Abraham Lincoln Birthplace National Historical Park 

Geologic Resources Inventory Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2010/219 

National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 
THIS PAGE: 

Knob Creek in the Boyhood Home Unit. The 

bedrock slabs on the left are likely from the

Borden Formation. A young Abraham Lincoln

fell into this creek and was pulled out by his 

friend Austen Gollaher. 

ON THE COVER:

At the Birthplace Unit, the Memorial Building 

enshrines an early 19th century Kentucky 

cabin, symbolizing the one in which 

Abraham Lincoln was born.

National Park Service photographs. 
Abraham Lincoln Birthplace National Historical Park 

Geologic Resources Inventory Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2010/219 

Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, Colorado 80225 

June 2010 

U.S. Department of the Interior 

National Park Service 

Natural Resource Program Center 

Ft. Collins, Colorado
The National Park Service, Natural Resource Program Center publishes a range of reports that 

address natural resource topics of interest and applicability to a broad audience in the National 

Park Service and others in natural resource management, including scientists, conservation and 

environmental constituencies, and the public. 

The Natural Resource Report Series is used to disseminate high-priority, current natural 

resource management information with managerial application. The series targets a general, 

diverse audience, and may contain NPS policy considerations or address sensitive issues of 

management applicability. 

All manuscripts in the series receive the appropriate level of peer review to ensure that the 

information is scientifically credible, technically accurate, appropriately written for the 

intended audience, and designed and published in a professional manner. This report received 

informal peer review by subject-matter experts who were not directly involved in the 

collection, analysis, or reporting of the data. 

Views, statements, findings, conclusions, recommendations, and data in this report do not 

necessarily reflect views and policies of the National Park Service, U.S. Department of the 

Interior. Mention of trade names or commercial products does not constitute endorsement or 

recommendation for use by the U. S. Government. 

Printed copies of this report are produced in a limited quantity and they are only available as 

long as the supply lasts. This report is available from the Geologic Resources Inventory website 

(http://www.nature.nps.gov/geology/inventory/gre_publications.cfm) and the Natural 

Resource Publications Management website (http://www.nature.nps.gov/publications/

NRPM). 

Please cite this publication as: 

Thornberry-Ehrlich, T. 2010. Abraham Lincoln Birthplace National Historical Park: geologic 

resources inventory report. Natural Resource Report NPS/NRPC/GRD/NRR—2010/219. 

National Park Service, Ft. Collins, Colorado. 

NPS 338/104291, June 2010 

ii NPS Geologic Resources Division 
ABLI Geologic Resources Inventory Report iii

Contents

List of Figures................................................................................................................ iv

Executive Summary ....................................................................................................... v

Acknowledgements...................................................................................................... vi

Credits........................................................................................................................................................................ vi

Introduction ................................................................................................................... 1

Purpose of the Geologic Resources Inventory ...............................................................................................................1

Park Setting .................................................................................................................................................................1

Geologic Issues .............................................................................................................. 5

Introduction.................................................................................................................................................................5

Caves and Karst ...........................................................................................................................................................5

Fluvial Flooding and Contamination..............................................................................................................................7

Mass Wasting ..............................................................................................................................................................8

Disturbed Lands...........................................................................................................................................................8

Paleontological Resources ............................................................................................................................................8

Geologic Features and Processes................................................................................ 11

Geology and History Connections...............................................................................................................................11

Karst Topography and the Pennyroyal Plateau ............................................................................................................12

Spring Development and Sinking Spring.....................................................................................................................13

Sinkhole Collapse.......................................................................................................................................................13

Map Unit Properties .................................................................................................... 18

Abraham Lincoln Birthplace National Historical Park Map Units...................................................................................18

Geologic History .......................................................................................................... 21

Precambrian (prior to 542 million years ago)...............................................................................................................21

Paleozoic Era (542 to 251 million years ago)...............................................................................................................21

Mesozoic Era to Present Day (the past 251 million years) ............................................................................................22

Glossary........................................................................................................................ 27

Literature Cited............................................................................................................ 31

Additional References ................................................................................................. 34

Appendix A: Overview of Digital Geologic Data....................................................... 36

Appendix B: Scoping Session Participants ................................................................. 39

Attachment 1: Geologic Resources Inventory Products CD
iv NPS Geologic Resources Division 

List of Figures

Figure 1. Topographic map showing both units of Abraham Lincoln Birthplace National Historical Park ............................3

Figure 2. Map and cross section of Kentucky ...................................................................................................................4

Figure 3. Sinking Spring...................................................................................................................................................9

Figure 4. Sinking Spring is a primary geologic feature in the park ...................................................................................10

Figure 5. Generalized block diagram of karst features occurring in the western Pennyroyal karst ....................................14

Figure 6. Generalized block diagram of karst features occurring in the eastern Pennyroyal karst .....................................14

Figure 7. Generalized block diagram of karst features within Larue County ....................................................................15

Figure 8. Cross-sectional view of the development of a karstic landscape analogous to the Pennyroyal Plateau ...............16

Figure 9. Cross-sectional diagrams of springs in a karst landscape ..................................................................................17

Figure 10. Cross-sectional view of the development of sinkholes....................................................................................17

Figure 11. Geologic timescale ........................................................................................................................................24

Figure 12. Paleogeographic map showing the regional setting of the Illinois basin during the Mississippian Period..........25
ABLI Geologic Resources Inventory Report v

Executive Summary

This report accompanies the digital geologic map for Abraham Lincoln Birthplace National 

Historical Park in Kentucky, produced by the Geologic Resources Division in collaboration 

with its partners. It contains information relevant to resource management and scientific 

research. This document incorporates preexisting geologic information and does not include 

new data or additional fieldwork.

Abraham Lincoln Birthplace National Historical Park 

was among the first units in the National Park System

set aside to preserve cultural resources associated 

with the 16th president of the United States. Today 

the park consists of the Birthplace Unit containing 

Sinking Spring and a memorial, and the Boyhood 

Home Unit several kilometers away at Knob Creek 

Farm. The park also preserves many natural resources 

in addition to these cultural features. 

Geology is the foundation of the park’s ecosystem and 

was a major control on early settlement patterns in the 

region. Many geologic factors contributed to the 

decision by Abraham Lincoln’s family to settle here, 

including the steady supply of water at Sinking Spring 

and Knob Creek, fertile soils, and gentle topographic 

expression. Interpreting the geologic resources and 

natural history of the area will enhance the visitor’s 

experience.

Abraham Lincoln Birthplace National Historical Park 

sits atop the karst Pennyroyal Plateau. The landscape 

of the plateau is the result of geologic processes and 

their interplay with structure and bedrock. The 

bedrock units of the Pennyroyal Plateau consist of 

thick, stacked beds of carbonate rocks such as 

limestone and dolomite, which are interlayered with 

insoluble sedimentary rocks such as sandstone, 

siltstone, and shale. The youngest geologic units at the 

park are unconsolidated deposits associated with 

local rivers and slope processes. The age gap between 

the lithified bedrock and the unconsolidated surficial 

deposits is more than 300 million years. 

Karst processes and features dominate the scene and 

create numerous geologic issues at the park. A karst 

landscape refers to a terrain produced by the chemical 

erosion and weathering of limestone and dolomite. 

This dissolution forms characteristic features such as 

sinkholes, springs, sinking streams, caves, voids, and 

conduits, which are interconnected in the karst 

network. 

The Pennyroyal Plateau is significant in being part of 

the largest continuous region of cavernous rocks in 

the United States. It contains thousands of shallow 

sinkholes. The system of underground voids in central 

Kentucky is an elaborate “plumbing system” through 

which water flows through discrete conduits. Karst

aquifer systems are especially vulnerable to

contamination from surficial runoff because any input 

is quickly transferred through the system with little if 

any natural filtering. Karst landscapes can also be 

prone to flooding and subsidence, especially when 

changes (natural or anthropogenic) occur in the local 

or regional water table.

The discrete nature of karstic channel networks and 

the difficulty of direct sampling pose major challenges 

in characterizing hydrogeologic systems in limestone 

aquifers. In order for resource management to predict 

hydrologic response to inputs such as increased 

runoff and contaminants, methods such as dye-tracer 

studies, fine-scale topographic measurements, 

continuous monitoring of discharge, and down-hole 

video cameras could be applied. There is significant 

regional expertise in karst hydrology and use of these 

methods at regional and state universities, as well as 

the Kentucky Geological Survey (at the University of 

Kentucky), where local experts could assist the 

National Park Service in conducting research and 

monitoring in the park.

At the park, the landscape is a testament to active 

karst processes of limestone dissolution, underground 

cavity development, spring activity, sinkhole collapse, 

and erosion. Most of the subsurface caves and 

conduits of the area are shallow and clogged with soil, 

assorted debris, and collapse material. Depressions in 

which the void is covered by soil or vegetation, called 

“cover collapse sinkholes,” are also common. This, in 

addition to the karst features’ proximity to the water 

table, makes some of them wet and prone to rapid 

flooding during high rainfall events. Collapse and 

subsidence associated with sinkhole development are 

most frequent during flooding events but can also 

occur during prolonged droughts. Weathered 

sinkholes define the rolling hill topography of the 

area, and a sinkhole provides the catchment for 

Sinking Spring. The potential for sinkhole collapse 

exists at both units of the park; careful determination 

of the nature of the underlying karst features may help 

resource managers to determine areas particularly at 

risk.

Although karst dominates, other geologic processes 

create issues at the park. These include fluvial issues 

associated with surficial streams at both units, mass 

wasting associated with slope processes, disturbed 

lands, and paleontological resources present in the 

fossiliferous Mississippian-age geologic units. 

Refer to the glossary for definitions of geologic 

terminology utilized in the report.
vi NPS Geologic Resources Division 

Acknowledgements

The Geologic Resources Inventory (GRI) is one of 12 inventories funded by the National 

Park Service Inventory and Monitoring Program. The GRI is administered by the 

Geologic Resources Division of the Natural Resource Program Center.

The Geologic Resources Division relies heavily on 

partnerships with institutions such as the U.S. 

Geological Survey, Colorado State University, state 

geologic surveys, local museums, and universities in 

developing GRI products.

Special thanks to Joe Meiman (NPS Cumberland 

Piedmont Network) for providing information,

comments and suggestions. 

Credits

Author

Trista L. Thornberry-Ehrlich (NPS-Colorado State 

University)

Review

Steve Greb (Kentucky Geological Survey)

Jim Currens (Kentucky Geological Survey)

Jason Kenworthy (NPS Geologic Resources Division)

Editing

Katie KellerLynn (NPS-Colorado State University)

Digital Geologic Data Production

Heather Stanton (NPS-Colorado State University)

Cory Karpilo (NPS-Colorado State University)

Digital Geologic Data Overview Layout Design

Aaron Rice (NPS-Colorado State University)

Phil Reiker (NPS Geologic Resources Division)
ABLI Geologic Resources Inventory Report 1

Introduction

The following section briefly describes the National Park Service Geologic Resources 

Inventory and the regional geologic setting of Abraham Lincoln Birthplace National 

Historical Park.

Purpose of the Geologic Resources Inventory 

The Geologic Resources Inventory (GRI) is one of 12 

inventories funded by the National Park Service (NPS) 

Inventory and Monitoring Program. The GRI, 

administered by the Geologic Resources Division of the 

Natural Resource Program Center, is designed to 

provide and enhance baseline information available to 

park managers. The GRI team relies heavily on 

partnerships with institutions such as the U.S. Geological 

Survey, Colorado State University, state geologic surveys, 

local museums, and universities in developing GRI 

products.

The goals of the GRI are to increase understanding of the 

geologic processes at work in parks and to provide sound 

geologic information for use in park decision making. 

Sound park stewardship requires an understanding of 

the natural resources and their role in the ecosystem. 

Park ecosystems are fundamentally shaped by geology. 

The compilation and use of natural resource information 

by park managers is called for in section 204 of the 

National Parks Omnibus Management Act of 1998 and in 

NPS-75, Natural Resources Inventory and Monitoring 

Guideline. 

To realize these goals, the GRI team is systematically 

conducting a scoping meeting for each of the 270 

identified natural area parks and providing a parkspecific digital geologic map and geologic report. These 

products support the stewardship of park resources and 

are designed for nongeoscientists. Scoping meetings 

bring together park staff and geologic experts to review 

available geologic maps and discuss specific geologic 

issues, features, and processes. 

The GRI mapping team converts the geologic maps 

identified for park use at the scoping meeting into digital 

geologic data in accordance with their Geographic 

Information Systems (GIS) Data Model. These digital 

data sets bring an interactive dimension to traditional 

paper maps. The digital data sets provide geologic data 

for use in park GIS and facilitate the incorporation of 

geologic considerations into a wide range of resource 

management applications. The newest maps contain 

interactive help files. This geologic report assists park 

managers in the use of the map and provides an overview 

of park geology and geologic resource management 

issues.

For additional information regarding the content of this 

report and current GRI contact information please refer 

to the Geologic Resources Inventory web site 

(http://www.nature.nps.gov/geology/inventory/).

Park Setting

Abraham Lincoln Birthplace National Historical Park 

has had many name designations. It was originally set 

aside as a memorial commemorating the birthplace of the 

16th president of the United States. The original 

memorial hosted an early 19th century Kentucky cabin, 

similar to the one in which Lincoln was born on 

February 12, 1808. “Abraham Lincoln National Park”

was established on July 17, 1916, and on August 10, 1933, 

was transferred from the War Department to the 

National Park Service and designated a national 

historical park. The name changed to “national historic 

site” on September 8, 1959 (73 Stat. 466), and most 

recently was redesignated as a national historical park on 

March 30, 2009. The park includes two units: the 

Birthplace Unit and the Boyhood Home Unit at Knob 

Creek, which was added in 1998 (fig. 1). The park, 

though originally set aside for cultural resources,

protects 139 ha (345 ac) in Larue County on the karstic 

Pennyroyal (or Mississippian) Plateau in central 

Kentucky. 

Abraham Lincoln Birthplace National Historical Park is 

located near the town of Hodgenville, Kentucky, more 

than 48 km (30 mi) south of Louisville and more than 32 

km (20 mi) north of the world’s longest cave at 

Mammoth Cave National Park. This entire region is 

often referred to as the “Central Kentucky Karst” part of 

a karstic limestone belt that extends from southern 

Indiana through Kentucky into Tennessee (White et al. 

1970). Nearly horizontal bedrock characterizes the 

underlying geologic framework of the area. The entire 

park area is underlain by soluble limestone units (fig. 2; 

Appendix A). The landscape is characterized by rolling 

hills (fig. 1), sinking streams, sinkholes, and springs. 

In an area dominated by karstic (groundwater) systems, 

surface water can be scarce on the Pennyroyal Plateau. 

This factor strongly influenced early settlement patterns. 

The Lincolns were farmers, and Sinking Spring Farm and 

the rented Knob Creek Farm were positioned to take full 

advantage of the available water supply. In addition, local 

bedrock weathers to a reddish clay-rich soil, the fertility 

and quality of which was a strong control on agricultural 

success. 

The soluble limestone units of central Kentucky are 

riddled with caves in the highlands and a series of 

sinkholes and sinking streams in the lowlands. Ridges 

where resistant cap rock persists, such as the Chester 

Upland of the Mammoth Cave area, can support vast 

cave networks. Areas such as the Pennyroyal Plateau 

have lost their resistant cap rocks—a necessary 

ingredient to extensive cave formation—to erosion. As 
2 NPS Geologic Resources Division 

the limestone dissolved below ground, sinkholes 

developed, which overlapped to form the characteristic 

rolling landscape of the area. 

Glaciers also played a role in landscape development. 

