Friendship Hill National Historic Site 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/022 

National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 
THIS PAGE: THIS PAGE: 

Waterfall on Ice Pond Run, Friendship Hill NHP. Waterfall on Ice Pond Run, Friendship Hill NHP.

ON THE COVER: ON THE COVER: 

Gallatin House, Friendship Hill NHP Gallatin House, Friendship Hill NHP

NPS Photos NPS Photos 
Friendship Hill National Historic Site 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/022 

Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, Colorado 80225 

February 2008 

U.S. Department of the Interior 

Washington, D.C.
The Natural Resource Publication series addresses natural resource topics that are of interest 

and applicability to a broad readership in the National Park Service and to others in the 

management of natural resources, including the scientific community, the public, and the NPS 

conservation and environmental constituencies. Manuscripts are peer- reviewed to ensure that 

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

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Natural Resource Reports are the designated medium for disseminating 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. Examples of the diverse array of reports published in this 

series include vital signs monitoring plans; "how to" resource management papers; 

proceedings of resource management workshops or conferences; annual reports of resource 

programs or divisions of the Natural Resource Program Center; resource action plans; fact 

sheets; and regularly- published newsletters. 

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not constitute endorsement or recommendation for use by the National Park Service. 

Printed copies of reports in these series may be produced in a limited quantity and they are 

only available as long as the supply lasts. This report is also available from the Geologic 

Resource Evaluation Program website (http://www2.nature.nps.gov/geology/inventory/

gre_publications) on the internet, or by sending a request to the address on the back cover. 

Please cite this publication as: 

Thornberry- Ehrlich, Trista. 2008. Friendship Hill National Historic Site Geologic Resource 

Evaluation Report. Natural Resource Report NPS/NRPC/GRD/NRR—2008/022. National 

Park Service, Denver, Colorado. 

NPS D- 46, February 2008 
 FRHI Geologic Resource Evaluation Report iii

Table of Contents 

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

List of Tables ................................................................................................................ iv

Executive Summary ...................................................................................................... 1

Introduction ................................................................................................................... 2

Purpose of the Geologic Resource Evaluation Program ............................................................................................2

Geologic Setting .........................................................................................................................................................2

Geologic Issues............................................................................................................. 9

Coal Mining and Abandoned Mine Drainage ..............................................................................................................9

Mine Shaft Subsidence and Associated Hazards.....................................................................................................10

Geologic Hazards.....................................................................................................................................................11

Water Issues.............................................................................................................................................................11

Paleontology Issues .................................................................................................................................................12

Geologic Features and Processes............................................................................. 13

Geology and History Connections ............................................................................................................................13

Geology and Biology Connections............................................................................................................................14

Wetlands ..................................................................................................................................................................14

Monongahela River ..................................................................................................................................................14

Ancient Lake Monongahela and Paleodrainage .......................................................................................................15

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

Map Unit Properties Table........................................................................................................................................19

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

Taconic Orogeny ......................................................................................................................................................21

Appalachian Basin....................................................................................................................................................21

Acadian Orogeny......................................................................................................................................................22

Alleghenian Orogeny ................................................................................................................................................23

Triassic Extension to the Present .............................................................................................................................23

Glossary....................................................................................................................... 26

References................................................................................................................... 28

Appendix A: Geologic Map Graphic .......................................................................... 31

Appendix B: Scoping Summary................................................................................. 33

Attachment 1: Geologic Resource Evaluation Products CD 
 NPS Geologic Resources Division iv 

List of Figures 

Figure 1. Location Map of Friendship Hill National Historic Site.....................................................................................4

Figure 2. Galatin House.......................................................................................................................... 5 

Figure 3. View of the Monongahela River from Gallatin House......................................................................................6 

Figure 4. Map of Pennsylvania with Physiographic Provinces.. .....................................................................................7

Figure 5. Generalized Geologic Map of Friendship Hill National Historic Site................................................................8

Figure 6. Reconstruction of Ancient Lake Monongahela..............................................................................................16

Figure 7. Maps Showing Drainage of Ancient Monongahela River ..............................................................................17

Figure 8. Geologic Time Scale.....................................................................................................................................24

Figure 9. Evolution of the Landscape in the Friendship Hill National Historic Site Area...............................................25

List of Tables 

Table 1. Deposition in the Appalachian Basin..............................................................................................................22
 FRHI Geologic Resource Evaluation Report 1

Executive Summary 

This report accompanies the digital geologic map for Friendship Hill National Historic Site 

in Pennsylvania, which the Geologic Resources Division produced in collaboration with its 

partners. It contains information relevant to resource management and scientific research. 

Friendship Hill, located in southwestern Pennsylvania 

(fig. 1) was set aside to commemorate the home of Albert 

Gallatin (fig. 2) and his invaluable contributions to the 

history of the United States as treasurer during the 

Jefferson presidency. His estate, established in what was 

then the frontier, sits atop a high bluff overlooking the 

Monongahela River (fig. 3). Today this river is a major 

transportation corridor and joins the Allegheny River in 

Pittsburgh to form the Ohio River. 

In addition to cultural resources such as Gallatin House 

and its grounds, Friendship Hill National Historic Site 

preserves land near the junction of three sections in the 

Appalachian Plateaus physiographic province (fig. 4): 

Waynesburg Hills, Pittsburgh Low Plateau, and 

Allegheny Mountain sections (fig. 5). The rocks in the 

Appalachian Plateaus province are relatively flat lying 

and undeformed in contrast to the rocks of the Valley 

and Ridge province just east of Friendship Hill. The 

Allegheny Mountains separate these two provinces. In 

the Friendship Hill area, geologic exposures consist 

primarily of sedimentary rocks of Pennsylvanian through 

Permian in age. These include sandstones, limestones, 

claystones, conglomerates, dolomites, and shales that 

contain fossils, commercially viable coals, and some 

iron- and sulfide- rich minerals. 

Geologic resources serve as the foundation of the entire 

ecosystem. Geologic processes initiate complex 

responses that give rise to rock formations, topographic 

expression, surface and subsurface fluid movement, and 

soils. These processes create a landscape that can either 

welcome or discourage human use. At Friendship Hill, 

human land- use disturbances are clear such as logging 

and farming on slopes and bluffs. Both surface and 

underground coal mining has altered the natural 

topographic expression of the landscape and continues 

to threaten natural and cultural resources at the national 

historic site. Mining related hazards include surface 

subsidence and acid- mine drainage. 

The following issues have a high level of management 

significance at Friendship Hill National Historic Site: 

• Acid Mine Drainage. Friendship Hill National Historic 

Site is located in an area of western Pennsylvania 

known for extensive coal mining. Abandoned mines 

pose health, safety, and environmental threats to the 

area. Foremost among these is acid- mine drainage. 

The potential for acid- mine drainage and heavy metal 

contamination that accompanies low pH (~2.7) runoff 

is a serious resource management concern. Four small 

tributaries of the Monongahela River within the 

national historic site have low pH. 

• Subsidence and Associated Hazards. Mine workings 

located beneath historic structures, trails, and other 

areas are prone to subsidence or collapse and require 

careful monitoring. Mine openings and airshafts pose 

hazards associated with both discharge of water and 

oxygen- depleted air. Deep underground mining and 

waste piles are associated with the potential for 

collapse. The NPS Disturbed Lands Restoration 

Program has been assisting park staff in the 

reclamation of abandoned mineral lands, including 

area closures, wetlands construction, waste 

stabilization, surface mine reclamation, subsidence 

mitigation, and historic stabilization. The legacy of 

past coal mining has impacted visitor safety and 

historic preservation of landscapes and structures and 

is an ongoing resource management concern. 

• Geologic Hazards. The steep terrain along the 

Monongahela River is prone to several geologic 

hazards: landslides, slumps, and rockfalls. In 

particular, slope failures may occur in areas where 

natural or anthropogenic processes undercut resistant 

rock units by eroding weaker underlying units. 

Though not common, seismic activity is possible in 

western Pennsylvania. Even minor tremors might 

damage cultural resources, or trigger landslides, mine 

collapse, and debris flows on steep or water- saturated 

slopes. 

• Water Issues. Fluvial erosion along the Monongahela 

River may impact the River trail as well as riparian 

environments and wetlands. Additionally water quality 

in the park has been affected by industrial 

development and coal mining near by. Understanding 

the hydrogeologic system is important for resource 

management. 

• Paleontology. Although fossil resources have not been 

documented inside the park, potentially fossiliferous 

formations are present and may contain undiscovered 

paleontological resources. 
 NPS Geologic Resources Division 2 

Introduction 

The following section briefly describes the National Park Service Geologic Resource 

Evaluation Program and the regional geologic setting of Friendship Hill National 

Historic Site. 

Purpose of the Geologic Resource Evaluation Program 

The Geologic Resource Evaluation (GRE) Program is 

one of 12 inventories funded under the NPS Natural 

Resource Challenge designed to enhance baseline 

information available to park managers. The program 

carries out the geologic component of the inventory 

effort from the development of digital geologic maps to 

providing park staff with a geologic report tailored to a 

park’s specific geologic resource issues. The Geologic 

Resources Division of the Natural Resource Program 

Center administers this program. The GRE team relies 

heavily on partnerships with the U.S. Geological Survey, 

Colorado State University, state surveys, and others in 

developing GRE products. 

The goal of the GRE Program is to increase 

understanding of the geologic processes at work in parks 

and provide sound geologic information for use in park 

decision making. Sound park stewardship relies on 

understanding natural resources and their role in the 

ecosystem. Geology is the foundation of park 

ecosystems. 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 this goal, the GRE team is systematically 

working towards providing each of the identified 270 

natural area parks with a geologic scoping meeting, a 

digital geologic map, and a geologic report. These 

products support the stewardship of park resources and 

are designed for non- geoscientists. During scoping 

meetings the GRE team brings together park staff and 

geologic experts to review available geologic maps and 

discuss specific geologic issues, features, and processes. 

Scoping meetings are usually held for individual parks 

and on occasion for an entire Vital Signs Monitoring 

Network. The GRE mapping team converts the geologic 

maps identified for park use at the scoping meeting into 

digital geologic data in accordance with their innovative 

Geographic Information Systems (GIS) Data Model. 

These digital data sets bring an exciting interactive 

dimension to traditional paper maps by providing 

geologic data for use in park GIS and facilitating the 

incorporation of geologic considerations into a wide 

range of resource management applications. The newest 

maps come complete with interactive help files. As a 

companion to the digital geologic maps, the GRE team 

prepares a park- specific geologic report that aids in use 

of the maps and provides park managers with an 

overview of park geology and geologic resource 

management issues. 

For additional information regarding the content of this 

report and up to date GRE contact information please 

refer to the Geologic Resource Evaluation Web site 

(http://www2.nature.nps.gov/geology/inventory/). 

Geologic Setting 

Friendship Hill was the home of Swiss emigrant Albert 

Gallatin, the famous secretary of the Treasury whose 

legacy extends all the way to the river named in his honor 

in southwest Montana. He served under Presidents 

Jefferson and Madison, working to reduce the national 

debt, purchase the Louisiana Territory, and fund Lewis 

and Clark’s discovery- filled journey. Gallatin’s home, 

commemorating his accomplishments in the late 18th and 

early 19th centuries, is located in southwestern 

Pennsylvania, near the border with West Virginia (fig. 1). 

