Geology of the Mammoth Cave and Nolin River Gorge Region
with Emphasis on Hydrocarbon and Karst Resources
Part I: Geomorphology, Stratigraphy, and Industrial Materials
by
Michael T. May, Kenneth W. Kuehn, and Fredrick D. Siewers
Kentucky Society of Professional Geologists (KSPG)
2007 Annual Field Conference
Day 1 of 2
September 14-15, 2007
2007 Field Trip Sponsors
Kentucky Society of Professional Geologists
American Association of Petroleum Geologists
Cambridge Market Café
Edmonson County Government
Scotty’s Contracting and Stone, LLC
Citizens of Kyrock and Brownsville, Kentucky
Ogden College of Science and Engineering, Western Kentucky University
Department of Geography and Geology, Western Kentucky University
Kentucky Geological Survey, University of Kentucky
Kentucky Society of Professional Geologists
2007 Executive Committee
President: Andrew Wulff
President Elect: David Williams
Past-President: Michael May
Secretary/Treasurer: Fredrick Siewers
Councilor-at-large: Kenneth Kuehn
Councilor-at-large: Richard Smath
Editor: Margaret Smath
Table of Contents for Day 1
Welcome.......................................................................................................................................................i
Acknowledgments........................................................................................................................................i
Field Trip Leaders.......................................................................................................................................ii
List of Figures ...........................................................................................................................................iii
Introduction to the Region...........................................................................................................................1
Roadcuts along KY 1435 - Barren River Road ..........................................................................................3
Dimension Stone Resources....................................................................................................................... 6
Aggregate Resources ..................................................................................................................................8
Hydrocarbon Resources..............................................................................................................................9
Roadways of Rock and Asphalt................................................................................................................10
Asphalt Pavement Basics..........................................................................................................................11
Glossary of Common Terms Relating to the Asphalt Paving Industry......................................................13
Itinerary: Friday, September 14, 2007 ......................................................................................................17
References Cited ......................................................................................................................................20
Rights and Permissions
This EDITION was for use by participants during the field conference and is for educational purposes
only. It may not be further duplicated or distributed, but it may be cited.
Welcome
We welcome members of the Kentucky Society of Professional Geologists and the American Association of Petroleum Geologists, students, and teachers, to south central Kentucky. Our field conference is
centered in a unique geologic area that includes world class karst geomorphology, including Mammoth
Cave - the world’s longest mapped cave system, a globally significant sequence boundary and a deeply
incised paleovalley at the Mississippian-Pennsylvanian systemic boundary.
We will discuss significant geologic resources of the southern Kentucky karst including region’s hydrocarbon occurrences within stratigraphic units ranging from Devonian (Clear Creek) through the
Chesterian sandstones (Big Clifty and Hardinsburg) and up through basal Pennsylvanian (Caseyville or
Kyrock/Bee Spring).
Most importantly, we welcome you to step back in history as we trek along the bluff-lined Nolin River
community of Kyrock to learn how this small area of Edmonson County, Kentucky with its 2,000 inhabitants literally helped pave the way to the future for many places around the country and the world.
Likewise, we invite you to see how natural rock asphalt is once again becoming an economically viable
material for the region’s paving industry and you will be provided a primer in modern hot mix asphalt
manufacturing.
Acknowledgments
We wish to thank numerous people who helped make this field trip and guidebook possible including the
support of the KSPG and the Eastern Section of AAPG. Mr. Larry “Butch” Carroll, our host at the former Carmichael home at Kyrock, and Jim Ashley of Edmonson County both have enthusiastically displayed to us the geological wonders and history of the lands just west of Mammoth Cave National Park.
We also acknowledge the guidance of Nancy Baird of the Kentucky Library at Western Kentucky University for uncovering many wonderful Kyrock publications from the early 1900s. Special thanks to the
Executive Committee of KSPG and Drew Andrews, KSPG Distinguished Site Chair for support of the
4th Distinctive Geologic Site nomination. We extend special thanks to Jared Nix of Scotty’s Contracting
and Stone for his educating us on all things asphalt and taking us through the mix plant and laboratory at
Bowling Green. Dr. Rick Toomey contributed as our guide for the Mammoth Cave portion of the trip.
Dr. Chris Groves and Pat Kambesis provided information on protecting karst resources near the Arthur
Oil Field adjacent to Mammoth Cave National Park. Nathan Rinehart provided expert graphical support
for several maps in the road log portion of the field guide.
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Field Trip Leaders
Dr. Michael T. May is a Professor of Geology at Western Kentucky University specializing in sedimentary geology, low-temperature geochemistry and environmental geology. Prior to starting his career at
WKU in 1996, he worked for two environmental consulting companies in the greater Kansas City area
and two major petroleum companies in Houston and Midland, Texas. He earned his Ph.D. from Indiana
University in 1992, specializing in subsurface and outcrop characterization of ancient fluvial systems.
He has published a wide variety of topics in environmental and sedimentary geology journals over the
past decade. His current research interests include mapping the Mississippian-Pennsylvanian unconformity in Kentucky, the origin of terra rossa soils common in karst areas, as well as sedimentary petrology.
In 2004, he was honored with the Faculty Award for Outstanding Public Service in the Ogden College of
Science and Engineering at WKU.
Dr. Kenneth W. Kuehn is a Professor of Geology at Western Kentucky University where he has been
employed since 1984. He earned his Ph.D. from Penn State University in 1981 emphasizing regional
geology, coal science, and geostatistics. He has consulted widely for government and industry in aspects
of coal, petroleum, and other natural resources. Active in research and publication, Dr. Kuehn endeavors
to integrate classroom, laboratory and field experiences. In 2002 he was named a University Distinguished Professor for his long-term contributions to teaching, research, public service, and contributions
to the geology profession.