During the last significant glacial advance, approximately 

19,000 to 21,000 years ago, thick ice sheets covered the 

Great Lakes area and extended south to approximately 

the position of the present-day Ohio River (the northern 

boundary of the state). These continental glaciers altered 

the trends of major waterways, which led to the 

formation of the Ohio River Valley and its tributary, the 

Green River. Moreover, during times of continental 

glaciation, water tables were lower than they are today. 

Advances and retreats of glacial ice resulted in multiple 

changes in the water table in the area that is now central 

Kentucky. This affected the landscape at the park 

through changes in the depth of caves and conduits, and 

changes in the slope and erosion rates of the Green 

River.
ABLI Geologic Resources Inventory Report 3

Figure 1. Topographic map showing both units of Abraham Lincoln Birthplace National Historical Park in central Kentucky. Note the 

differences in landforms between the two units. Compiled by Jason Kenworthy (NPS Geologic Resources Division) from ESRI ArcImage 

Service; World Topo Map imagery.

Birthplace Unit

Boyhood 

Home Unit
4 NPS Geologic Resources Division 

Figure 2. Map and cross section of Kentucky. The figure shows the major physiographic provinces and some large-scale geologic 

features in Kentucky. The cross-sectional diagram (bottom) illustrates the structural trends in the state. Note the location of Abraham 

Lincoln Birthplace National Historical Park (green circle) on the map. Graphic by Trista L. Thornberry-Ehrlich (Colorado State University) 

after figure 1 in Dougherty (1989).
ABLI Geologic Resources Inventory Report 5

Geologic Issues

The Geologic Resources Division held a Geologic Resources Inventory scoping session for

Abraham Lincoln Birthplace National Historical Park on June 15, 2006, to discuss 

geologic resources, address the status of geologic mapping, and assess resource 

management issues and needs. This section synthesizes the scoping results, in particular 

those issues that may require attention from resource managers. Contact the Geologic 

Resources Division for technical assistance.

Introduction

Issues in this section are identified in relative order of 

resource management significance with the most critical 

listed first. Potential research projects and topics of 

resource management interest are presented at the end 

of each issue.

Caves and Karst

Kentucky karst is among the most well-developed karst 

landscapes in the world (May et al. 2005). The term 

“karst” comes from a Slavic word that means “barren, 

stony ground.” The karst landscape of central Kentucky 

includes the Pennyroyal Plateau with its characteristic 

sinkhole plains. Karstic features influence groundwater 

and surface water at Abraham Lincoln Birthplace 

National Historical Park, and may have been important 

in the choice of this location as the Lincoln homestead.

Sinking Spring, a perennial karst spring at the site, was 

the primary reason Thomas Lincoln chose to settle here 

in 1808 (GRI scoping notes 2006). Reliable water sources 

on the Pennyroyal Plateau are relatively scarce. This 

spring flows from a small cave and is an important 

interpretive feature and visitor attraction at the park 

(figs. 3 and 4) (Seadler et al. 2002). Specific geologic 

hazards related to karst include sinkholes, cover collapse, 

and flooding (Ruthven et al. 2003).

Potential for Contamination and Development

Karst aquifer systems are especially vulnerable to 

nonpoint source contamination (e.g., runoff from 

agricultural areas) because any surficial input is quickly 

transferred through the system with little if any natural 

filtering or sorption (Ryan and Meiman 1996). 

Agriculture, septic systems, and roadways are the 

primary sources for groundwater contamination in the 

park area. Fortunately, dye tests indicated that drainage 

from Highway 31E does not directly flow to the spring 

(Seadler et al. 2002).

Despite signage discouraging the practice (fig. 3), Sinking 

Spring is also a popular coin-toss area for park visitors;

pollution of the spring is possible if litter and other 

inputs are not removed (J. Meiman, National Park 

Service, written communication, 2010). Park staff 

members periodically clean out the spring area (National 

Park Service 2006). 

A portion of the basin surrounding Sinking Spring is 

being developed along the northern boundary of the 

park. Impacts of this development, including 

contamination of the spring and alteration or cessation 

of flow, are resource management concerns (National 

Park Service 2006). As population growth demands more 

groundwater resources, the potential for karst collapse is 

increased as the water table is lowered (Dougherty 1989).

Hydrogeologic Modeling

Resource management would benefit from an 

understanding of the hydrogeologic system at the park. 

Knowledge of how water is traveling through the 

subsurface will assist the selection of future well sites and 

help predict hydrologic response to inputs such as 

contaminants and other wastes. The movement of 

nutrients and contaminants through the hydrogeologic 

system can be modeled by monitoring the composition 

of system inputs, such as rainfall, and outputs, such as 

springs. Other input sources include wind, surface 

runoff, groundwater transport, sewage outfalls, landfills, 

and fill dirt. Springs in effect integrate the surface runoff 

and groundwater flow of their watersheds. Thus, they 

provide a cumulative measure of the status of the

watershed’s hydrologic system. Consistent measurement 

of these water quality parameters establishes baselines 

for comparison. 

The discrete nature of karstic channel networks and the 

difficulty of downhole sampling (capturing groundwater 

samples in situ) pose major challenges in characterizing 

hydrogeologic systems in limestone aquifers 

(Worthington et al. 1999). Water in an aquifer tends to 

follow the most favorable flow paths. However, karst 

flow paths are not necessarily concordant with the 

direction of bedrock dip (i.e., they may follow fractures 

instead), and topographic divides do not necessarily 

correlate with karst basin divides (Wells 1974; Palmer 

1990). Most karst networks have high hydraulic 

conductivity and efficiency given the large apertures of 

major underground channels. This means they are able 

to move large flows of groundwater quickly. 

Certain types of measurements may aid in the study of 

the hydrogeologic system at the park. A potentiometric 

surface results from the intersection of a drilled borehole 

with a large, subterranean channel. This can be used to 

evaluate two indicators of the nature of channeling: (1) a 

decrease in hydraulic gradient in a down-gradient 

direction, and (2) channels associated with troughs in the 

potentiometric surface (Worthington et al. 1999). 

GIS Karst Mapping

In 1996, the National Park Service commissioned a study 

to assist park managers in better focusing their efforts on 
6 NPS Geologic Resources Division 

areas of concern that might affect the park’s spring. The

study incorporated fluorescent dye tracing, a short cave 

survey, and analysis of unit base-flow discharge to

determine the recharge area and flow system. 

Investigators combined spatial land-use patterns and 

high-resolution topographic information (a digital 

elevation model at approximately 0.3 m [1 ft]) to 

determine flooding mechanisms in the sinkhole 

surrounding Sinking Spring. Field measurements showed 

that the spring’s catchment area covers approximately 45 

ha (110 ac) and is largely contained within the 

boundaries of the park. Part of the catchment is also 

located within land used for agriculture nearby (Seadler 

et al. 2002; National Park Service 2006; Hoffman 

Institute 2007). Digital themes in the GIS included land 

use, property lines, streets, soils, caves, geology, and 

aerial photography. This GIS may offer insight to reduce 

groundwater problems such as flooding, storm drain 

blowouts, and water contamination (Hoffman Institute 

2007). This report accompanies digital geologic data 

compiled for Abraham Lincoln Birthplace National 

Historical Park (Appendix A).

Sinking Spring

The spring, which has produced a moderate flow of 

water since the 1800s, is actually part of a prominent type 

of karst window, called a doline, which is fed by a 

perched aquifer located atop a local shale unit within the 

Mississippian St. Louis Formation (J. Meiman, National 

Park Service, personal communication, 2006; National 

Park Service 2006). Dolines, sinking streams, and springs 

are useful in characterizing underground channeling in 

the hydrogeologic system (see “Geologic Features and 

Processes” section). Dolines are input points to 

continuous, large-aperture (typically 1 cm to 1 m [0.4 in 

to 3 ft]) channels that may traverse an entire carbonate 

aquifer and terminate at springs. Testing discharge from 

these “terminal” springs enables an estimate of channel 

hydraulic conductivity (i.e., the ease at which water 

moves through pore spaces or fractures) (Worthington et 

al. 1999).

Water from Sinking Spring immediately enters a small 

cave large enough to fit a person for approximately 24 m 

(80 ft) and flows below ground before its egress into the 

South Fork Nolin River, approximately 1.6 km (1 mi) 

southwest of the spring (National Park Service 2006). 

This natural and cultural feature is an excellent example 

of the pervasive karst processes at work on the landscape 

of the Pennyroyal Plateau. Sinking Spring may actually be 

part of a cave network (upgradient) and should be 

managed as such (GRI scoping notes 2006). Sinking 

Spring may support a variety of sensitive cave-adapted 

biota, though no official survey has been conducted to 

determine the extent of this possibility (J. Meiman, 

National Park Service, written communication, 2010). 

Water quality at karst springs characteristically 

undergoes high amplitude, but brief degradation follows

runoff influxes. Even brief increases in certain pollutants 

may have lasting detrimental effects on aquatic cave life 

and water supply (Ryan and Meiman 1996).

During heavy rains, soil and turf can subside through 

weak spots in the ceilings of limestone; sedimentation is 

evident in the spring’s flow (National Park Service 2006). 

These and other sediments in the spring and conduit 

system serve as storage reservoirs for heavy metals (e.g., 

chromium, cadmium, nickel, lead, and zinc). Transport 

and storage of sediment are integrally linked to metal 

cycling in karst systems. Karst sediment is either 

sedentary (as deposits) or mobile (as suspended material) 

with abundant exchange between the two. The testing 

procedure for heavy metals in sediments separates the 

metals into exchangeable, carbonate, oxide, organic, and 

residual fractions, and chemically analyzes and 

characterizes these materials (Vesper and White 2004). 

Karst Feature Potential

Because of the presence of caves, underground voids, 

and karst networks, the potential for sinkhole 

development is prevalent across the Pennyroyal Plateau, 

including Abraham Lincoln Birthplace National 

Historical Park. Weathered sinkholes define the rollinghill topography of the area, and a sinkhole provides the 

catchment for Sinking Spring at the park. A large 

depression near the northeastern corner of the 

Birthplace Unit is called Big Sink and once contained a 

spring that ceased flowing in the 1930s, possibly due to 

natural diversion into another groundwater flow basin 

(National Park Service 2006). 

The Kentucky Geological Survey (KGS) is using largescale geologic mapping and a GIS to prepare detailed 

analyses of the extensive karst terrain in the area. They 

created an index of relative karst development to 

compare conditions between regions because data are

not uniformly available across all areas. This karst 

development index (KDI) evaluates the development of 

karst geomorphic features and bulk porosity. The criteria 

included in the KDI are epikarst development (depth to 

bedrock); distribution of sinkholes, caves, and springs;

and channel density. Each of the criteria is placed in a 

weighted scoring matrix to determine a value and then is 

scaled regionally. A karst potential index (KPI) evaluates 

the lithologic characteristics inherent in specific geologic 

units (polygons in GIS) that lead to karst development. 

Criteria utilized in the determination of the KPI are 

bedding thickness, overall grain size, percentage of pure 

calcite in carbonate rock, and the bulk content of 

insoluble material. Designed and calibrated for specific 

use in Kentucky, these two indices should be available to 

resource management at the park for use in the 

anticipation of karst geologic hazards and the mitigation 

of human impacts on karst aquifer systems. However, the 

classification of karst areas, as well as classifications 

developed for land-use planning and engineering, have 

always been subjective. Therefore, further onsite 

measurements would provide specific data for planning 

purposes at the park (Currens et al. 2005).

Toomey (2009) presents a variety of “vital signs” for 

monitoring caves and associated landscapes. While many 

are geared for accessible caves, two vital signs in 

particular (surface expression and processes, and 
ABLI Geologic Resources Inventory Report 7

groundwater levels and quality) may be applicable to 

Abraham Lincoln Birthplace National Historical Park. 

Resource Management Suggestions for Caves and Karst

• Continue dye tracer analysis could be used to

determine the underground morphology of the karst 

network and understand groundwater flow at the park 

and the immediate surrounding area.

• Use GIS and large-scale geologic mapping to 

determine cave potential in the area. This same 

information may be used to evaluate the risk of 

sinkhole development locally. Consult the KGS karst 

terrain characterization program.

• KGS staff members suggest preparing a management 

assistance program for the groundwater springshed 

with guidance from Eckenfelder, Inc. (1996) and 

Ginsberg and Palmer (2002).

• Use continuous water quality measuring strategies at 

Sinking Spring and other springs to fully determine 

contaminant input before, during, and after influx 

events (Ryan and Meiman 1996). The Kentucky 

Geological Survey has maps to show the locations of 

wells and springs across the state (Ruthven et al. 2003).

• Create hydrogeologic models for the park to better 

manage the groundwater resource and predict the 

system’s response to contamination.

• Map and quantify subterranean water recharge zones. 

• Monitor the concentration of heavy metals in any 

sediments found within Sinking Spring and other 

springs at the park (Vesper and White 2004). 

• Investigate additional methods to characterize 

groundwater recharge areas and flow directions.

• Conduct an inventory, including maps, locations, and 

assessments, of known caves and karst features 

(National Park Service 2006) and produce associated 

GIS.

• For additional assistance with water quality issues, 

contact the NPS Water Resources Division.

Fluvial Flooding and Contamination 

Water resources in the park area include lakes and 

ponds, rivers and streams, and springs, including

Sportsman and McDougal lakes; the South Fork Nolin 

River and the North Fork Nolin River; Knob Creek; and 

Sinking, Howell, Terhune, and Heady springs (National 

Park Service 2006). The boundaries of the Boyhood 

Home Unit contain an entire watershed (north branch of 

Knob Creek). The surrounding areas are largely forested 

and undeveloped. At the Birthplace Unit, surface water 

issues include (1) subsurface hydraulic damming (with 

potential contamination from storm water), and (2) 

flooding along the South Fork Nolin River and the 

perennial stream. At the Boyhood Home Unit, flooding 

occurs along Knob Creek (Seadler et al. 2002). The park 

contains significant portions of the floodplains of these 

waterways and park infrastructure and visitor facilities 

could be threatened if water levels reach the 50-year 

floodplain mark. Structures at the Boyhood Home Unit 

are on the edge of the 100-year floodplain (National Park 

Service 2006).

During flood events, water from broader areas fluxes

into free-flow karst aquifers like the one underlying the 

park. If flow exceeds the capacity of the sinkhole drain, 

then flooding can result. Flood-event flow may also 

include nonpoint source and point source contaminants 

(Reeder and Crawford 1988). Therefore, there is a 

resource management need for storm event monitoring 

in the free-flow karst aquifers underlying the park.

Nearby studies have compared observation wells in 

trunk-cave streams and at nearby farms. These studies 

indicate that storm water from large cave streams flows 

(in part) back into karst aquifers. The process may be 

analogous to riverbank storage in alluvial aquifers. Water 

samples collected from cave streams and springs during 

and after storm events also show an increase in pointsource contaminants and suspended sediment 

(Crawford 2005). 

Studies begun in 1996 indicate that the water quality for 

the park is fair for karst flow draining agricultural land. 

Impacts from nitrates, fecal coliform bacteria, and the 

broadleaf herbicide Trifluralin are ongoing at the park

(Seadler et al. 2002; National Park Service 2006). 

Subsurface hydraulic damming of the South Fork Nolin 

River creates storm pulses into the large sink feeding 

Sinking Spring that may integrate larger concentrations 

of contaminants collected from a broader drainage area 

(Seadler et al. 2002). 

Lord et al. (2009) suggest “vital signs” for monitoring 

fluvial systems including: watershed landscape, 

hydrology, sediment transport, and channel cross 

section, plan form, and longitudinal profile.

