Wolf Trap National Park for the Performing Arts 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/041 

National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 
THIS PAGE: THIS PAGE: 

Concert at the Filene Center Concert at the Filene Center

ON THE COVER: ON THE COVER: 

Aerial view of the Filene Center Aerial view of the Filene Center—Photo by, Robert Lewellyn
Wolf Trap National Park for the Performing Arts 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/041 

Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, Colorado 80225 

June 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 

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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, T. 2008. Wolf Trap National Park for the Performing Arts Geologic 

Resource Evaluation Report. Natural Resource Report NPS/NRPC/GRD/NRR—2008/041 . 

National Park Service, Denver, Colorado. 

NPS D- 43, June 2008 
 WOTR Geologic Resource Evaluation Report iii

Table of Contents 

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

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

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

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

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

Geology and History at Wolf Trap National Park for the Performing Arts ...................................................................3

Geologic Issues........................................................................................................... 11

Sediment Load, Channel Storage and Morphology..................................................................................................11

Recreational Demands .............................................................................................................................................11

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

Soil Erosion ..............................................................................................................................................................12

General Geology ......................................................................................................................................................12

Map Unit Properties .................................................................................................... 14

Map Unit Properties Table........................................................................................................................................15

Geologic History.......................................................................................................... 17

Glossary....................................................................................................................... 22

References................................................................................................................... 24

Appendix A: Geologic Map Graphic .......................................................................... 26

Appendix B: Scoping Summary................................................................................. 29

Appendix C: NPS Monitoring Workshop Report ...................................................... 31

Appendix D: Geoindicator Notes ............................................................................... 40

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

List of Figures 

Figure 1: Map of NPS National Capital Region. .............................................................................................................7

Figure 2: Physiographic Map of Virginia.........................................................................................................................7

Figure 3: Geologic map of the Piedmont and Blue Ridge in central Virginia ..................................................................8

Figure 4: Photograph of the original historic farmhouse at Wolf Trap ............................................................................9

Figure 5: Photograph of historic Barn Road .................................................................................................................10

Figure 6: Geologic time scale diagram.........................................................................................................................20

Figure 7: Geologic time scale diagram specific to Virginia ...........................................................................................21
 WOTR Geologic Resource Evaluation Report 1

Executive Summary 

This report accompanies the digital geologic map for Wolf Trap National Park for the 

Performing Arts in Virginia, which the Geologic Resources Division produced in 

collaboration with its partners. It contains information relevant to resource management 

and scientific research. 

Wolf Trap National Park for the Performing Arts 

provides a venue for many significant cultural 

demonstrations and performances. The park also 

preserves vital natural habitat in the urban Washington, 

D.C., metropolitan area within the Potomac River 

watershed. It reflects a unique geologic history that spans 

from the ancient Precambrian through the formation of 

the Appalachian Mountains to the more recent Ice Age 

events and finally the modern day. 

Geologic processes give rise to rock formations, hills and 

valleys, waterfalls and wetlands. These processes play a 

prominent role in the history of the entire Potomac River 

valley and Washington, D.C., sculpting a landscape that 

influences patterns of human use. The geology- history 

connection inspires wonder in visitors, and the 

interpretation and preservation of geologic resources 

enhances the visitor’s experience. 

The experience of the park begins with the geology, with 

the processes that established the groundwork from 

which today’s environments, history, and scenery arise. 

Knowledge of the geologic resources can positively 

influence resource management decisions addressing a 

range of concerns, such as erosion, air and water quality, 

flooding, wildlife populations and invasive species, 

future scientific research projects, interpretive needs, 

future venue development, and urbanization. 

Humans have significantly modified the landscape 

surrounding Wolf Trap and the geologic processes of the 

area. Urban developments threaten this dynamic 

ecosystem, which is capable of noticeable change within 

a human life span. The following features, issues, and 

processes have geological importance and a high level of 

management significance within the park: 

• Sediment Load, Channel Storage and Morphology 

Erosion at Wolf Trap increases the sediment carried by 

park streams. Sediment loads and distribution affect 

aquatic and riparian ecosystems. Sediment loading can 

change channel morphology and increase the 

frequency of overbank flooding. Fine- grained 

sediments can transport contaminants in a water 

system. Sediment loading follows a seasonal cycle and 

may warrant further investigation. 

• Recreational Demands 

Wolf Trap National Park for the Performing Arts is a 

popular haven and venue in the densely populated 

Washington, D.C., area. Visitor use, from hiking to 

picnicking, places increasing demands on the 

protected areas within the park. Understanding the 

response of the landscape to visitor overuse is a 

resource management concern, as is visitor safety, 

especially along stream banks. 

• Soil Erosion 

Soils provide a critical link between geology and 

biology. Soils at Wolf Trap have been disturbed and 

altered by agriculture, development, urbanization of 

the surrounding area, and erosion. The Soil Resource 

Inventory (SRI) Program of the NPS Geologic 

Resources Division is equivalent to the Geologic 

Resource Evaluation Program but focused on soils 

rather than geology. SRI maps and databases for Wolf 

Trap National Park for the Performing Arts are slated 

for completion in 2009. 

Additional issues including general geologic research, 

water quality and quantity, and a range of other potential 

action items have been identified as management 

concerns for Wolf Trap National Park for the 

Performing Arts. It may be possible to link interpretive 

needs with land- use planning and visitor use in the park. 

Along with a detailed geologic map and a road or trail 

log, a guidebook connecting Wolf Trap National Park for 

the Performing Arts to the other parks in the Central 

Appalachian region would enhance a visitor’s 

appreciation of the region’s rich geologic history and the 

dynamic processes that created the natural landscape 

and affected human history showcased in the region. 
 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 Wolf Trap National Park for 

the Performing Arts. 

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. 

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 

Wolf Trap National Park for the Performing Arts is 

located in Virginia about 13 km (8 miles) west of 

Washington, D.C. in an area referred to herein as the 

National Capital Region (fig. 1). The park began as a gift 

from Catherine Filene Shouse. Formerly known as Wolf 

Trap Farm Park (October 15, 1966, by Public Law 89- 671 

89th Congress, S. 3423), it was designated the first 

national park for the performing arts on August 21, 2002. 

This park offers a 130- acre respite in the Washington, 

D.C., metro area. In addition to its rich historical 

context, the park provides a natural sanctuary for native 

bird, plant, and animal species. The park attracted 

485,689 visitors in 2006. 

This historic park protects a portion of the Piedmont 

Physiographic Province of the Appalachian Highlands, 

one of several geologically significant physiographic 

provinces in the eastern United States (fig. 2). Varied 

hydrological influences acting on the underlying geology 

have built a complex topography at Wolf Trap. The 

landscape consists of wooded rolling hills, a stream valley 

(Wolf Trap Run and its tributaries, Courthouse Branch 

and a smaller unnamed waterway), and flat to gently 

sloping areas. The overall elevation range is about 30 m 

(100 ft). The highest hills in the park are in the southeast 

corner; the lowest points are in the flood plain in the 

northwest corner. These topographic and elevation 

differences in addition to seasonal flooding support a 

diversity of habitats ranging from year- round wetlands 

to dry, steep, forested slopes. 

The following are general descriptions of several of the 

different physiographic provinces from the Atlantic 

Coastal Plain to the Appalachian Mountains (fig. 2). This 

information is relevant to understanding the geologic 

history of Wolf Trap National Park for the Performing 

Arts. 

Atlantic Coastal Plain Province 

The Atlantic Coastal Plain province is primarily flat 

terrain with elevations ranging from sea level to about 

100 m (300 ft) in Virginia. Located along the coast and in 

places stretching inland, it extends from New York to 

Mexico. Sediments eroding from the Appalachian 

highlands to the west were deposited intermittently in a 

wedge- shaped sequence during periods of higher sea 

level over the past 100 million years. The sediments are 
 WOTR Geologic Resource Evaluation Report 3

more than 2,400 m (7,900 ft) thick at the Atlantic coast. 

The deposits were reworked by fluctuating sea levels and 

the continual erosive action of waves along the coastline. 

The province continues off shore as the submerged 

continental shelf for another 120 km (75 miles) to the 

east. 

In northern Virginia the Coastal Plain province stretches 

from the Fall Line east to the Chesapeake Bay and 

Atlantic Ocean. Coastal Plain surficial materials are 

commonly well drained sandy or sandy- loam soils. 

Large streams and rivers in the Coastal Plain province, 

including the James, York, Rappahannock, and Potomac 

Rivers, continue to transport sediment and to extend the 

Coastal Plain eastward. 

Piedmont Province 

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

where the softer, less consolidated sedimentary rock of 

the Atlantic Coastal Plain to the east intersects the 

harder, more resilient metamorphic rock to the west, 

forming a series of ridges, waterfalls, and rapids (fig. 3). 

This zone covers more than 27 km (17 miles) of the 

Potomac River from Little Falls Dam, near Washington, 

D.C., west to Seneca, Maryland. Examples of this 

transition are present in the Potomac Gorge of the 

Chesapeake and Ohio Canal National Historic Park and 

at Great Falls Park. The Piedmont Physiographic 

Province encompasses the Fall Line westward to the Blue 

Ridge Mountains. 

The eastward- sloping Piedmont formed through a 

combination of folding, faulting, metamorphism, uplift, 

and erosion. The result was a landscape of gently rolling 

hills in the east starting at 60 m (200 ft) in elevation. The 

hills become gradually steeper toward the western edge 

of the province, where they reach 300 m (1,000 ft) above 

sea level. The Piedmont is composed of hard, crystalline 

igneous and metamorphic rocks including schists, 

phyllites, slates, gneisses, and gabbros. Soils in the 

Piedmont are highly weathered and generally well 

drained. 

A series of Triassic age extensional basins occurs in the 

Piedmont. Normal faulting during crustal extension 

formed these basins. This faulting created downdropped troughs (grabens) that rapidly filled with 

roughly horizontal layers of sediment. Examples include 

the Frederick valley in Maryland and the Culpeper valley 

of Northern Virginia. 

Blue Ridge Province 

The Blue Ridge province is located along the eastern 

edge of the Appalachian Mountains. The highest 

elevations in the Appalachian Mountains occur in this 

province in the Great Smoky Mountains of North 

Carolina and Tennessee. Precambrian and Paleozoic 

igneous, sedimentary, and metamorphic rocks were 

uplifted during several orogenic events forming the 

steep, rugged terrain. 

Resistant Cambrian age quartzites form the Blue Ridge, 

Bull Run Mountain, South Mountain, and Hogback 

Ridge in Virginia (Nickelsen 1956). The elongate belt of 

the Blue Ridge stretches from Pennsylvania to Georgia. 

South Mountain and Catoctin Mountain, both anticlines, 

are two examples of the pervasive folding in the Blue 

Ridge province. 

Eroding streams have narrowed the northern section of 

the Blue Ridge Mountains into a thin band of steep 

ridges, with heights of approximately 1,200 m (3,937 ft). 

The Blue Ridge province is typified by steep terrain 

covered by thin, shallow soils that allow rapid runoff 

contributing to low groundwater recharge rates. 

Valley and Ridge Province 

Long, parallel ridges separated by valleys characterize the 

landscape of the Valley and Ridge Physiographic 

Province. The valleys formed where resistant sandstone 

ridges border more easily eroded shale and carbonate 

formations. The province contains strongly folded and 

faulted sedimentary rocks in western Maryland. 