This estate, located on the frontier at the time of 

construction, was designated a national historic 

landmark in 1965, assigned to the National Register of 

Historic Places in 1966, and redesignated a national 

historic site by the National Parks and Recreation Act 

(P.L. 95- 625) on November 10, 1978 (92 STAT. 3509), 

during the presidency of Jimmy Carter. 

Friendship Hill National Historic Site is located on a 

knoll overlooking the Monongahela River near Point 

Marion, in western Fayette County, Pennsylvania. It 

preserves some 675 acres (273 ha) of forested rolling hills 

broken by steep valleys. Wide river valleys dominate the 

landscape; whereas local streams such as Georges Creek, 

Ice Pond Run, Jacobs Creek, and York Run serve as 

more subtle yet significant drivers of landscape change. 

The Monongahela River flows north from its source at 

the confluence of the West Fork and Tygart rivers near 

Fairmont, West Virginia. North of Friendship Hill, the 

river joins the Allegheny River to form the Ohio River. 

Humans have significantly altered the landscape 

surrounding Friendship Hill with a series of surface and 

underground mines along the length of the 

Monongahela River. Mining activities have effectively 

leveled preexisting topographic expression. 

The rock units at Friendship Hill are generally flat lying 

and undeformed with surface variations resulting from 

erosion and downcutting of rivers. This is a typical 

stratigraphic picture in the Appalachian Plateaus 

physiographic province. Friendship Hill sits near the 

junction of three physiographic sub- provinces: 

Waynesburg Hills, Pittsburgh Low Plateau, and 

Allegheny Mountain. West of the national historic site 

are the undulating hills and steep valleys of 

Monongahela and Dunkard townships, including Durrs 
 FRHI Geologic Resource Evaluation Report 3

Knob, Rocky Hollow, and Mundell Hollow. East of the 

site, Hardin, Bartons, and Victor hollows rise steeply 

towards Chestnut Ridge. Mississippian to Devonian 

sandstones cap this ridge. 

A general east to west description of several of the 

different physiographic provinces of the Appalachian 

Mountains follows (fig. 1). The information is relevant to 

understanding the geologic history and setting of 

Friendship Hill National Historic Site. 

Piedmont Province 

The “Fall Line” or “Fall Zone” marks a transitional zone 

where the softer, less consolidated sedimentary rock of 

the Atlantic Coastal Plain province to the east intersects 

the harder, more resilient metamorphic rock to the west, 

forming an area of ridges, waterfalls, and rapids. 

Examples of the transition are present in the Potomac 

Gorge of the Chesapeake and Ohio Canal National 

Historical Park (Maryland, District of Columbia, and 

West Virginia). The Piedmont physiographic province 

encompasses the Fall Line westward to the Blue Ridge 

Mountains. The eastward- sloping Piedmont Plateau of 

this province formed through a combination of folds, 

faults, uplifts, and erosion. The resulting landscape of 

gently rolling hills, starting at 60 m (200 f) in elevation, 

becomes gradually steeper toward the western edge, 

reaching 300 m (1,000 ft) above sea level. The Piedmont 

Plateau is composed of hard, crystalline igneous and 

metamorphic rocks such as gabbros, schists, phyllites, 

slates, and gneisses. 

Blue Ridge Province 

The Blue Ridge province is located along the eastern 

edge of the Appalachian Mountains. The highest 

elevations in the Appalachians are near Great Smoky 

Mountains National Park (Tennessee and North 

Carolina). Proterozoic and Paleozoic igneous, 

sedimentary, and metamorphic rocks were uplifted 

during several orogenic events (i.e., Taconic, Acadian, 

and Alleghenian) forming steep, rugged terrain. Resistant 

Cambrian quartzite forms most of the high ridges, 

whereas Proterozoic metamorphic rocks underlie the 

valleys (Nickelsen 1956). The elongated belt of Blue 

Ridge stretches from Georgia to Pennsylvania. Eroding 

streams have caused the narrowing of the northern 

section of the Blue Ridge Mountains into a thin band of 

steep ridges that rise to heights of approximately 1,200 m 

(3,900 ft). These streams link the adjacent Valley and 

Range and Piedmont provinces. 

Valley and Ridge Province 

Long, parallel ridges separated by valleys (100 to 200 m 

[330 to 660 ft] deep) characterize the landscape of the 

Valley and Ridge physiographic province. The landforms 

are strongly representative of the lithology and structure 

of the deformed bedrock: valleys formed in easily eroded 

shale and carbonate formations among resistant 

sandstone ridges. 

Averaging 80 km (50 miles) in width, the province 

contains strongly folded and faulted sedimentary rocks 

in central Pennsylvania. The eastern portion is part of the 

Great Valley; this section is rolling lowland formed on 

folded carbonate rocks and shale. 

Appalachian Plateaus Province 

Compared to the more eastern physiographic provinces, 

the Appalachian Plateaus province is relatively 

undeformed. Instead of highly folded and inclined strata 

like the Valley and Ridge province, the rock layers of this 

province are nearly flat. A steep scarp, known as the 

Allegheny Front, bounds the plateaus on the east. This 

escarpment rises abruptly 300 to 900 m (1,000 to 3,000 

ft). Maximum elevations at this front are generally 

greater than that of the ridges in the Valley and Ridge 

province. In Pennsylvania, elevations range from 520 to 

900 m (1,750 to 3,000 ft). 

Deep ravines carved into the horizontal sedimentary 

rock layers characterize the topography of this province. 

Geologic units are typically repeated sequences of shale, 

coal, limestone, and sandstone. Erosion of these units 

has created a rugged, jumbled topographic surface. In 

Pennsylvania and New York, the northern reaches of the 

province, modified by glaciation, display more rounded 

hills with gentler slopes, and gradually diminish in 

elevation toward the Great Lakes coastal plain. 

The Waynesburg Hills are composed of narrow hilltops 

separated by steep- sided narrow valleys with relief 

typically between 180 and 200 m (600 and 1,000 ft). 

Elevations in this section range from 150 to 500 m (500 to 

1,650 ft). 

A smooth, undulating topographic expression cut by 

numerous shallow river valleys characterizes the 

Pittsburgh Low Plateau. It contains much of the 

bituminous coal resources of Pennsylvania. Local relief is 

generally less than 60 m (200 ft) and elevations range 

from 200 to 520 m (600 to 1,700 ft). 

By contrast, the Allegheny Mountain section consists of 

roughly parallel, broad, rounded ridges separated by 

broad river valleys. The crests of the ridges in this section 

are exposed anticlinal cores of very resistant rocks such 

as Devonian sandstones. Relief in this section reaches 

greater than 300 m (1,000 ft), and elevations range from 

the highest point at Mount Davis (979 m [3,213 ft]) to the 

low point at 236 m (775 ft) (Pennsylvania Geological 

Survey 2000). 
 NPS Geologic Resources Division 4 

Figure 1. Map showing the location of Friendship Hill National Historic Site, Pennsylvania 
 FRHI Geologic Resource Evaluation Report 5

Figure 2. Gallatin House. The historic structure sits atop a knoll at Friendship Hill National Historic Site. The main wing (to the left) 

closely resembles the original structure; several wings attached to the house represent multiple renovations. Photo: Ralph Lotshaw 

http://www.worldisround.com/articles/200796/photo6.html (accessed February 6, 2006). 
 NPS Geologic Resources Division 6 

Figure 3. View of the Monongahela River from Gallatin House. From this vantage point, visitors at Friendship Hill National Historic Site 

can see the remnants of early engineering structures within the river and the obvious height of the house above the steep slopes 

leading down to the river’s edge. Photo: Ralph Lotshaw http://www.worldisround.com/articles/200796/photo7.html (accessed February 

6, 2006). 
 FRHI Geologic Resource Evaluation Report 7

 

Figure 4. Map of Pennsylvania with Physiographic Provinces. Numerous physiographic sections surround Friendship Hill National 

Historic Site. Red lines on the figure indicate boundaries between major physiographic provinces. The black arrow indicates the

northern terminus of the Blue Ridge province. Note location of national historic site as a green circle. Source: Pennsylvania Geological 

Survey (2000), map 13. Graphic design: Trista L. Thornberry-Ehrlich (Colorado State University). 
 NPS Geologic Resources Division 8 

Figure 5. Generalized Geologic Map of Friendship Hill National Historic Site. The physiographic sections surrounding the national 

historic site are labeled. Note location of site as a green circle. Source: Pennsylvania Geological Survey, digital geologic map data. 

Graphic design: Trista L. Thornberry-Ehrlich (Colorado State University). 
 FRHI Geologic Resource Evaluation Report 9

Geologic Issues 

A Geologic Resource Evaluation scoping session was held for Friendship Hill National 

Historic Site on June 22, 2004, to discuss geologic resources, address the status of geologic 

mapping, and assess resource management issues and needs. The following section 

synthesizes the scoping results, in particular those issues that may require attention from 

resource managers. 

In this section, issues are listed in relative order of 

resource management significance, with the most critical 

identified first. Potential action items (i.e., inventory, 

monitoring, and research needs) are presented at the end 

of each subsection. 

Coal Mining and Abandoned Mine Drainage 

Coal and iron mining (siderite in limestones) have long 

been associated with central Pennsylvania. One sixth of 

all abandoned coal mine areas in the United States are 

located in the 12 southwestern counties of the state 

(Bogovich 1992). The Freeport, Kittanning, and 

Brookville- Clarion commercially viable coal seams, 

associated with the Pennsylvanian Allegheny Group, 

occur near the national historic site. The Pittsburgh Coal 

seam, at the base of the Monongahela Group, contains 

some of the largest underground coal mines in North 

America and underlies Friendship Hill National Historic 

Site. Investigators estimate that 50%–60% of the coal 

reserves have been extracted (Donovan and Leavitt 

2002); however, these coal beds are also a potential 

source of coalbed methane (Markowski 2001). According 

to U.S. Geological Survey Open- File Report 95- 631, 

there are 239 acres of surface minable coal and 710 acres 

of underground minable coal at Friendship Hill National 

Historic Site, all in private ownership. 

According to briefing statements issued by the Geologic 

Resources Division of the National Park Service in 2006, 

regarding the management of coal resource development 

within and adjacent to units of the National Park Service, 

federally- owned coal in parks may not be leased for 

mining. This is in accordance with the Mineral Leasing 

Act of 1920 and the Mineral Leasing Act for Acquired 

Lands of 1947. Additionally, the Surface Mining Control 

and Reclamation Act of 1977 controls surface coal mining 

and reclamation activities on both federal and nonfederal lands. Surface coal mining includes activities 

conducted on the land surface in connection with a 

surface coal mine or surface operations and impacts 

associated with an underground mine. Section 522(e) of 

this Act contains provisions that protect “publicly owned 

parks” from adverse impacts of surface coal mining on 

lands within the boundaries of parks, unless there are 

“valid existing rights.” The Geologic Resources Division 

is providing policy and technical support to parks 

involved with external minerals issues. 

