eruptions were interpreted as
    signs of the gods displeasure with the people,
    and so various cultures established elaborate
    taboos, ceremonies, and sacrifices to appease the
    wrath of the gods. Earthquakes often replaced
    volcanic eruptions as evidence of the violence
    and power of the gods who dwelled in the
    mountains and of their displeasure with mortals.
  • Primitive people often closely identified
    mountains with the weather the home of storms,
    lightning, strong winds, cold, and clouds.
    Physiological reaction to mountains through
    high-altitude sickness.

Culture Mountains
  • Mountains were also the home of great beasts
    the Abominable Snowman of the Himalayas and
    Sasquatch (Bigfoot) of the mountains of western
    North America. But also mountains as something
    positive givers of life since they were a
    source of water through rainfall and mountain
    streams. In Native American religion and
    imaginations, mountains were important the
    Blackfeet Indians sang of Going to the Sun
    Mountain where the sun, a principal deity, made
    its home.
  • Perhaps the most spectacular display the world
    has ever known of human settlement in mountains
    is found in the Andes of South America ancient
  • The Western Tradition Mountains were objects of
    veneration and symbols of strength and peace to
    the Hebrews of the Old Testament God often
    chose a mountain as the place to meet with one of
    his prophets Mt. Sinai and Mt. Zion.

Classical Medieval Times
  • Classical Heritage Homers Illiad mentions
    mountains chiefly in contexts that evoke their
    wildness and isolation. They are the haunts of
    nymphs, wild beasts the only men to frequent the
    lonely slopes are hunters and woodcutters. Mt.
    Olympus is the most prominent mountain in Greek
  • Medieval Fears During the Middle Ages
    superstitions held sway, and mountains were
    considered no better than grotesque wastelands.
    Dante made mountains the guardians of hell. By
    the end of the 17th century, on the verge of the
    Enlightenment, publications began to appear which
    supported the idea of a purposefully designed
    earth and the uses of mountains wildlife,
    minerals, scenery.

Far East Region the Modern Period
  • The Far East In Japan, China, Tibet, and India,
    mountains have long been adored and worshipped.
    Buddhism, Taoism, Confucianism, Shintoism, and
    Hinduism all incorporated mountains worship into
    their beliefs. In early Chinese culture, the
    mountain was considered to be the body of God,
    the rocks his bones, the water his blood, the
    vegetation his hair, and the clouds and mists his
  • The Modern Period Romantic adoration of
    mountains by arts and philosophers science began
    studying the origin of mountains tourist resorts
    sprang up and sanitariums were built to treat the

Physical Geography of Mountains
  • Climate and Mountains key influences on the
    nature and rates of geomorphological processes.
    Operates at different scales. Mountains can
    modify global atmospheric processes and generate
    their own climatic conditions thus affecting the
    climates of adjacent regions. Influences
    include latitude, altitude, continentality, and
  • Latitude affects solar radiation receipts,
    temperature, seasonality, and modifies the
    influence of altitude, causing treeline and
    snowline altitudes, and the occurrence of
    permanent snow and ice to descend polewards.
  • Pressure systems Equatorial low pressure (0-20
    NS), Subtropical High Pressure (20-40), Subpolar
    Low pressure (40-70), and Polar high pressure
    (70-90). High pressure zones tend to be drier,
    whereas low pressure zones tend to be wetter.
    Seasonality and the day length vary from the
    equator to the pole.
  • Impact of latitude on solar radiation concerns
    the height of the sun and the angle at which its
    rays hit the surface of the earth. Slope angle
    and slope aspect are therefore important. The
    influence of global circulation also contributes
    to precipitation.

Altitude, Position, Barriers
  • Altitude general trend with increasing altitude
    is a reduction in temperature, air density and
    pressure, proportions of carbon dioxide, water
    vapor and concentrations of impurities such as
    dust. The intensity of solar radiation, and
    especially the UV component, increases with
  • Continentality distribution of land and sea in
    relation to the location of mountains is
    important. Oceans have the effect of moderating
    climate. Coastal mountains tend to be wetter and
    cloudier due to the effect of humid air blowing
    onshore and being forces up, thus giving rise to
    precipitation. Continental interiors tend to be
    more extreme with greater temperature
    fluctuations occurring more rapidly, drier
    conditions, less cloud and consequently higher
    solar radiation receipts.
  • Topographic and Barrier Effects barriers and the
    importance of relief and mountain mass affecting
    air circulation.