Dr. Fredrick D. Siewers is an Associate Professor of Geology at Western Kentucky University where
he has been employed since 1998. He is a specialist in sedimentary geology and paleontology with a
Ph.D. from the University of Illinois (1995). His Ph.D. work focused on the formation and stratigraphic
significance of discontinuity surfaces (hardgrounds and paleokarst features) in Ordovician limestones
of Nevada. More recently he has been working on the sedimentary petrology and genesis of Pennsylvanian coal-ball concretions, and with colleagues at other universities, projects focused on sedimentary
and biotic records of Holocene climate change as preserved in tropical saline lakes. Dr. Siewers teaches
courses in Earth History, sedimentary geology, paleontology, geological field techniques, and Earth
System Science. His courses range from intensive field experiences to on-line professional development
offerings. In 2001, he was presented with the Faculty Award for Outstanding Teaching in the Ogden College of Science and Engineering at WKU.
ii
List of Figures
Figure
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Physiographic regions of Kentucky
Oblique aerial view of karst plain, escarpment and plateau areas
Grikes and clints typical of Ste. Genevieve Limestone
Stratigraphic column for rocks in Mammoth Cave
Slabs of Ste. Genevieve Limestone showing salient lithologic variation
Intraformational disconformity in Ste. Genevieve Limestone
View of Whitestone Quarry west of Bowling Green
Buildings in Bowling Green constructed with oolitic Girkin Limestone
Large vug lined with pink “saddle” dolomite crystals
Aerial view of Rinker Materials’ Quarry and Scotty’s asphalt plant (2006)
Trays of graded aggregate for laboratory testing of asphalt mixes
Scotty’s Contracting & Stone Asphalt Plant
View of Scotty’s corporate office and technology center
Asphalt test cylinders or “pills”
Close up view of disconformity surface Ste. Genevieve Limestone
Oolitic facies in the Girkin Limestone at Richardsville Road and KY 185
Louisville and Nashville Railroad Depot
Additional Figures
Map of field trip area
Aerial view of field trip area with stops indicated
Geologic map of field trip area
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Introduction to the Region
Palmer that was developed over three decades
of stratigraphic mapping and leveling surveys
within Mammoth Cave that we will use as reference for the lithofacies we observe in the field. In
and around the city of Bowling Green, the Ste.
Genevieve Limestone predominates and typifies a
wide swath of Warren County along the southwestnortheast regional strike. Only in deeper, incised
areas such as along the Barren River or Drakes
Creek does the underlying St. Louis Limestone
crop out. The Girkin Limestone above is present
in only one location within the confines of the city
of Bowling Green atop the highest part of the hill
on the campus of Western Kentucky University.
From there, one can take in an excellent view of
the Dripping Springs Escarpment north and northwest of the city.
Mammoth Cave and the city of Bowling Green
are located in the Mississippian Plateaus region
of Kentucky (Figure 1). This region comprises
several physiographic subregions including the
Pennyroyal Plateau (or ‘sinkhole plain’) and the
Mammoth Cave Plateau (or Chester Upland)
which rises 150-200 feet above the Pennyroyal
surface to the west. These two roughly horizontal
surfaces are separated by the Dripping Springs (or
Chester) Escarpment as seen in Figure 2. Bowling Green itself is located entirely on the sinkhole
plain whereas Mammoth Cave developed beneath
the plateau which bears its name, about 25 miles
(40 kilometers) to the northeast. The regional
landscape owes its character, in large part, to the
sequence of nearly flat-lying, very pure limestones
of Mississippian age (Valmeyeran-Chesterian)
including (in ascending order) the St. Louis, Ste.
Genevieve, and Girkin Limestones.
The Ste. Genevieve Limestone is the main formation taken from the Rinker Materials Bowling
Green South Quarry that we will visit on our first
stop. This quarry supplies much of the material
for Bowling Green area roads such as the recent
expansion of Interstate 65 and the ongoing widening of the Veteran’s Memorial Parkway skirting the
western edge of the city.
These carbonates via weathering are replaced by
red, iron-rich and clay-rich, soil known as terra
rossa which is typical of the region. Strata near
the surface are attacked by chemically aggressive
waters and dissolve into a discontinuous pattern
known as clints (limestone islands) and grikes
(solutionally-enlarged fractures) as shown in
Figure 3.
Below the Ste. Genevieve, or worked part of the
quarry, lies the St. Louis, a high-calcium limestone
that is locally argillaceous or dolomitic and tends
to be cherty, especially in its upper portion.
Overlying the Girkin is the Big Clifty Sandstone
Member of the Golconda Formation which is the
resistant “caprock” that protects Mammoth Cave
beneath.
Because of the presence of chert, a deleterious
material for concrete aggregate, the St. Louis has
been used mainly for road aggregate and agricultural lime where it is accessible in the Bowling
Green area. The Ste. Genevieve Limestone has
been, and continues to be, quarried on a large scale
in Warren County and is the most quarried formation in the state. It is commonly oolitic and contains some chert, especially at the base, but much
less so than the underlying St. Louis Limestone.
There are multiple potential quarry locations
across the county, particularly at the break of slope
associated with the Dripping Springs Escarpment
and along outliers of knobs and low hills in front
of the escarpment proper. According to McGrain
Surface geology of the sinkhole plain includes the
upper St. Louis, and all of the Ste. Genevieve and
Girkin although the latter is mainly preserved in
the higher ‘clifty’ knobs and escarpment slope.
The upper boundary for major karst development
is the contact between the Girkin Limestone and
the Big Clifty Sandstone and in the case of Mammoth Cave National Park, the lower limit is set
by the Green River which pools at the middle
of the St. Louis Limestone Formation. Figure 4
is a detailed graphic section courtesy of Dr. Art
1
Figure 1. Physiographic regions of Kentucky (Modified from Kentucky Geological
Survey 2007).
Figure 2. Oblique aerial view depicting the main features of the Mammoth Cave region physiography just northeast of Bowling Green including the Karst Plain, Dripping
Springs Escarpment, and the Mammoth Cave Plateau. View is eastward. Note waterfilled sinkholes and wooded sinkholes of the mostly cleared agricultural land to right.
Escarpment slope is distinctly forested and the top of the plateau is a patchwork of forest and agricultural land. Escarpment is a cuesta with a dip to the west or northwest (to
the left of view).
2
genic in origin, associated with subaerial exposure
surfaces. Hunter (1993) for example, in southern
Indiana noted that some oolites are eolianites with
associated pedogenic breccias (cf. calcrete of Dever et al., 1990). Still other facies variations in the
Ste. Genevieve in the Bowling Green area include
myriad skeletal packstones and grainstones mostly
bryozoan, crinoidal and brachiopod-rich with a
few solitary and colonial corals. Several of the
significant lithologies and textures are shown as
polished slabs in Figure 5.