Resource Management Suggestions for Fluvial Flooding and 

Contamination Issues

• Contact the NPS Water Resources Division for 

technical assistance.

• Continue to sample spring water quality, especially 

during storm events at a high frequency level given the 

rapid response of the karstic system to changes in 

water input. If degraded water is detected, attempt to 

locate and mitigate the source (National Park Service

2006).

• Continue to support and cooperate with student 

research training programs and other agencies to 

increase understanding of the fluvial system at the 

park. 

• Prepare a quantitative analysis of the Knob Creek 

floodplain and assess the risk of damaging floods 

(National Park Service 2006).

• Investigate the potential of a “Wellcam” down-hole 

video camera to gain a better understanding of the 

voids associated with the drainage system at the park

(Reeder and Crawford 1988).
8 NPS Geologic Resources Division 

Mass Wasting

Though the topographic relief in the park area is 

relatively subdued, there is some potential for slope 

creep and mass wasting. The Mississippian-age Borden 

Formation contains abundant clay, glauconite, and shalerich layers (Johnson 2005) and can pose slope-stability 

problems when it forms steep slopes or where slopes are 

undercut. Note the steeper topography at the Boyhood 

Home Unit compared to the Birthplace Unit (fig. 1 and 

Appendix A). The newly exposed outcrops of the Borden 

Formation along the north branch of Knob Creek are 

likely susceptible to mass wasting. The clays of the 

Borden Formation are plastic when wet and small 

landslides are very common, even for moderate to gentle 

slopes. In layers where clay- rich zones are underlain by 

relatively impermeable sandstones or shales, a slip 

surface can develop, increasing the potential for mass 

wasting (Johnson 2005). Moreover, the shrink-and-swell 

potential of clays, which causes changes in volume

(i.e., swell when water saturated, shrink upon drying),

undermines ground stability. 

Large rockfall events are not likely at the park; however, 

when resistant rock units such as sandstone and 

limestone are located above weaker units, such as shale, 

rockfall hazards may exist. Any plans for future park 

infrastructure should carefully consider slope stability 

and rockfall potential.

Wieczorek and Snyder (2009) suggest monitoring 

strategies for slope stability. They present five 

monitoring “vital signs”: types of landslides, landslide 

triggers and causes, geologic materials in landslides, 

measurement of landslide movement, and assessing 

hazards and risks.

Resource Management Suggestions for Mass Wasting

• Monitor slope processes at both units of the park.

• Conduct site investigations of clay-rich layers and 

friable limestones exposed on slopes to determine a 

vulnerability index to slope failure.

• Determine composition of all clays in surficial 

deposits. Identify and map the distribution of shrinkand -swell clays for use in identifying potential 

problem areas.

• Cooperate with GRD Soils Inventory Program to 

update soil GIS data to include Boyhood Home Unit 

(National Park Service 2006).

Disturbed Lands

Sinkholes are generally efficient at collecting stormwater runoff and channeling it through the subsurface 

karst conduit network. However, human practices can 

disturb the natural drainage, resulting in increased 

potential for flooding. Infilling sinkholes for 

construction or mass wasting, can plug the natural karst 

drainage. Parking lots and roads (as well as other types of 

construction) tend to decrease infiltration and increase 

runoff. When storm-water runoff exceeds the capacity of 

the sinkhole drain to transmit water to the karst network,

the result is subsurface flooding (Reeder and Crawford 

1988). According to the NPS definition, the area of the 

basin surrounding Sinking Spring is not a floodplain. 

However, in flood situations, eruptions or blowouts of 

the storm drain system occur at the Birthplace Unit 

(National Park Service 2006).

To avoid this situation, storm-water management 

strategies include water-catchment basins and drainage 

wells (Reeder and Crawford 1988). Between 1929 and 

1930, the War Department constructed an entrance 

structure and drain for Sinking Spring to provide access 

and to alleviate a flood hazard posed by a seasonally 

ponded sinkhole. This infrastructure consists of a drain 

system of pipes and culverts, some of which are 1 m

(3.3 ft) in diameter and are buried 3–4 m (10–13 ft) below 

ground. Limestone steps with flagstone landings and 

walls lead to the spring. A spring pool is visible through a 

circular hole in flagstone paving, which is sheltered by a 

natural rock ledge (fig. 3)(National Park Service 2006). 

This system was intended to coalesce and funnel runoff 

towards the natural spring, but the structure was a failure 

and did not change the flood hazard at the site. Resource 

managers might consider removing the structure and

installing drainage wells, but need to investigate any 

potential effects (GRI scoping notes 2006).

Resource Management Suggestions for Disturbed Lands

• Cooperate with the Kentucky Geological Survey to 

obtain land-use planning maps (derivatives from the 

digital geologic map). 

• Investigate potential effects to the watershed, Sinking 

Spring, and surrounding landscape of removing the 

1920s era infrastructure designed to alleviate flood 

hazard at the Birthplace Unit. 

• Incorporate human impacts, historical land use 

evolution, and the influences of geologic resources on 

the park’s history into interpretive programs.

Paleontological Resources

Hunt-Foster et al. (2009) completed a literature-based

paleontological resource summary for the Cumberland 

Piedmont Network, including Abraham Lincoln 

Birthplace National Historical Park. Fossils add to the 

understanding of geologic history, help correlate units 

across time and space, and provide clues to the original 

depositional environment of the bedrock in which they 

occur. Some fossils can also provide information about 

post-burial geochemical changes, deformation, and 

changes in bedding orientation. 

Although not formally documented, fossils are known 

from bedrock within the park, including crinoids and 

other Mississippian-age fossils in the Borden Formation.

Some crinoids may be partly intact and show some colorbanding preservation (or it may just be normal quartz 

banding seen in many silicified fossils) (J. Meiman, 

National Park Service, personal communication, 2006; S. 

Greb, Kentucky Geological Survey, written 

communication, 2010). Brachiopods, bryozoans, and 

corals are relatively common in the Borden Formation 

and might occur in the park. The Borden Formation

crops out in broad areas throughout the region and 
ABLI Geologic Resources Inventory Report 9

generally does not contain rare fossils. However 

unauthorized collection or fossil theft is possible. Fossils 

exposed by erosion on slopes can concentrate in 

alluvium and colluvium derived from bedrock geologic 

units. Knowledge of the extent of the paleontological 

resources in the area may also influence future expansion 

directions for the park. 

Fossil resources require science-based resource 

management as directed by the 2009 Paleontological 

Resources Preservation Act (Public Law 111-11). The 

National Park Service is currently developing regulations 

associated with the Act (J. Brunner, Geologic Resources 

Division, personal communication, May 2010). Santucci 

et al. (2009) suggest strategies for monitoring in situ 

paleontological resources utilizing five “vital signs.” The 

paleontological resource monitoring vital signs include: 

natural erosion (geologic variables; e.g. rock type, degree 

of slope, bedding), natural erosion (climatic variables; 

e.g. precipitation, temperature, freeze/thaw cycles), 

catastrophic geologic processes (geohazards; e.g. 

landslides), hydrology and bathymetry (e.g. shoreline 

processes and water level fluctuation), and human 

impacts (e.g. unintentional impacts and intentional 

theft/vandalism).

Resource Management Suggestions for Paleontological 

Resources

• Perform a comprehensive field-based inventory and 

documentation of fossil resources in the geologic units 

exposed at the park.

• Monitor paleontological resources as they are exposed 

in the cutbanks and slopes at the park (National Park 

Service 2006). 

• Develop an interpretive program that incorporates the 

fossil story along with the geologic history of the area. 

Interpretation should also include a resource 

stewardship message.

Figure 3. Sinking Spring. Thomas Lincoln established “Sinking Spring Farm” to take advantage of this perennial water source. National 

Park Service photograph by Brenda Wells (Mammoth Cave National Park). 
10 NPS Geologic Resources Division 

Figure 4. Sinking Spring is a primary geologic feature in the park. The above image is a scan of a historic photograph of the spring. The 

lower image shows the modern path and access to the spring. National Park Service photographs available online: 

http://www.nps.gov/abli/photosmultimedia/photogallery.htm (accessed June 22, 2010).
ABLI Geologic Resources Inventory Report 11

Geologic Features and Processes

This section describes the most prominent and distinctive geologic features and processes 

in Abraham Lincoln Birthplace National Historical Park.

Geology and History Connections

Geology has a strong influence on the development of 

any landscape. In central Kentucky, where the limestone 

units have dissolved into a karstic underground drainage 

network, surface water can be scarce. Lakes and other 

large bodies of water are virtually nonexistent and most 

of the streams and surface runoff disappear rapidly 

underground. Thus, the presence of a consistent, reliable 

water source was a valuable asset to a family looking to 

settle in the area. The site chosen by Thomas Lincoln, 

near Hodgenville, Kentucky, in 1808, had a perennial 

spring, flowing from a small cave called Sinking Spring 

(Seadler et al. 2002).

Thomas Lincoln paid $200 cash and assumed a small 

debt of the previous owner to obtain Sinking Spring 

Farm in December 1808. His son, Abraham, was born on 

February 12, 1809, in a small (3.6 × 5 m [12 × 17 ft]),

chinked, log cabin. Due to an ongoing legal struggle 

regarding prior land claims asserted on the farm, the 

Lincoln family relocated to Knob Creek Farm where 

they leased 12 ha (30 ac) from George Lindsey’s 93-ha 

(230-ac) farm for six years before moving to Indiana 

(National Park Service 2006). The future president’s 

earliest memories would be of the Knob Creek Farm. He 

wrote of his experiences in 1860, recalling planting 

pumpkin seeds in the garden while others planted corn. 

The following day a large rainstorm caused local flooding 

of Knob Creek (inside front cover) that eroded away the 

newly planted garden (National Park Service 2009). 

Early settlement of the area was mainly due to 

agricultural endeavors. Then as now, farmers were 

attracted to a steady supply of water and thick, fertile 

soil. Patterns of population followed suit. Today, the 

sparsely populated, rugged Chester Upland south and 

west of the park, with its thin, rocky soil and rapid 

surface drainage stands in stark contrast to the 

Pennyroyal Plateau (fig. 2). The plateau contains nearly 

all the cities and larger towns of central Kentucky, as well 

as the state’s extensive and fertile farms (tobacco being a 

dominant crop). The extreme weathering of the 

limestone underlying the plateau has left a residue of 

thick, sticky reddish soil (Palmer 1981). As limestone 

dissolves, calcium carbonate is removed, and other 

elements and trace materials in the rocks are left as 

residue, including quartz sands and iron-rich clays that 

combine with organic material to create soil. 

Before European settlers came to Kentucky, American 

Indians used local caves as shelter and the natural 

resources of the area for tools, food, and clothing.

American Indian remains and artifacts are located in 

nearby caves including Mammoth Cave about 55 km

(35 mi) southwest of Hodgenville, Kentucky (Palmer 

1981). Evidence suggests people have inhabited the 

Pennyroyal Plateau region since at least 11,000 Before 

Common Era (BCE; preferred to “BC”). At the Boyhood 

Home Unit, a recent archaeological survey of the 

developed area and fields uncovered a possible large 

prehistoric site including stone tools and flakes. Shovel 

testing identified a large chert procurement and initial 

flaking site. Chert (microcrystalline quartz) is common in 

the area’s limestone units and commonly weathers from 

the limestone. Because chert is hard and tends to break 

along sharp, conchoidal fractures, prehistoric peoples

commonly used it to make stone tools. They may have 

collected chert from the Knob Creek area for tool 

making. Some evidence indicates that a prehistoric 

domestic camp may have been located in the developed 

portion of the park property (National Park Service

2006). 

The area’s fertile soil promoted maize agriculture, which 

supported human occupation through the prehistoric

period—1000 to 1650 Common Era (CE; preferred to

“AD”). An area called the barrens, burned off by native 

people to attract buffalo, was located near the Birthplace 

Unit. Historical evidence shows the Cherokee, 

Chickasaw, Shawnee, and Iroquois all used the region for 

hunting and fishing (National Park Service 2006).

Maintaining historic features may entail resisting natural 

geologic processes, which presents several management 

challenges. Geologic slope processes such as landsliding, 

slumping, chemical weathering, block sliding, and slope 

creep are constantly changing the landscape at the park. 

Runoff erodes sediments from open areas and carries 

them down streams and gullies. Erosion naturally 

diminishes higher areas and fills in the lower areas to 

distort the historical landscape conditions. Issues can 

arise from different objectives between cultural and 

natural resource management. For example, a proposal 

for maintenance of a historic building, field, or grove of 

trees may consist of removing surrounding natural 

resources or installing stabilization structures. These 

efforts can alter natural geologic processes. 

The fundamental resources at the Birthplace Unit 

include the historic memorial and cultural landscape, 

Sinking Spring, old-growth forest, and the historic 

Boundary Oak site (Lawliss and Hitchcock 2004). At the 

Boyhood Home Unit, resources include a 3-ha (7-ac)

field, rural 19th century landscape, Knob Creek and its 

tributaries, rare limestone glades (occurring on limestone 

outcroppings on south- or west-facing slopes 

characterized by shallow rocky soils and unique flora 

that have adapted to the harsh dry conditions), unusually 

diverse and abundant flora, boundary oak, fossil-bearing 

Mississippian limestone, and possibly a section of the 

original Louisville-Nashville Turnpike (Cumberland 

Road) (National Park Service 2006). 
12 NPS Geologic Resources Division 

Karst Topography and the Pennyroyal Plateau

A karst landscape refers to a characteristic terrain 

produced by the dominant geomorphic processes of 

chemical erosion and weathering of carbonate rocks (i.e., 

limestone and dolomite) (Palmer 1984). Dissolution 

occurs when acidic water reacts with carbonate rock

surfaces along cracks and fractures. Most meteoric water 

is of relatively low pH (“acidic”) due to the reaction 

between atmospheric carbon dioxide (CO2) and water

(H2O). The product of this reaction is carbonic acid 

(H2CO3). Groundwater may become even more acidic as 

it flows through decaying plant debris and soils (Florida 

Geological Survey 2005). The acid reacts with calcium 

carbonate (CaCO3) in the rocks to produce soluble 

calcium (Ca2+) and bicarbonate (HCO3

-

); that is, “rocks in 

solution” or “dissolved rocks.” In addition, most of the 

carbonaceous limestone and dolomite in central 

Kentucky are inherently porous, which facilitates 

dissolution. Over hundreds of thousands of years, 

dissolution has occurred between the intergranular pores 

and along fractures, creating larger and larger voids. 

Many of the larger surface karst features formed by 

mechanical processes such as collapse were triggered by 

subsurface dissolution. There is a strong correlation 

between underground conduits, geologic structure, and 

surficial karst features that evolved with groundwater 

recharge (figs. 5, 6, and 7). If the recharge influx is 

concentrated at discrete points, such as dolines, a 

dendritic flow pattern and cave system is the dominant 

form of karst drainage. Recharge dominated by one or a 

few sinking streams typically result in a single major 

conduit with minimal tributaries, whereas if the recharge 

is diffuse from many smaller sources, a network maze of 

intersecting fissure passages commonly develops (Palmer 

1984).

The system of underground voids in west-central 

Kentucky is extensive and varied with respect to network 

patterns. It can be viewed as an elaborate plumbing 

system through which water flows through discrete 

conduits (Palmer 1990). The Pennyroyal Plateau is 

significant in being the largest continuous region of 

cavernous rocks in the United States (Palmer 1981). It 

contains thousands of shallow sinkholes, occasional 

blind valleys, some karst pavement, and numerous karst 

windows (Mylroie and Dyas 1985). The Mammoth–Flint 

Ridge–Tooney Ridge cave network, located in the 

Chester Upland 64 km (40 mi) south of the park, is the 

longest known system of connected passages in the 

world. In areas where there are cavernous rocks, collapse 

of overlying rock and soil into underground voids (e.g., 

conduits and caves) can produce sinkholes. If the 

sinkhole occurs in a streambed, it may capture the water 

flow, creating a disappearing stream.

