An Introduction to Mountains

1
An Introduction to Mountains

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

2
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.

3
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
  interiors.
• 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
  characteristics.

4
Importance of Mountains

• Mountains cover one-fifth of the Earth's land,
  and support ten percent of the Earth's
  population.
• 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
  diversity.
• Especially in developing countries, they include
  some of the poorest people in the world, with
  little access to education, markets, and
  decision-making power.

5
Geomorphology

• 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.

6
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.

7
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
  Incas.
• 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.

8
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
  mythology.
• 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.

9
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
  breath.
• 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
  sick.

10
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
  topography.
• 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.

11
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
  altitude.
• 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.

12
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
  precipitation.
• 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.

13
(No Transcript)
14
(No Transcript)
15
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.

16
Treeline High Mountains

• Treeline most dramatic ecotone krummholz
  (stunted tree). As a general rule, timberlines
  globally correspond with the 10 degree C July
  isotherm.
• Meadows and Tundra above the treeline the open
  meadows and tundra comprise a treeless plain,
  dominated by herbs and grasses and in some cases
  shrubs.
• 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.

17
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.

18
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
  ago.

19
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
  year.
• 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.

20
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
  terminus.
• 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.

21
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.

22
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
  species.
• 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
  (endemic).

23
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
  elevation.
• 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.,
  centuries).

24
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.

25
Vegetation Forms

• Mosaic of communities of different ages and
  compositions offer different habitats, but in the
  absence of fire the landscape becomes more
  homogenous.
• 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.

26
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.

27
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
  altitude.
• 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.

28
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
  meters/second.
• 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.

29
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.

30
Some Theoretical Foundations

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