Certain areas dominated by carbonate formations exhibit 

karst topography dotted by sinkholes, caves, and 

caverns. The karstic eastern portion of the Valley and 

Ridge province is part of the Great Valley (Shenandoah 

Valley). The Valley and Ridge province connects to the 

Piedmont province by streams that cut through the Blue 

Ridge Mountains. 

Geology and History at Wolf Trap National Park for the 

Performing Arts 

The entire Potomac River valley is rich in archeological 

resources that document 10,000 years of human 

habitation. The geology of the area has always attracted 

people to its vast natural resources. Ancient people came 

here to use the unique stone, including flint and chert for 

tools, establishing base camps and processing sites in 

several locations. The Potomac and its tributaries 

provided Native Americans (Piscataway Tribe) with a 

concentration of fish, game, and numerous plant species, 

as well as wood, stone, shell, and bone necessary for 

tools and trade. 

Geology also played a vital role in early European 

settlement success. In the area around Washington, D.C., 

rivers supported local trade, developed fertile flood 

plains, and provided resources for the inhabitants. The 

geology influenced or even dictated placement of river 

crossings and fords. Likewise, early railroads and roads 

often followed the trends of natural geologic features. 

Educating the public about interconnections between 

history and science, and building a deeper understanding 

of the landscape, requires an explanation of the role of 

geologic controls during settlement and human history. 

A major National Park Service goal is to preserve the 

historical context of the Wolf Trap area (figs. 4, 5). 

Historic buildings and the landscape around them are to 

be preserved and restored, including the pastoral Shouse 

farm landscape at Wolf Trap. 
 NPS Geologic Resources Division 4 

There are several management challenges in maintaining 

this landscape, because it often means resisting natural 

geologic changes. Geologic slope processes such as 

chemical weathering, landslides, slumps, and slope creep 

are constantly changing the landscape at the park. 

Runoff erodes sediment from any open areas and carries 

it down streams and gullies. Erosion naturally diminishes 

higher areas and fills in the lower areas, distorting the 

historical context of the landscape. 

Issues also arise between cultural and natural resource 

management. For example, a proposal for restoration of 

an historic building or the development of new 

performance areas may include removing surrounding 

natural resources or planting exotic species. Streams and 

rivers are often altered to preserve fishing habitat and to 

protect trails, buildings, and stream banks from being 

undercut. These activities attempt to reverse natural 

geologic changes. 
 WOTR Geologic Resource Evaluation Report 7

Figure 2: Location of Wolf Trap National Park for the Performing Arts relative to the physiographic provinces of Virginia. Modified from 

Bailey (1999). 
 NPS Geologic Resources Division 8 

Figure 3: Geologic map of the Piedmont and Blue Ridge in central Virginia. Heavy dashed line indicates state boundaries. Modified 

from Bailey (1999). 
 WOTR Geologic Resource Evaluation Report 9

Figure 4: The original historic farmhouse at Wolf Trap. Photograph courtesy of the National Park Service. 
 NPS Geologic Resources Division 10 

 Figure 5: Historic Barn Road. Photograph courtesy of the National Park Service. 
 WOTR Geologic Resource Evaluation Report 11

Geologic Issues 

A Geologic Resource Evaluation scoping session was held for Wolf Trap National Park 

for the Performing Arts on April 30–May 2, 2001, to discuss geologic resources, address 

the status of geologic mapping, and assess resource management issues and needs. In 

addition two other meetings–one held on July 9–11, 2002 focused on monitoring and the 

other held on May 20, 2002 focused on the influence of geologic processes and humans–

are referenced in the following section. This section synthesizes results of these meetings, 

with emphasis on those issues that may require attention from resource managers. 

Sediment Load, Channel Storage, and Morphology 

Erosion of the landscape within the Difficult Run 

watershed leads to increases in sediment carried by 

streams flowing through the park. Sediment loads and 

distribution affect aquatic and riparian ecosystems. 

Sediment loading can result in changes to channel 

morphology and increase the frequency of overbankflooding. One of the most important functions of a 

riparian zone is theability of vegetation to improve water 

quality by trapping sediments containing contaminants 

from disturbed areas. However, little data exists 

quantifying the impacts of sediment deposition from

anthropogenic disturbances on processes within these

ecosystems. A study conducted in Georgia focused on 

disturbed areas generating a rangeof sedimentation 

levels in riparian zones near small ephemeral streams.

The results of this study suggest that fine root dynamics 

may be affected by sedimentdeposition rates commonly 

occurring in riparian areas near disturbed lands,and that 

the water filtration function performed by these 

ecosystemsmay also be affected (Cavalcanti and Lockaby 

2005). 

Suspended sediment load is a resource management 

concern, as the sediment can contaminate drinking water 

sources, and increase concentrations of toxic chemicals 

formerly trapped in stream bottom sediments. However, 

fine- grained sediments are also vital in the overall fluvial 

transport of contaminants in a water system. Channel 

storage of fine sediment (and the contaminants 

contained therein) follows a seasonal cycle. This cycle is 

subject to hydrologic variability with increased 

availability during the high stands of spring and 

decreased availability during the low stands in autumn. 

Fine- grained sediments do not travel downstream in a 

single pulse but are often resuspended bottom material 

(Miller et al. 1984). This intermittent transport of 

contaminants and fine- grained sediment enlarges the 

affected area. 

Recreational Demands 

The National Park Service is to protect park resources 

for the enjoyment of current and future generations of 

visitors. The inherent purpose of Wolf Trap is to act as a 

natural sanctuary (woodlands), an outdoor museum of 

pastoral farm use, and a venue for artistic performances. 

This introduces many visitors to the small natural area of 

the park. The park promotes activities that do not 

damage the park’s resources or endanger visitors. 

The park receives many visitors every year. In 2006, as 

many as 485,689 people entered the park to recreate. 

Approximately 24 acres (or 19%) of the parklands are 

developed as paved roads, trails, and structures, 

including the park administrative buildings and the 

Filene Center (accommodates 7,028 people) (NPS 2005). 

Visitors are placing increasing demands on the resources 

of the park, and management concerns vary from trail 

erosion, water quality, and wetland health to riverbank 

erosion. 

In numerous places throughout the park, unconsolidated 

soils and sediments are exposed on a slope (gradient as 

high as 30%) with sparse vegetation. The slope angle and 

lack of stabilizing vegetation renders the soil materials 

highly susceptible to erosion and degradation. Park 

management attempts to concentrate the impacts of 

recreation with designated trails and picnic areas. 

Continued use in prohibited or nondesignated areas 

places delicate ecosystems at risk for damage from 

increased impact and contamination from waste. 

Inventory, monitoring, and research suggestions for 

recreational demands include: 

• Include inventory and monitoring in future resource 

management plans that would further identify human 

impact to geomorphologic or geohydrologic processes 

within the park, 

• Design wayside exhibits to encourage responsible use 

of park resources, and 

• Plant stabilizing native vegetation along slopes at risk 

for slumping and erosion. 

Water Issues 

In the moist eastern climate of the National Capital 

Region, water seems present everywhere in streams, 

rivers, runoff, springs, and groundwater wells. Annual 

precipitation in Washington, D.C., averages ~100 cm 

(39.35 inches) per year, and almost half of the rain falls in 

the summer months during short intense storms. Water 

resources at the park are under constant threat of 

overuse and contamination because of surrounding 

development. 
 NPS Geologic Resources Division 12 

The park’s primary permanent water resource is Wolf 

Trap Creek. Two small tributaries, Courthouse Branch 

and an unnamed watercourse, are also present within the 

park. Wolf Trap Creek is a part of the Difficult Run 

watershed. In addition, a 2- acre farm pond (habitat for a 

variety of amphibians, and migrating and resident birds) 

and a permanent spring are components of the park’s 

hydrologic system. 

Major threats to water quality in the Wolf Trap area 

include (1) sediment, nutrients, heavy metals, and organic 

chemicals in urban and agricultural runoff, (2) bacteria, 

nutrients, and heavy metals from household sewage 

effluent discharges, and (3) organic chemicals, heavy 

metals, and high biochemical oxygen demand from 

effluents generated by industries and developed areas. 

Impacts from operations within the park proper are 

suspected, but have yet to be measured (NPS 2005). 

Threats to ground water quality include the influx of 

fertilizers, pesticides, herbicides, manure, septic effluent, 

and road salt, are concentrated in urban areas 

surrounding the park. Acid rain and snow are known to 

cause acidification of streams and rivers in the area 

(http://www.wilderness.org/Library/Documents/upload/

Potomac- River- Watershed- Facts.pdf, accessed March 

28, 2008). 

The hydrogeologic system is impacted by increased 

surface runoff from impervious surfaces such as parking 

lots, roads, and building footprints. Likewise, impervious 

surfaces decrease the base flow of streams by preventing 

infiltration into the aquifer. The difference between base 

and peak streamflows typically increases as a 

consequence of development in the absence of 

mitigation measures such as detention ponds. 

Sedimentation also increases due to land clearing 

activities for development. Water temperature increases 

because of the insulating nature of impervious surfaces. 

(Runoff from a parking lot on a hot July day is at a much 

higher temperature than runoff from a grassy slope.) 

The movement of nutrients and contaminants through 

the hydrogeologic system can be modeled by monitoring 

the composition of system inputs, such as rainfall, and 

outputs, such as streamflow. Other input sources include 

wind, surface runoff, groundwater transport, sewage 

outfalls, landfills, and fill dirt. 

Streams in effect integrate the surface runoff and 

groundwater flow of their watersheds. Thus, they 

provide a cumulative measure of the status of the 

watershed’s hydrologic system. Consistent measurement 

of these parameters is crucial to establishing baselines for 

comparison. 

Soil Erosion 

Soils provide an important link between geology and 

biology in the National Capital Region. Soils support life 

and are derived from underlying bedrock, augmented by 

transported sediments and nutrients as well as organic 

matter. The geology, or the rock types, from which the 

soils are derived, influences soil chemistry. Regional soils 

developed from a variety of basement rocks including 

limestone, greenstone, red shale, and quartzite. 

Since Colonial time (~1650s–1700), the National Capital 

Region has been cleared for farming and in the process 

stripped of much soil. The result has been increased 

sediment input into regional waterways. A large part of 

this sediment is permanently lost, unless manmade 

structures, or beaver dams are able to slow erosion and 

runoff. 

The Soil Resources Inventory (SRI) Program of the NPS 

Geologic Resources Division is working with the Natural 

Resources Conservation Service (NRCS) to complete a 

soil survey for Wolf Trap National Park for the 

Performing Arts. This project is underway and projected 

for completion in 2009. The SRI Program provides userfriendly products to park managers to facilitate effective 

resource management, as well as baseline information on 

soil resources for the Vital Signs Monitoring Program. 

Soil resource inventories equip parks with maps showing 

the locations and extent of soils; data about the physical, 

chemical, and biological properties of those soils, as well 

as information regarding potential uses and limitations of 

each kind of soil type. The products also can be used for 

park interpretive programs and to identify emerging Soil 

Program needs. 