At Abraham Lincoln Birthplace National Historical Park, 

the landscape is a testament to active karst processes of 

limestone dissolution, underground cavity development, 

spring activity, sinkhole collapse, and erosion (fig. 8). 

The dominant surficial geologic units include the St. 

Louis Limestone, the Harrodsburg Limestone, the Salem 

Limestone, and the Borden Formation. All but some 

members of the Borden Formation contain thick 

deposits of soluble limestone and dolomite, which

typically dip less than 1°—or 5 to 10 m/km (22 to 46 

ft/mi)—to the northwest, though local undulations are 

common (Mylroie and Dyas 1985; Palmer 1985). The 

four bedrock units record a longstanding marine basin—

the Illinois basin (see “Geologic History” section)—

during the Mississippian Period. Insoluble rocks such as 

shales and sandstones anchor dissected plateaus towards 

the center of the Illinois basin. Around the edges of the 

basin, these clastic cap rocks have been removed by 

erosion, exposing underlying limestone at the surface, 

which forms a broad, low-relief karst plain (the 

Pennyroyal Plateau) with characteristic sinkholes, small 

caves, springs, sinkhole ponds, and sinking streams 

(Palmer 1985). 

Southeast of the park area lies the borderland called the 

Chester Upland. The boundary between the Chester 

Upland and Pennyroyal Plateau is a sharp, irregular 60 m 

(197 ft) slope locally called the Chester Escarpment. 

Limestone ridges, riddled with caves and capped by 

insoluble rocks, characterize parts of the Chester 

Upland. The upland and plateau together form a 

crescent-shaped band of karst landforms that wraps 

around the southern and eastern edges of the Illinois 

basin from southern Indiana, through western Kentucky, 

and into southern Illinois. The configuration of the basin 

controls the morphology and evolution of the broad 

karst area (Palmer 1985). The Pennyroyal Plateau formed 

during the late Tertiary (Neogene) Period under 

conditions of very slow fluvial erosion (dominated by the 

Green River) alternating with periods of aggradation. 

The altitude of the plain correlates with wide, welldeveloped upper cave levels in nearby Mammoth Cave 

(Palmer 1984). 

The Pennyroyal Plateau contains large karst basins that 

drain into the area’s largest rivers, the Green and Barren 

rivers, primarily through the subsurface. Most of the 

subsurface caves and conduits of the Pennyroyal Plateau 

are shallow and clogged with soil, assorted debris, and 

collapse material. This in addition to their proximity to 

the water table makes them wet and prone to rapid 

flooding. These are dangerous places to explore and thus 

the number of explored caves in the area is relatively low 

(Palmer 1985).

Caves in the park area likely formed by both vadose 

(above the water table) and phreatic (at or below the 

water table) solution. In the Pennyroyal Plateau karst 

system , nascent passages conduct water through the 

vadose zone to the phreatic zone, and solutional 

enlargement of conduits occurs in both zones 

simultaneously. In these systems, the nature of the water 

table is highly irregular and discontinuous. The position 

of the water table can vary greatly on a short-term basis 

because it is partly controlled by the amount of 

groundwater flow. The distinction between phreatic and 

vadose karst features in a cave such as that of Sinking 

Spring is an essential component to the interpretation of 

the regional landscape evolution (Palmer 1984). Palmer 

(1984, 1990) described characteristic features in a 
ABLI Geologic Resources Inventory Report 13

conduit formed by vadose and phreatic solution; such 

descriptions are valuable to researchers and park 

mangers attempting to interpret cave features at 

Abraham Lincoln Birthplace National Historical Park.

Spring Development and Sinking Spring

Generally, springs develop where the ground surface 

intercepts the water table. In karst systems, almost all 

groundwater emerges at discrete springs in entrenched 

river valleys or karst windows (Palmer 1990). However, 

features of karst networks such as nonuniform porosity, 

irregular and discontinuous water table, and large areal 

variations in permeability make hydrologic 

characterization and predicting groundwater behavior 

difficult (Scanlon and Thrailkill 1987; Palmer 1990). 

The formation of springs requires the dissolution of 

discrete bedrock units. Additionally, through-flow of 

water is needed to carry away dissolved material, which 

depends on a preexisting interconnected network of 

openings not formed by solution (Palmer 1990). Upon 

the establishment of a hydrogeologic gradient across a 

carbonate (limestone) aquifer, a narrow enlargement of a 

bedding plane or joint extends toward the low surfaceflowing stream. Where this opening reaches the surface 

or the stream channel, a seep may form. Upon 

enlargement of this initial narrow conduit into a larger 

conduit (a diameter of a dime is sufficient), the flow 

conditions change and a spring develops (S. Greb, 

Kentucky Geological Survey, written communication,

2010). Springs may also develop in karst systems on 

slopes that intersect relatively impermeable layers such 

as shale or sandstone that form small, locally perched 

aquifers. In central Kentucky, dye-tracing studies have 

identified two physically distinct spring types: (1) local 

high-level springs discharging from shallow flow paths,

and (2) major low-level springs incorporating discharge 

from a deep integrated much longer conduit system

(fig. 9). Both types tend to show chemical similarities 

with respect to calcium, magnesium, bicarbonate, and 

hardness (Scanlon and Thrailkill 1987). 

Based on the relatively small size of the catchment basin 

at Sinking Spring (approximately 45 ha [110 ac]), the 

feature is likely a high-level spring type. The shallow flow 

paths inherent in this spring type are highly connected 

with surface runoff and thus have rapid responses to 

changes in precipitation and any contamination. 

Furthermore, there is little mitigating effect by long-term 

percolation. A shallow zone of interconnecting 

solutional openings is common in the upper few meters 

of limestone bedrock on the Pennyroyal Plateau, and 

relatively few individual openings receive enough water 

to enlarge into large conduits. At the inputs of larger 

conduits, sinkholes may develop in the landsurface 

because of the concentrated dissolution, collapse, and 

transport of “clogging” underburden by groundwater 

flow through the conduit. The sinkhole then acts as the 

primary influx point. The development of the Sinking 

Spring sinkhole depended on the presence of an 

underlying conduit (Palmer 1990). 

Much evidence indicates that Sinking Spring is a highlevel spring, but it is also associated with a type of karst 

window, called a doline, which forms by dissolution and 

gentle subsidence, and discharges near a major surface 

stream (the South Fork Nolin River)—both of which are 

characteristics of a major (low-level) spring type 

(Scanlon and Thrailkill 1987; GRI scoping notes 2006). 

Hence, further research into the development and 

evolution of Sinking Spring is needed to better 

understand its hydrogeologic character. 

Sinkhole Collapse

The Pennyroyal Plateau is a rolling landscape defined by 

thousands of rounded depressions. Nearly all karst 

depressions originate at least in part by collapse or slow 

subsidence of dissolved bedrock fragments into a 

preexisting underground conduit or void. On the 

surface, the expression of an old, weathered depression 

can look the same whether the feature formed by 

sinkhole collapse or solution (Palmer 1990). 

Most subsurface streams throughout the area are roofed 

by bedrock. When shallow underground stream conduits 

are roofed by thin layers of overlying rock, an eventual 

collapse produces a steep-walled sinkhole whose 

resultant debris is removed mechanically and by 

dissolution from below. This may form a karst window 

that allows direct access to the conduit. For about 10% 

of sinkholes, the debris produced as collapse takes up 

more volume than it did as solid bedrock thus selflimiting the process of sinkhole formation (Palmer 1990; 

J. Currens, Kentucky Geological Survey, written 

communication, 2010). Collapse and subsidence 

associated with sinkhole development are perhaps most 

frequent during flooding events, but the process can be 

continuous. Most dolines form by dissolution and the 

removal of solids and gradual subsidence (S. Greb, 

Kentucky Geological Survey, written communication,

2010). By contrast, rapid collapse can occur within a few 

hours of erosion. Collapses are limited to the depth of 

the active conduit passage below; however, lateral 

development can occur (fig. 10). The areas that are most

susceptible to collapse are shallow conduits at or just 

beneath the water table (Palmer 1990). The potential for 

sinkhole collapse exists at both units of the park and 

careful determination of the nature of the underlying 

karst features may help resource management to 

determine areas particularly at risk.
14 NPS Geologic Resources Division 

Figure 5 Generalized block diagram of karst features occurring in the western Pennyroyal karst. Kentucky Geological Survey graphic 

from Currens (2001b).

Figure 6. Generalized block diagram of karst features occurring in the eastern Pennyroyal karst. Kentucky Geological Survey graphic 

from Currens (2001a).
ABLI Geologic Resources Inventory Report 15

Figure 7. Generalized block diagram of karst features within Larue County. The figure shows landscape features typical of Abraham 

Lincoln Birthplace National Historical Park. Kentucky Geological Survey graphic from Davidson et al. (2006).
16 NPS Geologic Resources Division 

Figure 8. Generalized cross-sectional view of the development of a karstic landscape analogous to the Pennyroyal Plateau. Graphic by 

Trista L. Thornberry-Ehrlich (Colorado State University).
ABLI Geologic Resources Inventory Report 17

Figure 9. Cross-sectional diagrams of springs in a karst landscape. High-level springs discharge from shallow flow paths. Low-level 

springs incorporate discharge from long, deep conduits. Sinking Spring (lower diagram) combines features of both spring types. Graphic 

by Trista L. Thornberry-Ehrlich (Colorado State University) with information from figure 14 of Scanlon and Thrailkill (1987). 

Figure 10. Cross-sectional view of the development of sinkholes on a landscape analogous to the Pennyroyal Plateau and the formation 

of a doline spring analogous to Sinking Spring. Graphic by Trista L. Thornberry-Ehrlich (Colorado State University).
18 NPS Geologic Resources Division 

Map Unit Properties

This section identifies characteristics of map units that appear on the Geologic Resources 

Inventory digital geologic map of Abraham Lincoln Birthplace National Historical 

Park. The accompanying table is highly generalized and for background purposes only. 

Ground-disturbing activities should not be permitted or denied on the basis of 

information in this table. 

Geologic maps facilitate an understanding of Earth, its 

processes, and the geologic history responsible for its 

formation. Hence, the geologic map for Abraham 

Lincoln Birthplace National Historical Park provided 

information for the “Geologic Issues,” “Geologic 

Features and Processes,” and “Geologic History” 

sections of this report. Geologic maps are twodimensional representations of complex threedimensional relationships; their color coding illustrates

the distribution of rocks and unconsolidated deposits. 

Bold lines that cross or separate the color patterns mark 

structures such as faults and folds. Point symbols 

indicate features such as dipping strata, sample localities, 

mines, wells, and cave openings. 

Incorporation of geologic data into a Geographic 

Information System (GIS) increases the usefulness of 

geologic maps by revealing the spatial relationships 

among geologic features, other natural resources, and 

anthropogenic features. Geologic maps are indicators of 

water resources because they show which rock units are 

potential aquifers and are useful for finding seeps and 

springs. Geologic maps are not soil maps, and do not 

show soil types, but they do show parent material—a key 

factor in soil formation. Furthermore, resource managers 

have used geologic maps to make connections between 

geology and biology; for instance, geologic maps have 

served as tools for locating sensitive, threatened, and 

endangered plant species, which may prefer a particular 

rock unit. 

Although geologic maps do not show where earthquakes 

will occur, the presence of a fault indicates past 

movement and possible future seismic activity. Similarly, 

map units show areas that have been susceptible to 

hazards such as landslides, rockfalls, and volcanic 

eruptions. Geologic maps do not show archaeological or 

cultural resources, but past peoples may have inhabited 

or been influenced by depicted geomorphic features. For 

example, alluvial terraces may have been preferred use 

areas and formerly inhabited alcoves may occur at the 

contact between two rock units.

The geologic units listed in the following table 

correspond to the accompanying digital geologic data. 

Map units are listed in the table from youngest to oldest. 

Please refer to the geologic timescale (fig. 11) for the age 

associated with each time period. The table highlights 

characteristics of map units such as susceptibility to 

erosion and hazards; the occurrence of paleontological 

resources (fossils), cultural resources, mineral resources, 

and caves or karst; and suitability as habitat or for 

recreational use. Some information on the table is

conjectural and meant to serve as suggestions for further 

investigation.

The GRI digital geologic maps reproduce essential 

elements of the source maps including the unit 

descriptions, legend, map notes, graphics, and report. 

The following references are the sources for the GRI 

digital geologic data for Abraham Lincoln Birthplace 

National Historical Park: 

Johnson, T. L. 2005. Spatial database of the Hodgenville 

quadrangle, Larue and Nelson counties, Kentucky

(scale 1:24,000). Digitally Vectorized Geologic 

Quadrangle Data DVGQ-749_12, Series 12. Kentucky 

Geological Survey, Lexington, Kentucky.

Moore, F. B. 1968. Geologic map of the Hodgenville 

quadrangle, Larue and Nelson counties, Kentucky

(scale 1:24,000). Geologic Quadrangle Map GQ-749. 

U.S. Geological Survey, Reston, Virginia.

Kentucky Geological Survey. 2005. Kentucky oil and gas 

well data, NAD 83, version 10 (kyog83v10). Kentucky 

Geological Survey, Lexington, Kentucky.

Paylor, R. L., L. Florea, M. Caudill, and J. C. Currens. 

2003. A GIS sinkhole coverage for the karst areas of 

Kentucky. Unpublished data. Kentucky Geological 

Survey, Lexington, Kentucky

The GRI team implements a geology-GIS data model 

that standardizes map deliverables. This data model 

dictates GIS data structure including data layer 

architecture, feature attribution, and data relationships 

within ESRI ArcGIS software, and increases the overall 

utility of the data. GRI digital geologic map products 

include data in ESRI personal geodatabase, shapefile, 

and coverage GIS formats, layer files with feature 

symbology, Federal Geographic Data Committee 

(FGDC)–compliant metadata, a Windows help file that 

contains all of the ancillary map information and 

graphics, and an ESRI ArcMap map document file that 

easily displays the map. GRI digital geologic data are 

included on the attached CD and are available through 

the NPS Data Store at 

http://science.nature.nps.gov/nrdata/ (accessed May 21, 

2010).

Abraham Lincoln Birthplace National Historical Park

Map Units

The geologic bedrock units at Abraham Lincoln 

Birthplace National Historical Park are the Borden 

Formation, Harrodsburg Limestone, Salem Limestone, 
ABLI Geologic Resources Inventory Report 19

and St. Louis Limestone. The Mississippian Borden 

Formation contains seven distinct members in ascending 

order: New Providence Shale, Nancy, Cowbell, Halls 

Gap, Wildie, Nada, and Muldraugh members. The 

Muldraugh Member and a crinoidal limestone member

are present in the park area (Johnson 2005). In the 

mapped area, The Muldraugh Member is largely 

undifferentiated as interbedded shales, siltstones, and 

limestones (Moore 1968). The Muldraugh formed in 

prodeltaic environments on an abandoned delta front 

(the Borden delta complex). Deeper water was to the 

west and south.

The Harrodsburg Limestone is characterized by coarsegrained limestones and some silty dolomitic limestone 

interlayers. This unit contains abundant marine 

invertebrate fossils including crinoids. The limestone 

records the development of a carbonate platform on the 

underlying deltaic deposits. The carbonates accumulated 

in incredibly prolific crinoids-rich seas of the 

Mississippian Period (Johnson 2005). 