Figure 3. Solution enlarged fractures (grikes)
and blocks of digitate limestone between grikes
known as clints typifying Ste Genevieve limestone in the Bowling Green area. View just off
of Barren River Road in Warren County.
and Sutton (1973, p. 19) in the lower 20 to 30
feet there are bedded and nodular cherts (the Lost
River Chert) that essentially mark the lowest stratigraphic interval of the Ste. Genevieve suitable for
quarrying. They also note that the upper part of
the Ste. Genevieve is demarcated by the presence
of the colonial coral, Lithostrotion genevievenus.
The thickness of the Ste. Genevieve ranges from
180 to 215 feet in the Bowling Green North Geological Quadrangle to over 200 feet thick in the
Bowling Green South GQ (Shawe, 1963a, b).
Some of the carbonates have been partially replaced by chert and some have been dolomitized
creating complex intercalations which, in outcrop,
can appear as alternating light and dark layers.
The Fredonia Member in the lower portion of the
formation shows as regular rhythms that grade
upward from grainstones to dolostones. The highest encountered cherty limestone is the typical pick
for the top of the Ste Genevieve in this area.
Disconformities are present within the Ste. Genevieve, the most conspicuous of which is a pronounced, undulating surface with a few feet of
relief (Figure 6). In many places a thin shale bed is
present at the contact and some areas show calcitefilled fractures and other features below the contact
which are not continuous across it. This surface
most probably represents a combination of dissolution (paleokarst) and subsequent pressure dissolution (megastylolitic surface) during burial. Many
Roadcuts along KY 1435 - Barren River Road.
stylolites in the Ste. Genevieve and similar Mississippian carbonates in the region are controlled
A traverse westward along Barren River Road
by texture (e.g., grainstone versus mudstone as
from the quarry site (Stop 1) toward the Dripping
extreme examples) and mineralogical differences
Springs Escarpment provides several exposures of (e.g. dolomitic versus calcitic strata). Similar inSte. Genevieve Limestone where textures, mineral- traformational breaks or disconformities have been
ogic differences, and contacts between nearly half noted in other Kentucky locations such in Pulaski
a dozen distinct lithofacies can be observed. These County (e.g. Dever et al., 1990, Fig. 8).
range from muddy carbonates to grainstones or
coquinas. Ooid grainstones are present throughout Moving up topographically and stratigraphically as
and these are well recognized as good petroleum
we ascend the Dripping Springs Escarpment, the
producers in the Illinois Basin to the northwest.
Ste. Genevieve is capped by the Girkin Limestone.
Another recognized facies is an intraclastic limeThe Girkin is a skeletal grainstone and packstone
clast conglomerate or breccia, the result of localin many locations but can also be a lutite of carized channeling and reworking. Some of these
bonate mudstone or wackestone. The most famous
brecciated units have been recognized as pedo3
Figure 4. Stratigraphic Column in Mammoth Cave area (after Palmer, 1998).
4
A
D
B
E
C
F
Figure 5. Slabs of the Ste Genevieve Limestone showing salient lithologic variation.
A. Brachiopod Grainstone, B. Oolitic and Bioclastic Grainstone, C. Chert replacing Limestone,
D. Dolostone, E. Intraclastic Conglomerate and Breccia, F. Supratidal Limestone with typical
fenestral porosity or ‘birdseye vugs.’
5
Figure 6. Intraformational disconformity in Ste. Genevieve Limestone. Compare to modern karst
surface in Figure 3. View from cut along Barren River Road, Warren County.
lithology of the Girkin is the massive oolitic facies
which was a well-known dimension stone. The
formation ranges from about 75 to 125 feet in
thickness across the region. The oolite facies can
exceed 20 feet in thickness, and many of these
thicker units were quarried for building stone.
downcutting or eroded back from the ‘front’ of the
escarpment, karst valleys over 200 feet deep have
developed.
Dimension Stone Resources
In the late 1800s and early 1900s prior to the main
production of limestone as aggregate, the quarries
were buzzing with activity for another resource
– dimension stone. Cut blocks of limestone for
churches, schools, houses, fences and walls were
quarried at numerous locales in Warren County.
Probably the earliest operation began about 1845
according to Gardner (1910) and there are some
reports (McGrain and Sutton, 1973, p. 17) that
crude building stone was quarried as early as 1833,
thirty-five years after the founding of Bowling
Atop the Girkin, nearing the top of the Dripping
Springs Escarpment, the Big Clifty Sandstone
Member of the Golconda Formation is easily
picked by its brownish color, extensive crossbedding and, in some cases, its flaggy and ripple-laminated beds. The Big Clifty contains some shale
units, typically near the base, which along with
the sandstone create a resistant cap rock that helps
protects the Mammoth Cave Plateau. In areas
where the caprock has been breached by stream
6
Green. The first quarry on official record for the
area however dates from 1872 (Coons, 1923, p.
328).
By the early 1900s, Warren County had gained
nationwide recognition for its bustling dimension
stone industry and the quality of its “Bowling
Figure 7. View of Whitestone Quarry along
Dripping Springs Escarpment just west of
Bowling Green, ca. 1929. The Girkin limestone
was quarried here as part of the largest dimension stone district in Kentucky (Courtesy Kentucky Library).
Green Oolite” or beautiful “White Stone” (Figure
7 quarry).
Some accolades associated with the White Stone
include the gold medal at the World’s Columbian
Exposition at Chicago in 1893, and the highest award at the Louisiana Purchase Exposition,
also known as the 1904 St. Louis World’s Fair
(Richardson, 1923, p. 245). A great number of
architecturally significant buildings were constructed entirely or partially with the Bowling
Green Oolite such as the U.S. Post Office and
Customs House on Broadway in Nashville, Tennessee; Saint Thomas Cathedral on Fifth Avenue in
New York City; the Seelbach Hotel in Louisville;
Atlanta University buildings in Atlanta; St. Boniface School and Church in Evansville, Indiana;
Governor’s Mansion in Frankfort, Kentucky; St.
John’s Cathedral in Jacksonville, Florida and many
others. Significant structures made with the local
White Stone still survive in Bowling Green: State
Street Methodist Church, William H. Natcher
Federal Building (formerly the Post Office), the
gateways to Fountain Square Park, the fluted columns of Van Meter Auditorium on the campus of
Western Kentucky University; the Louisville and
Nashville Railroad Depot and the Kentucky Mu-
Figure 8. Buildings in Bowling Green constructed with Oolitic Girkin Limestone.