General Geology 

A meeting held in August 2002 to assess geologic 

monitoring objectives for the National Capital Region 

Vital Signs Network (including Wolf Trap National Park 

for the Performing Arts) identified the following geologic 

resource components: soils and bedrock, ground water, 

bare ground and exposed rock, karst, surface water, 

coastal areas, and riparian areas and wetlands. Resource 

management could benefit from consideration of these 

components and their contributions to the entire 

ecosystem. 

Stresses to these components include nutrient and 

chemical contamination, sediment erosion and 

deposition, shoreline changes, and geo- hazards. These 

stressors are potential areas for ecosystem monitoring. 

Development, acid rain, atmospheric deposition, climate 

change, abandoned mines and wells, and visitor use are 

thought to be primary sources of stress to the natural 

resources at Wolf Trap National Park for the Performing 

Arts. 

Digital geologic data facilitates science based decision 

making for resource managers by allowing integration 

with other spatial data in a GIS. Potential uses of digital 

geologic data include: 

1. identification and description of critical habitats for 

rare and endangered species; 

2. hazard assessments for events such as floods, 

rockfalls, or slumps; 
 WOTR Geologic Resource Evaluation Report 13

3. creation of interpretive programs to illustrate the 

evolution of the landscape and Earth history of the 

park in lay- person terms; 

4. identifying the location of sources of aggregate and 

building stone for historical reconstruction; 

5. determining environmental impacts for any new 

construction; 

6. inventory of natural features such as springs, cliffs, 

marker beds, fossil localities, and caves; 

7. characterizing land use; and 

8. defining ecological zones and implementing 

conservation plans (Southworth and Denenny 

2003). 

Inventory, monitoring, and research suggestions for 

general geology include: 

• Promote research investigating the processes active 

along fault zones in the Piedmont. 

• Consider performing geochemical studies to 

understand the path of nutrients through various 

bedrock lithologies. 

• Use historical photographs, descriptions, and surveys 

to determine the topography prior to human impact. 

• Research the surficial geologic story at the park and 

develop an interpretive program that relates the 

current landscape, ecosystem, history, and biology to 

the geology. 

• Document locations of swelling clays and assess any 

influence they may have on park resources, including 

roadways, trails, and buildings. 

• Compile baseline geologic data; develop a geologic 

bibliography; create a database of geologic maps; 

research geologic studies and reports; develop a 

geologic site bulletin or brochure; and, collect and 

display geologic data using GIS and GPS. 

• Promote interpretive exhibits to educate the public 

about the tectonic history of the eastern United States.
 NPS Geologic Resources Division 14 

Map Unit Properties 

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

Evaluation digital geologic map of Wolf Trap National Park for the Performing Arts. 

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 geologic bedrock map units within Wolf Trap 

National Park for the Performing Arts include 

Precambrian to lower Paleozoic metasedimentary and 

metaigneous rocks associated with a suture between the 

Piedmont and Blue Ridge physiographic provinces 

(Bailey 1999). The sedimentary and volcanic rocks that 

were thrust along faults during deposition in a Late 

Proterozoic to Early Cambrian oceanic trench setting 

mixed with unconsolidated sediments to form a mélange, 

or mixture, of rocks. 

This mélange was then metamorphosed into deformed 

crystalline rocks that now make up the geologic units 

shown on the map of the park. Locally these units 

include polydeformed schists, gneisses, phyllites, and 

metagraywackes of the Peters Creek Schist (mapped as 

the Mather Gorge Formation in nearby Great Falls Park 

by Southworth et al. 2000b). The Peters Creek Schist was 

thrust over the younger, mixed origin (mélange) 

phyllonitic rocks of the Sykesville Formation along the 

Plummers Island thrust fault (Southworth et al. 2001). 

Nearby igneous intrusive rocks include granites, quartz 

monzonites, and granodiorites (VDMR 1993; 

Southworth et al. 2000b). 

Elsewhere, artificial fill and local limonite- cemented 

alluvial clay, silt, sand, and lowermost colluvial gravel 

units vary in age from middle Miocene to present 

(Maryland Geological Survey 1968; Southworth et al.

2001). Prominent among these later sediments are terrace 

deposits perched on bedrock ledges carved by the 

Potomac River (Southworth et al. 2000a; Southworth et 

al. 2001). The oldest of these deposits is dated at 10 

thousand years ago to 5 Ma northeast of Wolf Trap at 

Glade Hill. Flood- plain alluvium including sand, gravel, 

silt, and clay makes up the most recent map units at Wolf 

Trap. 

The geologic units in the following table and their 

geologic features and properties correspond to the units 

found in the accompanying digital geologic data. Source 

data for the GRE digital geologic map are from: 

Southworth, S. and D. Denenny. 2006. Geologic Map of 

the National Parks in the National Capital Region, 

Washington D.C., Virginia, Maryland and West 

Virginia. Scale 1:24,000. U.S. Geological Survey. OpenFile Report: OF 2005- 1331. 

The following pages present a tabular view of the 

stratigraphic column and an itemized list of features for 

each map unit. This sheet includes properties specific to 

each unit present in the stratigraphic column, including 

map symbol, name, description, resistance to erosion, 

suitability for development, hazards, paleontologic 

resources, cultural and mineral resources, karst issues, 

habitat, recreational use, and significance. 
 WOTR Geologic Resource Evaluation Report 17

Geologic History 

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

geologic map of Wolf Trap National Park for the Performing Arts, the environment in 

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

present landscape. 

Wolf Trap National Park for the Performing Arts is 

located at the narrow north end of the western Piedmont 

Physiographic Province in northern Virginia. This 

location is near the Fall Line (between the Piedmont and 

Atlantic Coastal Plain) to the east, and the Blue Ridge 

province to the west. As such, it contains features that are 

innately tied to the long geologic history of the 

Appalachian Mountains and the evolution of the eastern 

coast of the North American continent. 

The rocks underlying Wolf Trap include lower Paleozoic 

metasedimentary and meta- igneous rocks associated 

with the suture zone between the Blue Ridge and the 

Piedmont (Bailey 1999). A regional perspective of the 

geologic history is presented here to situate the 

landscape and geology of the park within its larger 

region. 

The recorded history of the Appalachian Mountains 

begins in the Proterozoic (figs. 6, 7). In the midProterozoic, during the Grenville Orogeny, a 

supercontinent formed composed of most of the 

continental crust in existence at that time, including the 

crust of North America and Africa. Sedimentation, 

deformation, plutonism (igneous intrusions), and 

volcanism are manifested in the metamorphic granites 

and gneisses in the core of the modern Blue Ridge 

Mountains (Harris et al. 1997). 

The sediments that formed these rocks were deposited 

over a period of 100 million years and are more than 1 

billion years old, making the rocks among the oldest 

known from this region. Following uplift, they were 

exposed to erosive forces for hundreds of millions of 

years. Their subdued surface forms a basement upon 

which all other rocks of the Appalachians formed 

(Southworth et al. 2001). 

The late Proterozoic, roughly 800–600 million years ago, 

brought a tensional, rifting tectonic setting to the area. 

The crustal extension created fissures through which 

massive volumes of basaltic magma were extruded. This 

volcanic extrusion lasted tens of millions of years and 

alternated between flood basalt flows and ash falls. The 

metamorphosed remnants of these igneous rocks are 

found in the Catoctin Greenstones of Shenandoah 

National Park, and Catoctin Mountain Park, west of 

Wolf Trap. 

Because of the tensional tectonic forces, the 

supercontinent broke up, and a basin formed that 

eventually became the Iapetus Ocean. This basin 

subsided and accumulated much of the sediment that 

would eventually form the Appalachian Mountains. 

Thick layers of sand, silt, and mud deposited in the 

Iapetus Ocean became the Sykesville and Mather Gorge 

Formations after regional deformation and 

metamorphism. Large blocks of eroded fragments from 

the Grenville highlands mixed with these sediments 

(Southworth et al. 2000b). 

Some of the sediments were deposited as alluvial fans, 

large submarine landslides, and turbidites, which today 

preserve the dramatic features of their emplacement. 

These early sediments are exposed on Catoctin 

Mountain, Short Hill–South Mountain, Blue Ridge–Elk 

Ridge, and in areas to the west of the park as the 

Chilhowee Group (Loudoun Formation, Weverton 

Formation, Harpers Formation, and Antietam 

Formation) (Southworth et al. 2001). 

Associated with the shallow- marine setting along the 

eastern continental margin of the Iapetus Ocean were 

large deposits of sand, silt, and mud in near- shore, 

deltaic, barrier island, and tidal flat environments. Some 

of these are present in the Chilhowee Group in central 

Maryland, including the Harpers and Antietam 

Formations (Schwab 1970; Kauffman and Frey 1979; 

Simpson 1991). 

In addition, huge masses of carbonate rocks, such as the 

Cambrian age Tomstown Dolomite and Frederick 

Limestone, as well as the Upper Cambrian to Lower 

Ordovician Grove Limestone, were deposited on top of 

the Chilhowee Group. They formed a grand platform, 

thickening to the east, that persisted during the 

Cambrian and Ordovician Periods (545–480 Ma) and 

form the floors of Frederick and Hagerstown valleys 

(Means 1995). 

Somewhat later, 540, 470, and 360 million years ago, 

igneous granodiorite, pegmatite, and lamprophyre, 

respectively, intruded the sedimentary rocks including 

those of the Mather Gorge Formation. During several 

episodes of mountain building and continental collision 

(discussed below), the entire pile of sediments, 

intrusives, and basalts was deformed and 

metamorphosed into schist, gneiss, marble, slate, and 

migmatite (Southworth et al. 2000a). 
 NPS Geologic Resources Division 18 

Taconic Orogeny 

From Early Cambrian through Early Ordovician time, 

orogenic activity along the eastern margin of the 

continent began again. The Taconic Orogeny (~440–420 

Ma in the central Appalachians) was a volcanic arc–

continent convergence. Oceanic crust and the volcanic 

arc from the Iapetus basin were thrust onto the east edge 

of the North American continent. 

The Taconic Orogeny involved the closing of the ocean, 

subduction of oceanic crust, the creation of volcanic 

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

Initial metamorphism of the igneous and sedimentary 

rocks of the Sykesville and Mather Gorge Formations 

into schists, gneisses, migmatites, and phyllites occurred 

during this orogenic event. 

In response to the overriding plate thrusting westward 

onto the continental margin of North America, the crust 

bowed downwards creating a deep basin that filled with 

mud and sand eroded from the highlands to the east 

(Harris et al. 1997). This so- called Appalachian basin 

centered on what is now West Virginia. Infilling 

sediments covered the grand carbonate platform and are 

recorded today by the shale of the Ordovician 

Martinsburg Formation (Southworth et al. 2001). 

During the Late Ordovician, the oceanic sediments of the 

shrinking Iapetus Ocean were thrust westward onto 

other deepwater sediments of the western Piedmont. 

This occurred along the Pleasant Grove fault and other 

local faults such as the Plummers Island fault. Sediments 

forming sandstones, shales, siltstones, quartzites, and 

limestones were then deposited in the shallow- marine to 

deltaic environment of the Appalachian basin. These 

rocks, now metamorphosed, currently underlie the 

Valley and Ridge province west of Wolf Trap (Fisher 

1976). 