The Salem Limestone contains abundant coarse-grained 

limestone, dolomite, shale, and siltstone. This unit is also 

fossiliferous recording a nearshore marine depositional 

environment (Moore 1968; Johnson 2005).

The St. Louis Limestone is primarily limestone, dolomite, 

and limy shale with silty, carbonaceous, siliceous, and 

cherty zones present. The relatively pure limestone 

layers of the St. Louis Limestone were once quarried 

locally. The unit supports vast cave networks nearby.

Quaternary alluvium and colluvium overlie the 

Mississippian bedrock. These unconsolidated deposits 

consist of clay, silt, sand, pebbles, organic material, and 

gravel in channels, floodplains, and small alluvial fans 

(Moore 1968; Johnson 2005). 

The following page presents a tabular view of the 

stratigraphic column and an itemized list of features for 

each map unit. This sheet includes several properties 

specific to each unit present in the stratigraphic column 

including name and map symbol; description; resistance 

to erosion; suitability for development; hazards; potential 

paleontologic, cultural, and mineral resources;

recreational use potential, and global significance. For 

more information on understanding how to use geologic 

maps for managing geologic issues specific to Kentucky, 

please see Ruthven et al. (2003). Similarly, Davidson et al. 

(2006) prepared a geologic map specifically for land-use 

planning in Larue County, Kentucky. This map displays 

features including mapped sinkholes, flood zones, 

wetland areas, gas fields, and watershed boundaries that 

would be useful for resource managers at Abraham 

Lincoln Birthplace National Historical Park. 
ABLI Geologic Resources Inventory Report 20

Map Unit Properties Table: Abraham Lincoln Birthplace National Historical Park

Age Map Unit

(Symbol) Features and Description Erosion Resistance

Suitability for 

Infrastructure Hazards PaleontologicalResources Cultural Resources Mineral Occurrence Habitat Recreation Geologic Significance

QUATERNARY

Alluvium

(Qal)

Silt, clay, sand, and gravel present in 

floodplain deposits, channel deposits, and 

alluvial fan deposits associated with area 

waterways. Sand-rich beds are very fine to 

fine grained with silt and clay interbeds 

and poor sorting. Gravel layers contain 

granules, pebbles, and cobbles of chert, 

limestone, dolomite, silicified limestone, 

and limonite-cemented sandstone. Some 

colluvium present locally. 

Low

Highly permeable. 

Avoid for 

wastewater 

treatment facility 

development. 

Avoid fragile 

riparian areas.

May be 

undercut by 

erosion and 

subject to mass 

wasting (e.g., 

sliding and 

slumping)

May contain fossils 

derived from nearby 

limestone units. Fossils 

likely concentrated in 

gravel-rich layers.

May contain 

artifacts and Native 

American camps 

and mounds. Chert 

cobbles may have 

provided tool and 

trade material.

Sand, gravel, and 

silt

Supports 

riparian 

areas along 

waterways 

and some 

wetland 

areas locally

Suitable for 

most light 

recreation. 

Avoid 

undercut and 

riparian areas 

for 

campground 

development. 

Records the movement 

of waterways across 

the landscape and 

contains flood stage 

information

MISSISSIPPIAN

St. Louis Limestone 

(Msl)

Primarily light olive gray limestone, 

yellowish gray dolomite, and shale with 

silty, carbonaceous, siliceous, and cherty 

zones. Lower beds are clayey, laminated, 

and dolomitic. Bedding ranges from thick 

to thin and limy partings are common. 

Moderate

Prone to sinkhole 

and karst 

development.

Avoid for most 

development, 

especially 

wastewater 

treatment. Contains 

a viable aquifer for 

wells <30 m (100 ft) 

deep.

Prone to 

sinkhole 

development

Brachiopod fragments 

and colonial coral 

Chert layers may 

have provided tool 

material. Calcite 

vugs may have 

provided trade 

material. Caves may 

have provided 

shelter.

Prevalent 

petroliferous odor; 

may be 

hydrocarbon 

reservoir 

elsewhere. 

Limestone 

quarried 

elsewhere. Shale 

marl used as a soil 

conditioner.

Calcite-filled vugs.

Forms 

rolling-hill 

landscape 

and 

weathers to 

red, chertrich, thick 

clayey soils

Caves may 

attract 

spelunkers and 

other 

speleological 

interests. 

Sinkholes pose 

hazards.

Widespread carbonate 

layer prone to cave 

development in other 

areas

MISSISSIPPIAN

Salem Limestone 

(Ms)

Highly variable with olive gray limestone 

bedded with yellowish brown shale. 

Coarse-grained layers grade into finegrained layers, and bedding varies from 

thin to medium. Coarser layers are crossbedded. Lower layers are rich in shale, 

siltstone, and some calcareous fossil zones 

and siliceous cements. Some dolomitic 

layers present locally.

Moderate

Springs are 

common at base; 

avoid these areas 

for heavy 

development. 

Contains a poor 

aquifer.

Unstable on 

slopes and if 

undercut. Prone 

to sinkhole 

development.

Brachiopods, fenestrate 

bryozoans, 

foraminifera, horn 

coral, crinoid 

columnals, trilobites, 

and blastoid calyxes

Chert and geodes 

may have provided 

tool and trade 

material

Massive bedded 

limestone may 

provide building 

material; some 

glauconite. Geodes 

(some filled with 

gypsum) in 

dolomitic layers.

Vugs and 

geodes may 

provide 

burrow 

habitat

Sinkholes may 

pose 

recreational 

hazards and 

unstable base 

for recreation 

infrastructure. 

Widespread; correlates 

throughout the region

MISSISSIPPIAN

Harrodsburg 

Limestone

(Mhb)

Contains light olive gray, coarse to very 

coarse grained limestone with bedding 

ranging from thick to thin and local 

brownish gray, thin-bedded, calcareous, 

and siliceous silty dolomitic limestone 

interbeds. Matrix is mostly finely 

crystalline calcite. Cross-bedded and 

stylolitic.

Moderate to 

high

Springs form at 

base. Avoid spring 

areas and especially 

porous zones for 

wastewater 

treatment 

development. 

Minor aquifer 

potential.

Prone to cave 

and karst 

development, 

including 

sinkholes and 

landslides if 

exposed on 

steep slopes

Abundant crinoid 

columnals; fenestrate 

bryozoans, echinoid 

plates, and brachiopods

Chert layers may 

have provided tool 

material. Large 

geodes may have 

been trade material.

Green glauconite, 

ledge-forming 

building material; 

geodes up to 22 cm 

(9 in) in diameter.

Forms steep 

slopes with 

nearly pure 

calcite 

ledges. May 

provide 

nesting 

habitat.

Avoid steep 

slopes for 

recreation 

facility 

development. 

Ledges may 

attract 

climbers on 

cliffs.

Records prolific 

Mississippian seas with 

occasional terrestrial 

input

MISSISSIPPIAN

Borden Formation 

(Mb)

Muldraugh Member, 

Borden Formation 

(Mbm)

Crinoidal Limestone, 

Borden Formation 

(Mbls)

Contains seven members, of which only 

Mbm and Mbls are differentiated on the 

map. Dominated by shale, siltstone, and 

thick to thin bedded limestone. Some 

members contain shale, clay, and silt rich 

layers. Tabular bedding is commonly 

discontinuous in thick-bedded massive 

quartzose silty layers. Mbm contains 

siltstone, dolomite, and limestone grading 

into fine-grained sandstone interlayered 

with dolomitic, calcareous, micaceous, 

and locally glauctonitic layers. Mbls

contains thin to thick bedded, crossbedded, fossiliferous limestone layered 

with siltstone.

Moderate to 

high for 

silicified 

layers

Forms steep slopes 

prone to sliding and 

slumping. Avoid for 

heavy development. 

May be unstable for 

foundations and 

roads. Contains a 

poor aquifer.

Prone to 

landslide. 

Contains clay 

that is plastic 

when wet. 

Crinoid columnals and 

other marine fossils

Chert and 

ironstone 

concretions may 

have provided tool 

material

Ironstone, 

phosphatic 

nodules, glauconite 

layers; oxidized 

pyrite nodules, 

quartz geodes.

Forms steep 

slopes 

(Muldraugh 

Escarpment) 

with steeply 

plunging 

gullies

Plastic clays 

may be 

slippery as a 

road or trail 

base. Avoid for 

recreation 

infrastructure.

Records widespread 

Mississippian sea with 

reef deposits 

resembling those in 

south-central 

Kentucky

ABLI Geologic Resources Inventory Report 21

Geologic History

This section describes the rocks and unconsolidated deposits that appear on the digital 

geologic map of Abraham Lincoln Birthplace National Historical Park, the environment 

in which those units were deposited, and the timing of geologic events that created the 

present landscape.

Abraham Lincoln Birthplace National Historical Park 

sits on a Mississippian-age limestone karst plain—the 

Pennyroyal Plateau of central Kentucky. This area is part 

of the ancient Illinois basin. The park and surrounding 

area host physiographic features associated with the 

geologic history of this long-standing feature on the 

western edge of the Appalachian Mountains, as well as

the evolution of the North American continent (fig. 11). 

A regional perspective is presented here to connect the 

landscape and geology of the park to its surroundings. 

Precambrian (prior to 542 million years ago)

Deep below the sediments of the Illinois basin, coarsegrained, pink granitic rocks, dated at 1.2–1.4 billion years

old, record a deeply buried and overprinted mountainbuilding event—the Grenville Orogeny (Swann 2007). 

During this mid-Proterozoic orogeny, a supercontinent 

had formed that was made of most of the continental 

crust in existence at that time. This included the crust of 

North America and Africa (Harris et al. 1997). The 

continents had been squeezed together forming 

mountains; however, during the late Proterozoic, 

roughly 800–600 million years ago, crustal extension

rifted the supercontinent apart. A rift basin formed along 

the eastern margin of North America that eventually 

became the Iapetus Ocean (a precursor to the Atlantic 

Ocean). During this time, the central Kentucky area was 

subjected to more than three quarters of a billion years of 

erosion that beveled the mountains, stripped away 

overlying rocks, and exposed the granitic rocks of the 

orogenic roots (Swann 2007). In the southern reaches of 

the Kentucky area, layered volcanic and sedimentary 

rock formed during extensional events. The eroded 

surface of the Grenville rocks was to become the 

foundation of the Illinois basin. 

Paleozoic Era (542 to 251 million years ago)

From Early Cambrian through Early Ordovician time, 

orogenic activity along the eastern margin of the 

continent culminated in the Taconic Orogeny 

(approximately 440 to 420 million years ago in the central 

Appalachians). Oceanic crust and the volcanic arc from 

the Iapetus Ocean basin were thrust westward onto the 

eastern edge of the North American continent. The crust 

bowed downwards in response to the weight of the 

overriding plate, creating deep basins farther west that 

filled with mud and sand eroded from the highlands to 

the east (Harris et al. 1997). The Illinois basin is 

separated from the Appalachian basin to the east by the 

Cincinnati arch (Swann 2007). 

Illinois Basin

The Illinois basin is a spoon-shaped, asymmetrical 

depression that trends northwest-southeast through 

Kentucky, Indian, and Illinois (fig. 12). At its deepest, the 

basin is filled with more than 4,300 m (14,000 ft) of 

predominantly shallow marine Paleozoic sediments 

(Maverick Energy, Inc. 2002; Swann 2007). The basin is 

surrounded by arches and domes. To the north lies the 

Wisconsin arch, to the east is the Cincinnati arch, to the 

southwest is the Ozark dome, to the southeast is the 

Nashville dome, and to the northwest is the Mississippi 

River arch. Depositional and erosional thinning of strata 

occurs from the basin center towards the basin flanks. 

The park is on the eastern flank of the basin. For most of 

the Paleozoic (especially in western Kentucky), the 

Rough Creek graben was the center of deposition 

(depocenter), and strata thickened into it (S. Greb, 

Kentucky Geological Survey, written communication,

2010).

Since early in its history, the Illinois basin has been 

subjected to repeated uplifts, downwarpings, folding, 

and faulting of the depositional strata. Some of the 

largest structures within the basin including the Rough 

Creek fault system have all had a significant influence on 

the accumulation of hydrocarbons in the basin and attest 

to numerous deformational (uplift) events. During the 

Paleozoic, the basin was open to the south as recorded 

by finer, deep-water sediments (Maverick Energy, Inc.

2002; Swann 2007). Deposition in the Illinois basin was 

mixed with erosional episodes as the basin was emergent 

at least 50 times and marginal areas exposed 

approximately 100 times during the Paleozoic (Swann 

2007).

Shallow marine to fluvial sedimentation continued 

intermittently in these basins for a period of about 250 

million years during the Paleozoic. The Illinois basin 

sank and trapped sediment. The overall rate of 

subsidence was low, averaging only a few centimeters per 

thousand years (Swann 2007). However, this resulted in a 

thick sedimentary section. East of the park, older 

Ordovician through Devonian rocks crop out at the 

surface, but these are deep beneath the surface at the 

park itself. 

Local sea level was not constant in the Illinois basin 

throughout the Paleozoic as major unconformities and 

erosional surfaces attest. The major regional 

unconformities include the profound unconformities at 

the top and bottom of the entire Paleozoic stack, Middle 

Ordovician, Middle Devonian, and pre-Pennsylvanian 

surfaces. These unconformities mark changes in the 
22 NPS Geologic Resources Division 

pattern of basin architecture, record episodes of uplift 

and erosion, and define major rock units named the 

Sauk, Tippecanoe, Kaskaskia, and Absaroka sequences 

(Swann 2007).

Appalachian Mountain Building

Although focused north of the latitude of central 

Kentucky, the Acadian Orogeny (approximately 360 

million years ago) continued the mountain building of 

the Taconic Orogeny as the African continent drifted 

towards North America (Harris et al. 1997). The Acadian 

event involved land-mass collision, mountain building, 

and regional metamorphism (Means 1995). The Acadian 

event caused further uplift of Taconic highlands east of 

central Kentucky. Erosion of these highlands provided 

more sediment to the Illinois basin. In the Middle 

Devonian through Mississippian, deposition of the 

Kaskaskia sequence began with reworked sands filling 

erosional valleys and joints (Swann 2007). 

The Kaskaskia sequence contains vast limestone and 

dolomite deposits interlayered with thin sandstone, 

siltstone, shale, and chert beds. This sequence dominates 

the rock units found on the Pennyroyal Plateau and 

includes the Lower to Middle Mississippian Borden 

Formation, Harrodsburg Limestone, Salem Limestone, 

and St. Louis Limestone, which are exposed at Abraham 

Lincoln Birthplace National Historical Park (Moore 

1968; Johnson 2005; S. Greb, Kentucky Geological 

Survey, written communication, 2010). The Kaskaskia 

sequence records a long-standing, prolific marine basin 

marked with periodic influxes of alluvial sediments 

present in the Borden Formation carried south from 

Canada by the ancient Michigan River. When the 

sediments that became the bedrock at the park were 

deposited, a shallow sea covered what is now Kentucky, 

which was south of the equator (fig. 12). Sediment 

eroding from the Taconic highlands (proto-Appalachian 

Mountains) to the east was carried by rivers westward 

into the shallow seas (S. Greb, Kentucky Geological 

Survey, written communication, 2010). The Borden 

Formation, which is the oldest, lowermost bedrock at the 

park, was deposited in a deltaic environment (Borden 

delta front) in this shallow sea. Deeper water was to the 

west and south in the basin. Many of the shaly and silty 

members of the Borden Formation (e.g., Muldraugh 

Member) exposed in the park record the infilling of the 

shallow sea in front of the main wedge of deltaic 

sediments (S. Greb, Kentucky Geological Survey, written 

communication, 2010).

