G C Leong Summary - BureaucratONE

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1 THE EARTH AND THE UNIVERSE

2 THE EARTH'S CRUST

3 VOLCANISM AND EARTHQUAKES

4 WEATHERING, MASS MOVEMENT AND GROUNDWATER

5 LANDFORMS MADE BY RUNNING WATER

6 LANDFORMS OF GLACIATION

7 ARID OR DESERT LANDFORMS

8 LIMESTONE AND CHALK LANDFORM

9 LAKES

10 COASTAL LANDFORMS

THE EARTH AND THE UNIVERSE

EXPLORING THE UNIVERSE
- Stars occur in clusters known as galaxies or nebulas
- Light takes 6 seconds to reach earth from moon and 8min 2 sec from sun and nearest star 4 years
The solar system
- All planets revolve in elliptical orbit
- Surface temp of sun is 6000*C and 20 million*C in the interior
- Sun is 3 lakh times as big as earth
- Mercury is smallest planet and takes 88 day to revolve the sun
- Venus is the Earth's twin because of size, mass and density
- Mars next planet after earth to have life
- Jupiter is the largest planet
  - 12 satellite
  - Dark and light circular bands
- Saturn
  - 3 rings and 9 satellites
  - 2nd largest
- Uranus
  - 50 times larger and 15 times heavier than earth
  - Only clockwise orbiting planet
- Neptune
The shape of Earth
- Geoid or earth-shaped
Evidence of the Earth's Sphericity
- Circum-navigation of the earth
- The circular horizon
- Ship's visibility - Increasing altitude widens circular horizon and mast before ship
- Sunrise and sunset
- The lunar eclipse
- Planetary bodies are spherical
- Driving poles on level ground on a curved earth - 8 inches/mile
- Ariel photographs
Earth's Movement
- Rotates on own axis in west to east - 24 hr
- Revolves at 18.5 miles per second 365.25 days
- Varying lengths of day and night
  - 66 1/2* inclination
  - In summer artic circle - Land of midnight sun - 24 hrs sunlight
  - 6 months continuous daylight in poles

The altitude of the Midday sun
- Vertically overhead at the equator called equinoxes meaning equal nights
  - 21 March - spring equinox
  - 21 September - autumn equinox
Seasonal changes and their effects on temperature
- Summer - sun higher in the sky and days are longer so net gain
- Winter - oblique rays and net loss

Dawn and Twilight
- Due to diffused and diffracted light
- In equator it is short because sun is sets and rise in vertical path
- In poles and temperate sun is oblique so dawn and twilight is long
Mathematical location of places on the globe
- Intersection of latitude and longitude is the co-ordinates
- Latitude - angular distance of an point on the earth's surface, measured in degrees from the centre of the earth and is parallel to equator
  - 1* , 60', 60''
  - Distance between two latitude is 111Km or 60 miles
  - Tropics
    - Cancer - 23 1/2°N
    - Capricorn - 23 1/2°S
    - Antarctic circle - 66 1/2°S
    - Arctic circle - 66 1/2°N
- Longitude - angular distance measure along the equator east or west of Prime meridian
  - Royal astronomical observatory at Greenwich near London is Prime meridian
  - 15° - 1 hour
  - 1° - 4 minutes
  - Indian Standard time 5 hr 30 min - 82.5°
International date time
- East to west - gain a day
- West to east - lose a day