Extensive underground and surface mining in the area of 

the national historic site has resulted in lasting impacts 

on the landscape, including areas of altered topography 

mappable at a scale of 1:24,000. Negative impacts of coal 

mining include acid- mine drainage, subsidence, and 

collapse. 

At Friendship Hill National Historic Site, surrounding 

mining activities cause major pollution of waterways, 

including the Monongahela River and Ice Pond Run. 

Maps of the area show mine features and document past 

mine subsidence events (Pennsylvania Department of 

Environmental Protection 2007, 

http://www.depweb.state.pa.us/southwestro/site/ 

accessed January 14, 2008) 

Abandoned and inactive mines pose safety, 

environmental, and health problems to the Friendship 

Hill area. Foremost among these is acid- mine (and 

residual heavy metal) contamination of groundwater, 

surface water, and soils. Contaminated water and soil 

resources exceed the baseline concentrations of metals 

that existed prior to mining activities (Moore and 

Woessner 2000). In addition, fluvial sediments, remnant 

in river channels, can contain metals and mill waste 

materials. 

Acid- mine drainage occurs when sulfides (e.g. pyrite – 

FeS2

) react with water and lower the pH by producing 

sulfuric acid (H2

SO4), sulfate (SO4

2- ), and reduced ferrous 

iron (Fe2+). This reaction is self- sustaining in the 

presence of Thiobacillus bacteria, which generate energy 

by using oxygen from the atmosphere to oxidize ferrous 

iron (Fe2+) to ferric iron (Fe3+) which in turn reacts with 

more iron sulfide to produce more ferrous iron for the 

bacteria and sulfuric acid. The cycle continues until the 

iron sulfide supply is exhausted. This acidity increases 

the solubility of some potentially harmful metals. 

Groundwater and surface water disperse these metals 

from a mine source area as dissolved ions, suspended 

sediment, or as part of the fluvial bedload (Madison et al. 

1998). 

At least six components dictate the formation and 

severity of acid- mine drainage conditions (Trexler et al. 

1975): 

1. Availability of sulfides (including pyrite) 

2. Presence of oxygen and iron- oxidizing bacteria 

3. Water in the atmosphere 

4. Availability of other metals and minerals (calcite 

neutralizes acidity) 

5. Availability of water to transport dissolved 

components 

6. Mine and waste area characteristics 
 NPS Geologic Resources Division 10 

All of these components are present at Friendship Hill 

National Historic Site and have produced onsite acid 

mine drainage. Mine workings such as those below the 

Gallatin House are commonly flooded with acidic 

groundwater. A flooded mine area beneath the Gallatin 

House has a pH of 2.7. If water levels rise, acidic floods 

from these underground mines could result in largescale environmental impacts (Donovan and Leavitt 

2002). The acidic water dissolves other minerals 

commonly present in geologic units in central 

Pennsylvania, including other sulfides and 

aluminosilicate minerals. 

Metals such as manganese, aluminum, arsenic, zinc, 

cobalt, nickel, and iron as well as sulfides can be present 

in the drainage water (Kairies 2000). When cation 

concentrations are high enough and pH drops to low 

levels, minerals containing these dissolved metals begin 

to precipitate ferric hydroxide (Fe[OH]3

) and other 

insoluble minerals such as goethite, quartz, illite, 

kaolinite, and sulfates (Madison et al. 1998; Kairies 2000). 

Precipitates cloud surface water, coat rocks, form iron 

mounds around springs and seeps, and settle in 

floodplains and streambeds. 

More than 90, 718 metric tons (100,000 tons) of iron is 

discharged from coal mines in the United States each 

year as a result of the weathering of pyrite and other 

sulfide minerals (Kairies 2000). This iron- rich sludge is 

becoming increasingly interesting as a potential 

salvageable resource. 

Remediation of mine- affected areas in southwestern 

Pennsylvania is a cooperative effort among the National 

Park Service, U.S. Geological Survey, U.S. Department of 

Agriculture, Pennsylvania Department of Environmental 

Protection, and Pennsylvania Environmental Council. At 

Friendship Hill National Historic Site, wetlands 

consisting of a series of lanes and drained ponds along 

streams, including Ice Pond Run, have been shown to 

remediate the effects of acid- mine drainage. Wetlands 

naturally remediate contaminated water by slow filtering 

through organic sediments and by microbial sulfate 

reduction (Klusman et al. 1993). The performance of 

constructed wetlands is limited by the rate at which 

alkalinity is generated within the substrate via mineral 

(usually calcite) dissolution or microbial processes. This 

passive system can significantly improve the water 

quality at moderately acidic sites; however, the acidity of 

mine drainage at Friendship Hill is too low for 

significantly raising pH using this system (Hedin et al. 

1994). 

The Ice Pond Run drainage has higher acid and metal 

concentrations than 90% of acid- mine drainages in 

Pennsylvania (Hammarstrom et al. 2003). Friendship Hill 

National Historic Site is one of the first sites to employ a 

low- cost, acid- mine drainage treatment that uses 

limestone neutralization. Limestone is the least 

expensive material available to raise the pH of acid mine 

drainage (Reeder 2000). However, this low- cost method 

is hampered by coatings of gypsum (hydrous calcium 

sulfate), Fe- Al hydroxysulfate, and Fe(III) oxyhydroxide 

precipitated on the limestone grains, preventing contact 

between the acidic water and neutralizing limestone. An 

innovation developed at the U.S. Geological Survey, 

Leetown Science Center, adds carbon dioxide (CO2

) to 

the acid- mine drainage to increase the dissolution rate of 

the limestone. Water also pulses through the system 

enhancing grain- to- grain abrasion and reducing any 

armoring coatings that develop as pH is increased 

(Hammarstrom et al. 2003). This new method holds 

promise for the remediation of low pH–high metal, acidmine drainage. Heavy metal precipitates (metal 

hydroxides) settle out of the system into tanks and the 

treated water is pumped back to stream headquarters 

(Hammarstrom et al. 2003). 

Inventory, Monitoring, and Research Needs for Coal Mining 

and Abandoned Mine Drainage 

• Monitor biota (e.g., aquatic insects) for heavy metal 

contamination. 

• Incorporate Pennsylvania Department of 

Environmental Protection maps of mine features in a 

GIS layer. 

• Promote studies to reconstruct the hydrogeology of 

mined areas beneath Friendship Hill to identify areas 

in need of remediation. 

• Continue to promote acid- mine drainage remediation 

experimental efforts, such as that occurring at Ice 

Pond Run. 

• Promote studies to predict the location of discharge of 

flooded abandoned mines in the Friendship Hill area 

(e.g., Vandivort et al. 2001). 

• Generate maps showing groundwater contamination 

through time, using monitoring, well data, 

groundwater flow modeling and GIS. 

• Investigate the use of ozone to remediate dissolved 

manganese and other metals from coal mine drainage 

(U.S. Patent No. 6,485,696 B1, Nov. 26, 2002) at 

Friendship Hill. Toby Creek Treatment Plant in Elk 

County, Pennsylvania, uses this technique (Tewalt et 

al. 2004). 

• Investigate pumping at the net mine inflow rate 

(recharge) to maintain low groundwater levels locally, 

particularly beneath Gallatin House (Donovan et al. 

2000). 

Mine Shaft Subsidence and Associated Hazards 

Mine openings and airshafts pose hazards associated 

with discharge of water and low (<19%) free oxygen air 

(Bogovich 1992). Deep shaft mining and waste piles are 

associated with collapse, and mine openings and related 

structures pose safety hazards (Madison et al. 1998). The 

NPS Disturbed Lands Restoration Program has been 

assisting park staff in treating abandoned mineral lands 

including area closures, wetlands construction, waste 

stabilization, strip mine reclamation, subsidence 

mitigation, and historic stabilization (National Park 

Service 2001). The program staff inventoried three mine 

sites and 16 hazardous openings. Due to the pervasive 

mine features located within and beneath the national 
 FRHI Geologic Resource Evaluation Report 11

historic site, visitor safety and the preservation of historic 

landscapes and structures are ongoing resource 

management concerns. Park staff closely monitors 

subsidence areas. 

Inventory, Monitoring, and Research Needs for Mine Shaft 

Subsidence and Associated Hazards 

• Contact the NPS Disturbed Lands Restoration 

Program on a regular basis for current updates in 

information. 

• Incorporate inventories of mine features in a GIS layer. 

• Monitor discharge of low- oxygen air from any minerelated feature at Friendship Hill. 

Geologic Hazards 

The steep terrain of valleys and ravines between ridges 

and hills, which defines the Allegheny Mountain region, 

is prone to several geologic hazards including landslides, 

slumps, and rockfalls. Friendship Hill National Historic 

Site sits on a bluff above the Monongahela River. The 

geologic units underlying the slopes at Friendship Hill 

contain a heterogeneous mix of shale, sandstone, 

siltstone, limestone, dolomite, conglomerate, and 

mudstone. Clay- rich units (e.g., shale and mudstone) 

may disintegrate when they become water saturated and 

are prone to fail when exposed on a slope. When more 

resistant rock units such as sandstone and limestone are 

located above weaker units, undercutting occurs from 

preferential erosion, causing rockfall hazards. As the 

river erodes the base of the bluff at the national historic 

site, the potential for mass movement increases, which 

may threaten cultural resources. 

A unique and potentially hazardous stratigraphic setting 

exists in the Friendship Hill area. Between the clay- rich 

Pennsylvanian Glenshaw and Casselman formations is 

the resistant Ames Limestone. During high precipitation 

events, clays retain water in their structure weakening 

the crystalline bonds, resulting in slope failure. The 

undercut limestone layer may also collapse resulting in 

landslides and rockfalls. A site investigation by a slopestability expert could determine if these clays as well as 

the Ames Limestone are present on the slopes at 

Friendship Hill and their susceptibility to movement. 

Though not common, seismic activity is possible in 

south- central Pennsylvania. Some historic earthquakes 

in the area have been attributed to blasting at local coal 

mines (e.g., in 1893 and 1939), but natural seismicity is also 

known. A magnitude 5.2 (on the Richter scale) quake 

occurred in northwestern Pennsylvania in 1998 

(Scharnberger 1987; http://earthquake.usgs.gov/). Even 

minor seismic tremors might trigger landslides and 

debris flows on steep or water- saturated slopes. An 

assessment of the vulnerability to seismically induced 

geologic hazards at Friendship Hill National Historic Site 

would be a useful data set for resource management. 

Inventory, Monitoring, and Research Needs for Geologic 

Hazards 

• Conduct site investigations of clay- rich layers and 

friable limestones exposed on slopes to determine a 

vulnerability index to slope failure. 

• Monitor for landslides and rockfall along steep slopes 

of the bluff at Friendship Hill. 

• Promote seismic monitoring in southern Pennsylvania. 

Water Issues 

The geomorphic imprint of the Monongahela River and 

its tributaries dominate the landscape at Friendship Hill. 