Shallow- marine to fluvial sedimentation continued for 

about 200 million years during the Ordovician, Silurian, 

Devonian, Mississippian, Pennsylvanian, and Permian 

Periods. The thick piles of sediments were derived from 

the newly formed highlands during the Taconian 

(Ordovician) and Acadian (Devonian) orogenies. 

Acadian Orogeny 

The Acadian Orogeny (~360 Ma) continued the 

mountain building of the Taconic Orogeny as the African 

continent approached North America (Harris et al. 1997). 

Similar to the preceding Taconic Orogeny, the Acadian 

event involved land mass collision, mountain building, 

and regional metamorphism (Means 1995). This event 

was focused farther north than central Maryland–

Virginia. 

Alleghenian Orogeny 

Following the Acadian orogenic event, the protoAtlantic Iapetus Ocean closed completely during the late 

Paleozoic, as the North American and African continents 

collided. This collision formed the Pangaea 

supercontinent and the predecessor of Appalachian 

mountain belt we see today. The mountain- building 

episode, termed the Alleghenian Orogeny (~325–265 Ma), 

is the last major orogeny of Appalachian evolution 

(Means 1995). 

The rocks were deformed by folding and faulting to 

produce the Sugarloaf Mountain anticlinorium and the 

Frederick valley synclinorium in the western Piedmont, 

the Blue Ridge–South Mountain anticlinorium, and the 

numerous folds of the Valley and Ridge province 

(Southworth et al. 2001). 

During this orogeny, rocks of the Great Valley, Blue 

Ridge, and Piedmont provinces were transported 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: estimates of 20%–50% 

shortening translate into 125–350 km (78–217 miles) of 

transport (Harris et al. 1997). 

Deformed rocks in the eastern Piedmont were also 

folded and faulted and existing thrust faults were 

reactivated as both strike- slip and thrust faults during 

the Alleghenian orogenic events (Southworth et al. 2001). 

Paleoelevations of the Allegheny Mountains are 

estimated at approximately 6,000 m (20,000 ft) 

(analogous to the modern- day Himalayas). Erosion has 

beveled these mountains to elevations less than 600 m 

(2,000 ft) west of Wolf Trap National Park for the 

Performing Arts (Means 1995). 

Triassic Extension to the Present 

Following the Alleghenian Orogeny, during the Late 

Triassic (about 230 to 200 Ma), a period of rifting began 

as the deformed rocks of the joined continents began to 

break apart. The supercontinent Pangaea was segmented 

into roughly the continents that persist today. This 

episode of rifting or crustal fracturing initiated the 

formation of the current Atlantic Ocean and caused 

many block- fault basins to develop with accompanying 

volcanism (Harris et al. 1997; Southworth et al. 2001). 

The Newark Basin system is a large component of this 

tectonic setting. Large alluvial fans and streams carried 

debris shed from the uplifted Blue Ridge and Piedmont 

provinces. These sediments consolidated as nonmarine 

shales and sandstones in fault- created troughs (grabens) 

such as the Frederick valley in central Maryland and the 

Culpeper basin in the western Piedmont of central 

Virginia. Many of these rifted openings became 

lacustrine basins accumulating thick deposits of siltstone 

and sandstone. 

Large faults formed the western boundaries of the basins 

and provided an escarpment that was quickly covered 

with eroded debris. Igneous rocks intruded into the new 

sandstone and shale strata as subhorizontal sheets, or 

sills, and near- vertical dikes that extend beyond the 

basins into adjacent rocks. After these molten igneous 

rocks were emplaced, at approximately 200 Ma, the 

region underwent a period of slow uplift and erosion. 
 WOTR Geologic Resource Evaluation Report 19

The uplift was in response to isostatic adjustments within 

the crust, which forced the continental crust upwards 

and exposed it to erosion. 

Thick deposits of unconsolidated gravel, sand, and silt 

were shed from the eroding mountains. These were 

deposited at the base of the mountains as alluvial fans 

and spread eastward to be part of the Atlantic Coastal 

Plain (Duffy and Whittecar 1991; Whittecar and Duffy 

2000; Southworth et al. 2001). The Cretaceous Potomac 

Formation is a very thick unit of eroded material. The 

amount of erosion inferred from the now- exposed 

metamorphic rocks is immense. Many of the rocks 

exposed at the surface must have been at least 20 km (~10 

miles) below the surface prior to regional uplift and 

erosion. The erosion continues today: the Potomac, 

Rappahannock, Rapidan, Monocacy, and Shenandoah 

Rivers, and their tributaries strip Coastal Plain sediments, 

lower the mountains, and deposit alluvial terraces, 

creating the present landscape. 

Since the breakup of Pangaea and the uplift of the 

Appalachian Mountains, the North American plate has 

continued to drift toward the west. The isostatic 

adjustments that uplifted the continent after the 

Alleghenian Orogeny continued at a subdued rate 

throughout the Cenozoic Period (Harris et al. 1997). 

The landscape and geomorphology of the greater 

Potomac River valley are the result of erosion and 

deposition from about the mid- Cenozoic Period to the 

present, or at least the last 5 million years. The Potomac, 

flowing southeast, cuts obliquely across north- trending 

geologic units. Following the trend of joints and other 

fractures, the river flows straight through Mather Gorge. 

There is little to no evidence that the Potomac river 

migrated laterally across a broad, relatively flat region. 

The river apparently cut downward through very old, 

resistant rocks, overprinting its early course (Southworth 

et al. 2001). 

The distribution of flood- plain alluvium and ancient 

fluvial terraces of the regional rivers and adjacent 

tributaries records the historical development of both 

drainage systems. At least six different terrace levels are 

identifiable in the Wolf Trap National Park for the 

Performing Arts area. The oldest of these is located on 

the crest of Glade Hill in nearby Great Falls Park. Here 

the Potomac river cut though bedrock and left deposits 

of large quartzite and diabase boulders. In creating these 

terraces, the river left behind islands, islets, pinnacles, 

oxbows, shoestring canals, potholes, and plunge pools—

all erosional features that dot the landscape along the 

Potomac River today (Southworth et al. 2001). 

Although glaciers from the Pleistocene Ice Ages never 

reached the central Maryland–Virginia area (the 

southern terminus was in northeastern Pennsylvania), 

the colder climates of the ice ages played a role in the 

formation of the landscape at Wolf Trap. The periglacial 

conditions that must have existed near the glaciers 

intensified weathering and other erosional processes 

(Harris et al. 1997). The landforms and deposits are 

probably late Tertiary to Quaternary in age when a 

wetter climate, sparse vegetation, and frozen ground 

caused increased precipitation to run into the ancestral 

river channels, enhancing downcutting and erosion by 

waterways (Means 1995; Zen 1997a and 1997b). 
 NPS Geologic Resources Division 20 

Figure 6: Geologic time scale; modified from the U.S. Geological Survey and International Commission on Stratigraphy. 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. W, S, E, NE (cardinal directions) refer to parts of the North American continent.
 WOTR Geologic Resource Evaluation Report 21

Figure 7: Geologic time scale specific to Virginia. Dates are approximate. Modified from Bailey and Roberts (1997-2003). 
 NPS Geologic Resources Division 22 

Glossary 

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

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

here please visit: http://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. 

aquifer. Body of rock or sediment that is sufficiently 

porous, permeable, and saturated to be useful as a 

source of water. 

anticline. A generally convex fold with older rock in the 

center and progressively younger rock toward the 

edges. 

anticlinorium. A regional anticlinal structure composed 

of lesser folds. 

ash (volcanic). Fine pyroclastic material ejected from a 

volcano. 

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

ridge of sand that parallels the coast. 

base flow. Streamflow supported by groundwater flow 

from adjacent rock, sediment, or soil. 

basement. The undifferentiated rocks, commonly 

igneous and metamorphic, that underlie identified 

rock units. 

basin (structural). A doubly plunging syncline in which 

rocks dip inward from all sides. 

basin (sedimentary). Any depression, from continental 

to local scale, into which sediments are deposited. 

bed. The smallest sedimentary strata unit, commonly 

ranging in thickness from 1 centimeter to a meter or 

two and distinguishable from beds above and below. 

bedding. Depositional layering or stratification of 

sediments. 

bedrock geology. The geology of underlying solid rock 

as it would appear with the sediment, soil, and 

vegetative cover stripped away. 

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. 

clastic. Rock or sediment made of fragments of 

preexisting rocks. 

clay. Clay minerals or sedimentary fragments the size of 

clay minerals (grain size <0.002 mm). 

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 (16–37 mi) and a density of 

approximately 2.7 grams per cubic centimeter. 

continental shelf. The shallowly submerged portion of a 

continental margin extending from the shoreline to the 

continental slope with water depths of less than 200 m 

(656 ft). 

craton. The relatively old and geologically stable interior 

of a continent (also see continental shield). 

crust. The outermost compositional shell of Earth, 10–40 

km (6–25 mi) thick, consisting predominantly of 

relatively low density silicate minerals (also see oceanic 

crust and continental crust). 

crystalline. Describes the structure of a regular, orderly, 

repeating geometric arrangement of atoms. 

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 a stream’s mouth 

where it flows into a lake or sea. 

dike. A tabular, discordant igneous intrusion. 

dip. The angle between a structural surface and a 

horizontal reference plane measured normal to their 

line of intersection. 

ephemeral stream. A stream that flows only in direct 

response to precipitation. 

extrusive. Of or pertaining to the eruption of igneous 

material onto the surface of Earth. 

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

of water. The landform differs from a delta in that a fan 

delta is next to a highland and typically forms at an 

active margin. 

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 (for example, crack, joint, fault). 

graben. A down- dropped structural block bounded by 

steeply dipping normal faults. 

igneous. Refers to a rock or mineral that originated from 

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

igneous, metamorphic, and sedimentary. 

intrusion. A body of igneous rock that invades older 

rock. The invading rock may be a plastic solid or 

magma that pushes its way into the older rock. 

isostasy. The process by which the crust “floats” at an 

elevation compatible with the density and thickness of 

the crustal rocks relative to underlying mantle. 

joint. A semi- planar break in rock without relative 

movement of rocks on either side of the fracture 

surface. 

karst topography. Topography characterized by 

abundant sinkholes and caverns formed by the 

dissolution of calcareous rocks. 
 WOTR Geologic Resource Evaluation Report 23

lacustrine. Pertaining to, produced by, or inhabiting a 

lake or lakes. 

landslide. Any process or landform resulting from rapid 

mass movement. 

lava. Magma that has been extruded out onto Earth’s 

surface, both molten and solidified. 

mafic. Refers to a rock, magma, or mineral rich in 

magnesium and iron. 

magma. Molten rock generated within Earth that is the 

parent of igneous rocks. 

mélange. A body of rock that is mostly unstratified and 

characterized by rock fragments of all sizes embedded 

in matrix of finer- grained fragments. 

member. A lithostratigraphic unit with definable contacts 

that subdivides a formation. 

metamorphic. Pertaining to the process of 

metamorphism or to its results. 

metamorphism. Literally, “change in form.” 

Metamorphism occurs in rocks with mineral 

alteration, genesis, and (or) recrystallization from 

increased heat and pressure. 

migmatite. Literally, “mixed rock” with both igneous and 

metamorphic characteristics due to partial melting 

during metamorphism. 

