2. Why do we have continuing education requirements for
Professional Geologists?
3.
4.
5.
6.
7. Excerpted from an Amplified Record of Experience for a
PG Licensing examination application submitted in 2011
The [activity] revealed extensive soil and GW contamination. MWs were installed
into the Precambrian felsic gneiss overburden and sampled.
MWs were installed into the ----------- Wissahickon saprolite to determine the
extent of the GW plume. The -------- Wissahickon sediments accumulated in a rift
basin on top of Laurentian continental crust and consists of muscovite and
tourmaline-apatite-staurolite-kyanite-garnet-bearing metamorphic mineral
assemblages.
38. From Fetter, 2001. This is
a non-structural method of
estimating anisotropy
which requires
measurement of the
hydraulic conductivity in
two perpendicular
directions during an
aquifer testing program
53. Representative Elemental Volume
The size of an REV, therefore, must be larger than the scale of microscopic
heterogeneities created by individual geometries of the solid phase particles
and void spaces, and much smaller than the scale of the domain of interest.
It is the heterogeneity within the domain of interest which counts when
determining the size of the REV.
Bear, 1993
64. Example
A site in a jointed
diabase intrusion into
the Newark-Gettysburg
Basin.
Groundwater contours
on the site revealed a
semi-radial flow from a
high toward two steams
65. Obtained 1906 USGS
topo maps and mapped
features absent modern
development.
Streams described a
radial pattern from top
of ridge created by
diabase.
80. Resolution of the Field Hydraulic Gradient in a
Sub-Vertical Plane
The upper surface of the water table as resolved into the plane occurs at an
in-plane gradient equal to the apparent dip observed in that plane.
In such a case, the
magnitude of the field
hydraulic gradient is
greater than the
magnitude of the
resolved hydraulic
gradient.
81. Resolution of the Field Hydraulic Gradient in a
Sub-Vertical Plane
The only exception to that general condition is where the strike of the
plane is coincident with the azimuth of the flow vector in which case
flow would be precisely parallel to strike and the field gradient would
be equal to the in-plane gradient.
91. STRIKE & DIP
STRIKE = trend (azimuth, bearing) Another definition of Strike =
of a structural contour on a plane. trend of a line connecting points of
equal elevation on a plane.
………of a horizontal line on a
plane.
……….water level line on a plane.
In the field this horizontal line is
defined by using bulls eye level to On a plane, structural contours
hold compass as a horizontal plane will be straight lines with equal
and placing edge of compass against spacing – and all are parallel to
surface to be measured. strike.
Hence measuring strike of a plane is
the determination of a structural
Source: Donald Wise
contour line on the plane.
92. STRIKE & DIP
DIP = the angle from the horizontal to the
plane as measured in a plane
perpendicular to strike (or perpendicular
to a structural contour) .
NOTE: Dip must be measured in the
vertical plan (compass must be held in
vertical plane).
Dip is measured in direction of maximum
inclination ( normal to strike)
Measured in any direction other than
normal to strike, one measures an
APPARENT DIP which is somewhat less
than true dip.
NOTE: Apparent dip on any plane
measured parallel to strike is 0. (i.e. the
dip on a structural contour is zero)
Source: Donald Wise
93. REPRESENTATION OF A PLANE ON A MAP.
Ideal is structural contours on the plane (for a true planar surface they
are straight lines with equal spacing and all parallel to each other).
MAPS
Vertical plane 1000, 2000, 3000 contours all in same place.
Closer the spacing of the structural contours the steeper the dip of the plane.
Vertical plane has all the contours at the same place.
Commonly we only measure a tiny bit of the total plane and hence use the
symbol
If we are measuring a parallel set of planes (pile of dipping
sediments) they all will have the same strike and dip.
Source: Donald Wise
94. DETERMINING DIP FROM STRUCTURAL
CONTOURS - RIGHT SECTIONS
A right section is a view of the
plane running along a line at
right angles to strike.
Draw some convenient line (AB)
perpendicular to strike.
Draw line AB off the map,
marking off points A, B &
elevation points.
USING SAME SCALE AS MAP
go down to proper elevations,
draw plane & measure dip.
Source: Donald Wise
95. BASIC METHOD : RIGHT SECTIONS
A sandstone bed strikes N30W and dips 30 Either mentally or
SW. Its outcrop width on a flat surface is physically fold the
100m. Find its true stratigraphic thickness. paper along this line to
make a right section
If we could look at a true cross-section drawn below the line.
at right angles to the strike, we could measure
off the true thickness (to scale. Below = 1 cm Because this is a right
= 100 m). section the full dip of
30’ can be used to draw
Draw any random line FF’ at right angles to top and bottom of the
strike. bed in the cross-section.