The meandering nature of this river and human use of 

this waterway is a significant interpretive story. The 

Monongahela joins the Allegheny River in Pittsburgh to 

form the Ohio River, one of the most important water 

corridors in the United States. The park structures are 

located on a high bluff above the 500- year floodplain 

and are, therefore, relatively safe from flooding. 

However, fluvial erosion at the river’s edge threatens 

resources such as the River trail, riparian environments, 

and wetlands. Flooding as recent as July 2002 damaged 

areas adjacent to the river in the national historic site 

(National Park Service 2005). 

Surface water at Friendship Hill National Historic Site 

flows in four small- scale streams: Ice Pond Run, Dublin 

Run, Rhododendron Run, and South Run. All are 

tributaries of the Monongahela River (National Park 

Service 2005). Average annual runoff into these streams 

ranges from 63 to 102 cm (25 to 40 in) per year. The 

estimate of average recharge is 20 to 38 cm (8 to 15 in) per 

year, whereas annual average precipitation in the area is 

107 cm (42 in) (Pennsylvania Environment Council 

2006). 

Water quality has suffered from the pervasive industrial 

development and natural resource extraction throughout 

the Monongahela watershed. The meanders of the river 

near Friendship Hill are capturing sediments that may 

contain contaminants from nearby mines (Pennsylvania 

Environment Council 2006). Cooperative efforts are 

underway by entities including Rivers of Steel, county 

governments, the city of Pittsburgh, the Pennsylvania 

Environmental Council, the National Park Service, and 

the U.S. Geological Survey, are underway to remediate 

the watershed of both point and non- point sources of 

pollution (Pennsylvania Environment Council 2006). 

Understanding the hydrogeologic system, complicated 

by underground mine features, is crucial for resource 

management at Friendship Hill. To predict hydrologic 

response to inputs such as contaminants, acid- mine 

drainage, and other wastes, requires knowing how water 

is traveling through the subsurface. Monitoring inputs 

and outputs of the hydrologic system will facilitate 

predicting the response of the system to contaminants, 

acid- mine drainage, and other wastes. Input sources 

include rainfall, wind, surface runoff, groundwater 

transport, sewage outfalls, landfills, and fill dirt. The 

output is streamflow. Streams integrate the surface 
 NPS Geologic Resources Division 12 

runoff and groundwater flow of their watersheds, 

providing a cumulative measure of the watershed’s 

hydrologic condition. Consistent measurement of these 

parameters is crucial to establishing baselines for 

comparison. 

Inventory, Monitoring, and Research Needs for Water 

Issues 

• Define the influences of bedrock, including acidneutralizing limestones and geologic structures, and 

topography on local watersheds at Friendship Hill 

National Historic Site. 

• Map and quantify subsurface water recharge zones 

especially in areas known to contain mine features. 

Investigate additional methods to characterize 

groundwater recharge areas and flow directions. 

• Research alternatives for flood mitigation in the event 

of extreme flooding along rivers and streams at 

Friendship Hill National Historic Site. Estimate impact 

to surrounding areas of runoff from low pH acid- mine 

drainage during a flood event. 

• Consult Pennsylvania Geological Survey water reports 

for further data on the site’s hydrologic system. 

• Install monitoring stations to measure atmospheric 

inputs of important chemical components (e.g., 

nitrogen, mercury, and pH), and outputs to 

groundwater. 

Paleontology Issues 

According to the Paleontological Resource Inventory and 

Monitoring—Eastern Rivers and Mountains Network 

Report, two Pennsylvanian geologic units occur within 

Friendship Hill National Historic Site. Although these 

geologic units are fossiliferous elsewhere, neither the 

National Park Service nor its cooperators have formally 

recorded any fossils within the boundaries of the 

national historic site. 

The oldest geologic unit at Friendship Hill is the Upper 

Pennsylvanian Casselman Formation, which is 

composed of shale, siltstone, sandstone, limestone, and 

coal. The lowest portion of the formation contains a 

marine zone of fossiliferous shale (Edmunds et al. 1993). 

Additionally, fossils of non- marine bivalves (Eager 1975) 

and vertebrate fauna (Raymond 1911; Lund 1975) occur in 

the Casselman Formation. One of the more interesting 

fossil findings in the Casselman Formation is a pair of 

“problematic tracks” in Cambria County (Marks et al. 

1998). Comparison with an analogous trackway found in 

similarly aged rocks in Scotland suggests that a giant 

myriapod (6- foot- [1.8 m] long millipede- type 

invertebrate) created the trackway (Marks et al. 1998). 

The other Pennsylvanian geologic unit found at 

Friendship Hill National Historic Site is the Upper 

Pennsylvanian Monongahela Group. This group consists 

of limestone, shale, sandstone, and coal. Eager (1975) 

comments on the non- marine bivalves in this unit, and 

Lund (1975) describes fossil vertebrates found in the 

Monongahela Group. In southeastern Ohio, Bain (1992) 

reports stromatolites from the Monongahela Group, 

which vary in size from masses that are 12 inches (30 cm) 

in diameter to continuous beds,. 

Inventory, Monitoring, and Research Needs for Paleontology 

Issues 

• Promote paleontological research in the Friendship 

Hill National Historic Site area. Focus on areas 

previously ignored during coal exploration. 

• Conduct an onsite inventory of paleontological 

resources at Friendship Hill. 
 FRHI Geologic Resource Evaluation Report 13

Geologic Features and Processes 

This section provides descriptions of the most prominent and distinctive geologic features 

and processes in Friendship Hill National Historic Site. 

Geology and History Connections 

The history of the Friendship Hill area extends 

thousands of years before the first European settlers 

established forts here. Geology is intimately tied to this 

long story. The earliest known evidence of human 

activity in the area—from Sheep Rock, near Huntingdon, 

in south- central Pennsylvania—dates back 10,000 years. 

Early inhabitants were Native Americans of the 

Allegheny group. The name Allegheny, so prevalent in 

the geography and culture of Pennsylvania, stems from 

the mound- building Alligewi or Allegheny Indians from 

the western part of the state (Wells 1973). Monongahela 

is also a Native American derivative. Native Americans 

used the resources in this area as food, shelter, and stone 

for making tools. The area also served as a travel route to 

the south and west. 

Excavations of proto- historic sites such as McKees 

Rocks Village and Eisiminger have produced pottery 

fragments and other artifacts that record the movements 

of populations of Native Americans in the area (George 

2002). The onsite museum preserves artifacts 

representing the Late Archaic (4000 to 1000 B.C.) and 

Late Woodland (A.D. 900 to 1000) periods. However, 

neither the National Park Service nor its cooperators 

have conducted a systematic archaeological survey of 

early Native American sites at Friendship Hill (NPS Web 

site at http://www.nps.gov/frhi). 

The national historic site contains many cultural features 

that require protection, including protection from 

geologic processes such as erosion and mass wasting. 

The enabling legislation requires that these features be 

made available for public enjoyment but without 

compromising the natural resources or the historical 

context. Congress designated Friendship Hill National 

Historic Site in 1978, to honor Albert Gallatin and his 70-

year contribution to the development of the United 

States. His home served as a retreat for Gallatin and his 

family during the most illustrious and busy years of his 

career. When construction on the house began in 1789, 

the estate was in a region considered part of the western 

frontier. Over the years, the residence has changed hands 

and undergone extensive renovation (fig. 1). 

The National Park List of Classified Structures (LCS) 

contains 21 historic features at Friendship Hill National 

Historic Site including buildings, ruins, and roads. The 

house, a wooden- frame barn, and a younger gazebo on a 

nearby knoll are among the intact historic structures. 

The national historic site also preserves many features 

that are culturally significant but no longer intact such as 

foundations and other remnants of outbuildings 

associated with the estate. Ruins of a gardener’s cottage, 

the Painter House (ca. 1900), the River Tenant’s house, a 

silo, a stone cistern and wells, and a dairy barn are part of 

the site. A network of old roads possibly used for mining, 

farming, and logging are part of the cultural landscape as 

are several gravesites and a small cemetery. 

One of the major goals of the National Park Service is to 

preserve the historical context (buildings and the 

landscape) of the area. Issues arise, however, from 

balancing cultural and natural resource values. For 

example, a proposal for restoration of a historic building 

may include removing surrounding natural resources 

(i.e. fill material, stones, and trees), installing buttresses, 

or planting non- native crop species to reflect the historic 

landscape surrounding the structure. The park maintains 

several open spaces ranging from less than 1 acre (0.4 ha) 

to more than 60 acres (24 ha) for historical context. 

Maintaining this landscape often means resisting natural 

geologic changes (e.g., erosion) and not restoring 

disturbed lands, which presents several management 

challenges. A study of the evolution of historic land use 

would help prioritize interpretive and restoration efforts 

at Friendship Hill National Historic Site. 

Geologic slope processes such as landsliding, slumping, 

physical and chemical weathering, block sliding, and 

slope creep are constantly changing the landscape. 

Runoff erodes sediment from open areas and carries it 

down streams and gullies. Erosion naturally removes 

higher areas and fills in the lower areas, which distorts 

the historical context of the landscape. 

Friendship Hill is located 0n the Monongahela River 

atop a knoll. Slopes of this knoll are susceptible to 

erosion. Bluffs, cliffs, and banks along the river and its 

tributaries such as Ice Pond Run are prone to debris 

slides. This erosion also exposed commercially viable 

coal and limestone resources that sparked extensive 

mine activity in the area. Early European settlers 

recognized the potential of the area’s rivers to transport 

raw materials and manufactured goods. The 

Monongahela supported industries such as boat 

building, coal mining, iron smelting , and the 

manufacturing of steel and glass (Pennsylvania 

Environment Council 2006). 

Extensive coal mining and other activities such as logging 

and farming have changed the regional topographic 

expression. Associated with local mining is the potential 

collapse of underground workings. The knoll supporting 

the Gallatin House is riddled with approximately 15 acres 

(6 ha) of mine workings. The frame barn north of the 

main house rests on an unsound foundation near a 

mineshaft collapse. Subsidence in this area is prevalent, 

and park staff monitors the entire knoll. 
 NPS Geologic Resources Division 14 

Geology and Biology Connections 

Geology forms the basis of the entire ecosystem at 

Friendship Hill National Historic Site. The rivers and 

tributaries in the area are flowing over and eroding 

through geologic units. Dissolved minerals affect water 

chemistry and riparian habitats along waterways, which 

support numerous plant and animal species, including 

the occasional bald eagle. The geologic structures in the 

subsurface form a vital component of the hydrogeologic 

system. Water flows through the rock along fractures 

and intergranular pore spaces, so knowledge of the 

physical properties (e.g., porosity, permeability) of 

geologic units, even those not exposed at the surface, is 

important for resource management. 

Geologic units also weather and break down giving rise 

to soils, which support a variety of habitat types at the 

park including forests, early and mid- successional 

openings or thickets, meadows, and wetlands. Soil types 

vary by slope. At Friendship Hill, soils in areas of steep 

slope are typically shallow, weakly developed, poorly 

drained, with high erosion potential, whereas soils on 

gentle slopes or flat ground in the area are generally 

deep, fertile, and poor to well developed (Pennsylvania 

Environment Council 2006). Most of the soils at 

Friendship Hill occur on the level alluvial deposits along 

the river and upland terraces. The Pennsylvania State 

conservationist has designated much of the landscape at 

Friendship Hill as prime farmland. This land has 

supported various agricultural uses for several hundred 

years (Kopas 1991; National Park Service 2005). 

