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Landform
Terrain: a product of landform.
Landscape: assemblences of terrain.
Geomorphology:
The study of the origins & characteristics
of land form (contour). Earth’s cross
section:
atmosphere;
hydrosphere;
lithosphere +/‐ 25 miles thick.
Lithosphere:
ƒ Continental crust
ƒ Oceanic crust
• They’re dynamic masses broken down into 12 “plates floating on the mantel.
• Collision: plates coming together;
• Subduction; ocean plate sliding under the continent plate;
• Opposing: plates going in opposite direction;
• Accretion: mantel comes up through two opposing plates;
• Transform boundary: two plates slide by each other (San Andreas fault).
Tectonic activity:
bending, breaking and sliding at the
boundary of plates;
Volcanic activity:
the upheaval of magma between
opposing plates;
Mercalli intensity scale:
(not Richter) measures damage on a
scale of 1 thru 12, Richter measures
earth movement magnitude at a
logarithmic rate;
Sequential landform:
denudation – the forces influential in
shaping landform, i.e.. Weather, erosion,
mass‐wasting, etc. or the transformation
of matter brought upon by an agent
(water, glacial ice, wind, gravity.
© Professor Mark Comeau, AIA, Site Analysis
Landform
Rocks:
any aggregate of minerals in a
solid state (lithosphere) ages from
now to billions of years old.
Rock Categories:
Sedimentary (shale, limestone);
Formed by sedimentation
(transporting by stream) and
makes up 75% of lithosphere.
Igneous (basalt, granite);
Formed by the solidification
of magma and makes up 18%
of lithosphere.
Metamorphic (slate, marble).
Formed by a combination of
the other two and makes up
7% of lithosphere.
Denudation:
shaping of the earth’s surface by weather, erosion, mass‐wasting, etc.
Weathering:
Mechanical (disintegration) i.e.. Frost heaves;
Chemical (decomposition) i.e.. Changing rock compounds (mechanical simply rearranges).
Erosion:
materials are transported from one place to another by stream, ice, water, wind, etc.
Mass‐wasting:
materials settling through gravity and angle of repose (depends on mass and coarseness of material) i.e.. slump, mudflows.
© Professor Mark Comeau, AIA, Site Analysis
Landform
Landform agents:
Wind‐laid: Aeolian, i.e.. loess;
Water‐laid: fluvial (water transports sediments);
Riverine: flood plain, delta;
Alluvial: sand‐bar;
Fresh water formation: lake beds;
Marine formation: tidal flats, coastal plains.
© Professor Mark Comeau, AIA, Site Analysis
Landform
Landform agents:
Glacial: 30% of all land surface has been glacial at one point;
Alpine: mountain ranges, tarns (small hills);
Continental glaciation: (all of Greenland) 20,000 years ago the last North American glacier receded through 1/3 of the U.S. and was 300‐400’ thick over Rhode Island.
Himalayan Glacier
© Professor Mark Comeau, AIA, Site Analysis
Landform
© Professor Mark Comeau, AIA, Site Analysis
Landform
Topography:
two dimensional drawing illustrating surface configuration and relief features pertaining to a specific area of land.
Contour interval:
the vertical dimension between the contour elevation (usually uniform);
• Developed in Holland in 1730 but utilized for practical use in the 19th
century.
• Existing contour is a dashed line;
• Proposed contour is a solid line;
• Contour elevation always placed on the uphill;
• Every 5’ or 10’ interval is a heavier line
Hypsometric:
above sea‐level;
Bathymetric:
below sea‐level.
Slope:
the inclination of terrain defined either by ratio, percentage or degree inclination.
Ratio:
the ratio between the horizontal and vertical datum, i.e.. 40:20 or 2:1.
Percentage:
attained by dividing the vertical datum by the horizontal datum and getting a decimal percentage (multiply by 100).
V
G
H
G=V/H x 100
Degree:
is the angle the hypotenuse makes with the horizontal.
© Professor Mark Comeau, AIA, Site Analysis
Hypsometric Topography
© Professor Mark Comeau, AIA, Site Analysis
Bathymetric Topography
© Professor Mark Comeau, AIA, Site Analysis
© Professor Mark Comeau, AIA, Site Analysis