Determining Paleoflow of Glacial Fluvial Systems in Crawford County (2)
1. Determining Paleoflow of Glacial Fluvial Systems in Crawford County PA
Thomas Hunter
Professor Ron Cole
Allegheny College
9/7/15
2. Abstract
Constructing a map of the paleoflow of glacial
fluvial systems will help in the estimation of
economically beneficial resources such as sand,
gravel, and potential aquifers locations. The
paleoflow direction will be determined by
inverting the dip direction of imbricated clasts
of pebble to cobble sized gravel (as discussed in
[Rust,1972a]). Crawford County Pennsylvania
was chosen for local location near Allegheny
College and for its rich glacial deposits.
Introduction
The sediments deposited by the glaciers during
the late Pleistocene shape the Crawford County
landscape. Till and braided river deposits fill
the majority of the landscape. Construction
companies in Crawford County mine for these
deposits to use the sand and gravel for
infrastructure construction. These are all strip
mines and are also known as gravel pits. Gravel
pits provide outcrops for observing the glacial
deposits.
The braided river deposits are the only type of
glacial deposit that will give insight to the
paleoflow. Sedimentary clasts at the bottom of
a fluvial system will be moved by the flow in a
way that flow restriction is minimized. This is
known as clast imbrication, and clasts of
paleofluvial systems orientation within the
matrix can be measured to determine the
paleoflow direction. (Rust,1972a)
Brief Glacial History
(Summary of McQuillan,1995)
During the Pleistocene there were 3 glacial
advances, the first was during the late Illinoin
and early Wisconsonian. The next two
glaciations followed during the Kent stage of
the late Wisconsonian. The glaciers though
once abundant, never advanced too far south
out of Crawford County most likely because of
the bedrock topography, moraine deposits
from earlier glaciers, and climatic changes
(McQuillan, 1995).
During the interglacial periods, only parts of
Crawford County went through total glacial
recession, while the glacier remained in other
parts of the area. The glacier ultimately
retreated tothe Northwest leaving behind ice
lobes that melted slower after being cut off
from the main glacier (by no-through valleys)
and covered with sediment from meltwater
streams. These lobes went on to form kame
deposits and kettle lakes that define the
landscape today (McQuillan, 1995)
Methods
A Brunton Compass was used to measure the
orientation of clasts within lenticular beds at
gravel pit outcrops. The measurements made
include strike of the clasts and dip direction/
magnitude. Clast imbrications indicate the
paleoflow by the inverse of the dip direction
(e.g. a dip direction of 30 degrees NW indicates
a paleoflow vector of 210 degrees SW) (Rust
1972a), at each site 20 to 50 strike and dips
were taken combined into an average paleoflow
vector for the site.
Other observations made at an outcrop
include;
outcrop dimensions- the overall size of a
rock wall, may contain more than 1
different glacial deposit
bed shape and dimensions- lenticular
bedding indicates river channels while
no bedding generally indicated till
clast support vs. matrix support-both
give good data (imbrications present),
but clast support gives more
average clast size- boulders are too big
to be oriented by fluvial flow
sorting- tells how far the clasts have
been transported
roundness- clasts that are well rounded
orientations cannot be measured
accurately by a Brunton Compass
(Field Observations can be found in Appendix 4)
Sites were found on topographic maps of
Crawford County and then confirmed on
Google Earth. Before entering a gravel pit (pit)
a phone call or meeting with the contractor/
owner of the pit was conducted to gain
permission to observe the outcrop. Pits were
named after their location (road or town) and
after their owners.
3. Determining Paleoflow of Glacial Fluvial Systems in Crawford County 2015
3
At many pits imbrication data could not be
collected, reasons for this include;
Bed rock mine- some sites were not
glacial deposits but bedrock such as
shale and sandstone. Pits include;
Kosurick, Donovan, Route19 farm, and
Hickory Corners.
Reclamation- when a gravel pit is not
being used the Environmental
Protection Agency (EPA) makes
contractors collapse their walls/
potential outcrops in their pits. This is
because having a wall negatively affects
the turbidity of local streams. Pits
include; Atlantic, Lakeland main,
Lakeland ford, Lakeland honda,
Hindman, Crossingville, Merrit, Maple
drive, Route86, Stutsman, Gravel run,
Goodwill, Quarry Rd. a, Quarry Rd. b
(western).