According to standards established by the Pennsylvania 

State conservationist, farmland soils, though well 

drained, are not especially fertile (Kopas 1991; National 

Park Service 2005). Forest types growing in the soils at 

Friendship Hill include typical hardwood oak forest 

(second growth and mixed), mixed mesophytic 

hardwoods, pine and spruce groves, and old- growth 

white oak. 

Records at the national historic site indicate that the 

ecosystem supports 61 varieties of trees, 311 species of 

herbs and shrubs, as well as moss and fern species. 

Multitudes of mammal, bird, amphibian, reptile, and fish 

species thrive in the diverse ecosystem (National Park 

Service 2005). 

As described in the geologic issues section above, one of 

the major impacts is acid- mine drainage. A flooded mine 

area beneath the Gallatin House has a pH of 2.7. The acid 

mine drainage from surrounding areas, including 

Friendship Hill, negatively affects the fish population in 

the Monongahela River. Across Pennsylvania Route 166 

(outside of the national historic site) was the site of deep 

coal shaft and extensive surface mining activities. Now, 

this area supports mixed hardwood forests. 

Wetlands 

The western boundary of the national historic site is 

along the Monongahela River. A series of locks and dams 

allow boat navigation in this area. Near the northeastern 

portion of the park boundary is a navigational dam and 

transportation lock (lock and dam number 7). The 100- 

and 500- year floodplain levels near this structure are 

wetlands. Friendship Hill National Historic Site controls 

approximately 5 acres (2 ha) of wetlands (National Park 

Service 2005). 

Two small wetland areas are present where two park 

streams—Ice Pond Run (<3 acres [1.2 ha]) and Dublin 

Run (<1 acre [0.4 ha])—drain into the Monongahela 

River. Both streams, 2.9 km (1.8 miles) and 1.5 km (0.9 

miles) long respectively, originate within Friendship Hill 

National Historic Site. An abandoned coal drift mine in 

the southeast corner of the national historic site is the 

discharge location for acid- mine drainage generated by 

oxidation of pyrite exposed in the abandoned mine 

tailings. This drainage has severely polluted Ice Pond 

Run, which the National Park Service and the Bureau of 

Mines have intentionally manipulated into a series of 

wetlands filling formerly drained (~2 acre [0.8 ha]) pond 

areas. 

In July 2000, the National Park Service and partners 

diverted up to 230 liters (60 gallons) of water per minute 

from Ice Pond Run through an eight- phase treatment 

facility. The facility pumps water into four pulsed- bed 

limestone reactors, which buffer the low pH before 

returning it to the watershed. As water pH rises at Ice 

Pond Run, yellow iron compounds precipitate out of 

solution and color the stream sediments. 

Many NPS cooperators have made this ongoing largescale remediation possible: Bureau of Mines, U.S. 

Geological Survey (Leetown Science Center), Canon 

U.S.A., Inc., Conservation Fund’s Freshwater Institute, 

Pennsylvania Department of Environmental Protection, 

and California University of Pennsylvania (Reeder 2000). 

Monongahela River 

The Monongahela River runs 187 km (116 miles) in a 

meandering pattern north from the confluence of the 

West Fork and Tygart rivers near Fairmont, West 

Virginia, towards its confluence with the Allegheny River 

in Pittsburgh. It flows through the coal seams and 

mountains of West Virginia and into western 

Pennsylvania, draining a watershed area of 19,010 km2

(7,340 sq. miles) (Pennsylvania Environment Council 

2006). This river, a major tributary to the Ohio River, has 

a significant place in the history and natural resources of 

the Friendship Hill area. 

The Monongahela has functioned as the essential 

element in the area’s settlement and development. The 

first industry on the river was boat building. Builders 

took advantage of the abundant timber resources to 

produce boats that would transport farm goods and 

other materials downriver on a one- way trip to New 

Orleans, Louisiana. Here the boats were dismantled and 

used for lumber. The first steamboat launched on the 

river in 1811. In 1837, the Monongahela Navigation 

Company began building a series of seven locks and 

dams extending from Pittsburgh up the Monongahela to 
 FRHI Geologic Resource Evaluation Report 15

make the river more navigable. The federal government 

built an additional eight locks and dams upriver as far as 

Fairmont, West Virginia (U.S. Army Corps of Engineers 

2004). 

Today, the river is highly engineered to facilitate the 

movement of large watercraft. Following the Civil War, 

the U.S. Army Corps of Engineers continued 

constructing locks and dams on the river as well as 

renovating older structures. Modernization increased 

lock size and mechanized operations, thereby reducing 

the number of structures necessary for navigation. 

Today, nine locks and dams remain on the river 

providing 3 m (9 ft) of depth. These features allow boats 

to travel in a series of steps down the45 m (147 ft) 

elevation difference from Fairmont to Pittsburgh. Coal is 

the primary shipment, moving in both directions from 

mines to steel mills and power plants (U.S. Army Corps 

of Engineers 2004). 

Ancient Lake Monongahela and Paleodrainage 

The modern Monongahela River and most of western 

Pennsylvania’s creeks and rivers flow southwesterly into 

the Ohio River. Approximately 0.8- 1 Ma, the 

Monongahela was the dominant drainage in western 

Pennsylvania and flowed northwestward toward 

Canada. Based on studies of regional topography, river 

terraces, and erosional depth to bedrock in major river 

valleys (Harper 1997; Marine and Donahue 2000), 

investigators have found that the Monongahela River 

flowed coincident with its present course towards the 

Pittsburgh area then followed the channel of the Ohio 

River to the present site of Beaver, Pennsylvania. From 

there, it flowed north, up the modern Beaver River valley 

towards an ancestral Erie basin. 

This drainage pattern changed when glacial ice masses, 

flowing south from Canada blocked the northwestflowing streams, causing lakes to pool along the leading 

glacial edge. These lakes, collectively termed Ancient 

Lake Monongahela (fig. 6), eventually overflowed their 

drainage divides and reversed the ancient drainages of 

the Monongahela and Allegheny rivers to southerly 

courses (fig. 7). The rivers continue to cut through thick 

layers of silt, sand, gravel, and other sediments (Harper 

1997). Lacustrine deposits from this episode, called the 

Carmichael Formation, spread throughout the 

Monongahela and Allegheny drainages. These deposits 

consist of a clay, silt, and sand matrix with larger 

sandstone clasts derived from local bedrock, possibly the 

Lower Pennsylvanian Allegheny Group (Kirchner and 

Donahue 2001). 

The glacial advances during the Pleistocene Epoch 

caused repeated damming of rivers in western 

Pennsylvania. The outflow of the first flood cut new 

drainage patterns and lowered the outlets; hence, 

subsequent flood events occurred at progressively lower 

elevations, leaving lacustrine and river terrace deposits 

perched high in the valleys of the Monongahela, 

Allegheny, and Ohio rivers. The highest of these is 

located at approximately 335 m (1,100 ft) in elevation. At 

least five levels of terraces around Morgantown, West 

Virginia, record flood events of Ancient Lake 

Monongahela (Marine and Donahue 2000). John James 

Stevenson was the first to document these terraces in the 

Friendship Hill area: 

Coming from the south to Point Marion, where the 

Cheat and Monongahela rivers unite, one finds all 

the Stewartstown benches distinct except the third, 

which has been destroyed by erosion on the east 

side of the Monongahela.... Crossing the Ferry at 

Point Marion and taking the hill- road to New 

Geneva, at the mouth of George’s creek, one 

reaches the third bench at half a mile from the river. 

—John James Stevenson 

Presentation to the American Philosophical Society 

(1880) 
 NPS Geologic Resources Division 16 

Figure 6. Reconstruction of Ancient Lake Monongahela. The reconstruction in the figure is based on a 335 m (1,100 ft) maximum lake 

elevation during a Pleistocene glacial maximum. Source: Marine and Donahue (2000), figure 23. 
 FRHI Geologic Resource Evaluation Report 17

Figure 7. Maps showing drainage of Ancient Monongahela River. Prior to glacial activity, the river drained towards an ancestral Erie 

basin. Glacial maximum (right figure) shows the southernmost glacial extent and where the ice dammed the rivers, forming lakes that 

eventually flooded basins and directed river flow towards the south—the modern Ohio River drainage. Source: Harper (1997). Graphic 

design: Trista L. Thornberry-Ehrlich. Maps are not to scale. 
 NPS Geologic Resources Division 18 

Map Unit Properties 

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

Evaluation digital geologic map of Friendship Hill National Historic Site. The 

accompanying table is highly generalized and is provided for background purposes only. 

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

information in this table. More detailed map unit descriptions can be found in the help 

files that accompany the digital geologic map or by contacting the National Park Service 

Geologic Resources Division. 

The oldest rocks in the area are the grayish- red 

sandstones, siltstones, shales, and mudstones of the 

Devonian Catskill and Foreknobs formations. This 

combined unit locally is conglomeritic and forms a 

resistant ridge cap on Chestnut Ridge to the east of the 

national historic site (Berg et al. 1980; McElroy 1988). 

Late Devonian–Early Mississippian age units include the 

sandstone, siltstone, and shale of the Shenango and 

Oswayo formations. Above the Oswayo Formation are 

the Burgoon Sandstone and Mauch Chunk Formation 

(shale, siltstone, and limestone) (Berg et al. 1980; 

McElroy 1988). 

The cyclic sequences of sandstones, conglomerates, 

shales, claystones, limestones, and coals from former 

marshy peat swamps and wetlands (Freeport, Kittanning, 

and Brookeville- Clarion coals) of the Pennsylvanian 

Pottsville and Allegheny Groups are buried beneath the 

Glenshaw and Casselman formations (Conemaugh 

Group) and the Monongahela Group. These three units 

dominate the rock exposures within and immediately 

surrounding Friendship Hill (Berg et al. 1980; Whitfield 

et al. 2001; Milici 2005). 

The Glenshaw Formation consists of sequences of shale, 

sandstone, red beds, and thin limestone and coal 

interbeds. The Ames Limestone separates this unit from 

the overlying Casselman Formation of shale, siltstone, 

sandstone, red beds, and scant coal and limestone layers. 

The Monongahela is eroding into this unit south of the 

national historic site. The Monongahela Group contains 

cyclic sequences of limestone, shale, sandstone, and coal 

including the commercially valuable Pittsburgh coal at its 

base. 

The sandstones, shales, limestones, and coals of the 

Waynesburg Formation record the transition between 

the Pennsylvanian and Permian periods. The base of this 

unit is at the bottom of the commercial Waynesburg coal, 

one of several economically viable seams from this unit. 

Above the Waynesburg Formation are the Permian 

Washington and Greene formations. These units 

dominate the eastern Waynesburg Hills section. They are 

composed of sequences of sandstone, shale, red beds, 

and some impure limestones and coals separated by the 

upper Washington limestone. The Washington 

Formation contains the Washington coal deposit (Berg et 

al. 1980). 