Measure true thickness
in right section, normal
to bed, using map scale.
Source: Donald Wise
97. RIGHT SECTIONS AT RIGHT PLACES
A Coal Bed striking N20E, 50 NW Draw a line through the shaft,
crops out as shown. A mine shaft is to perpendicular to strike.
be drilled 500 meters due west of the
outcrop. How deep is the coal bed in Make this line FF’ a fold line to
the shaft? draw a right section which will
contain the shaft.
Select come convenient scale and
draw the map. Draw the dipping coal bed and the
shaft in this section.
Using the scale, measure the depth
of the shaft (550m).
Source: Donald Wise
99. The top and bottom of a
sandstone crop out at
elevations of 600 and 200
meters, respectively, at the
locations shown on the map.
The strike and dip at both
locations is N60~E, 20 NW.
Calculate the thickness of
the sandstone.
Source: Donald Wise
102. GREASY DRIP SANDSTONE AREA
The Greasy Drip Sandstone is a major
reservoir rock in the Petroleum Patch
Quadrangle. A small exploration
company owned by W.E. Findum and
U.R. Lost has hired you to get some
data from the outcrop above.
What is the strike of the sandstone?
_____
What is the dip of the sandstone?
_____ to the _____?
The thickness of the sandstone is
_____?
The depth to the top of the sandstone
at Grimy Station is _____?
What is the vertical thickness of the
Greasy Drip SS that would be
intersected in a coring made at Grimy
Station? _____
Source: Donald Wise
105. ONE POINT PROBLEMS
Given one point on a map where the strike, dip, and elevation of a planar bed
are known, draw the structural contours for this bed throughout the map area.
For example, in an area of very sparse exposure, you have only one outcrop of
a coal bed, point A, at an elevation of 1900 feet and strike N60W, 30 SW.
Nevertheless, you need to complete a geologic map of the concealed line of
outcrop of the bed across the area and get the predicted dill depths to the coal.
These determinations will require a knowledge of the structural contours
across the area.
106. ONE POINT PROBLEMS
Extend the line of strike from A to some convenient place off the map. This line is a
structural contour and all locations along it are at 1900 foot elevation.
Draw a line perpendicular to the structural contour. This will be a right section.
The line is at the same elevation as the structural contour (1900 feet). Using the
same scale as the map, put in the elevation lines below the 1900 foot elevation line of
DCE and mark their elevations as shown.
This is a right section, so the true 30 degree dip can be plotted starting from point C
(which is at 1900 feet elevation).
108. Find the intersections of the dipping plane in the cross section with the
appropriate elevations (F, G, H, I, etc.) and project them up to the surface as
L, M, N, O, etc. These are now map points below which the elevations of the
plane are known.
Structural contours can now be drawn through each of these points parallel
to the main 1900 foot contour (AB). The same spacing and trend of contours
can be continued across the entire map.
Source: Donald Wise
109.
110.
111. How deep
would you
need to drill
a well at
Point B to
intersect the
top of the
formation
which
outcrops at
Point A?
Contour Interval = 100 m
115. Three Point Problems
Given 3 points on a planar Draw structural contours through the
surface, find the strike & dip high and low points parallel to the
of that plane. strike. (AE&CG)
Connect the highest and lowest Draw a fold line perpendicular to strike.
of the three points on the map. Decide on elevation of this line using
(A&C) same scale as map, draw elevation lines
below the fold line for cross-section.
Interpolate between these
points for a point of elevation Project the structural contours of high
the same as that of the and/or low points onto the cross-section
intermediate elevation point. and draw the dipping plane on this right
(B) section.
Join these two points of equal *Measure its dip (Angle GEH).
elevation as a line of strike.
(BD)
*Read off this strike with
respect to north
Source: Donald Wise
117. Three Point Problem - Method 2
Draw two lines connecting the highest elevation point with both the lowest and
intermediate points: (AC; AB).
Scale off divisions of equal elevations along each line.
Connect points of equal elevations with structural contour lines.
Construct right section as in Method 1.
118. Interpolation
A common geologic problem is to be given some numerical value (elevation,
for example) at two locations on a map. Intermediate values need to be
calculated or INTERPOLATED as proportional distances along the line
joining the two points.
THE PROBLEM: Two points A and B are located on a map as shown and
have elevations of 435 and 715 feet respectively. Find a location
proportionally spaced between them which would have a proportional
elevation of 683 feet. While you are at it, find the proportional locations for
500, 600, and 700 feet elevations.
B 715
A 435
Draw the line connecting the two locations, A and B.