Atmosphere Mountains
  • Temperature closely related to solar radiation
    wet (3.2 F/1000ft) and dry adiabatic
    (5.5F/1000ft) lapse rates. Greater cloud cover of
    mountains compared with lowlands as a result of
    uplift and condensation enhances the effect of
    thinner air and reduced heat retention.
  • Precipitation convectional and synoptic. The
    type and amount of precipitation depends on the
    moisture content of the air, the rate of ascent,
    wind speed, and degree of uplift orographic
  • Solar Radiation thinner air at higher elevations
    causes rapid fluctuations in the response of
    temperature to changes in solar radiation.
    Affected by cloudiness, aspect and topography.
    Snow cover increases surface albedo, reduces the
    absorption of energy, and so affects total
    radiation receipts. Rapid cooling of air and
    surfaces causes an increase in relative humidity,
    less evaporation, more condensation, and fog.
  • Winds occur at different scales winds are
    either synoptic or thermally induced. Chinook
    winds on the Great Plains as air clears over the
    Rockies. Thermally induced winds, mountain and
    valley winds, and other more locally modified
    winds such as glacier winds.

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Mountain Processes
  • High mountains are dominated by freeze-thaw,
    periglacial and glacial activity, intermediate
    slopes by erosion and deposition processes of
    glaciers and rivers as will as mass movements.
  • Glaciers they reached their last maximum during
    the Quaternary period. The last glacial maximum
    ended around 14,000 years ago.
  • Fluvial Action closely related to precipitation
    and to snow and ice melt and thus is variable in
    time and space.
  • Mass Movements soil creep, mudflows, snow
    avalanches, debris flows, slumps
  • Mountain Soils develop on summits from sediment
    collected in pockets and on slopes, anchored by
    vegetation and protected from high winds. They
    tend to be thin, stony and often low in nutrients
    and in need of improvement. Finer, deeper
    material accumulates in alluvial fans and in
    valley bottoms with a better developed A-horizon.
    Glacial tills provide the basis for many soils.
    In high alpine meadows, the development of dens
    meadow turf protects the surface as long as it
    remains intact. Excessive trampling or other
    surface disturbance can quickly lead to deep
    gullies once the turf mantle is broken.

Treeline High Mountains
  • Treeline most dramatic ecotone krummholz
    (stunted tree). As a general rule, timberlines
    globally correspond with the 10 degree C July
  • Meadows and Tundra above the treeline the open
    meadows and tundra comprise a treeless plain,
    dominated by herbs and grasses and in some cases
  • Wildlife in poorly developed ecosystems, its
    advantageous for species to be more generalist in
    their habitat preferences to maximize options for
    survival. Faunas tend to be dominated by
    rodents, scavengers, and insects. Life resolves
    around an alternating life of feast or famine.
    Some larger mammals are well able to cope with
    hypoxia lamas and alpaca.
  • Human Physiology one of the most important
    parameters for determining stress to human
    biology is the fact that atmospheric pressure
    reduces with altitude and limits the
    oxygen-absorbing capacity of the blood. With the
    decline in pressure the process by which oxygen
    is bound into the hemoglobin in the bloodstream
    does not work so efficiently. This is known as
    hypoxia, normally encountered at 2500 meters at
    which oxygen stress can be clearly identified.

Snow, Glaciers, Snow Avalanches
  • Snow precipitation in the solid form that
    originates from freezing of super-cooled water
    around tiny nuclei of foreign matter, especially
    clay minerals, in the air. They grown through
    condensation, and diminish through evaporation
    often a hexagonal pattern of the snowflakes.
  • Polar areas, sub-polar areas, and mid-latitudes
    snow fall.
  • Behavior of fallen snow densification through
    freeze-thaw and firn (i.e., dense snow at least
    1-yr old).
  • Snowline zone between seasonal snow that melts
    every summer and the permanent snow that does not
    melt each summer regional snowline represents
    the minimum elevation where a glacier may form
    generally lowest in areas of heavy precipitation.