Most Mesozoic and all but the most recent Cenozoic 

rock units are missing from the landscape surrounding 

Friendship Hill National Historic Site. Jurassic micaperidotite igneous rocks of the Gates- Adah Dike 

represent a local intrusive event (McElroy 1988). 

Pleistocene lacustrine deposits from Ancient Lake 

Monongahela are present as high- level terraces on bluffs 

above the river and tributaries. The Carmichaels 

Formation contains silts, clays, and sands as 

intergranular matrix to larger quartzarenite (quartz 

sandstone) clasts (Kirchner and Donahue 2001). 

Quaternary alluvium lines local river and stream valleys. 

Alluvial deposits are also present on floodplains; in some 

places, they form low terraces above the river valleys. 

Terraces consist of unconsolidated clay, silt, sand, gravel, 

and occasional boulder deposits derived from local 

bedrock units (McElroy 1998). 

The following pages present a tabular view of the 

stratigraphic column and an itemized list of features for 

each map unit. This table highlights properties specific to 

each unit in the stratigraphic column, including map 

symbol, name, description, resistance to erosion, 

suitability for development, hazards, potential 

paleontologic resources, cultural and mineral resources, 

potential karst issues, recreational use potential, and 

global significance. 
 FRHI Geologic Resource Evaluation Report 21

Geologic History 

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

geologic map of Friendship Hill National Historic Site, the environment in which those 

units were deposited, and the timing of geologic events that created the present 

landscape. 

Friendship Hill sits near the eastern edge of the 

Appalachian Plateaus physiographic province near the 

boundaries of the Waynesburg Hills, Pittsburgh Low 

Plateau, and Allegheny Mountains sections of the 

Appalachian Plateaus physiographic province (fig. 5). To 

the east, marked by the Allegheny Mountains, is the 

Valley and Ridge province. As such, Friendship Hill 

National Historic Site contains features intimately tied to 

the long geologic history of the Appalachian Mountains 

and the evolution of the eastern coast of North America. 

The recorded history of the Appalachian Mountains 

begins in the Proterozoic (fig. 8). During the Grenville 

orogeny in the mid- Proterozoic, a supercontinent 

(Pangaea) formed, composed of most of the continental 

crust in existence at that time, including North America 

and Africa. The metamorphic granites and gneisses in the 

core of the modern Blue Ridge Mountains south and east 

of Friendship Hill manifest the sedimentation, 

deformation, plutonism, and volcanism at the time 

(Harris et al. 1997). Deposited over a period of 100 

million years, these rocks are more than a billion years 

old, making them among the oldest rocks known in this 

region. Following uplift, erosion beveled the land surface 

for hundreds of millions of years, leaving a basement 

upon which all other rocks of the Appalachians were 

deposited (Southworth et al. 2001). 

Tensional forces, including rifting, characterized the area 

during the late Proterozoic, roughly 800–600 million 

years ago. Crustal extension created fissures that 

extruded massive volumes of basaltic magma (fig 9A). 

Volcanic activity lasted for tens of millions of years 

alternating between flood basalt flows and ash falls. The 

volcanic rocks covered the basement rocks (i.e., granite 

and gneiss) in the south- central Pennsylvania area. 

The rifting broke up the supercontinent, and formed a 

sea basin, which became the Iapetus Ocean, the protoAtlantic Ocean. This basin subsided and collected 

sediments that later formed the Appalachian Mountains 

(fig. 9B). These sediments were deposited in alluvial fans, 

large submarine landslides, and turbidity flows 

(Southworth et al. 2001). Later deposits of sands, silts, 

and muds covered these previous sediments in 

nearshore, deltaic, barrier- island, and tidal flat areas 

along the eastern margin of the continent (Schwab 1970; 

Kauffman and Frey 1979; Simpson 1991). 

A grand marine platform, thickening to the east, was the 

depositional setting for huge masses of carbonate, 

sandstone, and shale that persisted during from the 

Cambrian through the Ordovician periods (545–480 Ma) 

(Means 1995). Ordovician units exposed east of 

Friendship Hill record the transition from carbonate 

platform to more nearshore terrestrial deposition 

associated with nascent uplift during the Taconic 

Orogeny. 

Taconic Orogeny 

From Early Cambrian through Early Ordovician time, 

orogenic activity along the eastern margin of the 

continent began again. During the Taconic Orogeny 

(~440–420 million years ago in the central Appalachians), 

an island arc converged with the main continent. 

Oceanic crust and the volcanic arc from the Iapetus basin 

were thrust onto the eastern edge of North America. The 

Taconic Orogeny involved the closing of the ocean basin, 

subduction of oceanic crust, the creation of volcanic 

arcs, and the uplift of continental crust (Means 1995). 

Initial metamorphism of the deeply buried igneous and 

nearshore sediments into metabasalts, quartzites, and 

phyllites occurred during this orogenic event. 

The crust bowed downwards west of the rising 

mountains in response to the overriding plate thrusting. 

The resulting deep foreland basin filled with mud and 

sand eroded from the highlands to the east (fig. 9C) 

(Harris et al. 1997). The center of this so- called 

Appalachian Basin was in what is now West Virginia. 

During the Late Ordovician, the oceanic sediments of the 

shrinking Iapetus Ocean were thrust westward onto 

other deepwater sediments of the western Piedmont 

province. Sandstones, shales, siltstones, quartzites, 

limestones, and other Silurian- age rocks became part of 

the shallow marine and deltaic environment of the 

Appalachian Basin. These rocks, now metamorphosed, 

currently underlie the Valley and Ridge physiographic 

province east of Friendship Hill (Fisher 1976). 

Appalachian Basin 

Most of the rock units of the Appalachian Plateaus 

physiographic province were deposited in the longstanding Appalachian Basin. As mentioned previously, 

this foreland basin formed in response to tectonic 

downwarping (thrust loading) during the Taconic 

Orogeny; however, it continued in response to later 

sediment loading (Milici 2005). Downwarping was 

balanced by eustatic crustal adjustments. 

The depositional setting of the basin was predominantly 

shallow marine with some fluvial and deltaic 
 NPS Geologic Resources Division 22 

components. Basin formation continued intermittently 

for approximately 200 million years during the 

Ordovician, Silurian, Devonian, Mississippian, 

Pennsylvanian, and Permian periods, resulting in very 

thick deposits of sandstone, siltstone, mudstone, and 

shale deposited above basal Cambrian units. The major 

source of these sediments was the highlands to the east, 

which rose during the Taconic and later orogenies (e.g., 

Acadian Orogeny [Devonian] and Alleghenian Orogeny 

[Permian]). 

Basal sandstone units of Cambrian, Silurian, 

Mississippian, and Pennsylvanian strata in the basin are 

representative of sediment influx induced by orogenic 

uplift. By contrast, laterally extensive shale and limestone 

deposits such as the Ordovician Martinsburg Formation 

and Devonian black shale units record times of relative 

tectonic quiescence and resulted from sediment trapping 

and chemical precipitation (Fedorko et al. 2004). 

The units deposited in the Appalachian Basin record 

geographic (e.g., the movement of continents through 

paleolatitudes) and climatic conditions during 

sedimentation (table 1). Paleolatitude and climate played 

major roles in the deposition of coal resources in the 

Appalachian Basin. The central Appalachian Basin region 

drifted northward from about latitude 40° south in the 

Proterozoic and Early Cambrian to about latitude 30° 

south during the Early Ordovician where it remained 

well into the Mississippian Period. The continent 

continued to move northward from about latitude 30° 

south in the Early Mississippian to about latitude 3° 

north by the beginning of the Permian (Fedorko et al. 

2004). 

During the Early Mississippian and Early Triassic 

periods, the paleoclimate of the area was arid. However, 

during the intervening Pennsylvanian and Permian 

periods, this basin was centered in tropical, equatorial 

latitudes. This tropical climate produced vast amounts of 

organic material in peat swamps and other wetlands 

(Cecil and Englund 1989). The rising mountains to the 

east also produced significant amounts of sand, silt, and 

clay that are interspersed with the organic layers. These 

units, notably the Conemaugh, Allegheny, and 

Monongahela groups, are associated with numerous coal 

systems that vary in rank (lignite to anthracite), 

thickness, geometry, aerial extent, petrology, and 

geochemistry (Milici 2005). 

Interbedded shales, sandstones, limestones, and thin 

coals dominated the local Dunkard Basin, a sub- basin of 

the Appalachian Basin, in southwestern Pennsylvania. 

Within this basin, the Monongahela Group formed from 

the cycling of freshwater bay, river channel- deltaic, 

alluvial fan, and marine storm surge environments 

(Reynolds and Capo 2000; Edwards and Nadon 2001; 

Cassle et al. 2003). 

The Allegheny Group and Monongahela Group coals 

were formed during wetter climatic conditions than the 

intervening Conemaugh Group, which contains thinner, 

more discontinuous coal lenses, reflecting a slightly drier 

climate (Milici 2005). 

Table 1. Deposition in the Appalachian Basin 

Period Climate Deposits 

Triassic Early semiarid 

to arid 

sandstone, 

conglomerate 

Late 

cyclic 

moist 

subhumid 

to 

semiarid 

sandstone, 

shale, red beds, 

thin limestone, 

coal 

Permian 

Early 

cyclic 

moist 

subhumid 

to 

semiarid 

coal, nonmarine 

limestone, 

sandstone 

Late dry 

subhumid 

calcareous red 

beds, 

paleosols, 

scant coal 

Middle moist 

subhumid 

siliciclastics, 

non- marine 

limestone, coal 

Pennsylvanian 

Early humid to 

perhumid 

sandstone, 

limestone, 

paleosols, coal 

Late semiarid 

to humid 

limestone, 

eolianites, red 

beds Mississippian 

Early subhumid 

to arid 

sandstones, 

red beds, 

evaporites 

Late 

semiarid 

to dry 

subhumid 

black shale, 

sandstones 

Devonian 

Early arid 

subtidal 

carbonates, 

sandstones 

Upper arid 

peritidal 

carbonates, 

evaporites Silurian 

Early arid sandstones 

Late 

semiarid 

to dry 

subhumid 

siliciclastics 

red beds 

Ordovician 

Early arid 

limestone, 

dolomite, 

evaporites 

Middle arid 

limestone, 

dolomite, 

evaporites Cambrian 

Early semiarid siliclastics 

Source: Fedorko et al. (2004). 

Acadian Orogeny 

The Acadian Orogeny (~360 million years ago) continued 

the mountain building of the Taconic Orogeny as the 

African continent approached North America (Harris et 

al. 1997). The Acadian event involved landmass collision, 
 FRHI Geologic Resource Evaluation Report 23

mountain building, and regional metamorphism similar 

to the preceding Taconic orogeny (Means 1995). 

However, this event affected areas farther north. The 

Acadian event caused further uplift of Taconic highlands 

in central Pennsylvania. Erosion of these highlands 

provided more sediments leading to the basin- wide 

(Appalachian Basin) deposition of the Devonian Catskill 

Formation, exposed on Chestnut Hill in the Friendship 

Hill area. 