When deltaic sedimentation ceased, ending the influx of 

clastic material, a series of carbonate units precipitated 

on top of the deltaic deposits, creating a broad carbonate 

platform (S. Greb, Kentucky Geological Survey, written 

communication, 2010). Low-energy shallow marine 

environments dominated the formation of the 

fossiliferous, relatively pure limestone units including the 

Harrodsburg, Salem, and St. Louis limestones, which all 

record widespread carbonate sedimentation in shallow, 

tropical seas (S. Greb, Kentucky Geological Survey, 

written communication, 2010). Toward the end of the 

Mississippian Period, the shallow seas withdrew from 

the region, and erosion created the next regional 

unconformity (Maverick Energy, Inc. 2002; Swann 2007).

In the Upper Mississippian (known locally as the Chester 

series), sea-level fluctuations and renewed tectonism 

(mountain-building orogeny, see below) on the eastern 

margin of North America led to the deposition of 

alternating coastal and deltaic deposits (sandstones and 

shales), and shallow marine carbonates. These are the 

units that form much of the Chester Upland, located 

south of the park. Though still enigmatic, sea-level 

fluctuations during this part of the Mississippian may 

have been caused by continental glacier development in 

the southern hemisphere at this time (S. Greb, Kentucky 

Geological Survey, written communication, 2010). 

Sandstones of the Upper Mississippian and Lower 

Pennsylvanian form impermeable cap rock atop the 

limestones of the Mississippian to the west and south of 

the park. In areas such as the Chester Upland, these cap 

rocks cover vast cave networks such as the Flint–

Mammoth Cave system (Palmer 1981). Younger Upper 

Mississippian and Pennsylvanian strata crop out to the 

west, but these have eroded from the surface at the park. 

Rocks in the western Kentucky coal field, approximately 

50 km (30 mi) west of the park, were deposited in the 

Pennsylvanian Period. The Lower Pennsylvanian began 

with downcutting and formation of deep erosional 

valleys, which filled with river channel and floodplain 

deposits of sandstone, shale, and conglomerate. As sea 

level rose, the river valleys were converted to estuaries.

During the Middle Pennsylvanian, sea level fluctuated 

many times. The area that is now Kentucky (and the 

Illinois basin) was located in a rainy climate belt near the

equator. Vast marshy peatlands, which upon burial 

eventually became the coal that is mined to the west of 

the park, were deposited during this time (S. Greb, 

Kentucky Geological Survey, written communication,

2010). 

During the Pennsylvanian through Permian the protoAtlantic (Iapetus) Ocean closed as the North American 

continent collided with the African continent. This 

mountain-building episode is called the Alleghanian 

Orogeny (approximately 325 to 265 million years ago), 

the last major orogeny of the Appalachians (Means 

1995). This orogeny was one of several around the world 

at the time. By the end of the Permian, most of the 

world’s continents had collided together and formed the

supercontinent Pangaea. 

Rocks younger than the Permian are not preserved in 

most of Kentucky (except in the Jackson Purchase area 

of far western Kentucky). Throughout most of the time 

since the late Paleozoic, Kentucky was above sea level

and exposed to erosion and weathering. If any additional 

sediments were deposited in parts of Kentucky, they 

eroded away long ago (S. Greb, Kentucky Geological 

Survey, written communication, 2010). 

Mesozoic Era to Present Day (the past 251 million years)

Following the Alleghenian Orogeny during the Upper

Triassic (approximately 230 to 200 million years ago), a 
ABLI Geologic Resources Inventory Report 23

period of rifting began as the deformed rocks of the 

joined continents began to break apart. Pangaea was 

segmented into roughly the continents that persist today. 

This episode of rifting initiated the formation of the 

current Atlantic Ocean and caused many block-fault 

basins to develop on the eastern margin of the continent 

with accompanying volcanism (Harris et al. 1997; 

Southworth et al. 2001). At some time in the Mesozoic 

Era, the Illinois basin became structurally closed to the 

south as the Pascal (Pascola) arch uplifted (Maverick 

Energy, Inc. 2002; Swann 2007). Any Mesozoic and 

Cenozoic rocks that may have been deposited in the 

Illinois basin area have been lost due to the 

predominantly terrestrial (above sea level) system 

prevalent since the end of the Paleozoic. 

The North American plate has continued to drift toward 

the west since the breakup of Pangaea and the uplift of 

the Appalachian Mountains. Isostatic adjustments 

uplifted the continent and exposed the Illinois basin to 

erosion after the Alleghanian Orogeny continued at a 

lesser rate throughout the Cenozoic Period (Harris et al.

1997). The landscape and geomorphology of the 

Pennyroyal Plateau area of central Kentucky are the 

result of steady-state uplift and erosion in addition to 

relatively minor deposition along the area’s rivers from 

the Mesozoic Period to the present (Palmer 1985). 

Shifting rivers changed gradient and base level (S. Greb, 

Kentucky Geological Survey, written communication, 

2010). Much of the karst development is correlative with 

changing base level and river orientation, especially 

during glacial (ice age) events. 

The locus of karst development is migrating with time 

toward the northwest in the bedrock dip direction. In 

uplifted areas still capped by insoluble rocks, cave 

development is greatest (e.g., Chester Upland). The 

Pennsylvanian cap rocks to the west have already been 

eroded from the Pennyroyal Plateau. During the late 

Tertiary (Neogene) and earliest Quaternary, cyclic 

climatic changes caused alternating periods of slow 

erosion and deposition, forming a low-relief landscape. 

At this time, the uppermost levels of the Flint–Mammoth 

Cave system formed, and surface drainage was still 

prevalent on the proto-Pennyroyal Plateau (Palmer 1981; 

Palmer 1985). 

During the last million years, Pleistocene (ice age)

glaciers advanced and retreated. The southernmost 

extent of the ice sheets was approximately the presentday course of the Ohio River. The river valley formed 

when the last ice melted. Although the continental 

glaciations did not reach into Kentucky, glaciation 

played a significant role in the formation of the modern 

landscape at Abraham Lincoln Birthplace National 

Historical Park. The region likely experienced periglacial 

conditions (possibly discontinuous permafrost, tundralike vegetation, and freeze-thaw cycles) because of its 

proximity to the glaciers. Freeze-thaw cycles may have 

led to frost wedging in bedrock fractures. This process 

still happens during the winter, but may have been 

accentuated during the colder climates of the Pleistocene

(Means 1995). 

Although changing climatic conditions likely influenced 

karst development, perhaps the most important 

influences were reorganization of the surface drainage 

system (S. Greb, Kentucky Geological Survey, written 

communication, 2010). Prior to the ice-age events, the 

Monongahela River of southwestern Pennsylvania 

flowed north towards an ancestral basin that was to 

become Lake Erie. It was the dominant drainage in 

western Pennsylvania (Harper 1997; Marine and 

Donahue 2000). However, advancing glacial fronts 

dammed the north flowing rivers in northern Ohio,

Pennsylvania, and New York, forming large ponded 

areas and flooded river valleys. The glacial damming and 

lake development occurred several times during the 

Pleistocene coincident with four major glacial advances. 

These lakes eventually overflowed drainage divides, 

reversing the ancient drainages of the Monongahela and 

Allegheny rivers to their modern southerly courses 

(Harper 1997). 

The last ice advance and retreat changed the course of 

the major river at the time, from a northerly position in 

Ohio to the present position of the Ohio River. This 

change in drainages significantly changed base-level 

gradients in the region. The major rearrangements of the 

Ohio River drainage caused tributaries such as the White 

River in Indiana and the Green River to accelerate their 

rate of erosion and downcutting (Palmer 1984; Swann 

2007). This event had a marked effect on local cave 

formation as downcutting abandoned long-standing, 

well-developed upper cave passages and broad erosional 

surfaces (the Pennyroyal Plateau) and focused active 

erosion at lower elevations (Palmer 1984; Palmer 1985). 

During rapid erosion, major rivers became entrenched,

and minor tributaries, left hanging, were diverted 

underground, developing karst drainage, caves, 

sinkholes, and karst valleys between capped ridges 

(Palmer 1985). Karst topography continues to develop 

on the Pennyroyal Plateau; as erosion and limestone 

dissolution are the prevalent geologic processes of the 

region today.
24 NPS Geologic Resources Division 

Figure 11. Geologic timescale. Included are major life history and tectonic events occurring on the North American continent. Red lines 

indicate major unconformities between eras. Isotopic ages shown are in millions of years (Ma). Compass directions in parentheses indicate 

the regional location of individual geologic events. Adapted from the U.S. Geological Survey (http://pubs.usgs.gov/fs/2007/3015/; accessed 

May 21, 2010) with additional information from the International Commission on Stratigraphy

(http://www.geomorph.org/sp/arch/ISChart2009.pdf; accessed May 21, 2010).
ABLI Geologic Resources Inventory Report 25

Figure 12. Paleogeographic map showing the regional setting of the Illinois basin during the Mississippian Period. Base map by Ron Blakey 

(Northern Arizona University Department of Geology) modified by Jason Kenworthy (NPS Geologic Resources Division) after figure 1A from 

Smith and Read (2001). Paleogeographic maps available for download at: http://jan.ucc.nau.edu/~rcb7/index.html (accessed May 21, 2010).

ABLI Geologic Resources Inventory Report 27

Glossary

This glossary contains brief definitions of technical geologic terms used in this report. Not all 

geologic terms used are referenced. For more detailed definitions or to find terms not listed

here please visit: http://geomaps.wr.usgs.gov/parks/misc/glossarya.html. Definitions are 

based on those in the American Geological Institute Glossary of Geology (fifth edition; 2005).

active margin. A tectonically active margin where 

lithospheric plates come together (convergent 

boundary), pull apart (divergent boundary) or slide 

past one another (transform boundary). Typically 

associated with earthquakes and, in the case of 

convergent and divergent boundaries, volcanism. 

Compare to “passive margin.”

alluvial fan. A fan-shaped deposit of sediment that 

accumulates where a hydraulically confined stream 

flows to a hydraulically unconfined area. Commonly 

out of a mountainous area into an area such as a valley 

or plain.

alluvium. Stream-deposited sediment.

aquifer. A rock or sedimentary unit that is sufficiently 

porous that it has a capacity to hold water, sufficiently 

permeable to allow water to move through it, and 

currently saturated to some level.

base flow. Stream flow supported by groundwater; flow 

not attributed to direct runoff from precipitation or 

snow melt.

base level. The lowest level to which a stream can erode 

its channel. The ultimate base level for the land surface 

is sea level, but temporary base levels may exist locally. 

basement. The undifferentiated rocks, commonly 

igneous and metamorphic, that underlie rocks 

exposed at the surface.

basin (structural). A doubly plunging syncline in which 

rocks dip inward from all sides.

basin (sedimentary). Any depression, from continental to 

local scales, into which sediments are deposited.

bed. The smallest sedimentary strata unit, commonly 

ranging in thickness from one centimeter to a meter or 

two and distinguishable from beds above and below.

bedding. Depositional layering or stratification of 

sediments.

bedrock. A general term for the rock that underlies soil 

or other unconsolidated, surficial material.

block (fault). A crustal unit bounded by faults, either 

completely or in part.

calcareous. Describes rock or sediment that contains the 

mineral calcium carbonate (CaCO3).

calcite. A common rock-forming mineral: CaCO3 

(calcium carbonate).

carbonaceous. Describes a rock or sediment with 

considerable carbon content, especially organics, 

hydrocarbons, or coal.

carbonate. A mineral that has CO3

-2 as its essential 

component (e.g., calcite and aragonite).

carbonate rock. A rock consisting chiefly of carbonate 

minerals (e.g., limestone, dolomite, or carbonatite).

cementation. Chemical precipitation of material into 

pores between grains that bind the grains into rock.

chemical sediment. A sediment precipitated directly from 

solution (also called nonclastic).

chemical weathering. Chemical breakdown of minerals 

at Earth’s surface via reaction with water, air, or 

dissolved substances; commonly results in a change in 

chemical composition more stable in the current 

environment.

chert. A extremely hard sedimentary rock with 

conchoidal (smooth curved surface) fracturing. It 

consists chiefly of interlocking crystals of quartz. Also 

called “flint.”

clast. An individual grain or rock fragment in a 

sedimentary rock, produced by the physical 

disintegration of a larger rock mass.

clastic. Describes rock or sediment made of fragments of 

pre-existing rocks (clasts).

clay. Can be used to refer to clay minerals or as a 

sedimentary fragment size classification (less than 

1/256 mm [0.00015 in]).

concordant. Strata with contacts parallel to the 

orientation of adjacent strata.

concretion. A hard, compact aggregate of mineral matter, 

subspherical to irregular in shape; formed by 

precipitation from water solution around a nucleus 

such as shell or bone in a sedimentary or pyroclastic 

rock. Concretions are generally different in 

composition from the rocks in which they occur.

conglomerate. A coarse-grained, generally unsorted, 

sedimentary rock consisting of cemented, rounded 

clasts larger than 2 mm (0.08 in).

continental crust. Crustal rocks rich in silica and alumina 

that underlie the continents; ranging in thickness from 

35 km (22 mi) to 60 km (37 mi) under mountain ranges.

convergent boundary. A plate boundary where two 

tectonic plates are colliding.

craton. The relatively old and geologically stable interior 

of a continent (also see “continental shield”).

crinoid. A marine invertebrate (echinoderm) that uses a 

stalk to attach itself to a substrate. “Arms” are used to 

capture food. Rare today, they were very common in 

the Paleozoic. Crinoids are also called “sea lilies.” 

cross-bedding. Uniform to highly varied sets of inclined 

sedimentary beds deposited by wind or water that 

indicate flow conditions such as water flow direction 

and depth.

cross section. A graphical interpretation of geology, 

structure, and/or stratigraphy in the third (vertical) 

dimension based on mapped and measured geological 

extents and attitudes depicted in a vertically oriented 

plane.

crust. Earth’s outermost compositional shell, 10 to 40 km 

(6 to 25 mi) thick, consisting predominantly of 
28 NPS Geologic Resources Division 

relatively low-density silicate minerals (also see 

“oceanic crust” and “continental crust”).

cutbank. A steep, bare slope formed by lateral erosion of 

a stream.

debris flow. A moving mass of rock fragments, soil, and 

mud, in which more than half the particles of which 

are larger than sand size. 

deformation. A general term for the process of faulting, 

folding, and shearing of rocks as a result of various 

Earth forces such as compression (pushing together) 

and extension (pulling apart).

delta. A sediment wedge deposited where a stream flows 

into a lake or sea.

depocenter. An area or site of maximum deposition; the 

thickest part of any specified stratigraphic unit in a 

depositional basin.

dip. The angle between a bed or other geologic surface 

and horizontal.

dip-slip fault. A fault with measurable offset where the 

relative movement is parallel to the dip of the fault.

disconformity. An unconformity where the bedding of 

the strata above and below are parallel.

divergent boundary. An active boundary where tectonic 

plates are moving apart (e.g., a spreading ridge or 

continental rift zone).

doline. A type of sinkhole, or a karst collapse feature.

dolomite. A carbonate sedimentary rock of which more 

than 50% by weight or by areal percentages under the 

microscope consists of the mineral dolomite (calciummagnesium carbonate).

dolomitic. Describes a dolomite-bearing rock, or a rock 

containing dolomite.

downcutting. Stream erosion process in which the 

cutting is directed in primarily downward, as opposed 

to lateral erosion.

drainage basin. The total area from which a stream 

system receives or drains precipitation runoff.

dripstone. A general term for a mineral deposit formed in 

caves by dripping water.

ephemeral stream. A stream that flows briefly only in 

direct response to precipitation in the immediate 

locality and whose channel is at all times above the 

water table. 

evaporite. A sedimentary rock composed primarily of 

minerals produced from a saline solution as a result of 

extensive or total evaporation of the solvent (usually 

water).

facies (sedimentary). The depositional or environmental 

conditions reflected in the sedimentary structures, 

textures, mineralogy, fossils, etc. of a sedimentary 

rock.

fan delta. An alluvial fan that builds into a standing body 

of water. This landform differs from a delta in that a 

fan delta is next to a highland and typically forms at an 

active margin.

fanglomerate. A sedimentary rock of heterogeneous 

materials that were originally deposited in an alluvial 

fan and have since been cemented into solid rock.

fault. A break in rock along which relative movement has 

occurred between the two sides.

floodplain. The surface or strip of relatively smooth land 

adjacent to a river channel and formed by the river. 