Glaciers Masses of Moving Ice
  • Mass of moving ice created by the accumulation of
    snow transformation of snow into ice is a
    process of densification and expulsion of air,
    which is accomplished by sublimation, melting,
    refreezing, and compaction.
  • Firn is an intermediate stage ion the progress
    towards glacial ice.
  • Glacial retreat height of the ice age was
    1,000-yrs ago cirque glaciers, ice-fields,
    valley glaciers, piedmont glaciers.
  • The Pleistocene represents 2.5 million years of
    major fluctuations in the environment at least
    4-major advances of ice.
  • We are now in an interglacial period, after the
    last major ice advance melted about 15,000 years

More on Glaciers
  • The annual snowline or firn limit represents the
    maximum extent of summer melting. from a mass
    balance perspective, it is the equilibrium line
    and the concept of steady state. the equilibrium
    line marks the zone on the glacier where the mass
    of the glacier stays nearly the same during the
  • Periods of environmental change following the
    final advance, a warm and dry period ensued
    (hypsithermal) that last from 4,000 10,000
    years ago the next major change was a widespread
    advance of mountain glaciers, 2000-4,000 years
    ago, followed by a warming trend of about 1,000
    years, which was followed by a period of glacial
    advance during the Little Ice Age in the 17th
    and 18th centuries.

Glacial Movement
  • Determined by the thickness of the ice, its
    temperature, the steepness of the glacial
    surface, and the configuration of the underlying
    and confining topography.
  • In general, the greatest movement of the ice
    takes place in the center of the glacier and
    decreases towards the edges longitudinally,
    greatest at the center and least at the head and
  • The area above the equilibrium line is the zone
    of accumulation, and the area below the line is
    the zone of ablation.
  • Glacier surges move through plastic flow and
    basal sliding water as a lubricant abrasions
    and striations left on the bedrock are evidence
    of glacial movement.

Glacier Structure, Erosion, Associated
Landscape Features
  • Crevasse and tensional stress increase
    efficiency of rock transport and hasten ablation,
    danger of snow-bridges, conspicuous features
    (e.g., lateral moraines, cirques, aretes, horns,
    U-shaped valleys, hanging valleys, patternoster
    lakes, and more).
  • Primary erosion processes are abrasion and
    plucking upstream side of bedrock overrun by a
    glacier is smoother and gentle, while the
    lee-side becomes steep and irregular.
  • Erosional and depositional features.
  • Snow avalanches (loose snow and slab avalanches),
    avalanche triggers, snow avalanche paths,
    vegetation and geomorphic processes.

Mountain Vegetation
  • Mountains display the most rapid and striking
    changes in vegetation of any region on earth
    they serve as pathways for plant migration,
    because they extend into areas of lower
    temperature and provide an environment more like
    that found near the poles.
  • Mountains act as barriers to the migration of
  • Isolated peaks often serve as mainland islands
    with many of the biogeographic characteristics of
    oceanic islands.
  • Migration is hindered to or from mountains,
    therefore, species have a limited gene pool that
    receives little infusion from the outside.
  • Adaptation becomes adjusted primarily to local
    conditions evolution frequently results in the
    creation of species found only on the mountain

Mountains Vegetation Species
  • The number of plant species decrease with
    increasing elevation.
  • Tendency is toward smaller and less elaborate
    plants with slower growth rates, decreased
    productivity, decreased plant diversity, and less
    interspecies competition with increasing
  • The primary characteristic of mountain vegetation
    is the presence of sequential plant communities
    with increasing altitude.
  • Climax community is the culminating stage in
    natural plant succession where a complex of
    species is so well adjusted to each other that
    they are able to reproduce and maintain
    themselves for long periods of time (e.g.,

Mountain Forests
  • Consist of three dominant life forms
    needle-leaf evergreen conifers, broad-leaf
    evergreen, broadleaf deciduous.
  • Needle-leaf conifer grows primarily in middle and
    higher latitudes of the northern hemisphere.
  • Broad-leaf evergreens tend to be dominant in warm
    and humid regions with small temperature ranges.
  • Conifers dominant in the higher reaches of
    elevation and latitude (e.g., the boreal forest
    that stretches in an almost unbroken band across
    North America and Eurasia.
  • Photosynthesis as soon as conditions permit no
    new leaves to grow.

