Transcript Geological maps

Structure labs/drawing
• Recent labs often “sloppy”
• Not taking time to draw contacts properly
– Units must maintain thickness
– Contacts should be parallel and “smooth”
– Contacts should be in the right place
– Angles should be approximately correct (use
a protractor if you cannot draw angles to
within 10°) and consistent
Drawing a strike and dip symbol
What is the orientation determined?
115/37 NE
Drawing a strike and dip symbol
115/37
115
37 NE
What is the strike?
N
Done!
Remember that if it is a cleavage measurement,
the symbol
like dip
this…direction?
What is the
What
is isthe
dip?
Geological maps
…and on the CROSS-SECTIONS
Wolfville map
…on the
Information is available on the:
LEGEND
MAP
Also some more
detailed information
in the
“Descriptive Notes”
Section A
• 11 (relatively straightforward) questions.
• Some hints
– Use the legend and cross-sections
– “a deep well” means hundreds of metres (scale of
the cross sections)
– Contacts are:
• Conformable (bedding)
• Cross cutting (faults, intrusions, unconformities)
– For question 10, think of the rule of vees
– For question 11, think of your fieldtrip to Black River
At a spreading ridge
Away from the ridge segments
Plates are moving BUT in the same
direction and thus faults are not
tectonically active (a “fracture zone”)
Between the ridge segments
Active relative motion on the fault
BUT in the opposite sense to the
“offset” of the ridge
Right lateral fault…
• Fault on which the “other side” appears to
have moved to the right.
Symbol for right
lateral fault
Left lateral fault…
• Fault on which the “other side” appears to
have moved to the left.
Symbol for left
lateral fault
Plate tectonic animation
Features on the ocean floor…
(6e: 32–34; 5e: pp. 227–234)
• Abyssal plain = flat portion of the deep ocean
(away from spreading ridges)
• Continental shelf = portion of the continental
crust that is submerged
• Continental slope = the marked change in slope
of the ocean floor that indicates the change from
continental crust to oceanic crust
• Deep sea fan = a “fan shaped” pile of sediment
off shore of major rivers (Amazon, Ganges, etc.)
Features on the ocean floor…
(6e: 32–34; 5e: pp. 227–234)
• Mid-ocean ridge = the high range of
mountains that runs under the oceans and
is the site of “spreading”
• Seamount chain = line of undersea peaks
that extends from a “hot spot” in the
mantle (only one end of the chain can be
volcanically active and there is no
associated “trench”)
Features on the ocean floor…
(6e: 32–34; 5e: pp. 227–234)
• Transform fault = fault that offsets
spreading ridges
• Trench = the over deepened portion of the
crust where an oceanic plate is “diving”
into the mantle (associated with a volcanic
arc)
• Volcanic arc = A (usually arcuate) line of
volcanoes (all can be active at any one
time) usually associated with a trench