Covered with water when the river overflows its 

banks.

fold. A curve or bend of an originally flat or planar 

structure such as rock strata, bedding planes, or 

foliation that is usually a product of deformation.

foliation. A preferred arrangement of crystal planes in 

minerals. In metamorphic rocks, the term commonly 

refers to a parallel orientation of planar minerals such 

as micas.

footwall. The mass of rock beneath a fault surface (also 

see “hanging wall”).

formation. Fundamental rock-stratigraphic unit that is 

mappable, lithologically distinct from adjoining strata, 

and has definable upper and lower contacts.

fracture. Irregular breakage of a mineral; also any break 

in a rock (e.g., crack, joint, or fault).

frost wedging. The breakup of rock due to the 

expansion of water freezing in fractures.

geology. The study of Earth including its origin, history, 

physical processes, components, and morphology.

hanging wall. The mass of rock above a fault surface 

(also see “footwall”).

intrusion. A body of igneous rock that invades (pushes 

into) older rock. The invading rock may be a plastic 

solid or magma.

island arc. A line or arc of volcanic islands formed over 

and parallel to a subduction zone.

isostacy. The condition of equilibrium, comparable to 

floating, of the units of the lithosphere above the 

asthenosphere. Crustal loading (commonly by large ice 

sheets) leads to isostatic depression or downwarping; 

removal of the load leads to isostatic uplift or 

upwarping.

joint. A break in rock without relative movement of 

rocks on either side of the fracture surface.

karst topography. Topography characterized by 

abundant sinkholes and caverns formed by the 

dissolution of calcareous rocks.

karst valley. A closed depression formed by the 

coalescence of several sinkholes.

karst window. A collapse sinkhole opening into a cave.

lamination. Very thin, parallel layers.

landslide. Any process or landform resulting from rapid, 

gravity-driven mass movement.

limestone. A sedimentary rock consisting chiefly of 

calcium carbonate, primarily in the form of the mineral 

calcite.

lithification. The conversion of sediment into solid rock.

lithify. To change to stone or to petrify; especially to 

consolidate from a loose sediment to a solid rock 

through compaction and cementation. 

lithology. The physical description or classification of a 

rock or rock unit based on characters such as its color, 

mineral composition, and grain size.

matrix. The fine grained material between coarse (larger) 

grains in igneous rocks or poorly sorted clastic 

sediments or rocks. Also refers to rock or sediment in 

which a fossil is embedded.

mechanical weathering. The physical breakup of rocks 

without change in composition. Synonymous with 

“physical weathering.”

member. A lithostratigraphic unit with definable 

contacts; a member subdivides a formation.
ABLI Geologic Resources Inventory Report 29

metamorphic. Describes the process of metamorphism 

or its results. One of the three main classes of rocks—

igneous, metamorphic, and sedimentary.

metamorphism. Literally, a change in form. 

Metamorphism occurs in rocks through mineral

alteration, formation, and/or recrystallization from 

increased heat and/or pressure.

meteoric water. Pertaining to water of recent 

atmospheric origin.

mid-ocean ridge. The continuous, generally submarine 

and volcanically active mountain range that marks the 

divergent tectonic margin(s) in Earth’s oceans.

mineral. A naturally occurring, inorganic crystalline solid 

with a definite chemical composition or compositional 

range.

nonconformity. An erosional surface preserved in strata 

in which crystalline igneous or metamorphic rocks 

underlie sedimentary rocks.

normal fault. A dip-slip fault in which the hanging wall 

moves down relative to the footwall.

obduction. The process by which the crust is thickened 

by thrust faulting at a convergent margin.

oceanic crust. Earth’s crust formed at spreading ridges 

that underlies the ocean basins. Oceanic crust is 6 to 7 

km (3 to 4 miles) thick and generally of basaltic 

composition.

orogeny. A mountain-building event.

outcrop. Any part of a rock mass or formation that is 

exposed or “crops out” at Earth’s surface.

outwash. Glacial sediment transported and deposited by 

meltwater streams.

Pangaea. A theoretical, single supercontinent that 

existed during the Permian and Triassic periods.

parent rock. The original rock from which a

metamorphic rock was formed. Can also refer to the 

rock from which a soil was formed.

passive margin. A margin where no plate-scale tectonism 

is taking place; plates are not converging, diverging, or 

sliding past one another. An example is the east coast 

of North America (compare to “active margin”).

pebble. Generally, small rounded rock particles from 4 to 

64 mm (0.16 to 2.52 in) in diameter.

peneplain. A geomorphic term for a broad area of low 

topographic relief resulting from long-term, extensive 

erosion.

perched aquifer. An aquifer containing unconfined 

groundwater separated from an underlying main body 

of groundwater by an unsaturated zone.

permeability. A measure of the relative ease with which 

fluids move through the pore spaces of rocks or 

sediments.

plateau. A broad, flat-topped topographic high 

(terrestrial or marine) of great extent and elevation 

above the surrounding plains, canyons, or valleys.

platform. Any level or nearly-level surface, ranging in 

size from a terrace or bench to a plateau or peneplain.

pluton (plutonic). A body of intrusive igneous rock that 

crystallized at some depth beneath Earth’s surface.

porosity. The proportion of void space (e.g., pores or 

voids) in a volume of rock or sediment deposit.

potentiometric surface. A surface representing the total 

head of groundwater and defined by the levels to 

which water will rise in tightly cased wells. The water 

table is a particular potentiometric surface.

prodelta. The part of a delta below the level of wave 

erosion.

progradation. The seaward building of land area due to 

sedimentary deposition.

protolith. The parent or unweathered and/or 

unmetamorphosed rock from which regolith or 

metamorphosed rock is formed. 

provenance. A place of origin. The area from which the 

constituent materials of a sedimentary rock were 

derived.

radioactivity. The spontaneous decay or breakdown of 

unstable atomic nuclei.

radiometric age. An age expressed in years and 

calculated from the quantitative determination of 

radioactive elements and their decay products. 

recharge. Infiltration processes that replenish 

groundwater.

regression. A long-term seaward retreat of the shoreline 

or relative fall of sea level.

sand. A clastic particle smaller than a granule and larger 

than a silt grain, having a diameter in the range of 1/16 

mm (0.0025 in) to 2 mm (0.08 in).

sandstone. Clastic sedimentary rock of predominantly 

sand-sized grains.

scarp. A steep cliff or topographic step resulting from 

displacement on a fault, or by mass movement, or 

erosion. Also called an “escarpment.”

sediment. An eroded and deposited, unconsolidated 

accumulation of rock and mineral fragments.

sedimentary rock. A consolidated and lithified rock 

consisting of clastic and/or chemical sediment(s). One 

of the three main classes of rocks—igneous, 

metamorphic, and sedimentary.

sequence. A major informal rock-stratigraphic unit that 

is traceable over large areas and defined by a 

sediments associated with a major sea level 

transgression-regression.

shale. A clastic sedimentary rock made of clay-sized 

particles that exhibit parallel splitting properties.

silt. Clastic sedimentary material intermediate in size 

between fine-grained sand and coarse clay (1/256 to 

1/16 mm [0.00015 to 0.002 in]).

siltstone. A variably lithified sedimentary rock composed 

of silt-sized grains.

sinkhole. A circular depression in a karst area with 

subterranean drainage and is commonly funnelshaped.

slope. The inclined surface of any geomorphic feature or 

measurement thereof. Synonymous with “gradient.”

slump. A generally large, coherent mass movement with a 

concave-up failure surface and subsequent backward 

rotation relative to the slope.

soil. Surface accumulation of weathered rock and 

organic matter capable of supporting plant growth and 

often overlying the parent material from which it 

formed.

speleothem. Any secondary mineral deposit that forms in 

a cave.

spring. A site where water issues from the surface due to 

the intersection of the water table with the ground 

surface.
30 NPS Geologic Resources Division 

strata. Tabular or sheet-like masses or distinct layers of 

rock.

stratification. The accumulation, or layering of 

sedimentary rocks in strata. Tabular, or planar, 

stratification refers to essentially parallel surfaces. 

Cross-stratification refers to strata inclined at an angle 

to the main stratification.

stratigraphy. The geologic study of the origin, 

occurrence, distribution, classification, correlation, 

and age of rock layers, especially sedimentary rocks.

stream. Any body of water moving under gravity flow in 

a clearly confined channel.

stream channel. A long, narrow depression shaped by the 

concentrated flow of a stream and covered 

continuously or periodically by water.

stream terrace. Step-like benches surrounding the 

present floodplain of a stream due to dissection of 

previous flood plain(s), stream bed(s), and/or valley 

floor(s).

strike. The compass direction of the line of intersection 

of an inclined surface with a horizontal plane.

strike-slip fault. A fault with measurable offset where the 

relative movement is parallel to the strike of the fault. 

Said to be “sinistral” (left-lateral) if relative motion of 

the block opposite the observer appears to be to the 

left. “Dextral” (right-lateral) describes relative motion 

to the right.

structural geology. The branch of geology that deals with 

the description, representation, and analysis of 

structures, chiefly on a moderate to small scale. The 

subject is similar to tectonics, but the latter is generally 

used for the broader regional or historical phases.

structure. The attitude and relative positions of the rock 

masses of an area resulting from such processes as 

faulting, folding, and igneous intrusions.

subduction zone. A convergent plate boundary where 

oceanic lithosphere descends beneath a continental or 

oceanic plate and is carried down into the mantle.

subsidence. The gradual sinking or depression of part of 

Earth’s surface.

system (stratigraphy). The group of rocks formed during 

a period of geologic time.

terrestrial. Relating to land, Earth, or its inhabitants.

thrust fault. A contractional dip-slip fault with a 

shallowly dipping fault surface (less than 45°

) where 

the hanging wall moves up and over relative to the 

footwall.

topography. The general morphology of Earth’s surface, 

including relief and locations of natural and 

anthropogenic features.

transgression. Landward migration of the sea as a result 

of a relative rise in sea level.

trend. The direction or azimuth of elongation of a linear 

geologic feature.

unconformity. An erosional or non-depositional surface 

bounded on one or both sides by sedimentary strata 

that marks a period of missing time.

uplift. A structurally high area in the crust, produced by 

movement that raises the rocks.

water table. The upper surface of the saturated zone; the 

zone of rock in an aquifer saturated with water.

weathering. The physical, chemical, and biological 

processes by which rock is broken down.
ABLI Geologic Resources Inventory Report 31

Literature Cited

This section lists references cited in this report. A more complete geologic bibliography is 

available from the National Park Service Geologic Resources Division.

Crawford, N. C. 2005. The flux of water and both nonpoint source and point source contaminants during 

storm events in free-flow karst aquifers. Geological 

Society of America Abstracts with Programs 37(7):174. 

Currens, J. C. 2001a. Generalized block diagram of 

eastern Pennyroyal karst. Map and Chart 17, Series 

XII. Kentucky Geological Survey, University of 

Kentucky, Lexington, Kentucky. 

(http://kgs.uky.edu/kgsweb/olops/pub/kgs/mc17_12.p

df). Accessed 21 May 21 2010.

Currens, J. C. 2001b. Generalized block diagram of 

western Pennyroyal karst. Map and Chart 16, Series 

XII. Kentucky Geological Survey, University of 

Kentucky, Lexington, Kentucky. 

(http://kgs.uky.edu/kgsweb/olops/pub/kgs/mc16_12.p

df). Accessed 21 May 21 2010.

Currens, J. C., M. M. Crawford, and R. L. Paylor. 2005. 

Karst potential and development indices; tools for 

mapping karst using GIS. Geological Society of 

America Abstracts with Programs 37(2):48. 

Davidson, B., D. I. Carey, and A. Pike. 2006. Generalized 

geologic map for land-use planning: Larue County, 

Kentucky. Kentucky Geological Survey, Lexington, 

Kentucky. (http://kgs.uky.edu/kgsweb/olops/pub/

kgs/mc133_12.pdf). Accessed 21 April 2010.

Dougherty, P. H. 1989. Geomorphic transect of the 

Cumberland Plateau, Pottsville Escarpment and 

Pennyroyal Plateau of east central Kentucky. Pages 31–

38 in D. Stecko and J. Kessel, editors. Kentucky 

Speleofest Guidebook, Volume 18. National 

Speleological Society, Miami Valley Grotto, Kentucky.

Eckenfelder, Inc. 1996. Guidelines for wellhead and 

springhead protections area delineation in carbonate 

rocks. Report 904-B-97-003. U.S. Environmental 

Protection Agency, Groundwater Protection Branch, 

Region 4, Atlanta, Georgia, USA.

Florida Geological Survey. 2005. Sinkholes. Florida 

Department of Environmental Protection, Florida 

Geological Survey, Tallahassee, Florida. 

(http://www.dep.state.fl.us/geology/geologictopics/sin

khole.htm). Accessed 21 May 2010.

Ginsberg, M., and A. Palmer. 2002. Delineation of 

source-water protection areas in karst aquifers. Report

816-R-02-015. U.S. Environmental Protection Agency,

Groundwater Protection Branch, Region 4, Atlanta, 

Georgia.

Harper, J. A. 1997. Of ice and waters flowing; the 

formation of Pittsburgh’s three rivers. Pennsylvania 

Geology 28(3–4):2–8. 

Harris, A. G., E. Tuttle, and S. D. Tuttle. 1997. Geology of 

national parks. Kendall/Hunt Publishing Company, 

Dubuque, Iowa.

Hoffman Institute. 2007. Sinking Spring at Lincoln 

Birthplace. (http://hoffman.wku.edu/gis/lincoln.htm).

Accessed 21 May 2010.

Hunt-Foster, R., J. P. Kenworthy, V. L. Santucci, T. 

Connors, and T. L. Thornberry-Ehrlich. 2009. 

Paleontological resource inventory and monitoring—

Cumberland Piedmont Network. Natural Resource 

Technical Report NPS/NRPC/NRTR—2009/235. 

National Park Service, Fort Collins, Colorado.

Johnson, T. L. 2005. Spatial database of the Hodgenville 

quadrangle, Larue and Nelson counties, Kentucky

(scale 1:24,000). Digitally Vectorized Geologic 

Quadrangle Data DVGQ-749_12, Series 12. Kentucky 

Geological Survey, Lexington, Kentucky.

Kentucky Geological Survey. 2005. Kentucky oil and gas 

well data, NAD 83, version 10. 10-May-2005, 

kyog83v10. Kentucky Geological Survey, Energy and 

Minerals Section, Lexington, Kentucky.

Lawliss, L. and S. Hitchcock. 2004. Abraham Lincoln 

Birthplace Unit, Abraham Lincoln Birthplace National 

Historic Site, Cultural Landscape Report. National 

Park Service, Southeast Regional Office, Cultural 

Resources Division, Atlanta, Georgia. 