Round clasts/ till- many glacial deposits
are and therefore cannot produce good
imbrication data. While other glacial
deposits that have lenticular beds end
up having rounded clasts that cannot be
measured with a Brunton compass. Pits
include; Phelps (till), Route19 field (till),
Plank (till), Glover (round clasts), and
Hasbrook (round clasts).
No permission- sometimes the owner of
a gravel pit would be unable to give
permission to enter their pits due to
safety or government regulations. Pits
include; Redimix main, Route322 a,
Route322 b (nearer to Cochranton),
Deckards, Seagertown, Mackey hill
north, Mackey hill south, Hogback.
Of the 35 sites found in Crawford County only 5
were observed for successful imbrication data.
These pits include; Infield, Hunter, Miller-
Hunter, Miller-Centerville, and Hillside.
Paleoflow Data
Chart 1a describes the paleoflow direction at
each of the sites where data could be collected.
A rose diagram was generated for each datum
of paleoflow. (Figure 1a, 1b, 1c, 1d, 1e)
Maps 1 and 2 were created using a parcel
search as base map. All sites were plotted
precisely using latitude and longitude. Average
paleoflow vectors are represented by arrows
pointing in the direction of paleoflow, at the
sites were paleoflow data was recorded. (Maps
are in appendix 1)
Map 3 was created using Google Earth as base
map, paleoflow sites were plotted using latitude
and longitude. The sites each have a rose
diagram petal pointing in the direction of
paleocurrent.
Pit AveragePaleoflowVector GeneralCompassDirection
Hunter 205 SW
Hunter-Miller 206 SW
Infield 198.5 SW
Centerville-Miller 152 SE
Hillside 198.5 SW
4. Determining Paleoflow of Glacial Fluvial Systems in Crawford County 2015
4
Figure 1a (Centerville-Miller)
Figure 1b (Hunter-Miller)
Figure 1c (Hunter)
Figure 1d (Infield)
5. Determining Paleoflow of Glacial Fluvial Systems in Crawford County 2015
5
Figure 1e (Hillside)
Due to the lack of imbrication data present in
Crawford County, a more accurate paleoflow
map could not be constructed.
Conclusions
The meltwater streams of receding glaciers
deposited sand and gravel in Crawford County.
Through paleoflow data collected in the eastern
half of Crawford County the glacial fluvial
systems are confirmed to have a southward
trend. The western half of Crawford County did
not have any available fluvial imbricated
sedimentary datum, therefore the paleoflow
cannot be determined.
These data reveal that present day southward
drainage systems are inherited from the
Pleistocene. An interesting future study of
paleoflow through clast imbrications of glacial
fluvial sediments would be to study other areas
of the Mississippi river basin and see if the
drainage patterns are inherited from the glacial
systems. Another interesting future study
would look at determining the protoliths of
gravel clasts in glacial sediments (by its
mineral content and/or sedimentary structures
present).
6. Determining Paleoflow of Glacial Fluvial Systems in Crawford County 2015
6
Appendix 1: Maps
Map 1
Map 2
15. Determining Paleoflow of Glacial Fluvial Systems in Crawford County 2015
15
Acknowledgements
Funding:
• Allegheny College
• Christine Scott Nelson Faculty Support Fund
Field sites:
• R. Hunter Inc.
• Glover Sand and Gravel
• Hillside Stone
• Centerville Sand and Gravel
• Lakeland Construction
• Hasbrook Sand and Gravel
• Kosurick Construction
References
• Dahms, D.E., 2002, Glacial stratigraphy of Stough Creek Basin, Wind River Range, Wyoming:
Geomorphology, v. 42, p. 59-83, doi: 10.1016/S0169-555X(01)00073-3.
• DeCelles, P., Langford, R., and Schwarz, R., Two New Methods of Paleocurrent Determination
from Trough Cross-Stratification: , 629-643 p.
• Rust, 1972a, Pebble Orientation in Fluvial Sediments: Journal of Sedimentary Petrology, v. 42,
p. 384-388.
• Rust, 1972b, Structure and Process in a Braided River: Sedimentology, v. 23, p. 213-234.