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

moves down relative to the footwall. 

oceanic crust. Earth’s crust formed at spreading ridges 

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

km (3–4 mi) thick and generally of basaltic 

composition. 

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

orogeny is one well- recognized example.) 

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

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

overbank deposits. Alluvium deposited outside a stream 

channel during flooding. 

paleontology. The study of the life and chronology of 

Earth’s geologic past based on the phylogeny of fossil 

organisms. 

Pangaea. A theoretical, single supercontinent that 

existed during the Permian and Triassic. 

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). 

pluton. A body of intrusive igneous rock. 

plutonic. Describes igneous rock intruded and 

crystallized at some depth in Earth. 

porosity. The proportion of void space (cracks, 

interstices) in a volume of a rock or sediment. 

recharge. Infiltration processes that replenish ground 

water. 

sandstone. A sedimentary rock of predominantly sandsized grains, especially quartz. 

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 and (or) chemical sediment(s). 

shale. A clastic sedimentary rock made of clay- sized 

particles that exhibit parallel splitting properties. 

sill. A tabular, igneous intrusion that is concordant with 

the country rock. 

silt. Clastic sedimentary material intermediate in size 

between very fine sand and coarse clay (1/256- 1/16 

mm). 

siltstone. A variably lithified sedimentary rock with siltsized grains. 

slump. A generally large, coherent mass movement with 

a concave- up failure surface and subsequent 

backward rotation relative to the slope. 

soil. Surface accumulation of weathered rock and 

organic matter capable of supporting plant growth and 

often overlying the parent rock from which it formed. 

strata. Tabular or sheetlike masses or distinct layers (as, 

of rock). 

stratigraphy. The geologic study of the origin, 

occurrence, distribution, classification, correlation, 

and age of rock layers, especially sedimentary rocks. 

strike. The compass direction of the line of intersection 

that an inclined surface makes with a horizontal plane. 

subduction. The process by which one crustal plate 

descends beneath another. 

suture. The linear zone where two continental 

landmasses become joined due to obduction. 

syncline. A fold generally convex upward wit hyiuner 

rock in the center and progressively older rock toward 

the edges. 

synclinorium. A regional synclinal structure composed 

of lesser folds. 

tectonic. Relating to large- scale movement and 

deformation of Earth’s crust. 

tectonics. The geologic study of the broad structural 

architecture and deformational processes of the 

lithosphere and aesthenosphere (a main focus of 

structural geology). 

terraces (stream). Step- like benches surrounding the 

present flood plain of a stream due to dissection of 

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

floor(s). 

thrust fault. A contractional, dip- slip fault with a 

shallowly dipping fault surface (<45o) where the 

hanging wall moves up and over relative to the 

footwall. 

topography. The general morphology of Earth’s surface 

including relief and location of natural and 

anthropogenic features. 

trend. The direction or azimuth of elongation of a linear 

geologic feature. 

unconformity. A surface within sedimentary strata that 

marks a prolonged period of nondeposition or 

erosion. 

uplift. A structurally high area in Earth’s crust, produced 

by movement that raises the rocks. 

water table. The upper surface of the saturated (phreatic) 

zone. 

weathering. The set of physical, chemical, and biological 

processes by which rock is broken down in place. 
 NPS Geologic Resources Division 24 

References 

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

available from the National Park Service Geologic Resources Division. 

Bailey, C.M. 2000. Major faults & high- strain zones in 

Virginia. 

http://www.wm.edu/geology/virginia/va_faults.pdf 

(accessed June 6, 2005); College of William and Mary, 

Williamsburg, Va. 

Bailey, C.M. 1999. Generalized geologic terrane map of 

the Virginia Piedmont and Blue Ridge. 

http://www.wm.edu/geology/virginia/terranes.html 

(accessed June 6, 2005). 

Bailey, C.M., and Roberts, C. 1997–2003. The geology of 

Virginia. http://www.wm.edu/geology/virginia/ 

(accessed June 6, 2005); College of William and Mary, 

Williamsburg, Va. 

Boon, J.D., Bohlen, W.F., and Wright, L.D. 1987. 

Estuarine versus inner shelf disposal sites; a 

comparison of benthic current regimes. In Coastal 

sediments '87. ed. Kraus, N.C., 571- 583. New York, NY: 

American Society of Civil Engineering 

Cavalcanti, G.G., and Lockaby, B.G. 2005. Effects of 

Sediment Deposition on Fine Root Dynamics in 

Riparian Forests. Soil Science Society of America 

Journal 69: 729- 737. 

VDMR (Commonwealth of Virginia Department of 

Mines, Minerals, and Energy, Division of Mineral 

Resources). 1993. Geologic Map of Virginia, 1:500,000 

scale. 

Duffy, D.F., and Whittecar, G.R. 1991. Geomorphic 

development of segmented alluvial fans in the 

Shenandoah Valley, Stuarts Draft, Virginia. Abstracts 

with Programs - Geological Society of America 23 (1): 24. 

Fisher, G.W. 1976. The geologic evolution of the 

northeastern Piedmont of the Appalachians. Abstracts 

with Programs - Geological Society of America 8 (2): 

172- 173. 

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

national parks. Dubuque, Ia: Kendall/Hunt Publishing 

Company. 

Kauffman, M.E, and Frey, E.P. 1979. Antietam sandstone 

ridges; exhumed barrier islands or fault- bounded 

blocks? Abstracts with Programs - Geological Society of 

America 11 (1): 18. 

Maryland Geological Survey. 1968. Geologic Map of 

Maryland, 1:250,000 scale 

http://www.mgs.md.gov/esic/geo/index.html 

(accessed July 27, 2006). 

Means, J. 1995. Maryland's Catoctin Mountain parks; an 

interpretive guide to Catoctin Mountain Park and 

Cunningham Falls State Park. Blacksburg, Va: 

McDonald & Woodward Publishing Company. 

Miller, A.J.; Smith, J.A.; and Shoemaker, L.L. 1984. 

Channel storage of fine- grained sediment in the 

Monocacy River basin. Eos, Transactions, American 

Geophysical Union 65 (45): 888 

National Park Service. 2005. Wolf Trap National Park for 

the Performing Arts, Environmental Assessment for 

Encore Circle Addition. 

http://data2.itc.nps.gov/parks/wotr/ppdocuments/EC

- - Environmental%20Assessment.doc (accessed June 

6, 2005). 

Nickelsen, R.P. 1956. Geology of the Blue Ridge near 

Harpers Ferry, West Virginia. Geological Society of 

America Bulletin 67 (3): 239- 269. 

Schwab, F.L. 1970. Origin of the Antietam Formation 

(late Precambrian?; lower Cambrian), central Virginia. 

Journal of Sedimentary Petrology 40 (1): 354- 366. 

Simpson, E.L. 1991. An exhumed Lower Cambrian tidalflat; the Antietam Formation, central Virginia, U.S.A. 

In Clastic tidal sedimentology eds. Smith, D G, Zaitlin, 

B.A, Reinson, G.E, and Rahmani, R.A. Memoir - 

Canadian Society of Petroleum Geologists 16: 123- 133. 

Southworth, S., and D.K. Brezinski. 1996. Geology of the 

Harpers Ferry Quadrangle, Virginia, Maryland, and 

West Virginia. Bulletin - U.S. Geological Survey: 

Report B 2123. 

Southworth, S., Brezinski, D.K., Orndorff, R.C., Chirico, 

P.G., and Lagueux, K.M. 2001. Geology of the 

Chesapeake and Ohio Canal National Historical Park 

and Potomac River Corridor, District of Columbia, 

Maryland, West Virginia, and Virginia; A, Geologic 

map and GIS files (disc 1); B, Geologic report and 

figures (disc 2). U.S. Geological Survey, Open- File 

Report: OF 01- 0188. 

Southworth, S., Brezinski, D.K., Orndorff, R.C., Lagueux, 

K.M., and Chirico, P.G. 2000a. Digital geologic map of 

the Harpers Ferry National Historical Park. U.S. 

Geological Survey, Open- File Report: OF 00- 0297, 1 

disc. 

Southworth, S., Fingeret, C., and Weik, T. 2000b. 

Geologic Map of the Potomac River Gorge: Great Falls 

Park, Virginia, and Part of the C & O Canal National 

Historical Park, Maryland; U.S. Geological Survey 

Open- File Report 00- 264. 
 WOTR Geologic Resource Evaluation Report 25

Southworth, S., Chirico, P., Denenny, D., and Triplett, J. 

2002. Geology and GIS in the parks of the National 

Capital Region. Abstracts with Programs – Geological 

Society of America 34 (6)

Southworth, S., and Denenny, D. 2003. Geologic Maps 

Support Land Resource Management in the National 

Parks in the Eastern U.S. Abstracts with Programs – 

Geological Society of America 35 (6): 331. 

Whittecar, G.R., and Duffy, D.F. 2000. Geomorphology 

and stratigraphy of late Cenozoic alluvial fans, Augusta 

County, Virginia, U.S.A. In Regolith in the Central and 

Southern Appalachians eds. Clark, G.M., Mills, H.H., 

and Kite, J.S. Southeastern Geology 39 (3- 4): 259- 279. 

Zen, E- an 1997a. The Seven- Storey River: 

Geomorphology of the Potomac River Channel 

Between Blockhouse Point, Maryland, and 

Georgetown, District of Columbia, With emphasis on 

the Gorge Complex Below Great Falls. U.S. Geological 

Survey Open- File Report 97- 60. 

Zen, E- an. 1997b. Channel Geometry and Strath Levels 

of the Potomac River Between Great Falls, Maryland 

and Hampshire, West Virginia. U.S. Geological Survey 

Open- File Report 97- 480. 
 NPS Geologic Resources Division 26 

Appendix A: Geologic Map Graphic 

The following page is a preview or snapshot of the geologic map for Wolf Trap National 

Park for the Performing Arts. 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). 
 WOTR Geologic Resource Evaluation Report 29

Appendix B: Scoping Summary 

The following excerpts are from the GRE scoping summary for Wolf Trap National 

Park for the Performing Arts. The scoping meeting was on April 30–May 2, 2001; 

therefore, the contact information and Web addresses referred to in this appendix may 

be outdated. Please contact the Geologic Resources Division for current information. 

Executive Summary 

Geologic Resource Evaluation (GRE) workshops were 

held for National Park Service (NPS) Units in the 

National Capital Region (NCR) on April 30–May 2, 2001. 

The purpose was to view and discuss the park’s geologic 

resources, to address the status of geologic mapping for 

compiling both paper and digital maps, and to assess 

resource management issues and needs. Cooperators 

from the NPS Geologic Resources Division (GRD), 

Natural Resources Information Division (NRID), 

individual NPS units in the region, and the U.S. 

Geological Survey (USGS) were present for the 

workshop. 

This meeting involved half- day field trips to view the 

geology of Catoctin Mountain Park, Harpers Ferry NHP, 

Prince William Forest Park, and Great Falls Park, as well 

as another full- day scoping session to present overviews 

of the NPS Inventory and Monitoring (I&M) program, 

the GRD, and the ongoing GRE. Round- table 

discussions involving geologic issues for all parks in the 

National Capital Region included the status of geologic 

mapping efforts, interpretation, paleontologic resources, 

sources of available data, and action items generated 

from this meeting. 