On left - Kentucky Museum on the WKU campus was constructed with some of the last quarried
stone from the Whitestone Quarry (ca. 1937). Columns on front of building are single pieces of
stone 22 feet in length. As is typical, the stone making up the columns is beautifully crossbedded.
On right - Louisville and Nashville (L & N) Train Depot showing detail of fluted column and
carved capital. Girkin oolitic limestone was used in the construction ca. 1925.
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seum at WKU (Figure 8). The latter two edifices
have single-stone columns to 22 feet in length that
beautifully display crossbedding.
Quarry. The huge blocks were cut by channeling
machines in the vertical dimension and gadding
machines made the horizontal channels or cuts.
The blocks were then hoisted from the quarry by
derricks and loaded onto cars. The Bowling Green
Stone and Green River Quarries operated a cutting
plant outside of the city limits of Bowling Green
where some of the smaller scale cutting was done.
Regional mills such as one at Evansville, Indiana
(e.g., McGrain and Sutton, 1973, p. 22) fashioned
the Bowling Green Oolite after it was shipped as
large blocks.
According to Richardson (1923, p. 236) most of
the building stones of Warren County in the early
1900s were from the Gasper (an abandoned stratigraphic name equivalent to the Girkin) oolitic
limestone. In a rather boastful manner he notes
that the oolitic limestone varied in thickness from
10 to 22 feet “without seam or flaw” and he called
it the “Aristocrat of all the limestones.” Of note
is the fact that the stone upon weathering became
lighter in color but the freshly quarried stone often
had a petroliferous odor and was stained by “bituminous substances.” Gardner (1910) stated that
the oolitic “Bowling Green Stone” whitened over
time because of gradual evaporation of the light
hydrocarbons (or volatile petroleum) it contained.
Richardson (1923, p. 244) thought that the stone’s
beautiful color (“Royal White” as he called it) and
uniform texture, made it worth waiting through
the curing or bleaching period. He furthermore
stated that the stone possessed great strength and
durability as noted by hearthstones and chimney
caps over a hundred years old that showed little
effect from weathering. It also could be worked
with remarkable ease because of its “perfect rift
and grain and its uniformity of texture” though he
does note that there are “occasional” occurrences
of lenticular pyrite that discolor the stone as the
sulfide mineral oxides. He concludes his quality
assessment of the Bowling Green Oolite with a
strong statement that it is “fully the equal of the
oolitic limestones of Bedford, Lawrence County,
Indiana,” the much more famous and more widely
distributed Indiana Limestone.
Aggregate Resources
In the 1920s (Richardson, 1924) many quarries
were opened in the Ste. Genevieve for railroad ballast and aggregate for the L & N railroad and roads
in the Bowling Green area in addition to the dimension stone being produced from the Girkin. A
small amount of aggregate was obtained from the
Girkin as well (Shawe, 1963). When the majority
of the dimension stone quarries closed during the
Depression Era of the 1930s, the Girkin quarries
were then utilized solely for aggregate production,
as is the case today.
The present economic expansion noted by continued road construction in the Bowling Green area
as anywhere demands a proximally located series
of quarries for aggregate. Limestone aggregate
resources are of tremendous economic importance
in the region and the Commonwealth. In 200405, Kentucky averaged about 60,000,000 tons per
year with a total value of more than $400 million
(USGS, 2007). Moreover, there are few locations
in the local area that possess sufficient sand or
gravel deposits for use as fine aggregate, as is the
general case for the karst plain region. This is because karst terrains are characterized by a paucity
of surface water and the associated alluvium that
could be exploited for aggregate.
The Warren County dimension stone was transported by rail via the Louisville and Nashville
(L & N) railroad and by barge. Ballast, building
stone and agricultural lime were noted by Richardson (1924, p 326-327) as coming from the Bowling Green White Stone Company, the Bowling
Green Whitehouse Quarry at Memphis Junction
southwest of Bowling Green, and the Kissler and
Rigelwood Quarry located near the Whitestone
Chemical assays of the local stone show that the
Ste. Genevieve, though a high-calcium limestone,
can be dolomitized to various degrees including to
a nearly pure dolostone. Associated with the pure
8
dolostone units are pink ‘saddle’ crystals of dolomite lining vugs, some of which attain more than a
foot in length in their longest dimension (Figure 9)
which absorbs additional asphalt and adds cost.
The pure, high-calcium limestones from the Ste.
Genevieve have a specialty use in scrubber slurries
to purify the stack gases of coal-fired power plants.
Rinker Materials, Inc. presently operates three
quarries in the immediate Bowling Green area.
We will visit their Bowling Green South Quarry
on Barren River Road which supplies an on-site
asphalt operation owned by Scotty’s Contracting
and Stone. An oblique aerial view of this combined operation is shown in Figure 10. The two
main benches in the quarry have highwalls of 68
feet and 44 feet and the lowest exposes the top of
the Saint Louis Limestone formation.
Hydrocarbon Resources
Figure 9. Vuggy pore lined with pink ‘saddle’
dolomite crystals common in the Bowling Green
North Quarry dolostone.
Dolomite is a positive characteristic of aggregate
to be used in the surface coat of hot mix asphalt
because it provides excellent non-skid properties.
However, this advantage is offset somewhat because the dolostones tend to have a higher porosity
Surface sheens were observed and recorded during
the late 1700s on water issuing from Oil Spring
near Drakes Creek, a tributary of the Barren River
in Warren County. The first oil discovered in Warren County by drillers was south of Bowling Green
circa 1920, and included several ‘gushers’ such as
occurred on the farm of Yeager, Foster and White
at Rockfield which began the area’s big oil boom.
Put in the context of current market prices that are
in the range of $70 per barrel, the 1924 oil
Figure 10. Aerial view of Rinker Materials Bowling Green Quarry (2006). View to southwest with
Scotty’s Contracting and Stone’s asphalt plant in foreground.
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production from Warren County reported at
580,224 barrels reported by Jillson (1928) would
add more than $40 million to the county’s economy in 2007
Two major plays were well established within the
first decade of commercial petroleum production
in Warren County – the Warsaw Formation of
Mississippian age and the “Corniferous” limestone
of Devonian age (e.g., Jillson, 1928, p. 374). The
Corniferous is informally defined as the limestone
immediately underlying the Chattanooga Shale (or
black shale). This is an easy pick on a wireline log
because there is a huge deflection between the radioactive “hot” shale and the underlying limestone.