Source: Donald Wise
119. Interpolation
From the end of this line with the lower elevation (point A in this case)
draw a random line (AC) at about 30 to 45 degrees from AB.
Use some scale of a ruler (in tenths) with values which correspond to the
elevation differences between A and B. Put the 4.35 value of the ruler on
the 435 ft elevation of point A and locate point D at the same value as the
elevation point B (7.15 for the 715 foot elevation in this case).
B 715
A 435
Source: Donald Wise
120. Interpolation
Using the scale of the ruler mark off on line AD all the locations corresponding to all
the elevations you seek (6.83, 500, 600, 700).
Make a large triangle by connecting points D and B. By ruling parallel to line DB
make a series of similar triangles through each of the points you located in the above.
A THEOREM OF PLANE GEOMETRY IS THAT DISTANCES WHICH ARE
PROPORTIONAL TO THE LENGTHS OF LEGS OF ONE SET OF SIMILAR TRIANGLES
ARE ALSO PROPORTIONAL TO THE OTHER LEGS OF THOSE TRIANGLES.
Thus, the locations along line AB have
spacing proportional to their elevations.
121. Outcrop Patterns
If the structural contour on some horizon has the same elevation as the
topography at that point, then that bed crops out at that location.
Conversely, if an outcrop occurs at some location, the structural contour
of that elevation on that unit passes through that point.
Source: Donald Wise
122. Outcrop Patterns
In general, the outcrop of a dipping plane will “V” in crossing a valley,
such that the “V” will point in the direction of dip.
With flat dips and steep stream gradients these V’s might point in
other direction.
If there is no V at all, then the plane is very steep to vertical.
This V principal applies to all kinds of planes: beds, dikes, faults,
unconformities.
Source: Donald Wise
123. A planar coal bed crops
out a points A, B and C.
What is the bed’s
orientation _______
Draw the outcrop
pattern
How deep would you
need to dig at point D to
intersect the coal?
__________
Source: Donald Wise
124.
125.
126. Horsefeather Creek Area
Structural Contours on top of Horsefeather Sandstone. Construct a right
section.
What is the orientation of the unit? __________
How deep would you drill at P _______ and Q________ to intersect the
unit?
Draw the outcrop pattern. Source: Donald Wise
127.
128.
129. Draw section FF’, the axial trace, and fully describe the structure
(The numbers represent stratigraphic superposition)
Source: Donald Wise
130.
131. Describe the structure at
left.
What is the direction of
dip of the ss? _______
What is its strike?
_________
Source: Donald Wise
132.
133. The St. Valentine Sandstone
crops out along ILUVU
Creek Valley as shown.
Sketch Section A-B.
Source: Donald Wise
143. What kind of fault?
Which way does dike A-B dip? Why?
Which side went up?
Give approximate azimuth and plunge of
the net slip and explain how you got it.
M, S, T are all faults.
Which is the oldest fault?
If all the fault movements are dip slip, mark
the up and down for those faults where it
can be determined.
Source: Donald Wise
146. Guano Creek Field Area
Two of the more intrepid members of our class, Jon and Dave, have been mapping in
the Guano Creek region, so named for the famed bird rookeries at its headwaters.
(The nearly extinct “tweety bird” is rumored to roost in that area.) They are trying
to locate the source of the sulfide ores which oxidize to form a high concentration of
sulfuric acid in Guano Creek, a condition which prompted them to make a boat out
of lead to withstand these corrosive waters. Using this field vehicle, they have
produced the accompanying map but are still up the creek, still in their water craft,
still without finding the ores. They need help (in many ways). Should you wish to
give a concise one-line description of their condition, please feel free to do so. In
addition please answer for them:
Why is the outcrop width of the Sludge Bucket Sandstone (stippled pattern on the
map) three times as wide on the SW side as on the NE side?
Describe the Guano Creek fold in as full a detail as possible, including the general
orientation of cleavage you might expect associated with it.
In as much detail as possible describe Jon’s major fault (including approximate
strike, dip direction, approximate motion sense, fault type, relative age).
In as much detail as possible describe the Tweety Bird fault (same items as above).
Source: Donald Wise
148. Guano Creek Field Area – Solutions
Why is the outcrop width of the Sludge Bucket Sandstone (stippled
pattern on the map) three times as wide on the SW side as on the NE side?
Asymmetric fold – N.E. limb is close to vertical.
Describe the Guano Creek fold in as full a detail as possible, including the
general orientation of cleavage you might expect associated with it.
Asymmetric, N.W. Plunging Anticline.
In as much detail as possible describe Jon’s major fault (including
approximate strike, dip direction, approximate motion sense, fault type,
relative age).