• van Rensbergen, P., de Batist, M., Beck, C., and Chapron, E., 1999, High-resolution seismic
stratigraphy of glacial to interglacial fill of a deep glacigenic lake: Lake Le Bourget,
Northwestern Alps, France: Sedimentary Geology, v. 128, p. 99-129, doi: 10.1016/S0037-
0738(99)00064-0.
• Glacial Facies. (1984). In R. Walker (Ed.), Facies Models, Second Edition (2nd ed., Vol. 1, pp.
19-26). Hamilton, Ontario: Geological Association of Canada.
• Compton, R. (1985). Chapters 9 & 10. In Geology in the Field (1st ed., Vol. 1, pp. 169-176, 203-
206). New York, New York: John Wiley & Sons.
• Schiner, G., & Gallaher, J. (1979). Groundwater. In Geology and Groundwater Resources of
Western Crawford County, Pennsylvania (1st ed., Vol. 1, pp. 8-11). Harrisburg, Pennsylvania:
United States Geological Survey.
• McQuillan, E., 1995, The Glacial Geology of the Townville 15 Quadrangle, Northwestern
Pennsylvania [Senior thesis]: Allegheny College, .
![Abstract
Constructing a map of the paleoflow of glacial
fluvial systems will help in the estimation of
economically beneficial resources such as sand,
gravel, and potential aquifers locations. The
paleoflow direction will be determined by
inverting the dip direction of imbricated clasts
of pebble to cobble sized gravel (as discussed in
[Rust,1972a]). Crawford County Pennsylvania
was chosen for local location near Allegheny
College and for its rich glacial deposits.
Introduction
The sediments deposited by the glaciers during
the late Pleistocene shape the Crawford County
landscape. Till and braided river deposits fill
the majority of the landscape. Construction
companies in Crawford County mine for these
deposits to use the sand and gravel for
infrastructure construction. These are all strip
mines and are also known as gravel pits. Gravel
pits provide outcrops for observing the glacial
deposits.
The braided river deposits are the only type of
glacial deposit that will give insight to the
paleoflow. Sedimentary clasts at the bottom of
a fluvial system will be moved by the flow in a
way that flow restriction is minimized. This is
known as clast imbrication, and clasts of
paleofluvial systems orientation within the
matrix can be measured to determine the
paleoflow direction. (Rust,1972a)
Brief Glacial History
(Summary of McQuillan,1995)
During the Pleistocene there were 3 glacial
advances, the first was during the late Illinoin
and early Wisconsonian. The next two
glaciations followed during the Kent stage of
the late Wisconsonian. The glaciers though
once abundant, never advanced too far south
out of Crawford County most likely because of
the bedrock topography, moraine deposits
from earlier glaciers, and climatic changes
(McQuillan, 1995).
During the interglacial periods, only parts of
Crawford County went through total glacial
recession, while the glacier remained in other
parts of the area. The glacier ultimately
retreated tothe Northwest leaving behind ice
lobes that melted slower after being cut off
from the main glacier (by no-through valleys)
and covered with sediment from meltwater
streams. These lobes went on to form kame
deposits and kettle lakes that define the
landscape today (McQuillan, 1995)
Methods
A Brunton Compass was used to measure the
orientation of clasts within lenticular beds at
gravel pit outcrops. The measurements made
include strike of the clasts and dip direction/
magnitude. Clast imbrications indicate the
paleoflow by the inverse of the dip direction
(e.g. a dip direction of 30 degrees NW indicates
a paleoflow vector of 210 degrees SW) (Rust
1972a), at each site 20 to 50 strike and dips
were taken combined into an average paleoflow
vector for the site.
Other observations made at an outcrop
include;
outcrop dimensions- the overall size of a
rock wall, may contain more than 1
different glacial deposit
bed shape and dimensions- lenticular
bedding indicates river channels while
no bedding generally indicated till
clast support vs. matrix support-both
give good data (imbrications present),
but clast support gives more
average clast size- boulders are too big
to be oriented by fluvial flow
sorting- tells how far the clasts have
been transported
roundness- clasts that are well rounded
orientations cannot be measured
accurately by a Brunton Compass
(Field Observations can be found in Appendix 4)
Sites were found on topographic maps of
Crawford County and then confirmed on
Google Earth. Before entering a gravel pit (pit)
a phone call or meeting with the contractor/
owner of the pit was conducted to gain
permission to observe the outcrop. Pits were
named after their location (road or town) and
after their owners.](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)