In the 1920s both these plays were recognized as
‘sands’ or most probably what today we would call
carbonate grainstones or calcarenites.
Roadways of Rock and Asphalt
According to the National Center for Asphalt
Technology (NCAT, 2007), 96% of all paved roads
in the United States, nearly two million miles, are
surfaced with asphalt. Although pavements of
various types including the use of tars and natural asphalt can be traced back thousands of years,
modern road construction techniques largely began
with three Scottish engineers who worked in the
mid 18th century.
John Metcalfe, (b. 1717) designed roads having
three distinct layers. The base was laid of large
stones to establish a firm foundation, then an intermediate layer of excavated stone was added, and
then a top layer of gravel. His roads were arched
in the center to help water runoff into ditches on
each side keeping the roadway well drained.
John McAdam (or MacAdam, b. 1756) designed
his roads using a tightly laid mosaic of broken
stones to cover the soil. This base was topped
with a layer of small stones. He is credited with
discovering that the best gravel for road surfacing
was angular, crushed stone that was screened to
a constant size consist. These “macadam roads,”
as they became known were considered a great
advancement in road construction of the time.
By the early 19th century a binder of hot coal tar
was incorporated to stabilize the top coat and this
developed into our modern method of road building. The tar and gravel mixture became known as
“tarmacadam” a term later shortened to the more
familiar “tarmac”.
Thomas Telford (b. 1757) is known for his technical engineering innovations. He first placed a base
of broken stones of differing thicknesses according
to the weight and volume of traffic on the road.
He also raised the foundation of the road in the
center to help water drainage and considered factors such as the road’s alignment and gradient. His
roads were more costly to build than those of his
contemporary, McAdam.
Road builders of the mid-18th century depended
solely on stone, gravel, and sand plus water as a
binder to stabilize the road surface. By the early
19th century, coal tar, rock asphalt and natural asphalt also were being used as road paving materials. The first road use of asphalt occurred in Paris,
in 1824. The first recorded asphalt pavement in
the United States was a sand mix laid in Newark,
NJ, in 1870 by Edmund J. DeSmedt, a chemist
at Columbia University. Other applications soon
followed including Fifth Avenue in New York City
and Pennsylvania Avenue in Washington, DC.
These used as a binder the famous natural asphalt
from Pitch Lake on the island of Trinidad. Discovered by Sir Walter Raleigh, Pitch Lake is the
largest natural asphalt lake in the world. Raleigh
used it to waterproof his ships; just as such deposits had been used for thousands of years and Pitch
Lake became the first source of asphalt available in
the United States.
Refined petroleum asphalt appeared commercially
in the mid-1870s and was originally mixed with
the natural Trinidad asphalt to soften it and improve its workability. By 1910, however, increasingly large supplies of refined petroleum asphalt
overtook the use of natural and rock asphalt.
As automobile traffic gradually increased, so did
10
the need for more and better asphalt products.
Manufacturers tried to develop new materials
but were hampered by widely varying properties,
limited laboratory testing, and a growing list of
specifications that did not relate well to how the final product was going to be used. One outcome of
this industry chaos was the creation in 1919 of the
Asphalt Association, later known as the Asphalt
Institute. The initial intention of the Association
was to bring standardization to the industry, reduce
and unify the asphalt specifications, and to unify
state and federal agencies in this regard. Today the
Asphalt Institute is an association of international
petroleum asphalt producers, manufacturers, and
affiliated businesses. It is located in Lexington,
Kentucky across from the Kentucky Horse Park.
Over the course of the 20th century, asphalt
roadways have vastly improved in terms of their
longevity, safety, and smoothness such that our
modern roads bear little resemblance to their early
predecessors of the 1870s. Today, for example,
material layers are usually placed in order of descending load-bearing capacity with the strongest
(and most expensive) on top and the lowest load
bearing capacity material (and least expensive) on
the bottom.
A typical asphalt cover for an interstate highway
may be a total of 28-30 inches thick as follows:
Top Course placed in two layers:
1.5 inches depth of surface mix (3/8”) also
called the “wearing course.”
3 inches depth of (3/4”) intermediate binder
course .
Base Course (9-10 inches) of 1½ ” material. This
is the layer immediately beneath the surface course
that provides additional load distribution and contributes to drainage and frost resistance.
Subbase (8 inches) of ¾” material. This layer
functions primarily as structural support but it can
also (1) minimize the intrusion of fines from the
subgrade into the pavement structure, (2) improve
drainage and (3) minimize frost action damage.
Dense Graded Aggregate (6-8 inches) is applied
over the Subgrade.
The Subgrade is the in situ soil or surface material
upon which the pavement structure is placed. An
unstable subgrade can be the most significant factor in pavement performance.
Asphalt Pavement Basics
Aggregate can either be natural or manufactured.
Natural aggregates are generally quarried from
rock formations in open excavations. The rock is
blasted or scraped from quarry walls then reduced
in size using a series of crushers and screens.
Manufactured aggregates typically consist of
industrial byproducts such as the slag from metallurgical processing or specialty rocks produced to
have a particular physical characteristics not found
in natural rock (such as the low density of lightweight aggregate).
Aggregates can be classified by their mineral,
chemical, and physical properties though the
pavement industry typically relies on physical properties for performance characterization.
Important physical properties include size consist
(gradation), maximum particle size, particle shape,
surface texture, abrasion resistance, toughness
(resistance to physical degradation), and durability
(resistance to weathering). The size consist of the
aggregate in the HMA is a key influence on almost
every important property of the product and thus
is a primary concern in mix design (WAPA 2007).
Figure 11 shows some trays of graded aggregate
prepared for laboratory testing.
Asphalt is a dark brown to black, highly viscous
mixture of high molecular weight hydrocarbons
produced as a residue from petroleum distillation.
This distillation can occur naturally, resulting in
asphalt bearing rock strata or surface seeps, but
mainly it is a byproduct of petroleum refining. In
HMA, the asphalt functions as a waterproof binder.
11
Fatigue resistance: HMA should not crack when
subjected to repeated loads over time. HMA fatigue cracking is related to asphalt binder content
and stiffness.