Geologic Mapping 

Existing Geologic Maps and Publications 

The index of published geologic maps is a useful 

reference for the NCR. However, some of these maps are 

dated and in need of refinement; in other places, no 

existing large- scale coverage is available. Through their 

project to map the Baltimore- Washington, D.C., area at 

1:100,000 scale, the USGS learned that modern, largescale geologic mapping of the NCR NPS areas would be 

beneficial to NPS resource management. 

The USGS therefore proposed to re- map the NCR at 

large scale (1:24,000 or greater) accompanied by digital 

geologic databases. Scott Southworth (USGS- Reston, 

VA) is the project leader and main contact. The original 

PMIS (Project Management Information Systems) 

statement is available on the NPS intranet (PMIS number 

60900). 

Desired Enhancements in the Geologic Maps for NCR Parks 

To facilitate the geologic mapping, Scott Southworth 

would like to obtain better topographic coverage for 

each of the NCR units. Tammy Stidham knows that some 

of these coverages are already available and will supply 

them to Scott and the USGS. In general, anything in 

Washington, D.C., proper has 1- meter topographic 

coverage and Maryland’s Prince George's County has 

1:24,000 coverage. 

Notes on Wolf Trap National Park for the Performing 

Arts 

Wolf Trap Farm (WOTR) has 1:24,000- scale 

topographic coverage. 

Digital Geologic Map Coverage 

The USGS will supply digital geology in ArcInfo format 

for all NCR parks. GRE staff will add the Windows help 

file and NPS theme manager capability to the digital 

geology and will supply to the region for distribution to 

each NCR park. 

Other Desired Data Sets for NCR 

Soils 

Pete Biggam (GRD Soil Scientist) supplied the following 

information about park soils: National Capital Parks—

Central is covered by the "District of Columbia" Soil 

Survey (State Soil Survey Area ID MD099). It has been 

mapped, and is currently being refined to match new 

imagery. An interim digital product is available via 

NRCS, but the "final certified" data set most likely will 

not be available until FY03. National Capital Parks—East 

is covered by portions of three soil survey areas: "District 

of Columbia" (MD099), "Charles County, Maryland" 

(MD017), and "Prince George's County, Maryland" 

(MD033). Both Charles and Prince George's Counties 

are currently being updated, with Charles County 

scheduled to be available sometime in 2002, and Prince 

George's County sometime in 2003. 

Paleontology 

• Greg McDonald (GRD Paleontologist) recommends a 

systematic paleontological inventory for the NCR, 

describing the known resources in all parks, with 

suggestions on how to best manage these resources. 

His current database shows parks containing 

paleontological resources in NACE and NCR. 

Geologic Report 

A "stand- alone" encompassing report on each park’s 

geology is a major focus of the GRE. The proposed 

USGS mapping of the NCR will include a report 

summarizing the major geologic features of each park. 

Participants recommended that a regional physiographic 

report be completed for the entire NCR after the 

individual reports are finished. 
 NPS Geologic Resources Division 30 

List of Attendees for NPS National Capital Region Workshop 

NAME AFFILIATION PHONE E- MAIL 

Joe Gregson NPS, Natural Resources 

Information Division 970- 225- 3559 Joe_Gregson@nps.gov 

Tim Connors NPS, Geologic Resources 

Division 303- 969- 2093 Tim_Connors@nps.gov 

Bruce Heise NPS, Geologic Resources 

Division 303- 969- 2017 Bruce_Heise@nps.gov 

Lindsay 

McClelland 

NPS, Geologic Resources 

Division 202- 513- 7185 Lindsay_mcclelland@nps.gov 

Scott Southworth USGS 703- 648- 6385 Ssouthwo@usgs.gov 

Pete Chirico USGS 703- 648- 6950 Pchirico@usgs.gov 

Pat Toops NPS, NCR 202- 342- 1443, ext. 212 Pat_toops@nps.gov 

James Voigt NPS, CATO 301- 416- 0536 Cato_resource_management@nps.

gov 

Marcus Koenen NPS, NCR 202- 342- 1443, ext. 

216 

Marcus_koenen@nps.gov 

Ellen Gray NPS, NCR 202- 342- 1443, ext. 

223 

Ellen_gray@nps.gov 

Dale Nisbet NPS, HAFE 304- 535- 6770 Dale_nisbet@nps.gov 

Suzy Alberts NPS, CHOH 301- 714- 2211 Susan_alberts@nps.gov 

Dianne Ingram NPS, CHOH 301- 714- 2225 Dianne_ingram@nps.gov 

Bill Spinrad NPS, CHOH 301- 714- 2221 William_spinrad@nps.gov 

Debbie Cohen NPS, ANTI 301- 432- 2243 Debbie_cohen@nps.gov 

Ed Wenschhof NPS, ANTI/MONO 301- 432- 2243 Ed_wenschhof@nps.gov 

Ann Brazinski NPS, GWMP 703- 289- 2541 Ann_brazinski@nps.gov 

Melissa Kangas NPS, GWMP 703- 289- 2542 Melissa_Kangas@nps.gov 

Barbara Perdew NPS, GWMP 703- 285- 2964 Barbara_Perdew@nps.gov 

Barry Wood NPS, GWMP 703- 289- 2543 Barry_wood@nps.gov 

Marie Sauter NPS, CHOH 301- 714- 2224 Marie_frias@nps.gov 

Carol Pollio NPS, PRWI 703- 221- 2176 Carol_pollio@nps.gov 

Duane DonnellyMorrison NPS, PRWI 703- 221- 6921 Duane_donnellymorrison@nps.gov 

Diane Pavek NPS- NRS 202- 342- 1443, ext. 

209 

Diane_Pavek@nps.gov 

Chris Jones NPS- WOTR 703- 255- 1822 Christopher_Jones@nps.gov 

Doug Curtis NPS- NCR- NRS 202- 342- 1443, ext.228 Doug_Curtis@nps.gov 

Brent Steury NPS- NACE 202- 690- 5167 Brent_Steury@nps.gov 

Dave Russ USGS 703- 648- 6660 Druss@usgs.gov 

Tammy Stidham NPS- RTSC 202- 619- 7474 Tammy_stidham@nps.gov 

Dan Sealy NPS- GWMP 703- 289- 2531 Dan_Sealy@nps.gov 

Sue Salmons NPS- ROCR 202- 426- 6834, ext. 33 Sue_salmons@nps.gov 
 WOTR Geologic Resource Evaluation Report 31

Appendix C: Report of the NPS Monitoring Workshop

Planning for the Future in the National Capital Network 

The following excerpts are from the National Capital Network monitoring workshop 

held on July 9- 11, 2002, in Shepherdstown, West Virginia. This appendix includes pages 

29- 44 of the original workshop report; their content is directly relevant to the geologic 

resource evaluation of Wolf Trap National Park for the Performing Arts. 

B. Geology Workgroup 

Purpose: 

Continue the development of vital signs indicators for 

geologic resources in the National Capital Region of the 

National Park Service to provide essential information 

needed to preserve and enhance the region’s most 

important geologic resources. 

Outcomes: 

1) Complete the geology table from previous meetings, 

allowing time to clarify items already in the table and 

identify additional information gaps 

2) Prioritize items in the geology table for future 

monitoring efforts 

3) Develop monitoring objectives for high priority 

threats in the geology table. 

4) Develop a list of potential protocols that would meet 

the above monitoring objectives from the geology table. 

Overview 

This breakout session began by reviewing the conceptual 

model describing the geologic resources developed by 

the geology workgroup of the SAC including (1) resource 

components, (2) stressors to those resources, (3) sources 

of stressors, (4) ecological effects, and (5) potential vital 

signs monitoring indicators. Terminology was clarified, 

existing information was edited, and new information 

was added. The results of this discussion are captured in 

Table 4 below. 

One point that was not captured in Table 4 (but which 

should be noted) is that the geology workgroup 

examined soil from an agricultural perspective, rather 

than from an engineering perspective. In addition, 

several people in the group commented that geology is 

an integrative, long- term perspective for monitoring, 

although there are both short- and long- term indicators 

that may be used to examine threats to the geological 

resources in the NCN. 

Other topics of discussion during the morning session 

were urban soils and "engineered or created landscapes". 

Urban soils are generally horticultural in context, some 

of which may be "engineered" but, by far, most urban 

soils are not. Urban soils tend to be non- agricultural or 

non- forest situations where man has, to one degree or 

another, manipulated the landscape such that the natural 

soil regime no longer exists. In most cases, soil structure 

has been lost or redeveloped. In many cases, urban soils 

were composed from subsurface soils and, therefore, 

nothing resembling an "A" horizon exists. 

Urban soils are often compacted, resulting in high bulk 

densities, and, as a result, have reduced oxygen content 

(e.g. trails, campsites, etc.). In addition, these soils are 

poorly drained, low in organic matter, retain little 

moisture, may be disconnected from the water table or 

capillary water, could be contaminated or have 

considerable "artifacts" (ash, glass, etc.), and are often 

depauperate in microfauna (bacteria, fungi) and 

macrofauna such as worms (even if most worms are 

non- native). Thus, many of the highly important 

landscape areas of National Capital Region, including the 

National Mall, battlefield cemeteries, visitor centers, 

picnic areas, trails, tow paths, etc., are places where 

manipulated soils need to be understood from their 

creation, through use and then management. 

In addition, created landscapes were identified as one of 

the more unique, geological components of the National 

Capital Network (and especially, Washington DC), and 

for which the group felt that very little information 

currently was available. On one hand, these changed 

environments could lead to increased diversity - due to 

the potentially more- complex mosaic of soils and 

resulting vegetation communities. On the other hand, 

these landscapes are commonly affected by human 

manipulation, horticultural and agricultural practices, 

and urban landscaping efforts, all of which tend to lower 

biodiversity and lead to an increased occurrence of 

exotic species. 

Several potential research topics were also discussed: 

historical records of floods, sedimentation, and land use 

in the region. Historical records of floods should be 

relatively easy to find for the National Capital Region. 

For example, Metro records and historical documents 

may provide an indication of historic structures affected 

by flooding on a sequential basis. In addition, Jim 

Patterson (NPS - retired) may have a lot of background 

information on NCR parks. 

Sediment coring may also be used to provide a historical 

perspective on sediment "cycling" throughout the 

history of this region. The use of aerial photos, as 

available, may provide the necessary data to examine 

land use change over time, changes in stream 

morphology over time, and shoreline change over time. 
 NPS Geologic Resources Division 32 

Finally, through the use of newer technologies such as 

LIDAR and GPS, it is possible to examine changes in 

topography and geomorphology, at a fine scale, which is 

especially important in the Piedmont and Coastal Plain 

areas of the National Capital Region that have little or no 

topographic relief (e.g. Dyke Marsh). 

In the afternoon session, the workgroup focused upon 

ways to condense the list of 30 threats to geological 

resources into a more manageable size (Table 5). This 

proved to be a difficult task due to the varied nature of 

some of the components in Table 4. The first two 

categories, (1) nutrients and contaminants and (2) 

erosion and sedimentation, were natural groupings of 

many of the entries in Table 4. The remaining 

components of Table 4 were more difficult to categorize 

because they did not fit nicely into a single group 

heading. However, the workgroup was finally able to 

group the components into the following subject 

headings: nutrient and contaminant cycling, sediment 

cycling, engineered lands and urban soils, shoreline 

change, geo- hazards, human influences within the park 

boundary, and human influences outside the park 

boundary. The group next began to prioritize these 

subject areas, but decided that some of these categories 

were too contrived, or overlapped too much, to be 

separated out in this way. 