THE EARTH'S CRUST

The structure of the earth
- Lithosphere
  - Upper
    - Granitic rocks
    - Forms continental crust
    - SIAL
    - Density - 2.7
  - Lower
    - Basaltic
    - Oceanic crust
    - SIMA
    - Density - 3
    - SIAL floats on SIMA
- Moho discontinuity
- Asthenosphere
- Mantle
  - a.k.a Mesosphere
  - Dense rocks rich in OLIVINE
  - 2850 Km
- Gutenburg Discontinuity
- Core - 3470 Km
  - Outer Core - Liquid
    - 2200 Km
  - Inner Core - Solid
    - 1270 km
  - a.k.a Barysphere
  - NIFE
- Hydrosphere
  - Part of crust filled with water
- Atmosphere
The Classification of Rocks
- Igneous
  - Fossil is not found
  - Cooling and solidification of molten rock magma
  - Crystalline structure
  - Sub division based on mineral composition
    - High Silica - acidic/lighter/less dense/granite
    - Oxides of fe, al, mg - basic/dense/darker/
  - Sub division based on origin
    - Plutonic rocks
      - Slowly solidified beneath so large crystal - granite, diorite, gabbro
    - Volcanic
      - Solidified rapidly outside so small crystal - hard and resistant/ basaltic
      - Eg.antrim of northern Ireland, deccan plateau in India, Columbia-snake plateau
- Sedimentary
  - Layer and stratified rocks
  - Fossil is found
  - Division based on origin
    - Mechanically formed sedimentary rocks
      - Sandstones by sand grains and quartz fragments
      - Conglomerate - rounded pebbles
      - Breccia - angular pebbles
      - Shale or mudstone - clay
    - Organically formed
      - Remains of living organism like corals or shellfish
      - Calcareous like chalk and limestone
      - Carbonaceous like peat, lignite or coal
    - Chemically formed
      - Rock salt
      - Gypsum or calcium sulphate or potash or nitrates
- Metamorphic
  - Due to heat and pressure caused by intense earth movement
  - Clay into slate
  - limestone into marble
  - Sandstone into quartzite
  - Granite into gneiss
  - Shale into schist
  - Coat into graphite
- Earth movements and major landforms
  - Caldonian folds - oldest - scandinavia, scotland
  - Hercynian folds - urals, welsh, harz, appalachians
  - Young alpine - alps, himalayas, andes and rockies
- Types of mountains
  - Fold mountains
    - Himalayas, Rockies, Andes and Alps
    - Anticline(up) & syncline(down)<overfold<recumbent fold<nappe over thrust plane or fault line
    - A.k.a mountains of elevation
    - Volcanic activity
    - Rich minerals like tin, copper, gold and petroleum
  - Block mountains
    - horsts or block mountain
    - Graben or rift valley
    - Hunsruck mountains, vosges and black forest of rhineland, east african rift valley
  - Volcanic mountains
    - A.k.a mountains of accumulation
    - Mt.Fuji of japan, Mt.Mayon of Phhilippines, Mt.Merapi of sumatra, Mt.Agung of Bali and Mt.catopaxi of Ecuador
  - Residual mountain
    - Mt.Mandnock in USA, Highlands of scotland, scandinavia and deccan plateau
    - A.k.a mountain of denudation
- Types of Plateaux
  - elevated uplands with extensive level surface and usually descend steeply to the surrounding lowland
  - A.k.a tablelands
  - Tectonic plateaux
    - caused by earth movements
    - Continental blocks like deccan plateau
    - Tilted plateau - meseta if central Iberia
    - Faulted like Harz of Germany
    - Enclosed by fold mountains - intermont plateaux like Tibetan plateau between Himalayan and kunlun / Bolivian plateau between andes range - Highest and extensive
  - Volcanic plateaux
    - Antrim plateau of Northern Ireland and north western deccan plateau
    - Columbia snake plateau
  - Dissected plateaux
    - Scottish highlands
    - Humid highlands, glaciation, drier areas
    - Mesas and buttes
- Types of plains
  - Area of lowland that is either level or undulating
  - Most fertile and occupied
  - Indo-Gangetic plain, Mississippi plain, Yang-tze plain
  - Grasslands of Russian steppers, the north american praries and argentinian pampas
  - Structural Plain
    - Structurally depressed
    - Russian platform, great plains of USA, central lowlands of Australia
  - Depositional Plain
    - alluvial, flood, delta plain
      - Nile delta, ganges, Hang Ho
    - Outwash plain
      - Not fertile
      - Unsorted fluvio-glacial sands and gravels
    - Till plain or drift plain
      - Fertile
      - Boulder clay
    - Coastal plain
    - Loess plain
      - Aeolian deposits or very fine dust
  - Erosional plain
    - Plains of denudation
    - Peneplains or almost plains
    - Ice-scored plains
    - Pediments or Pediplains and inselberg