Low temperature cracking resistance: HMA
should not crack when subjected to low ambient
temperatures. Low temperature cracking is primarily a function of the asphalt binder low temperature stiffness.
Durability: HMA should not age excessively during production and service life. HMA durability
is related to air voids as well as the asphalt binder
film thickness around each aggregate particle.
Figure 11. Trays of graded aggregate for laboratory testing of asphalt mixes.
Typically, the most important physical properties
of asphalt are its durability and rheology. Durability is concerned with how the material continues to
perform over time. Rheology concerns the deformation and flow of the material which are affected
by its composition, temperature, and age.
Moisture damage resistance: HMA should not
degrade substantially from moisture penetration
into the mix. Moisture damage resistance is related to air voids as well as aggregate mineral and
chemical properties.
Hot mix asphalt (HMA) pavement is approximately 95 percent aggregate (stone, sand, or gravel)
mixed with about 5 percent asphalt as a binder.
The aggregate and asphalt are heated, sometimes
combined with reclaimed asphalt products (RAP),
mixed, loaded into trucks and delivered to the job
site. The types and specifications of the materials
used in the asphalt pavement are carefully engineered to best suit a specific application. Aggregate is also used by itself for the base and sub-base
courses.
According to Roberts et. al. (1996), by manipulating the properties of the aggregate, the asphalt
binder, and the ratio between the two, the pavement mix is designed in order to maximize the
qualities of:
Skid resistance: HMA placed as a surface course
should provide sufficient friction when in contact
with a vehicle’s tire. Low skid resistance is generally related to aggregate characteristics or high
asphalt binder content.
Workability: HMA must be capable of being
placed and compacted with reasonable effort.
Workability is generally related to aggregate texture/shape/size/gradation, asphalt binder content
and asphalt binder viscosity at mixing and laydown temperatures.
Figure 12 shows the asphalt plant owned by
Scotty’s Contracting and Stone that we will visit.
It is located on-site at the Rinker Materials, Inc.,
Bowling Green South Quarry. A virtual tour of
a hot mix asphalt plant by the National Asphalt
Pavement Association is available online at: http://
www.hotmix.org/tour.php
Deformation resistance: HMA should not distort (rut) or deform (shove) under traffic loading.
HMA deformation is related to aggregate surface
and abrasion characteristics, aggregate gradation,
asphalt binder content and asphalt binder viscosity
at high temperatures.
12
Figure 12. Scotty’s Contracting & Stone Asphalt Plant showing dispensing hoppers and reclaimed
asphalt product (RAP) in left foreground.
Glossary of Common Terms Relating to the Asphalt Paving Industry
(Source: WAPA Asphalt Pavement Guide, http://www.asphaltwa.com/wapa_web/index.htm)
Aggregate
A collective term for the mineral materials such as sand, gravel and crushed stone that are used with a
binding medium (such as water, bitumen, portland cement, lime, etc.) to form compound materials (such
as asphalt concrete, portland cement concrete, etc.).
Alligator cracks
A series of interconnected cracks caused by fatigue failure of the HMA surface (or stabilized base) under
repeated traffic loading.
Asphalt
A dark brown to black cementitious material in which the predominating constituents are bitumens,
which occur in nature or are obtained in petroleum processing.
13
Asphalt binder
The principal asphaltic binding agent in HMA. “Asphalt binder” includes asphalt cement as well as any
material added to modify the original asphalt cement properties.
Base course
The portion of a pavement structure immediately beneath the surface course. Its major function is structural support and usually consists of aggregate and can be either stabilized or unstabilized.
Batch plant
A manufacturing facility for producing HMA. They manufacture HMA in batches rather than continuously.
Bitumens
A class of black or dark-colored (solid, semi-solid or viscous) cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons, of which asphalts, tars, pitches,
and asphaltenes are typical.
Drum plant
A manufacturing facility for producing HMA. They manufacture HMA continuously rather than in
batches.
Durability
A measure of how asphalt binder physical properties change with age (sometimes called age hardening).
In general, as an asphalt binder ages, its viscosity increases and it becomes more stiff and brittle.
ESAL
Equivalent Single Axle Load. Based on the results from the AASHO Road Test, the most common approach to determining traffic loading is to convert wheel loads of various magnitudes and repetitions to
an equivalent number of “standard” or “equivalent” loads. The most commonly used equivalent load in
the U.S. is the 80 kN (18,000 lbs.) equivalent single axle load.
Fatigue cracking
Cracks caused by fatigue failure of an HMA surface (or stabilized base) under repeated traffic loading.
Geotextiles
Fabric-like materials used in the paving process. Geotextiles are manufactured for specific uses and
performance characteristics. Some uses include stabilization of base material to prevent migration into
sub-grades, retarding of reflective cracking in asphalt overlays, and serving as a moisture barrier between pavement layers (NPCA).
HMA
Hot Mix Asphalt. A high quality, thoroughly controlled hot mixture of asphalt binder and aggregate that
can be compacted into a uniform dense mass.
HMAC
Hot Mix Asphalt Concrete. Another term for HMA.
14
Lift
A layer or course of paving material.
Macadam
Type of early bituminous pavement named after its inventor, a Scotsman named John McAdam (1756 –
1836). McAdam (sometimes spelled “Macadam”) pavements used smaller angular aggregate over larger
angular aggregate over a well-compacted, sloped subgrade.
NAPA
National Asphalt Pavement Association (2007). NAPA supports an active research program designed to
improve the quality of HMA pavements and paving techniques used in the construction of roads, streets,
highways, parking lots, airports, and environmental and recreational facilities. The Association provides
technical, educational, and marketing materials and information to its members, as well as product information to users and specifiers of paving materials. The Association, whose members number more than
1,100 companies, was founded in 1955.
NCAT
National Center for Asphalt Technology. NCAT was established at Auburn University in 1986 with an
endowment set up by the NAPA Research and Education Foundation. Its mission is to improve HMA
performance through research, education, and information services. http://www.eng.auburn.edu/center/
ncat.
Pothole
Bowl-shaped openings in a pavement resulting from localized disintegration.
RAP
Reclaimed Asphalt Pavement. RAP is typically generated by (1) milling machines in rehabilitation projects or (2) a special crushing plant used to break down large pieces of discarded HMA pavement.
