2. Archimedes’ principle
– The mass of the water displaced by the
block of material equals the mass of the
whole block
– Thus for a material with a lower density
than water, the proportion of material above
the water surface is constant
– For example wood (density 0.8 gm/cm) will
have 20% of its mass above water (density
of 1.0 gm/cm). Thus for a 1 m block 0.2 m
will be above water and 0.8 m below, but
for a 2 m block .4 m will be above water
and 1.6 m below
Fig. 6.28
3. Isostasy & Mountain Roots
– Continental Crust has “roots”
– As a result of isostacy, the thicker the surface exposure of rock, the thicker the
crustal “roots”
– As continental crust is compressed it shortens and thickens
– Avg. continental crust is 35-40 km thick, under deformed crust avg. is 50-70 km,
with the majority of the difference in the “roots”
Fig. 6.29
6. Mountain-Types
• Upwarped Mountains
– Formed from compressional stress
– Broad arching of the crust or great vertical displacement
along faults
– Example: Black Hills SD
7. Mountain-Types
• Folded Mountains
–
–
–
–
Formed from compressional stress
Reverse Faulting and Folding – highly deformed rocks
Will have highly metamorphosed rocks
Example: Appalachians, Himalayas
8. Mountain-Types
• Volcanic Mountains
– Formed volcanic activity
– Associated with plate
boundaries or hot spots
– Example: Cascade Mts. Or
mountains within Japan
11. Accreted Terranes
• As exotic blocks collide
with continents they
become sutured to the
continent.
• The blocks are referred to
accreted terranes
• Accreted Terranes are
island arcs, portions of
ocean floor, fragments of
continental crust
17. Why does the Earth
have mountains of
various height?
• Erosion attacks
mountains – remember
Earth wants to be flat
• Orogenic collapse.
18. classified on the basis of1-direction of the camera axis
2-combination of more than one
photograph
3-according to angle of coverage
4-on the basis of colour
20. 1-the lens axis is perpendicular to
the surface of the earth.
2-it covers a relatively small area.
3-the shape of the ground area
covered on a single vertical photo
closely approximates a square or
rectangle.
4-being a view from above, it
gives an unfamiliar view of the
ground
5-distance and direction may
21. theodolites from camera station
on the ground.
2-these are used for survey of
structures and mounments of
architectural or archaeological
value.
22. the optical axis of the aerial
camera tilted fro, the vertical
2-these photographs cover large
areas of ground.
3-but the clarity of details
diminishes towards the far end of
the phothgraph.
23. trapezoid, althouth the photo is
square or rectangular.
3-the objects have a more
familiar view, comparable to
viewing from the top of a a high
hill or tall building.
4-no scale is applicable to the
entire photograph, and distance
cannot be measured.
Parallel lines on the ground are
24. all usable)
2-the ground area covered is a
trapezoid, but the photographis
square or rectangular.
3-the view varies from the very
familear to unfamiliar, depending
on the height at which the
photograph is taken.
4-distances and directions are not
measured on this photograph for
the same reasons that they are not
25. camera exposed simultaneously
at successive exposure station,
with their axis tilted at a fixed
inclination from vertical in
opposite directions in the
direction of flight line so that the
forward exposure of the first
station forms a stereopair with
the backward exposure of the
next station.
26. which the central photograph is
vertical and the side ones are
oblique.
2-this photography can be used
for rapid production of
reconnaissance maps on small
scales.
27. through the front nodal point of
the lens.
1-standard or normal angle
photography- the angle of
coverage is of the order of 60
2-wide angle photography-the
angle of coverage is of order of
90/
3-super wide angle-the angle of
coverage is of order of 120.
28. -these photographs present the
objects as they appear in their
natural colour.
-for good colour cintrast, scale
larger than 1:25000 is normally
used.
-it has better in terpretation
capabilities.
-it is better ofr photogrammeric
studies.
29. -infrared raiaions which are
invisible to human eye have
wavelengths ranging from 0.7 um
to about 1.6um.
-infrared photography can be
black and white or in colouir
depending on the type of film
used.
30. of red.
-the differentiation between types
of healthy and unhealthy
vegetation is brought out in
distinctive colours.
-infrared colour with the
combination of panchromatic
capabilities.
31. photography appears in lighter
tones on ir black and white
photographs.
-water appears dark in ir black
and white because water has high
absorption characteristics in
infrared.
Yellow filter is used to reduce
haze.
32. -the film used in iR black and
white negatives.
-dispositive are made from the
negatives and the four images are
combined in registration in an
additive colour viewer to produce
a true colour or a false colour
viewer to produce a true colour
or a false colour image on a
screen which can subsequently
be photographed.