The final geology working group session was held on 

Thursday morning. The group decided to continue 

through the prioritization process by beginning with the 

categories that they were satisfied with - nutrient and 

contaminant cycling, and sediment cycling. For these 

two groupings, the group suggested established 

protocols for monitoring, wrote monitoring goals and 

objectives and identified potential collaborators. Once 

this analysis was completed for nutrient/contaminant 

and sediment cycling, the discussion continued for 

engineered lands and urban soils, shoreline change and 

geo- hazards. 

The categories of human influences within the park 

boundary and human influences outside the park 

boundary were decided to be too broad and thus were 

eliminated from Table 4. 

Categories were then ranked by considering the 

significance of the threat to the parks in the NCN, which 

included the following factors: amount of area affected 

by the threat, intensity of the threat to the resource, 

urgency of the threat to the resource, monitoring 

feasibility, and cost of monitoring. 

By the end of the morning session, the group had 

decided upon the following categories, in priority order: 

nutrient and contaminant cycling, sedimentation and 

erosion, lack of understanding of engineered lands, 

shoreline change and geo- hazards. The workgroup then 

went back through Table 4 to assign all 30 elements to 

one (or more) of these specific groupings. 

In addition to the work above, the workgroup noted 

information needs and studies of interest throughout the 

discussion. These are summarized below. 

Information Needs: 

A more recent and complete soils map for the region is 

needed. 

Inventory information regarding land changes and the 

creation of lands for baseline data as well as how these 

lands change towards equilibrium is needed. 

Are locations of air quality monitoring stations that also 

capture atmospheric deposition known? They need to be 

checked at the National Atmospheric Deposition 

Program (http://nadp.sws.uiuc.edu) or discussed with 

the air workgroup. 

What about non- point source pollution monitoring in 

the region? 

Is anyone considering the effects of acid rain on 

monuments in the region? There was, at one time, a 

long- term monitoring project regarding this process (in 

DC)? 

Has anyone examined the flood and floodplain history of 

this area? 

Previous studies of interest in NCR: 

There were studies at 4- Mile Run beginning in the 1950's 

(pre- urbanization) to look at or capture the effects of 

urbanization. 

Jeff Houser (Oak Ridge) has looked at the effects of 

sedimentation on streams and stream biota. 

Personnel Involved: 

Facilitators: Christina Wright, NPS – NCN I & M 

Program and Dale Nisbet, NPS – HAFE 

Participants: Joe Calzarette, Michelle Clements, Sid 

Covington, Dick Hammerschlag, Bob Higgins, Wright 

Horton, Lindsay McClelland, Wayne Newell, Scott 

Southworth, L. K. Thomas, and Ed Wenschhof.
 WOTR Geologic Resource Evaluation Report 33

Table 4. Revised conceptual model for geological resources in the NCN. 

Resource 

Component Stressor Sources Ecological Effects 

Priority of 

Threat to 

Resource 

Grouping 

used in 

priority 

table 

Indicator/ Vital 

Sign Protocol Monitoring Goal 

Potential 

contacts or 

collaborators 

Soil Pesticide 

loading 

Agricultural, 

residential, and 

commercial use 

Accumulation 

of pesticides 

that adhere to 

soil particles, 

causing changes 

to or the 

elimination of 

non- target soil 

fauna 

populations 

High 1 

Test soils and 

sediment for suite 

of pesticides 

commonly used in 

local area 

Lithogeochemical 

studies (USGS), 

mass balance or 

input/output 

approach 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 

Soil/Bedrock Nutrient 

loading 

Agricultural, 

residential and 

commercial use 

Acidification of 

the soil, 

reduction of soil 

organic matter, 

change in soil 

fertility status 

High 1 

Soil pH, soil N and 

P status, soil 

organic matter 

levels 

Lithogeochemical 

studies (USGS), 

mass balance or 

input/output 

approach 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 

Soil/Bedrock 

Change in 

pH, loss 

of 

buffering 

capacity 

Acid rain, 

atmospheric 

deposition 

Change in 

vegetation 

types, 

mycorrhiza and 

other soil flora, 

fauna 

Unknown 1 

Soil pH, acid 

neutralizing 

capacity (ANC) 

Lithogeochemical 

studies (USGS), 

mass balance or 

input/output 

approach. Mass 

flow/hydrologic 

modeling. 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 

Soil 

Temperat

ure 

Change 

Climate change Changes in soil 

micro- climate Unknown, locally high 

Soil 

temperature/moist

ure regime, 

changes in soil 

flora, fauna and 

mycorrhiza suite 

Soil temperature and moisture monitoring. Soil organism 

analysis. 

Soil/Surficial 

Factors 

Clearing 

of land 

Soil surface 

exposure, 

development, 

agriculture, 

zoning laws 

(local and 

county 

governments) 

Loss of soil 

surface cover, 

increased soil 

surface and 

groundwater 

temperatures 

High 2 and 3 

Soil and 

groundwater 

temperature/moist

ure regime. 

Change in 

vegetation 

community. Land 

use change. 

Measurement of soil 

surface and 

groundwater 

temperature, 

monitoring of bare 

soils in region. Land 

use change analysis, 

vegetation 

community analysis. 

Use survey and 

analysis methods 

to evaulate 

changes in 

topography, 

sediment loading 

and water flow 

rates. 

Rebecca 

Beavers (NPS - 

GRD), Wayne 

Newell, Nancy 

Simon, Pete 

Chirico (USGS 

- Reston), EPA 

- Office of 

Water and 

ORD, USGS - 

NAWQA, 

Loren Setlaw 

(?), Doug Curtis 

(NPS - CUE), 

Don Weeks 

(NPS - Denver)
 NPS Geologic Resources Division 34 

Resource 

Component Stressor Sources Ecological Effects 

Priority of 

Threat to 

Resource 

Grouping 

used in 

priority 

table 

Indicator/ Vital 

Sign Protocol Monitoring Goal 

Potential 

contacts or 

collaborators 

Soil Erosion 

Development, 

land clearing, 

increasing 

impervious 

surface 

Increased 

siltation, 

reduced 

productivity/he

alth/abundance 

of soil, plants, 

and aquatic 

organisms 

High 2 and 4 

Sediment loading, 

increased 

sedimentation and 

changes in 

sedimentation 

patterns, land use 

change, change in 

topography, 

shoreline change, 

change in wetland 

extent and 

condition. 

Shoreline 

change/Wetland 

extent - aerial photo 

analysis. Change in 

topography - 

LIDAR, GPS. 

Changes in 

sedimentation - 

bedload analysis, 

storm water event 

sampling, total 

suspended solids, 

light penetration in 

water column. 

Condition of 

wetland - changes 

in wetland plant 

species, multiband 

aerial photography. 

Use survey and 

analysis methods 

to evaulate 

changes in 

topography, 

sediment loading 

and water flow 

rates. 

Rebecca 

Beavers (NPS - 

GRD), Wayne 

Newell, Nancy 

Simon, Pete 

Chirico (USGS 

- Reston), EPA 

- Office of 

Water and 

ORD, USGS - 

NAWQA, 

Loren Setlaw 

(?), Doug Curtis 

(NPS - CUE), 

Don Weeks 

(NPS - Denver)

Soil/Surficial 

Factors Erosion Development 

Change in 

“normal” 

sedimentation 

sequence and 

composition 

Unknown, 

low 2 and 4 

Increased 

deposition, change 

in scouring and 

deposition 

patterns, change in 

hydrologic flow 

regimes. 

See above protocols. 

Also, analysis of 

sediment cores, 

including an analysis 

of historical 

sediment records. 

Use survey and 

analysis methods 

to evaulate 

changes in 

topography, 

sediment loading 

and water flow 

rates. 

Rebecca 

Beavers (NPS - 

GRD), Wayne 

Newell, Nancy 

Simon, Pete 

Chirico (USGS 

- Reston), EPA 

- Office of 

Water and 

ORD, USGS - 

NAWQA, 

Loren Setlaw 

(?), Doug Curtis 

(NPS - CUE), 

Don Weeks 

(NPS - Denver)

Soil 

Change in 

vegetation

/exotics 

Development, 

nursery use of 

exotics 

Change in soil 

organic matter 

composition, 

changes in soil 

flora and fauna, 

pH, nitrification 

rates 

Unknown Exotic species monitoring and control measures, soil chemistry, soil organic 

matter levels, soil pH, soil nitrification rates 

Soil, creation of 

new soils 

Fill dirt: 

complete 

changes in 

soil 

physical 

and 

chemical 

compositi

on 

resulting 

from 

filling in 

land areas 

with soil 

from 

another 

location 

(esp. DC) 

Landfills, 

abandoned 

mines, land 

engineering 

Changed, 

destroyed, or 

new soil profile, 

change in 

chemical 

composition of 

soil, 

introduction of 

toxics, 

introduction of 

impervious 

structures into 

soil profile, 

compaction. 

Resultant 

changes to 

biodiversity and 

vegetation 

communities. 

Changes to 

hydrologic 

cycle. 

High - esp. 

urban 1 and 3 

Assessment and 

description of soil 

profile, change in 

subsurface 

temperatures, 

change in land 

surface elevation 

profile, movement 

of physical debris 

from land, soil 

compaction, 

change in 

biodiversity of 

flora and fauna 

Assessment and 

description of soil 

profile, surface and 

ground water 

monitoring 

(lithogeochemical 

studies), bulk 

density, porosity or 

other soil 

compaction 

measures. 

To understand 

the functioning 

and components 

of engineered 

landscapes 

(components - 

landfills, 

engineered soils, 

etc.) 

USDA - NRCS, 

Dick 

Hammerschlag 

(USGS - 

Patauxent), 

Wright Horton 

(USGS - 

Reston). Also 

see contacts for 

nutrient and 

sediment 

cycling. 
 WOTR Geologic Resource Evaluation Report 35

Resource 

Component Stressor Sources Ecological Effects 

Priority of 

Threat to 

Resource 

Grouping 

used in 

priority 

table 

Indicator/ Vital 

Sign Protocol Monitoring Goal 

Potential 

contacts or 

collaborators 

Soil Compacti

on Visitor Use 

Changes in 

vegetation 

survival, 

changes in soil 

physical 

properties, 

creation of soil 

crusts (an 

impervious 

surface). 

Urban, 

locally - high 1 and 3 

Monitor soil 

compaction, bulk 

density, porosity, 

or other soil 

compaction 

measures. 

Formation of soil 

crusts. 

Soil coring, bulk 

density, porosity or 

other soil 

compaction 

measures. 

To understand the effects of visitor 

use upon the soil profile - includes 

social and official trails. 

Soil Imperviou

s surfaces 

Paving, walls, 

armored banks 

Scouring, 

cutting/changin

g shoreline, 

flooding, 

High 1 and 3 

Increased velocity 

of storm water 

flow, land use 

change 

Storm water event 

sampling, aerial 

photos to examine 

land use change. 