080 ° - 90, Right Lateral Transform, younger fault.
In as much detail as possible describe the Tweety Bird fault (same items
as above).
045, Dipping S.E., Reverse, older fault.
Source: Donald Wise
154. Systems of Planar Discontinuities
Fold-Related Joints
Although also the result of tectonic stresses, fold-related joints are shear
joints and occur in distinct patterns of conjugate sets.
Source :Twiss & Moores, 2007
158. Description of Joints –USEPA, Manual of Field Procedures
Description of Bedding or of Joint or Fracture Spacing: Description
should be according to the following:
Spacing Joints Bedding or Foliation
< 2 in. Very close Very thin
2 in. to 1 ft Close Thin
1 ft to 3 ft Moderately close Medium
3 ft to 10 ft Wide Thick
>10 ft Very wide Very thick
(after Deere, 1963)
159. Description of Joints –USEPA, Manual of Field Procedures
Weathering: Terms used to describe weathering are described below:
Descriptive Term Defining Characteristics
Fresh Rock is unstained. May be fractured, but discontinuities
are not stained.
Slightly Rock is unstained. Discontinuities show some staining on
the surfaces of rocks, but discoloration does not penetrate
rock mass.
Moderate Discontinuity surfaces are stained. Discoloration may
extend into rock along discontinuity surfaces.
High Individual rock fragments are thoroughly stained and can
be crushed with pressure hammer. Discontinuity surfaces
are thoroughly stained and may be crumbly.
Severe
Rock appears to consist of gravel-sized fragments in a
“soil” matrix. Individual fragments are thoroughly
discolored and can be broken with fingers.
184. If we divide a circle into ten
Contouring Structural Data zones of equal width, the
innermost circle will contain
1% of the area. The next circle
is twice as large and will
contain 4%, but 1% is in the
inner circle, so the annulus will
contain 3% of the area, and so
on.
If we stack triangles, each row
will contain 1, 3, 5... triangles. A
stack ten rows high will contain
100 triangles.
If we divide a 60 degree sector
of the circle into triangles of
equal area, each sector will
contain 100 triangles, each with
1% of the area of the sector.
From:http://www.uwgb.edu/dutchs/structge/SL133Kalsbeek.HTM
185. Contouring Structural Data
The Kalsbeek counting
net is based on this
principle. It consists of
ten equally spaced
circles. Each annulus is
divided into triangles.
Altogether there are 600
triangles. At each vertex,
six triangles meet. The
hexagon of triangles
around each vertex
contains 1% of the area
of the net.
From:http://www.uwgb.edu/dutchs/structge/SL133Kalsbeek.HTM
186. Plot the data on an equal
Contouring Structural Data area net then transfer the
overlay to the counting net.
Of course, the two nets must
be the same diameter!
From:http://www.uwgb.edu/dutchs/structge/SL133Kalsbeek.HTM
187. Contouring Structural Data
At each vertex, count the
number of points in the
surrounding six triangles
and plot the number at the
vertex. You may want to do
this on a second overlay
above the data overlay.
Each triangle is common to
three hexagons so every
point is counted three times.
(No, this does not mean the
densities have to be divided
by three.) Be certain to check
every vertex close to the data
points to be sure of not
missing any.
From:http://www.uwgb.edu/dutchs/structge/SL133Kalsbeek.HTM
188. Contouring Structural Data
Remove the
numbered
overlay and
contour the
data.
From:http://www.uwgb.edu/dutchs/structge/SL133Kalsbeek.HTM
189. Contouring Structural Data
Place the contoured
data over a Schmidt
Net and rotate it so
the highest
concentration data
is on the E-W
diameter
From:http://www.uwgb.edu/dutchs/structge/SL133Kalsbeek.HTM
190. Contouring Structural Data
Construct a plane
90° from the central
cluster of the data
and read the dip
angle directly off the
E-W diameter
From:http://www.uwgb.edu/dutchs/structge/SL133Kalsbeek.HTM
191. Contouring Structural Data
Rotate the entire
overlay back to
north and read off
the predominant
orientation of the
joint set.
From:http://www.uwgb.edu/dutchs/structge/SL133Kalsbeek.HTM
224. Using the Structural Data measured earlier, calculate the direction and degree
of anisotropy for the following situation:
Joint Set No 1 – 049 60NW
Joint Set No. 2 – 336 56 NE
Field Hydraulic gradient - 0.05 180°
Field Hydraulic Gradient
100 ft
243. Current Research
The simple partitioning of groundwater into intersecting joints is
complicated by the differential partitioning which occurs between
upgradient-facing and downgradient-facing intersections
Plan View