The tectonic quiescence between the Acadian and 

Alleghenian orogenic events led to the deposition of the 

vast marsh and wetland deposits of the Mississippian and 

Pennsylvanian periods. Buried and compressed, these 

deposits became the vast coal- bearing units of the 

Mississippian Burgoon Sandstone and the Pennsylvanian 

Casselman and Glenshaw formations and Allegheny and 

Pottsville groups (Berg et al. 1980; Whitfield et al. 2001). 

Alleghenian Orogeny 

Following the Acadian orogenic event, the protoAtlantic Iapetus Ocean completely closed as African 

collided with North America. This collision formed the 

supercontinent Pangaea and the Appalachian mountain 

belt. The Alleghenian Orogeny (~325–265 Ma) is the last 

major orogeny of the Appalachian evolution (fig. 9D) 

(Means 1995). The rocks were deformed during as many 

as seven phases of folding and faulting to produce the 

Sugarloaf Mountains and Frederick Valley in the western 

Piedmont province, the Blue Ridge–South Mountain 

anticline structure, and the numerous folds of the Valley 

and Ridge province west of Friendship Hill (Nickelsen 

1983; Southworth et al. 2001). The strata of the 

Appalachian Basin (now the Appalachian Plateaus 

province) remained relatively undeformed; however, 

small- scale thrust faults and parallel low- amplitude 

regional folds exist throughout the area (Boen 1972). 

Rocks of the Valley and Ridge, Blue Ridge, and Piedmont 

provinces were transported during this orogeny as a 

massive block (Blue Ridge–Piedmont thrust sheet) 

westward onto younger rocks of the Valley and Ridge 

along the North Mountain fault. The amount of 

compression was extreme; estimated shortening was 

20%–50%, 125- 200 km (75–125 miles) (Harris et al. 1997). 

Estimates of the elevation of the Alleghenian Mountains 

are around 6,000 m (20,000 ft), which is analogous to the 

present- day Himalayas in Asia. Erosion has beveled 

these mountains to elevations less than 730 m (2,400 ft) 

above sea level east of Friendship Hill (Means 1995). 

Triassic Extension to the Present 

During the late Triassic following the Alleghenian 

orogeny (~230–200 million years ago), a period of rifting 

began as the joined continents began to break apart. 

Pangaea fragmented into roughly the continents that 

persist today. This episode of rifting initiated the 

formation of the Atlantic Ocean and caused many blockfault basins to develop with accompanying volcanism 

(fig. 9E) (Harris et al. 1997; Southworth et al. 2001). 

The dominant geologic process in the Friendship Hill 

region during the Mesozoic Era was erosion. The 

Allegheny Mountains shed thick deposits of 

unconsolidated gravel, sand, and silt. Some of this 

sediment remained at the base of the mountains as 

alluvial fans; it also spread eastward as part of the 

Atlantic Coastal Plain province and westward to cover 

the Appalachian Basin sediments (Duffy and Whittecar 

1991; Whittecar and Duffy, 2000; Southworth et al., 

2001)., The amount of material was immense, as inferred 

from the now- exposed metamorphic rocks in the Blue 

Ridge province. Many of the rocks exposed at the 

surface must have been at least 12 miles (20 km) below 

the surface prior to regional uplift and erosion. These 

Mesozoic rocks are now “missing” from the Friendship 

Hill landscape. Erosion continues to create the present 

landscape; the Monongahela, Allegheny, and Juniata 

rivers and their tributaries take sediment from the 

lowering mountains and deposit it as alluvial terraces 

along their banks (fig. 9F). 

The North American plate has continued to drift 

westward since the breakup of Pangaea and the uplift of 

the Appalachian Mountains. The isostatic adjustments 

that uplifted the continent after the Alleghenian Orogeny 

continued at a subdued rate throughout the Cenozoic 

Period (Harris et al. 1997). 

Pleistocene glaciers never reached as far south as 

Friendship Hill. The southern terminus reached 365 to 

610 m (1,200 to 2,000 ft) in elevation in northwestern and 

northeastern Pennsylvania. Here glacial processes 

eroded the upland surfaces into rounded ridges, and 

glacial outwash (i.e., sand and gravel) filled the valleys 

(Davies 2005). However, the colder climates of the ice 

ages, as well as the movement of glacial ice, played a 

significant role in the formation of the modern landscape 

at Friendship Hill National Historic Site. 

Prior to glacial activity, the Monongahela River flowed 

north towards an ancestral basin became Lake Erie. It 

was the dominant drainage in western Pennsylvania 

(Harper 1997; Marine and Donahue 2000). However, 

advancing glacial ice dammed the north flowing rivers in 

northern Ohio, Pennsylvania, and New York, forming 

large ponded areas and flooding river valleys. These lakes 

(including Ancient Lake Monongahela) eventually 

overflowed their drainage divides, transforming flow of 

the ancient Monongahela and Allegheny rivers to their 

modern southerly courses (Harper 1997). 

Glacial damming occurred at least four times during the 

Pleistocene. The first flood event left remnant lacustrine 

terrace deposits high above the pre- glacial river valleys. 

Subsequent lake levels were lower, leaving a traceable 

pattern of different flood events along the Monongahela 

River (Marine and Donahue 2000). 

Since the Pleistocene, the rivers and tributaries in the 

Friendship Hill area continue to cut through thick 

deposits of glacial and alluvial sediments. Today, human 

activities augment natural erosion processes. 
 NPS Geologic Resources Division 24 

Figure 8. Geologic Time Scale. Red lines indicate major unconformities between eras. Included are major events in life history and tectonic 

events occurring on the North American continent. Absolute ages shown are in millions of years (Ma). Source: U.S. Geological Survey. 

Graphic design: Trista L. Thornberry-Erlich (Colorado State University). 
 FRHI Geologic Resource Evaluation Report 25

Figure 9. Evolution of the Landscape in the Friendship Hill National Historic Site Area. The figure shows landscape-scale changes from the 

Proterozoic (A) to the present (F). Sources: Means (1995); Fedorko et al. (2004). Graphic design: Trista L. Thornberry-Ehrlich. 
 NPS Geologic Resources Division 26 

Glossary 

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

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

visit http://wrgis.wr.usgs.gov/docs/parks/misc/glossarya.html. 

alluvial fan. A fan- shaped deposit of sediment that 

accumulates where a high gradient stream flows out of 

a mountain front into an area of lesser gradient such as 

a valley. 

alluvium. Stream- deposited sediment that is generally 

rounded, sorted, and stratified. 

barrier island. A long, low, narrow island formed by a 

ridge of sand that parallels the coast. 

basement. The undifferentiated rocks, commonly 

igneous and metamorphic, that underlie the rocks of 

interest. 

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. 

bedding. Depositional layering or stratification of 

sediments. 

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

completely or in part. 

calcareous. A rock or sediment containing calcium 

carbonate. 

chemical weathering. The dissolution or chemical 

breakdown of minerals at Earth’s surface via reaction 

with water, air, or dissolved substances. 

clay. Clay minerals or sedimentary fragments the size of 

clay minerals (2 or 4 micrometers). 

conglomerate. A coarse- grained sedimentary rock with 

clasts larger than 2 mm in a fine- grained matrix. 

continental crust. The type of crustal rocks underlying 

the continents and continental shelves; having a 

thickness of 25–60 km and a density of approximately 

2.7 grams per cubic centimeter. 

cross-bedding. Uniform to highly varied sets of inclined 

sedimentary beds deposited by wind or water that 

indicate distinctive flow conditions. 

cross section. A graphical interpretation of geology, 

structure, or stratigraphy in the third (vertical) 

dimension based on mapped and measured geologic 

extents and attitudes depicted in an oriented vertical 

plane. 

crystalline. Describes the structure of a regular, orderly, 

repeating geometric arrangement of atoms 

debris flow. A rapid and often sudden flow or slide of 

earth materials involving a wide range of types and 

sizes. 

deformation. A general term for the process of faulting, 

folding, shearing, extension, or compression of rocks 

as a result of various Earth forces. 

delta. A sediment wedge deposited at the mouth of a 

river where it flows into a lake or sea. 

dike. A tabular, discordant igneous intrusion. 

eolian. Formed, eroded, or deposited by or related to the 

action of wind. 

evaporite. Chemically precipitated mineral(s) formed by 

the evaporation of solute- rich water under restricted 

conditions. 

fault. A subplanar break in rock along which relative 

movement occurs between the two sides. 

formation. Fundamental rock- stratigraphic unit that is 

mappable and 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, fault) 

igneous. Refers to a rock or mineral that originated from 

molten material; one of the three main classes or rocks: 

igneous, metamorphic, and sedimentary. 

island (or volcanic) arc. A line or arc of volcanic islands 

formed over and parallel to a subduction zone. 

lacustrine. Pertaining to, produced by, or inhabiting a 

lake or lakes. 

landslide. Any process or landform resulting from rapid 

mass movement under gravitational influence. 

lithology. The description of a rock or rock unit, 

especially the texture, composition, and structure of 

sedimentary rocks. 

magma. Molten rock generated within Earth that is the 

source of igneous rocks. 

matrix. The fine- grained interstitial material between 

coarse grains in porphyritic igneous rocks and poorly 

sorted clastic sediments or rocks. 

meanders. Sinuous lateral curves or bends in a stream 

channel. 

member. A lithostratigraphic unit with definable contacts 

that subdivides a formation. 

metamorphism. Literally, “change in form;” occurs in 

rocks with mineral alteration, genesis, or 

recrystallization from increased heat and pressure. 

mineral. A naturally occurring, inorganic, crystalline 

solid with a definite chemical composition or 

compositional range. 

oceanic crust. Earth’s crust formed at spreading ridges 

that underlies the ocean basins. Oceanic crust is 3–4 

miles (5–6 km) thick and generally of basaltic 

composition. 

orogeny. A mountain- building event, particularly a wellrecognized event in the geologic past (e.g., the 

Laramide orogeny). 

outwash. Glacial sediment transported and deposited by 

meltwater streams. 

paleontology. The study of the life and chronology of 

Earth’s geologic past based on the phylogeny of fossil 

organisms. 

Pangaea. A supercontinent that existed during the 

Permian and Triassic periods that included most of the 

continental crust. 
 FRHI Geologic Resource Evaluation Report 27

pebble. Generally, small, rounded, rock particles from 4 

to 64 mm in diameter. 

plateau. A broad, flat- topped topographic high of great 

extent and elevation above the surrounding plains, 

canyons, or valleys (both land and marine landforms). 

plutonism. A general term used for the phenomena 

associated with the formation of plutons (i.e., deepseated igneous magma intruded into preexisting rock). 

recharge. Infiltration processes that replenish 

groundwater. 

red beds. Sedimentary strata composed largely of 

sandstone, siltstone, and shale that are predominantly 

red due to the presence of ferric oxide (hematite) that 

coats individual grains. 

sandstone. Clastic sedimentary rock of predominantly 

sand- sized grains. 

scarp. A steep cliff or topographic step resulting from 

vertical displacement on a fault or by mass movement. 

sediment. An eroded and deposited, unconsolidated 

accumulation of lithic and mineral fragments. 

sedimentary rock. A consolidated and lithified rock 

consisting of detrital or chemically precipitated 

sediment(s). 