(http://www.nps.gov/abli/parkmgmt/planning.htm). 

Accessed 23 June 2010.

Lord, M. L., D. Germanoski, and N. E. Allmendinger. 

2009. Fluvial geomorphology: Monitoring stream 

systems in response to a changing environment. Pages 

69–103 in Young, R. and L. Norby, editors. Geological 

Monitoring. Geological Society of America, Boulder, 

Colorado.

Marine, J. T. and J, Donahue. 2000. Terrace deposits 

associated with ancient Lake Monongahela. Pages 28–

37 in Harper, J. A., editor. Pittsburgh at the 

Millennium: The Impact of Geoscience on a Changing 

Metropolitan Area, Guidebook for the Annual Field 

Conference of Pennsylvania Geologists, Volume 65, 

October 5–7, 2000. Pittsburgh Geological Society, 

Slippery Rock University, and Pennsylvania Geological 

Survey, Pittsburgh, Pennsylvania.
32 NPS Geologic Resources Division 

Maverick Energy, Inc. 2002. Geology and history of 

Illinois basin. Maverick Energy, Inc., Robinson, 

Illinois. (http://www.maverickenergy.com/

illinois.htm). Accessed 21 May 2010.

May, M. T., K. W. Kuehn, C. G. Groves, and J. Meiman. 

2005. Karst geomorphology and environmental 

concerns of the Mammoth Cave region, Kentucky. 

American Institute of Professional Geologists, 

Kentucky Section, Lexington, Kentucky.

Means, J. 1995. Maryland’s Catoctin Mountain parks: An 

interpretive guide to Catoctin Mountain Park and 

Cunningham Falls State Park. McDonald & 

Woodward Publishing Company, Blacksburg, Virginia.

Moore, F. B. 1968. Geologic map of the Hodgenville 

quadrangle, Larue and Nelson counties, Kentucky 

(scale 1:24,000). Geologic Quadrangle Map GQ-749. 

U.S. Geological Survey, Reston, Virginia.

Mylroie, J. E., and M. Dyas. 1985. Western Kentucky 

region. Pages 119–145 in P. H. Dougherty, editor. 

Caves and karst of Kentucky. Special Publication 12. 

Kentucky Geological Survey, Lexington, Kentucky. 

National Park Service. 2006. Abraham Lincoln Birthplace 

National Historic Site, final general management plan, 

environmental impact statement. U.S. Department of 

the Interior, National Park Service, Hodgenville, 

Kentucky. 

National Park Service. 2009. Abraham Lincoln’s 

Boyhood Home at Knob Creek. 

(http://www.nps.gov/abli/planyourvisit/boyhoodhome.htm). Accessed 20 May 2010.

Palmer, A. N. 1981. A geological guide to Mammoth 

Cave National Park. Zephyrus Press, Teaneck, New 

Jersey.

Palmer, A. N. 1984. Geomorphic interpretation of karst 

features. Pages 173–209 in R. G. LaFleur, editor. 

Groundwater as a Geomorphic Agent. The 

Binghamton Symposium in Geomorphology, Volume

13, Troy, New York. 

Palmer, A. N. 1985. The Mammoth Cave region and 

Pennyroyal Plateau. Pages 97–118 in P. H. Dougherty, 

editor. Caves and karst of Kentucky, Special 

Publication 12. Kentucky Geological Survey, 

Lexington, Kentucky. 

Palmer, A.N. 1990. Groundwater processes in karst 

terranes. Pages 177–209 in Higgins, C. G. and D. R. 

Coates, editors. Groundwater Geomorphology: The 

Role of Subsurface Water in Earth-Surface Processes 

and Landforms. Special Paper 252. Geological Society 

of America, Boulder, Colorado. 

Paylor, R. L., L. Florea, M. Caudill, and J. C. Currens. 

2003. A GIS sinkhole coverage for the karst areas of 

Kentucky. Unpublished data. Kentucky Geological 

Survey, Lexington, Kentucky

Reeder, P. P., and N. C. Crawford. 1988. Application of 

the “wellcam” down-hole video camera system to 

optimally locate new drainage wells and examine 

entranceless caves in Bowling Green, Kentucky. 

Central Kentucky Cave Survey Bulletin 2:49–58. 

Ruthven, C. L., J. D. Kiefer, S. F. Greb, and W. M. 

Andrews Jr. 2003. Geologic maps and geologic issues 

in Kentucky: A Citizen’s Guide. Kentucky Geological 

Survey, Lexington, Kentucky. . (http://kgs.uky.edu/

kgsweb/olops/pub/kgs/sp03_12.pdf). Accessed 21 

April 2010. 

Ryan, M., and J. Meiman. 1996. An examination of shortterm variations in water quality at a karst spring in 

Kentucky. Ground Water 34(1):23–30.

Santucci, V. L., J. P. Kenworthy, and A. L. Mims. 2009. 

Monitoring in situ paleontological resources. Pages 

189-204 in Young, R. and L. Norby, editors. Geological 

monitoring. Geological Society of America, Boulder, 

Colorado.

Scanlon, B. R., and J. Thrailkill. 1987. Chemical 

similarities among physically distinct spring types in a 

karst terrain. Journal of Hydrology 89(3–4):259–279. 

Seadler, K. J., C. G. Groves, J. Meiman, A. J. Glennon, W.

T. Hawkins, and D. Anthony. 2002. Land use and 

groundwater quality at Sinking Spring, Abraham 

Lincoln Birthplace National Historical Site, Kentucky. 

Geological Society of America Abstracts with 

Programs 34(6):521. 

Smith, L. B. Jr., and J. F. Read. 2001. Discrimination of 

local and global effects on upper Mississippian 

stratigraphy, Illinois Basin, U.S.A. Journal of 

Sedimentary Research 71(6):985–1002.

Southworth, S. D., K. Brezinski, R. C. Orndorff, P. G. 

Chirico, and K. M. Lagueux. 2001. Geology of the 

Chesapeake and Ohio Canal National Historical Park 

and Potomac River Corridor, District of Columbia, 

Maryland, West Virginia, and Virginia. Open-File 

Report OF 01-0188. U.S. Geological Survey, Reston, 

Virginia. (http://pubs.usgs.gov/of/2001/of01-188/). 

Accessed 20 May 2010.

Swann, D. H. 2007. A summary geologic history of the 

Illinois basin. (http://www.ioga.com/

Special/Geohist.htm). Accessed 21 May 2010.

Toomey, R., III. 2009. Geological monitoring of caves 

and associated landscapes. Pages 27–46 in in Young, R. 

and L. Norby, editors. Geological Monitoring. 

Geological Society of America, Boulder, Colorado.
ABLI Geologic Resources Inventory Report 33

Vesper, D. J., and W. B. White. 2004. Spring and conduit 

sediments as storage reservoirs for heavy metals in 

karst aquifers. Environmental Geology Berlin

45(4):481–493. 

Wells, S. G. 1974. Drainage basin morphology in the 

sinkhole plain of the central Kentucky karst. 

Conference on Karst Geology and Hydrology 

Proceedings 1974 (4): 91.

White, W. B., R. A. Watson, E. R. Pohl, and R. Brucker. 

1970. The Central Kentucky Karst. Geographical 

Review 60(1): 88–115. 

Wieczorek, G. F. and J. B. Snyder. 2009. Monitoring 

slope movements. Pages 245–271 in in Young, R. and 

L. Norby, editors. Geological Monitoring. Geological 

Society of America, Boulder, Colorado.

Worthington, S. R., D. C. Ford, and G. J. Davies. 1999. 

Techniques for estimating scaling effects associated 

with channeling in carbonate aquifers. Geological 

Society of America Abstracts with Programs 31(7):287
34 NPS Geologic Resources Division 

Additional References

This section lists additional references, resources, and web sites that may be of use to 

resource managers. 

Kentucky Karst Resources

Currens, J. C. 2002. Kentucky in karst country! What you 

should know about sinkholes and springs. Information 

Circular 4, Series XII. Kentucky Geological Survey, 

Lexington, Kentucky. 

http://kgs.uky.edu/kgsweb/olops/pub/kgs/ic04_12.pdf

Kentucky Geological Survey. 2006. Introduction to karst 

groundwater. Kentucky Geological Survey, Lexington, 

Kentucky.

http://www.uky.edu/KGS/water/general/karst/karstint

ro.htm

McDowell, R. C., editor. 1986. The geology of Kentucky:

A text to accompany the geologic map of Kentucky. 

Professional Paper 1151-H. U.S. Geological Survey, 

Reston, Virginia.

General Geology and Paleontology

Paleobiology Database: http://paleodb.org/cgibin/bridge.pl

Ron Blakey (Northern Arizona University) 

paleogeographic reconstructions: 

http://jan.ucc.nau.edu/~rcb7/index.html

Geology of National Park Service Areas

NPS Geologic Resources Division (Lakewood, 

Colorado): http://nature.nps.gov/geology/

NPS Geologic Resources Inventory:

http://www.nature.nps.gov/geology/inventory/gre_pu

blications.cfm

U.S. Geological Survey Geology of National Parks 

(includes 3D photographs):

http://3dparks.wr.usgs.gov/

Harris, A. G., E. Tuttle, and S. D. Tuttle. 2003. Geology of 

national parks. Sixth edition. Kendall/Hunt Publishing 

Company, Dubuque, Iowa.

Kiver, E. P. and D. V. Harris. 1999. Geology of U.S. 

parklands. John Wiley and Sons, Inc., New York, New 

York.

Lillie, R. J. 2005. Parks and plates: The geology of our 

national parks, monuments, and seashores. W.W. 

Norton and Co., New York, New York.

[Geared for interpreters].

NPS Geoscientist-in-the-parks (GIP) internship and 

guest scientist program:

http://www.nature.nps.gov/geology/gip/index.cfm

Resource Management/Legislation Documents

NPS 2006 Management Policies (Chapter 4—Natural 

Resource Management): 

http://www.nps.gov/policy/mp/policies.html#_Toc157

232681

NPS-75: Natural Resource Inventory and Monitoring 

Guideline: 

http://www.nature.nps.gov/nps75/nps75.pdf

NPS Natural Resource Management Reference Manual 

#77: http://www.nature.nps.gov/Rm77/

Geologic Monitoring Manual

R. Young, R., and L. Norby, editors. Geological 

monitoring. Geological Society of America, Boulder, 

Colorado. [Website under development]. Contact the 

Geologic Resources Division to obtain a copy.

NPS Technical Information Center (Denver; repository 

for technical (TIC) documents): http://etic.nps.gov/

Geological Survey Websites

Kentucky Geological Survey (University of Kentucky): 

http://www.uky.edu/KGS/

U.S. Geological Survey: http://www.usgs.gov/

Geological Society of America: 

http://www.geosociety.org/

American Geological Institute: http://www.agiweb.org/

Association of American State Geologists: 

http://www.stategeologists.org/

Other Geology/Resource Management Tools

Neuendorf, K. K. E., J. P. Mehl Jr., and J. A. Jackson. 

2005. Glossary of geology. Fifth edition. American 

Geological Institute, Alexandria, Virginia.

Bates, R. L., and J. A. Jackson, editors. Dictionary of 

geological terms. Third edition. Bantam Doubleday 

Dell Publishing Group, New York, New York.

U.S. Geological Survey National Geologic Map Database 

(NGMDB): http://ngmdb.usgs.gov/

U.S. Geological Survey Geologic Names Lexicon 

(GEOLEX; geologic unit nomenclature and summary): 

http://ngmdb.usgs.gov/Geolex/geolex_home.html
ABLI Geologic Resources Inventory Report 35

U.S. Geological Survey Geographic Names Information 

System (GNIS; search for place names and geographic 

features, and plot them on topographic maps or aerial 

photos): http://gnis.usgs.gov/

U.S. Geological Survey GeoPDFs (download searchable 

PDFs of any topographic map in the United States): 

http://store.usgs.gov (click on “Map Locator”)

U.S. Geological Survey Publications Warehouse (many 

USGS publications are available online): 

http://pubs.usgs.gov

U.S. Geological Survey, Tapestry of Time (description of 

physiographic provinces): 

http://tapestry.usgs.gov/Default.html
36 NPS Geologic Resources Division 

Appendix A: Overview of Digital Geologic Data

The following page is an overview of the digital geologic data for Abraham Lincoln 

Birthplace National Historical Park. For a poster-size PDF of this overview and 

complete digital data, please see the included CD or visit the Geologic Resources 

Inventory publications web site (http://www.nature.nps.gov/geology/inventory/

gre_publications.cfm).


ABLI Geologic Resources Inventory Report 39

Appendix B: Scoping Session Participants

The following is a list of participants from the GRI scoping session for Abraham Lincoln 

Birthplace National Historical Park, held on June 15, 2006. The contact information 

and email addresses in this appendix may be outdated; please contact the Geologic 

Resources Division for current information. The scoping meeting summary was used as 

the foundation for this GRI report. The original scoping summary document is available 

on the GRI web site: http://www.nature.nps.gov/geology/inventory/

gre_publications.cfm.

Name Affiliation Position Phone E-Mail

Addison, 

Aaron

Cave Research Foundation GIS Specialist 314-369-6562 aadison@wustl.edu

Chappell, Jim Colorado State University Geologist/GIS Specialist 970-491-5147 jrchapp@lamar.colostate.edu

Connors, Tim NPS Geologic Resources 

Division

Geologist 303-969-2093 tim_connors@nps.gov

Crawford, 

Matt

Kentucky Geological Survey Geologist 859-257-5500 

ext. 140

mcrawford@uky.edu

Edwards, Amy Mammoth Cave National 

Park

Geologist/Intern amy_edwards@wicu.edu

Finn, Meg Grayson County Middle 

School

Teacher 270-286-9910 meg_finn@grayson.kyschools.us

Heise, Bruce NPS Geologic Resources 

Division

Geologist 303-969-2017 bruce_heise@nps.gov

Kerbo, Ron NPS Geologic Resources 

Division

Cave Specialist 303-969-2097 ron_kerbo@nps.gov

Liebfried, 

Teresa

NPS Cumberland Piedmont 

Network

Coordinator 270-758-2135 teresa_liebfried@nps.gov

Meiman, Joe NPS Gulf Coast and 

Cumberland Piedmont 

Networks

Hydrologist 270-758-2137 joe_meiman@nps.gov

Merideth, 

Johny

Mammoth Cave National 

Park

Interpreter 270-758-2434 johny_merideth@nps.gov

Olson, Rick Mammoth Cave National 

Park

Ecologist 270-758-2138 rick_olson@nps.gov

Osborn, Bob Cave Research Foundation Geologist 314-984-8453 osburn@levee.wust1.edu

Palmer, Art State University of New 

York/Cave Research 

Foundation

Hydrologist 607-432-6024 palmeran@oneonta.edu

Palmer, Peggy State University of New 

York/Cave Research 

Foundation

Hydrologist 607-432-6024

Scoggins, 

Lillian

Mammoth Cave National 

Park

GIS Specialist 270-758-2149 lillian_scoggins@nps.gov

ThornberryEhrlich, TristaColorado State University Geologist Report Writer 757-416-5928 tthorn@cnr.colostate.edu

Toomey, Rick Mammoth Cave 

International Center for 

Science and Learning

Director 270-758-2145 rick_toomey@contractor.nps.gov

The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides scientific and other 

information about those resources; and honors its special responsibilities to American Indians, Alaska Natives, and affiliated Island 

Communities. 

NPS 338/104291, June 2010 
National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 

1201 Oakridge Drive, Suite 150 

Fort Collins, CO 80525 

www.nature.nps.gov 

EXPERIENCE YOUR AMERICATM