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Lab evaluations
• Go to Acadia Centralhttp://central.acadiau.ca/my
• Log in
• Click on Online Registration
• Click on Information
• Click on GEOL1010L(A,B,C)1
• Click on Evaluate
Vertical exaggeration
• On all the profiles you’ve drawn the vertical and horizontal scales are not the same
• Whelan Cove – Canning: vertical scale is 1:5000, horizontal scale is 1:50 000
• This is ten times vertical exaggeration
Calculating vertical exaggeration
• Vertical exaggeration (VE) is the vertical scale divided by the horizontal scale
• Remember that scales are ratios to begin with• If vertical scale is 1:5000 and horizontal scale is
1:50000 the VE is
= (1/5000)/(1/50000) = 50000/5000 = 10• If vertical scale is 1:20000 and horizontal scale is
1:50000 the VE is
= (1/20000)/(1/50000) = 50000/20000 = 2.5
Rule of Vs (vees)
• Helps in reading geological maps
• As a contact changes elevation, when viewed from overhead (map view), it shifts in the direction of dip
i.e., a contact “vees” in the direction of dip
Rule of Vs
a) Shallowly dipping contacts make “large” Vs
b) Horizontal contacts run parallel to the topographic contours
c) Steeply dipping contacts make “small” Vs
d) Vertical contacts run straight across topographic contours
Horizontal(parallel to contours)
Shallow dip(big “vees”)
Steep dip(small “vees”)
Vertical dip(runs straight across topo)
A couple of points…
• Rock units are assumed to be planar and of equal thickness throughout the area
• Wider outcrop in one place and narrower outcrop in another indicates differences in dip
• When drawing sections try to maintain thickness of units around folds.
Structure labs/drawing
• Recent labs often “sloppy”
• Take 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
Block diagrams…
• See if you can work these ones out for yourself
• But ask questions
• Hint: look at the strike and dip symbols.
Dykes and faults
• This exercise is fairly intuitive• Note: we cannot tell the
absolute sense of motion on a fault thus we indicate relative motion with two “half” arrows
Strike and dip
Put strike FIRST (up to 3 digits)
Then DIP (only 2 digits)
Then DIP direction
110 / 25 NE
Drawing a strike and dip symbol (important for final test)
What is the orientation determined?
115/37 NE
Drawing a strike and dip symbol
115/37 NE
What is the strike?
115
What is the dip direction?
NE
What is the dip?
37
Done!Remember that if it is a cleavage measurement, the symbol is like this…
N
Wolfville mapInformation is available on the:
MAP
…on the
LEGEND
…and on the CROSS-SECTIONS
Also some more detailed information
in the
“Descriptive Notes”
Wolfville Map questions 6 – 13
• 13 (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 12, think of the rule of vees– For question 13, think of your fieldtrip to Black River