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 (1/256–1/16 

mm). 

siltstone. A variable- lithified sedimentary rock with siltsized grains. 

slope. The inclined surface of any geomorphic feature or 

rational measurement thereof (syn: gradient). 

slump. A generally large, coherent, mass- movement 

deposit with a concave- up failure surface and 

subsequent backward rotation relative to the slope. 

spring. A site where water flows out of the ground 

because the water table intersects the surface at this 

point. 

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

rock. 

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 

and confined within a channel. 

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. 

tectonic. Relating to large- scale movement and 

deformation of Earth’s crust. 

terraces (stream). Step- like benches surrounding the 

present floodplain of a stream due to dissection of 

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

floor(s). 

terrestrial. Relating to Earth or Earth’s dry land. 

topography. The general morphology of Earth’s surface 

including relief and location of natural and 

anthropogenic features. 

uplift. A structurally high area in the crust produced by 

movement that raises the rocks. 

volcanic. Related to volcanoes; describes igneous rock 

crystallized at or near Earth’s surface (e.g., lava). 

weathering. The set of physical, chemical, and biological 

processes by which rock is broken down in place. 
 NPS Geologic Resources Division 28 

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 FRHI Geologic Resource Evaluation Report 31

Appendix A: Geologic Map Graphic 

The following page is a preview or snapshot of the geologic map for Friendship Hill 

National Historic Site. For a poster- size PDF of this map or for digital geologic map 

data, please see the included CD or visit the Geologic Resource Evaluation publications 

Web page (http://www2.nature.nps.gov/geology/inventory/gre_publications). 

 FRHI Geologic Resource Evaluation Report 33

Appendix B: Scoping Summary 

The following excerpts are from the GRE scoping summary for Friendship Hill National 

Historic Site. The scoping meeting occurred on June 22, 2004; therefore, the contact 

information and Web addresses referred to herein may be outdated. Please contact the 

Geologic Resources Division for current information. 

Executive Summary 

The Geologic Resources Evaluation Program hosted a 

geologic resources evaluation workshop for Friendship 

Hill National Historic Site on June 22, 2004, to view and 

discuss the park’s geologic resources, address the status 

of geologic mapping for compiling both paper and digital 

maps, and assess resource management issues and needs. 

Cooperators from the NPS Geologic Resources Division 

(GRD), Allegheny Portage Railroad and John Fitzgerald 

Kennedy national historic sites, and local geologic 

experts participated in the workshop. 

Overview of Geologic Resource Evaluation 

The NPS GRE has the following goals: 

• to assemble a bibliography of associated geologic 

resources for NPS units with significant natural 

resources (“GRBIB”), 

• to compile and evaluate a list of existing geologic maps 

for each unit, 

• to conduct a scoping session for each park, 

• to develop digital geologic map products, and 

• to complete a geologic report that synthesizes much of 

the existing geologic knowledge about each park. 

The emphasis of the evaluation program is not to 

routinely initiate new geologic mapping projects but to 

aggregate existing “baseline” information and identify 

where serious geologic data needs exist in the National 

Park System. In cases where map coverage is nearly 

complete or maps simply do not exist, then funding may 

be available for geologic mapping. 

After introductions by the participants, GRD staff 

presented overviews of the Geologic Resources Division, 

the NPS I&M Program, the status of the natural resource 

inventories, and the GRE in particular. 

They also presented a demonstration of some of the 

main features of the GRE digital geologic database. This 

has become the prototype for the NPS digital geologic 

map model as it reproduces all aspects of a paper map, 

including cross sections, legend, and other map- related 

information, with the added benefit of being geospatially 

referenced. 

Map products are displayed in ESRI ArcView shape files 

and feature a built- in Microsoft Windows help file 

system to identify the map units. Products can also 

display scanned JPG or GIF images of the geologic cross 

sections supplied with the paper “analog” map. Geologic 

cross section lines (e.g., A- A') are subsequently digitized 

as a line coverage and are hyperlinked to the scanned 

images. 

The team further demonstrated the developing NPS 

Theme Manager for adding GIS coverages into projects 

“on- the- fly.” With this functional browser, users can 

add numerous NPS themes to an ArcView project with 

relative ease. Such themes might include geology, 

paleontology, hypsography (topographic contours), 

vegetation, and soils. 

GRBIB 

At the scoping session, individual Microsoft Word 

documents of geologic bibliographies for Friendship Hill 

National Historic Site and surrounding parks were 

distributed. 

The sources for this compiled information are 

• AGI (American Geological Institute) GeoRef 

• USGS GeoIndex 

• ProCite information taken from specific park libraries 

GRE staff validated these bibliographic compilations to 

eliminate duplicate citations and typographical errors, as 

well as check for applicability to the specific park. After 

validation, they become part of a Microsoft Access 

database parsed into columns based on park, author, 

year of publication, title, publisher, publication number, 

and a miscellaneous column for notes. 

From the Access database, they are exported as 

Microsoft Word documents for easier readability and 

eventually turned into PDF documents. They are then 

posted to the GRE Web site at 

http://www2.nature.nps.gov/grd/geology/gri/products/g

eobib/ for general viewing. 

Geologic Mapping 

Existing Geologic Maps and Publications 

After the bibliographies were assembled, a separate 

search was made for any existing surficial and bedrock 

geologic maps for Friendship Hill National Historic Site. 

The bounding coordinates for each map were noted and 

entered into a GIS to assemble an index geologic map. 

Separate coverages were developed based on various 

scales (e.g., 1:24,000, 1:100,000) available for the specific 

parks. Numerous geologic maps at varying scales and 

vintages cover the area. Index maps were distributed to 

each workshop participant during the scoping session. 
 NPS Geologic Resources Division 34 

For both Friendship Hill National Historic Site and 

nearby Fort Necessity National Battlefield the GRE will 

use PA GA W- 60 (Groundwater Resources of Fayette 

County) at 1:50,000 scale. GRE staff will likely need to 

digitize this data. 

However, for Friendship Hill National Historic Site, the 

GRE team needs to inquire with park staff whether more 

detail to the west in Greene County (i.e., Masontown 

quadrangle), which is available from W- 63 

(Groundwater Resources of Greene County), would be 

useful for resource management. 

These W reports should be more detailed than the atlas 

maps (1981), Map 61. 

The Pennsylvania Geological Survey has 1:250,000- scale 

digital geology of the entire state to compare/contrast to 

larger scale (1:50,000) maps. 

M- 91 has coal information at 1:62,500 scale based upon 

1:24,000 scale (Coal Resources of Fayette County, 

Pennsylvania, Part 1). 

Other Topics of Discussion 

A discussion of geologic resource management issues 

followed the mapping discussion and touched upon the 

following features and processes (Note: No FRHI 

representatives were present at this meeting, thus the 

discussion was based on the consensus of the group 

present): 

• Eolian: NA 

• Fluvial (surface water) processes: FRHI has some 

deposition of sediment at bottom of hill from river 

• Groundwater: NA; but can reference the Pennsylvania 

Geological Survey water reports 

• Hazards: Rockfall potential likely at Jumonville based 

upon stratigraphy of Mauch Chunk and Pottsville 

formations 

• Paleontology: See Koch and Santucci (2004) report 

about Eastern Rivers and Mountains Network 

• Mineral extraction: Jumonvill area has had limestone 

quarrying for mostly aggregate; not likely building 

stone quality 

• Caves/karst: Potential because of nearby limestones 

being mined. Laurel Caverns are nearby and are largest 

caverns in Pennsylvania; no known caves in 

Friendship Hill National Historic Site though. 

• Glacial: Glacio- lacustrine Lake Monangahela backed 

up a minimum of three times during the Pleistocene 

Epoch. 

• Lacustrine: Carmichaels formation is lacustrine 

• Coastal/Marine: NA 

• Geologic interpretation: Chestnut Ridge serves as 

good place to interpret the local geologic story. 

• Monangahela River meandering is part of story too 

• Also see http://www.watershedatlas.org SITE MAP 

• Unique geologic features: Chestnut Ridge, Great 

Meadows 

• Geothermal: NA 

• Disturbed lands: Subsidence at Friendship Hill 

National Historic Site from coal mining; has bad acidmine drainage problem from sulfur in coal (e.g., Ice 

Pond Run) 

Monitoring Issues 

Monitor for landslides and rockfalls beneath Friendship 

Hill. 

Meeting Attendees and Contact Information 

Tim Connors, NPS, Geologic Resources Division, 303-

969- 2093, tim_connors@nps.gov 

John Harper, Pennsylvania Geological Survey, 412- 442-

4230, jharper@state.pa.us 

Bruce Heise, NPS, Geologic Resources Division, 303-

969- 2017, bruce_heise@nps.gov 

John Inners, Pennsylvania Geological Survey, 717- 702-

2034, jinners@state.pa.us 

Matt Marshall, NPS, Eastern Rivers and Mountains 

Network, 814- 863- 0134, matt_marshall@nps.gov 

Kathy Penrod, NPS, Allegheny Portage Railroad and 

John Fitzgerald Kennedy national historic sites, 814- 886-

6128, kathy_penrod@nps.gov 

Nate Piekielek, NPS, Eastern Rivers and Mountains 

Network, 814- 863- 2320, nathan_piekielek@nps.gov 

Santucci Vince, NPS, George Washington Memorial 

Parkway, 703- 289- 2531, vincent_santucci@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. 

Friendship Hill National Historic Site 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/022 

NPS D-46, February 2008 

National Park Service 

Director • Mary A. Bomar 

Natural Resource Stewardship and Science 

Acting Associate Director • Mary Foley, Chief Scientist of the Northeast Region 

Natural Resource Program Center 

The Natural Resource Program Center (NRPC) is the core of the NPS Natural Resource Stewardship and 

Science Directorate. The Center Director is located in Fort Collins, with staff located principally in 

Lakewood and Fort Collins, Colorado and in Washington, D.C. The NRPC has five divisions: Air 

Resources Division, Biological Resource Management Division, Environmental Quality Division, Geologic 

Resources Division, and Water Resources Division. NRPC also includes three offices: The Office of 

Education and Outreach, the Office of Inventory, Monitoring and Evaluation, and the Office of Natural 

Resource Information Systems. In addition, Natural Resource Web Management and Partnership 

Coordination are cross- cutting disciplines under the Center Director. The multidisciplinary staff of NRPC 

is dedicated to resolving park resource management challenges originating in and outside units of the 

national park system. 

Geologic Resources Division 

Acting Chief • John Vimont 

Planning Evaluation and Permits Branch Chief • Carol McCoy 

Credits 

Author • Trista Thornberry- Ehrlich

Review • Lindsay McClelland 

Editing • Katie KellerLynn and Sid Covington 

Digital Map Production • Heather Stanton and Giorgia de Wolfe 

Map Layout Design • Georgia Hybels
Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, CO 80225 

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

(303) 969-2090 

EXPERIENCE YOUR AMERICATM 

National Park Service 

U.S. Department of the Interior