VOLCANISM AND EARTHQUAKES

Landforms of Igneous rocks
- Sill and Dykes
  - Commonest
  - Sill - horizontal - e.g Great Whin Sill
  - Dykes - vertical - e.g cleveland dyke and kaula lampur
- Liths
  - Larger size
  - Loccolith
    - Large blister or dome shaped
    - Level base with pipe like conduit from below
    - Henry mountain in USA
  - Lopolith
    - Saucer shape
    - Bushveld lopolith in Transvaal
  - Phacolith
    - Lens shaped
    - Anticline or syncline
    - Fed by conduit from below
    - Condon Hill in Shropshire, England
  - Batholith
    - Granite
    - Huge
    - Wicklow Mountains of Ireland, Uplands of Britanny,France and Main range of Malaysia
Origin of volcanoes
- Crustal disturbances
  - Basic lavas
    - Hottest
    - Highly fluid
    - Dark coloured like Basalt
    - Rich in iron and Magnesium
    - Not very explosive and flows quietly
    - Shield or dome volcanoes
  - Acid Lava
    - Highly vicious
    - Light coloured
    - Silica rich
    - Loud explosion as rapid congealing in vents
    - Forms spine or plug - Mt.Pelee in Martinique and Puy de dome of france
Types of volcanoes
- Active, dormant and extinct - Mt.Vsusvius and Mt.Krakatau once thought extinct
Extrusive landforms
- Lava plains and basalt plateaux - snake Basin, USA
- Lava domes and shield volcanoes - Hawaii Mauna Loa and Kilauea
- Caldera - eruptions weakens structure and blows of top and forms a depression
- Crater - smaller caldera
- Ash and cinder cones
- Composite cones or strato volcanoes
  - Highest and most common
  - Parasitic cones and subsidiary crater

Geysers and Hot springs
- Geysers
  - Volcanic region
  - Upto 150 feet
  - Explosive
  - 3 major areas - Iceland, the rotorua district of north island and yellow stone national park
  - Old faithful erupts every 63 minutes in yellow stone national park
- Hot springs
  - Common
  - Not explosive
  - Contains minerals
  - Heated by interior forces
  - Iceland, hawaii, japan
The distribution of earthquake
- Circum pacific areas with epicentres - 70%
- Mediterranean-Himalayan belt -20%

WEATHERING, MASS MOVEMENT AND GROUNDWATER

Internal forces - Constructive (orogenesis)
External forces destructive (denudation) - 4 phases
- Weathering
  - Chemical - felspar(easily weathered), quartz and mica of granite
    - Regolith - mineral remains of decomposed rocks
    - enhanced in underlying rocks
    - 3 process
      - Solution - most potent
      - Oxidation - iron content
      - Decomposition of organic acids - acids
  - Mechanical or physical
    - Repeated temp changes
    - Onion peeling or exfoliation of rounded boulders
  - Repeated wetting and drying
  - Frost action
    - Frost shattered peaks
  - Biotic factor
    - Roots
Mass Movement
- Weathered material due to gravity
- Soil creep
  - Gradual
  - Common in damp - water lubricates soil particles
- Soil flow or solifluction
  - Arid region during rain
  - Frozen under ground during spring
  - Big-bursts in Ireland
- Landslide
  - Rapid
  - Steel slopes
  - Earthquakes or volcanic disturbances
  - Lubricating action of rain
  - Slumping - permeable layer over non-permeable layer like clay
Ground water
- Porous rocks - sand stone
- Permeable and porous - sand stone
- Non permeable but porous - clay
- Permeable and non-porous -granite
Water table
- Permeable rock that stores water is aquifer
- Karst region - limestone - vauclusian spring