Reflective cracking
Cracks in an HMA overlay caused by cracks in the existing pavement “reflecting” up through the overlay.
Rubblization
Reducing a material or structure to rubble. Regarding pavements, rubblization usually refers to reducing
an existing rigid pavement to rubble in preparation for an HMA overlay. This helps prevent reflective
cracking in the new overlay.
Rutting
Surface depression in the wheelpath of a pavement.
Screed
The part of a paving machine that spreads, smoothes, and provides initial compaction of the HMA.
Subbase
The portion of the pavement structure between the subgrade and the base course. A subbase course is not
always needed or used.
15
Subgrade
The material upon which the pavement structure is built. It can either be in-situ material or structural fill
material.
Superpave
Superior Performing Asphalt Pavements. An overarching term for the results of the asphalt research
portion of the 1987 - 1993 Strategic Highway Research Program (SHRP). Superpave consists of (1) an
asphalt binder specification, (2) an HMA mix design method and (3) HMA tests and performance prediction models. Each one of these components is referred to by the term “Superpave”.
Thermal cracking
Cracking caused by shrinkage of the pavement surface due to low temperatures.
TMD
Theoretical maximum density. The theoretical maximum density of an HMA if it contained zero air
voids.
VMA
The volume of intergranular void space between the aggregate particles of a compacted paving mixture
that includes the air voids and the effective asphalt content, expressed as a percent of the total volume of
the specimen.
Wearing course
The pavement layer in direct contact with traffic loads. Sometimes “wearing course” is used interchangeably with “surface course” and sometimes it is used to mean the top portion of the surface course.
It is meant to take the brunt of traffic wear and can be removed and replaced as it becomes worn.
Wheelpath
That portion of a pavement that is contacted by the wheels/tires of vehicles in a typical traffic stream.
There are generally two wheelpaths per lane.
Workability
Regarding HMA, a term that refers to an HMA’s ability to be placed and compacted. Workable mixes
are easy to place and compact and are generally more viscous than mixes with poor workability.
16
Itinerary: Friday, September 14, 2007
Overview
Today’s field trip focuses on Mississippian stratigraphy, geomorphic features and karst resources in the
area around Bowling Green, Kentucky, including the Pennyroyal ‘sinkhole’ Plain, Dripping Springs
Escarpment and the Chester Uplands associated with Mammoth Cave. We will also discuss some of the
history of economic development of some of the region’s including oil, limestone as dimension stone,
limestone as aggregate, and we will enjoy a guided visit to a hot mix asphalt (HMA) manufacturing
facility and testing laboratory.
Our route for the day begins on the south side of Bowling Green (pop. 63,000) on the karst plain. We
traverse the city along flat to gently rolling terrain to the first range of low hills above the Barren River
Valley (all within the Ste. Genevieve Limestone) where we will visit an asphalt plant and observe the
adjacent limestone aggregate quarry. We continue north on the Barren River Road (HWY 1435) to
observe weathering features and lithologic variations within the Ste. Genevieve Limestone as exposed in
a series of road cuts. Continuing northwestward we move topographically and stratigraphically upward,
leaving the Karst Plain and ascending the Dripping Springs Escarpment where the upper Ste. Genevieve,
Girkin Limestone and Big Clifty Sandstone are exposed. From atop the escarpment on the Mammoth
Cave Plateau surface we will take an excellent easterly view from Glen Lily Road (HWY 2665) as we
head south toward Bowling Green. Returning to the karst plain we will drive eastward on Morgantown
Road (US 231), view some exposures of the Girkin Formation on KY 185 north of the city and finish the
day at the old Louisville and Nashville Railroad Depot at US highway 68-80. The depot is one of the
many extraordinary buildings constructed using the local Girkin Limestone, known by the trade names
of “White Stone” or “Bowling Green Oolite.”
Note: The final three pages of this guidebook are maps you can refer to throughout the day. The first
is a general road map showing the area cover by our travels. Second is an aerial photograph with the
locations of our stops indicated, and third is a geologic map of the field trip area.
ROAD LOG
12:00 pm CDT: The group gathers in the parking lot of Microtel Hotel located at I-65, Exit 22, Bowling
Green, KY. We will travel in caravan to our first stop.
Mileage
Interval
Total
0.0
0.0
Stop 1. (approximately two hours) Scotty’s Contracting and Stone, LLC,
2300 Barren River Road, Bowling Green, KY 42102 (Figure 13). We will
visit Scotty’s Technology Center Laboratory, cross the road to the asphalt
plant, look into Rinker Materials Bowling Green South Quarry and watch
a nearby paving operation. Mr. Jared Nix, Scotty’s Asphalt Quality Control Manager, will be our host. Figure 14 shows two pressed cylinders (or
“pills”) of reclaimed asphalt products ready for testing. Turn right (north)
from McFarland Lane (entrance road to Scotty’s Technology Center) onto
KY 1435, Barren River Road. Rinker Materials Bowling Green South
Quarry is on your left.
17
Figure 13. View of Scotty’s Contracting &
Stone corporate office and technology center in
Bowling Green.
Mileage
Interval
Total
0.5
0.5
0.9
1.4
0.6
2.0
1.0
3.0
0.5
3.5
Figure 14. Asphalt test cyclinders or pills. Various compaction and rutting tests are conducted
on such samples routinely to assure high-quality
paving on roadways.
Stop 2. Pull off on right near the old stone fence for a view of the Pennyroyal ‘sinkhole’ Plain and Dripping Springs Escarpment. At this stop we
will discuss stratigraphy and geomorphic expression of the major landscape
elements.
Stop 3. At this exposure of Ste. Genevieve Limestone we will walk the
roadcut, discuss possible subdivisions of the formation, and examine prepared slabs of the major lithofacies. The southeast end of the cut exposes
a well laminated brachiopod grainstone or coquina that can best be recognized on the weathered surfaces. Interbeds of green shale indicate a flooding surface over the shoal deposits here. Architecture is rhythmic, beginning with grainstones.
Stop 4. Exposure of Ste. Genevieve Limestone at Belle Rive Circle. Now
higher in the formation, we will examine details of the prominent disconformity described earlier and shown in Figure 6. Calcite-filled fractures and
other features below the erosional surface are truncated by it (Figure 15).
We will also discuss ways to pick the Ste. Genevieve/Girkin contact and
determine which works best at this location.