Vegetation Forms
  • Mosaic of communities of different ages and
    compositions offer different habitats, but in the
    absence of fire the landscape becomes more
  • Mountain meadows are generally maintained by
    either poor drainage, excessive fire, snow, or
    wind meadow invasion by conifers due to
    environmental change.
  • Timberline is the transition from forest to
    tundra, one of the most dramatic ecotones on
    earth suggests a transition from closed canopy
    forest to treeless tundra upper limit of erect
    trees represented by scattered clumps of trees or
    isolated individuals krummholz is the upper
    limit of stunted and deformed trees.
  • In general, timberlines are lower in marine
    locations and higher in continental areas
    dominance of evergreen species and some deciduous.

More on Alpine Treeline
  • Patterns at treeline are characterized by
    different life forms, but a prostrate form is
    common flagging, tree islands, ribbon forests
    separated by snow glades (occurring at right
    angles to the prevailing wind that tends to pile
    snow up in drifts deep snow accumulation
    inhibits forest encroachment.
  • Causes of treeline excessive snow, strong
    winds, poor or excessive drainage, lack of soil,
    recent disturbance sunshine, high temperatures,
    and high degrees of ultraviolet radiation that
    can restrict tree growth animals eat leaders,
    humans and fire (e.g., native Americans).
  • Inability of shoots to ripen when they freeze or
    dry out most plants are perennials at the alpine
    tundra most are evergreen and have large and
    extensive root systems reproduction of tundra
    and alpine plants through pollination can be
    limited by the short growing season and late
    lying snow patches plants can reproduce through
    rhizones, i.e., root-like stems that run out from
    the plant with the ability to send up new shoots.

Landforms Geomorphic Processes
  • Mountains are rapidly worn-down (denudation) and
    can never be very old compared to the vastness of
    geologic time erosion increases with increasing
  • The form, structure, and material composition of
    mountains greatly affects the rate and type of
    geomorphic processes.
  • The horizontal or vertical orientation of rock as
    well as the nature of the rock type have major
    impacts on landscape development.
  • Nivation is a combination of frost action and the
    downslope movement of earth material by gravity
    (mass-wasting) often resulting from the presence
    of snow patches best developed at treeline and
    the narrow transition between the glacial and the
    periglacial environments.

Mass Wasting
  • Downslope movement of material due to gravity
    creep is the slow movement frost creep is the
    downslope movement as the result of frost heaving
    and settling upon thawing.
  • Solifluction (to flow) essential elements
    include water, soil texture, slope gradient, rock
    type, and vegetation.
  • Mudflows is the massive failure of large sections
    of slopes and often confined to a definite
    channel, high speed of movement, up to several
  • Conditions for mudflows abundant water, land of
    stabilizing vegetation, unconsolidated material
    with enough fines to serve as lubrication, and
    moderately steep slopes.
  • Slumping (slippage of unconsolidated material)
    rockfall the falling of rock from a cliff or
    headwall landslides and debris avalanches.

Features of Mass-Wasting
  • Talus is an accumulation of rocks at the base of
    cliffs, headwalls, or steep slopes falling rocks
    come to rest to form a ramp or rock apron also
    known as scree or a rock debris slope.
  • Talus slope is determined by the supply of
    material, movement of material within the talus,
    and removal of material.
  • Protalus rampart is an accumulation of rocky
    debris found near the base of a slope, but
    separated from it by a small trough or
    depression best developed above treeline in
    shaded spots near steep rock walls or in cirques
    where there is ample rock material and where
    abundant snow accumulates and melts slowly they
    resemble glacial moraines in that they occur as
    sinuous ridges.
  • Rock glaciers are accumulations of rocky debris
    with a form similar to that of true glaciers.

Some Theoretical Foundations
  • A Systems Approach
  • Hierarchy Theory
  • Complexity Theory
  • See the course outline for details.
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