Erosion
Transportation
Deposition

LANDFORMS MADE BY RUNNING WATER

The development of a river system
- Rain fall
  - Evaporated
  - Seepage
  - Runoff - causes denundation or general lowering of the earth's surface
    - Rivulets
    - Brooks
    - Streams
    - Tributaries
- Sources of river
  - Lake
  - Marsh
  - Upland and catchment areas
    - Crest of mountains - divide or watershed
    - Initial stream consequence of slope is consequent stream
    - Consequent streams are joined by tributaries either obliquely or right angles
    - Homogenous beds of uniform resistance - tributaries obliquely as insequent stream
    - Consequent stream + insequent stream = dendritic drainage pattern or tree-like
    - Rocks with alternate hard and soft rocks - tributaries join as subsequent stream at right angle
    - Consequent stream + subsequent stream = trellised or rectangular drainage
The mechanism of Humid Erosion
- Mass movement due to lubricating action and gravity
- Not Steep = slow + soil creep
- Steep = sudden + landslide
The process of river action
- River load
  - Material in solution - dissolved solution
  - Material in suspension - sand, silt and mud
  - The traction load - pebbles, rocks and boulders
River erosion and Transportation
- Corrasion or abrasion - mechanical grinding of traction load on banks and beds
  - Lateral corrasion - widens V-Valley
  - Vertical Corrasion - deepens
- Corrosion or solution - chemical or solvent
  - Calcium carbonate in limestones
- Hydraulic action - Mechanical loosening and sweeping by water itself
- Attrition - wear and tear of transported material themselves
The course of a River
- The upper or mountain course or youth stage
  - Predominantly erosion
  - Source of river
  - Swift
  - Vertical corrasion
  - Deep, narrow and deep V shaped valley
  - Very resistant rocks - lateral corrasion is absent - gorges(indus is kashmir) and canyons(Bryce in USA)
  - Features
    - River capture - river piracy or river beheading
      - Back cutting or headwards erosion into divide
      - Elbow of capture
      - Beheaded stream is called misfit
      - Valley below elbow is wind gap
      - E.g - Irrawaddy captured Upper sittang, Northumberland, North tyne
    - Rapids, cataracts and waterfalls
      - Uneven resistance - rapids or jump or fall down stream
      - Cataracts - greater rapid
      - Waterfall - greater cataract - forms lunge pool beneath
- The middle or valley course or mature stage
  - Lateral corrasion replaces vertical corrasion
  - Predominantly transports sediments
  - Features
    - Meanders
    - (concave)River cliff and (convex)slip-off slopes(shingle deposition)
    - Interlocking spurs
- The lower or plain course or old age
  - Vertical corrasion ceases and lateral continues
  - Predominantly deposition
  - Braided streams
  - Features
    - Flood plains
      - Levees and artificial embankment
      - Hwang-Ho china's sorrow
    - Ox-Bow lakes or mortlake or dead lake
      - cut-off or bayous in Mississippi basin
      - Meander is more pronounced
    - Delta
      - River reaches sea and drops fine material at the mouth
      - Fan-shaped alluvial area called delta
      - Actually seaward extension of flood plane
      - Due to obstruction caused by alluvium river discharges its water through distributaries
      - Delta extends over time
      - E.g - Mississippi has birds -foot delta, Nile,ganges and Mekong has fan-shaped delta
      - Amazon, ob and vistula estuarine deltas, ebro of spain has tooth like projection called cuspate delta
      - Conditions for delta
        Active erosion
        Tideless and sheltered coast
        No large lake to filter sediments
        no strong current perpendicular to rive mouth
- River rejuvenation
  - Being young again
  - -ve movement -When land uplifts or sea level falls
  - Active down-cutting
  - Leaves behind terraces
  - Knick point or rejuvenated head
  - Deepening of gorges and deep valley with entrenched or incised meanders
  - +ive movement - depression of land and rise in sea level -ice melting
The human aspects of rivers
- Navigation
- Boundary