Climb the Dripping Springs Escarpment. Look for the lowest exposures
of the Big Clifty (caprock) Member of the Golconda Formation along the
roadside.
Turn left onto Glen Lily Road (KY 2665). We are now traveling along the
eastern edge of the Mammoth Cave Plateau. The Dripping Springs Escarpment generally ranges from 100 to 200 feet in height and is regionally
prominent.
18
Figure 15. Close-up view of disconformity surface
showing calcite filled fractures (arrows) that are
truncated at the unconformity surface.
Mileage
Interval
Total
0.9
4.4
0.8
5.2
Stop 5. Right-of-way clearing for the power lines at this location provides
an eastward view from the escarpment overlooking the city of Bowling
Green and the sinkhole plain.
Bear left on Glen Lily Road at fork.
0.6
5.8
Cross bridge over the William Natcher Parkway.
1.0
6.8
2.3
9.1
Intersection with Briggs Hill Road on the right. Bear left to remain on Glen
Lily Road.
Turn left (west) at intersection onto KY 880, Veterans Memorial Lane.
0.9
10.0
Pass KY 1435, Barren River Road on left
1.9
11.9
Turn left (north) onto KY 185, Gordon Avenue.
2.0
13.9
2.5
16.4
Cross the bridge at Barren River. From this lowest point, we will again
climb the Dripping Springs Escarpment and observe an intermittent series
of roadcuts through the Ste. Genevieve limestone.
Excellent roadcuts at North Campbell Lane.
1.8
18.2
Stop 6. “T” intersection with KY 263, Richardsville Road is on the left.
Here we will examine upper Ste. Genevieve and Girkin lithologies and
locate the contact with the Big Clifty caprock. We will also examine the
Bowling Green Oolite, the once popular dimension stone which is exposed
here (Figure 16).
19
Figure 16. Oolitic facies in the Girkin Limestone at Richardsville Road and HWY 185
north of Bowling Green.
Figure 17. Louisville & Nashville Railroad Depot was constructed with Bowling Green “Oolite”, “Whitestone” or Girkin Limestone. Built
1923-25.
Mileage
Interval
Total
6.3
24.5
0.3
24.8
Return southbound along KY 185 back to intersection with KY 880, Veterans Memorial Lane. Turn left at the intersection.
Intersection with US 68/80, Louisville Road, at stoplight. Turn left (north).
Stop 7. Louisville and Nashville (L & N) Railroad Depot. The depot was
constructed from 1923-25 in the Classical Revival architectural style (Figure 17). It is faced with the Bowling Green Oolite that we examined in the
roadcut at the previous stop. The depot has undergone several phases of
recent renovation and houses a railroad museum along with several retired
rail cars. We will use the depot building as an outdoor laboratory to provide
us a detailed look at bedforms, fossils, and textures of the Bowling Green
Oolite.
End of Field Trip - Return to Microtel Hotel.
0.2
25.0
References Cited
Asphalt Institute. (2001). Superpave Mix Design. Superpave Series No. 2 (SP-02). Asphalt Institute.
Lexington, KY, 102 p.
Coons, A.T. 1923, Production of Stone in Kentucky, in The Building Stones of Kentucky: Kentucky
Geological Survey, Series 6, v. 11, p. 328-332.
Dever, G.R., Greb, S.F., Moody, J.R., Chesnut, D.R., Jr., Kepferle, R.C., and Sergeant, R.E., 1990,
Tectonic Implications of Depositional and Erosional Features in Carboniferous Rocks of SouthCentral Kentucky: Annual Field Conference of the Geological Society of Kentucky, September
28-29, 1990; published by the Kentucky Geological Survey, University of Kentucky, Lexington,
53 p.
20
Gardner, J.H., 1910, Oolitic Limestone at Bowling Green and Other Places in Kentucky: Structural
Materials, Advance Chapter from Contributions to Economic Geology: U.S.G.S. Bulletin 430-F,
1909.
Hunter, R.E., 1993, An Eolian Facies in the Ste. Genevieve Limestone in Southern Indiana, in B.D.
Keith and C.W. Zuppann (Eds.), Mississippian Oolites and Modern Analogs: American Association of Petroleum Geologists Studies in Geology # 35, Tulsa, Oklahoma, p. 31-48.
Jilson, W.R., 1928, The Geology and Mineral Resources of Kentucky: Kentucky Geological Survey,
Series VI, Frankfort, Kentucky, 409 p.
McGrain, P., and Sutton, D.G., 1973, Economic Geology of Warren County, Kentucky: Kentucky Geological Survey, Series X, County Report 6, University of Kentucky, Lexington, 28 p.
National Asphalt Pavement Association (NAPA 2007) http://www.hotmix.org/, accessed August 15,
2007.
National Center for Asphalt Technology (NCAT 2007), http://www.eng.auburn.edu/center/ncat/ accessed
August 15, 2007.
Palmer, A., 1998, Unpublished stratigraphic column of Mammath Cave area.
Richardson, C.H., 1923, The Building Stones of Kentucky: Kentucky Geological Survey, Frankfort,
355 p.
Richardson, C.H., 1924, The Road Materials of Kentucky: Kentucky Geological Survey, Frankfort,
209 p.
Roberts, F.L.; Kandhal, P.S.; Brown, E.R.; Lee, D.Y. and Kennedy, T.W. (1996). Hot Mix Asphalt Materials, Mixture Design, and Construction. National Asphalt Pavement Association Education
Foundation. Lanham, MD. Second edition, 575 p.
Shawe, F.R., 1963a, Geology of the Bowling Green North Quadrangle, Kentucky: U.S. Geological
Survey GQ-234.
Shawe, F.R., 1963b, Geology of the Bowling Green South Quadrangle, Kentucky: U.S. Geological
Survey GQ-235.
United States Geologic Survey (USGS), 2007, Minerals Yearbook 2005 – Kentucky,
http://minerals.usgs.gov/minerals/pubs/state/2005/myb2-2005-ky.pdf, accessed August 2, 2007.
Washington Asphalt Pavement Association (WAPA 2007), Asphalt Pavement Guide,
http://www.asphaltwa.com/wapa_web/index.htm accessed August 17, 2007.
21
Map of field trip area.
22
23
Aerial view of field trip area with stlops indicated.
24
Geologic map of the field trip area.