LANDFORMS OF GLACIATION

Pleistocene - 30,000 years ago ice sheets over entire temperate region
Today only Greenland and Antarctica
Ice shelves break into ice bergs
Nunataks - peaks of mountain projects above surface
Repeated melting and freezing of snow forms hard granular neve or firn
Glacier river of ice
Glaciers flow in tongue shape - greatest rate of movement in middle
Glaciers converge to form an extensive ice-mass called a piedmont glacier. E.g malaspina glacier
LANDFORMS OF HIGHLAND GLACIATION
- Glacier erodes by plucking and abrasion
- All glaciated floors have striation or scratching
- Rock flour
- Features
  - Corrie, cirque or cwm
  - Aretes and pyramidal peaks
  - Bergschrund
  - U-Shaped glacial trough
  - Hanging valleys
  - Rock basins and rock steps
  - Moraines
- Landform of Glaciated Lowlands
  - Roche Moutonnee
  - Crag and Tail
  - Boulder clay or glacial till
  - Erratics
  - Drumlins
  - Eskers
  - Terminal Moraines
  - Outwash plains
- The Human aspects of Glaciated Landforms

ARID OR DESERT LANDFORMS

Types
- Hamada or rocky desert
- Reg or stony desert
- Erg or sandy desert
- Badlands
- Mountain deserts
The Mechanism of Arid Erosion
- Weathering
- Actions of wind in deserts
  - Deflation
  - Abrasion
  - Attrition
Landforms of Wind Erosion in Deserts
- Rock pedestals or mushroom rocks
- Zeugen
- Yardangs
- Mesas and buttes
- Inselberg
- Ventifacts or dreikanter
- Deflation hollows
Landforms of wind Deposition in Deserts
- Dunes
  - Barchan
  - Seifs or longitudinal dunes
- Loess
Landforms due to Water Action in deserts

LIMESTONE AND CHALK LANDFORM

Limestone and chalk
Characteristic Features of a Karst Region

LAKES

THE FORMATION AND ORIGIN OF LAKES
- Lakes formed by earth movements
  - Tectonic lakes
  - Rift valley lakes
- Lakes formed by Glaciation
  - Cirque lakes or tarns
  - Kettle lakes
  - Rock-hollow lakes
  - Lakes due to morainic damming of valleys
  - Lakes due to the deposition of glacial drifts
- Lakes formed by Volcanic Activity
  - Crater and caldera lakes
  - Lava-blocked lakes
  - Lakes due to subsidence of a volcanic land surface
- Lakes formed by erosion
  - Karst lakes
  - Wind-deflated lakes
- Lakes formed by Deposition
  - Lakes due to river deposits
  - Lakes due to Marine deposits
  - Lakes due to landslides, screes and avalanches
- Lakes formed by Human and Biological Activity
  - Man-made lakes
  - Lakes made by animals
  - Other types of lakes
- Lakes and Man
  - Communication
  - Economic and industrial development
  - Water storage
  - Hydro-electric power generation
  - Regulating river flows
  - Moderation of climate
  - Source of food
  - Source of minerals
  - Tourist attraction and health resorts

COASTAL LANDFORMS

The action of waves, tides and currents
- Zone of erosion - area between the low water level and high water level
- Swash and backwash
The mechanism of Marine Erosion
- Corrasion - debris erode the base
- Attrition - against each other
- Hydraulic action - water into joints
- Solvent action - limestone coasts
Coastal feature of Erosion
- Capes and bays
  - softer rocks - inlets, coves or bays
  - Harder rocks - headlands, promontories and capes
- Cliffs and wave cut platforms(eroded base) - notch becomes big and eroded material settles in off-shore terrace
  - Strata dipping seaward - easily eroded
  - Strata dipping landward - resistant
- Cave, arch, stack and stump
  - Caves - local weakness
  - Arch - two caves
  - Stack - eroded arch
  - Stump - further eroded stack
- Geos and gloups
  - Gloups are blow-holes of caves
  - Geos - enlarged gloups
Costal feature of Deposition
- Beaches
- Spits and bars
- Marine dunes and dune Belts
Types of coasts
- Coastlines of submergence
- Coastlines of emergence
  - Ria coasts
  - Fiord coasts
  - Dalmatian coast
  - Estuarine coast
- Coastlines of Emergence
  - Uplifted lowland coast
  - Emergent upland coast