To understand 

the effects of 

increasing 

impervious 

surfaces in the 

watershed upon 

hydrology. 

Pat Bradley - 

EPA, USGS - 

NAWQA, EPA 

- Office of 

Water 

Unique soils: 

calcareous and 

serpentine soils 

Lack of 

informati

on for 

these soils 

and soil in 

general 

Lack of 

information for 

these soils and 

soil in general 

Potential for 

damage to 

unknown/unma

pped resource 

unknown 1 Soils inventory 

work necessary. 

Complete, up- todate, high resolution 

soil maps 

N/A 

Pete Biggam - 

NPS, USDA - 

NRCS 

Groundwater 

Consumpt

ion of 

groundwa

ter in 

excess of 

replenish

ment 

Human, 

agricultural, 

residential, 

commercial use 

and domestic 

animal use 

Reduced 

groundwater 

quantity, and 

quality. Loss of 

springs and 

seeps, wetland 

loss, changed of 

soil saturation 

zones. Change 

in drinking 

water quality 

and quantity. 

High 1 and 2 

Changes in 

groundwater table, 

Changes or loss of 

springs and seeps, 

change in extent of 

wetlands, changes 

in soil moisture 

profile. 

Survey of groundwater table and groundwater chemistry. 

Groundwater flow monitoring wells 

Groundwater 

Introducti

on of 

toxics, 

acid 

drainage 

(natural 

and 

mining) 

Landfills, 

abandoned 

mines, land 

engineering, 

bedrock. 

Reduced 

groundwater 

quality 

high 1 

Change in 

groundwater 

quality, quantity, 

and temperature. 

Increased toxics in 

groundwater. 

Groundwater 

monitoring wells in 

conjunction with 

lithogeochemical 

studies (USGS), 

Mass balance or 

input/output 

approach 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 

Groundwater Physical 

Failure 

Landfills, 

abandoned 

mines, land 

engineering 

Change in 

subsurface 

water flow 

patterns, change 

in subsurface 

temperatures, 

introduction of 

contaminants 

High 5 

Groundwater 

monitoring wells 

(flow and 

mapping), 

subsurface 

temperature 

changes 

Aerial photo 

mapping of areas 

with potential 

physical failures. 

Park staff 

observations of 

potential geohazard sites. Expert 

analysis of geohazard sites on a 

periodic basis. 

To use 

observation and 

assessment to 

provide an early 

warning of 

physical failure in 

order to protect 

the resource, 

visitors, and park 

infrastructure. 

John Pallister, 

Bula Gori, 

Gerry Wieczoff 

- USGS 
 NPS Geologic Resources Division 36 

Resource 

Component Stressor Sources Ecological Effects 

Priority of 

Threat to 

Resource 

Grouping 

used in 

priority 

table 

Indicator/ Vital 

Sign Protocol Monitoring Goal 

Potential 

contacts or 

collaborators 

Groundwater 

Water 

bypasses 

the soil 

profile 

Old - 

abandoned 

wells (farms) 

Increased 

groundwater 

contamination 

with nutrients, 

pesticides and 

other chemicals 

Unknown 1 

Change in 

groundwater 

quality, increased 

toxics in 

groundwater. 

Groundwater 

monitoring and 

monitoring of 

abandoned wells in 

conjunction with 

lithogeochemical 

studies (USGS), 

Mass balance or 

input/output 

approach. 

Abandoned wells 

need to be found 

and sealed to 

minimize 

contamination. 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 

Groundwater Imperviou

s Surfaces 

Roads, 

buildings, 

infrastructure 

Reduced water 

infiltration 

leading to 

reduced 

groundwater 

recharge, 

movement of 

water between 

watersheds 

Medium 1 and 2 Map and monitor groundwater recharge areas, monitor groundwater table 

levels and chemistry, subsurface temperature monitoring. 

Exposed rock 

Cutting 

the toe of 

slopes, 

oversteepened 

slopes, 

dipslopes 

Development, 

roads, 

structures, 

trails, flooding, 

vegetation 

death (hemlock 

etc.), logging 

Reduced slope 

stability Low 5 

Slope failure, 

reduced slope 

stability, 

movement of 

materials 

downslope, 

erosion, gully 

formation 

Aerial photo 

mapping of areas 

with potential 

physical failures. 

Park staff 

observations of 

potential geohazard sites. Expert 

analysis of geohazard sites on a 

periodic basis. 

Monitoring for 

gulley formation or 

increasing erosion. 

To use 

observation and 

assessment to 

provide an early 

warning of 

physical failure in 

order to protect 

the resource, 

visitors, and park 

infrastructure. 

John Pallister, 

Bula Gori, 

Gerry Wieczoff 

- USGS. Also 

see personnel 

under erosion 

categories. 

Karst 

Toxics: 

pesticides, 

dumping, 

spills 

Agriculture, 

septic systems, 

sewage, 

dumping, 

industry, spills 

Rapid 

movement of 

contaminants to 

ground water, 

change in 

ground water 

chemistry and 

resulting in 

change in 

biology 

High – 

locally 1 

Subterranean 

invertebrates, 

ground water 

chemistry/ quality 

Analysis of 

subterranean 

invertebrates. 

Lithogeochemical 

studies (USGS), 

Mass balance or 

input/output 

approach 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Smithsonian 

Institute 

Invertebrate 

specialists. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 
 WOTR Geologic Resource Evaluation Report 37

Resource 

Component Stressor Sources Ecological Effects 

Priority of 

Threat to 

Resource 

Grouping 

used in 

priority 

table 

Indicator/ Vital 

Sign Protocol Monitoring Goal 

Potential 

contacts or 

collaborators 

Karst Nutrient 

loading 

Agriculture, 

septic systems, 

sewage, 

dumping, 

industry, spills 

Rapid 

movement of 

nutrients to 

ground water 

resulting in 

change to 

ground water 

quality and 

change in 

biology 

High – 

locally 1 

Subterranean 

invertebrates, 

ground water 

nutrient content 

Analysis of 

subterranean 

invertebrates. 

Lithogeochemical 

studies (USGS), 

Mass balance or 

input/output 

approach 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Smithsonian 

Institute 

Invertebrate 

specialists. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 

Karst 

Structural 

collapse, 

sinkholes 

Inappropriate 

construction 

practices, 

dissolution in 

karst areas 

Change in 

biology due to 

changes in air 

flow and 

temperature, 

volume and 

flow of water 

increased in 

areas 

dissolution of 

bedrock 

High – 

locally 5 

Change in sinkhole 

size, aerial photos 

to capture surface 

changes, 

subsurface 

temperature 

monitoring 

Aerial photo 

mapping of areas 

with sinkholes. Park 

staff observations of 

potential geohazard sites. Expert 

analysis of geohazard sites on a 

periodic basis. 

To use 

observation and 

assessment to 

provide an early 

warning of 

physical failure in 

order to protect 

the resource, 

visitors, and park 

infrastructure. 

John Pallister, 

Bula Gori, 

Gerry Wieczoff 

- USGS 

Surface water Imperviou

s surfaces 

Infrastructure, 

development, 

residential and 

agricultural use, 

rip rap, 

armoring etc. 

Increased storm 

water flow, 

increased 

erosion, 

changes in 

sedimentation, 

changes in 

stream 

morphology, 

increased 

exposure to 

nutrients/pestici

des, change in 

hydrologic 

cycle effecting 

floodplains, and 

floodplain/ripar

ian buffer 

capacity, change 

in base flow 

High 1 and 2 

Stream storm 

water flow, flood 

frequency, 

sedimentation 

load, stream 

morphology. 

Photo points. 

Storm event 

sampling, Mass 

flow/hydrologic 

modeling 

Lithogeochemical 

studies (mass 

balance 

approach).Shoreline 

change/Wetland 

extent - aerial photo 

analysis. Change in 

topography - 

LIDAR, GPS. 

Changes in 

sedimentation - 

bedload analysis, 

storm water event 

sampling, total 

suspended solids, 

light penetration in 

water column. 

Condition of 

wetland - changes 

in wetland plant 

species, multiband 

aerial photography. 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. Use 

survey and 

analysis methods 

to evaluate 

changes in 

topography, 

sediment loading 

and flow rates. 

Rebecca 

Beavers (NPS - 

GRD), Owen 

Bricker, Nancy 

Simon, Wayne 

Newell, Pete 

Chirico, Wright 

Horton, David 

Russ (USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA - Office of 

Water, USGS - 

NAWQA 

Surface water Pesticide 

loading 

Agricultural, 

residential, and 

commercial use 

Reduced water 

quality, fishery 

health, and 

aquatic 

invertebrate 

communities 

and populations 

High 1 

Test for suite of 

pesticides 

commonly used in 

local area. 

Lithogeochemical 

studies (USGS), 

Mass balance or 

input/output 

approach 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 
 NPS Geologic Resources Division 38 

Resource 

Component Stressor Sources Ecological Effects 

Priority of 

Threat to 

Resource 

Grouping 

used in 

priority 

table 

Indicator/ Vital 

Sign Protocol Monitoring Goal 

Potential 

contacts or 

collaborators 

Surface water Nutrient 

loading 

Agricultural, 

residential and 

commercial use 

Reduced water 

quality, fishery 

health, and 

aquatic 

invertebrate 

communities 

and 

populations. 

Algal blooms, 

eutrophication 

High 1 

Soil water and 

stream levels of N 

and P. High algal 

growth, low light 

penetration 

Lithogeochemical 

studies (USGS), 

Mass balance or 

input/output 

approach 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 

Coastal areas Imperviou

s surfaces 

rip rap, 

armoring, 

coastal walls, 

dredging 

Changes in 

water flow 

rates, unnatural 

erosion and 

deposition, 

changes in 

natural 

shoreline, 

changes in 

sedimentation, 

wetland 

flooding, 

changes in 

wetland extent. 

High – 

locally 1 and 2 

Sedimentation 

coring (deep cores 

- research, shallow 

cores - 

monitoring), 

mapping of 

shoreline change, 

use of Pope's 

Creek as a 

reference area 

Using aerial photos 

or survey methods 

to map shoreline 

and shoreline 

change over time. 

Use mapping or 

survey methods 

to track changes 

in shoreline and 

depositional 

patterns, over 

time. 

NOAA (?) 

Lakes, ponds, 

seeps, vernal 

pools 

Nutrient 

loading 

Agriculture, 

residential lawn 

care, vegetation 

change 

Eutrophication, 

change in fauna 

(esp. herps), 

effect upon 

T&E species 

Unknown 1 

Size/volume, 

chemistry, and 

temperature of 

surface water 

component 

Lithogeochemical 

studies (USGS), 

Mass balance or 

input/output 

approach 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 

Lakes, ponds, 

seeps, vernal 

pools 

Pesticide 

loading 

Agriculture, 

residential, and 

commercial use 

Addition of 

herbicides and 

pesticides to 

surface water, 

change in fauna, 

effect upon 

T&E species 

Unknown 1 

Pesticide, 

herbicide content 

of surface water 

component 

Lithogeochemical 

studies (USGS), 

Mass balance or 

input/output 

approach 

Use an 

input/output 

approach to 

understand 

nutrient and 

contaminant 

cycling in the 

ecosystem. 

Owen Bricker, 

Nancy Simon, 

Wayne Newell, 

Wright Horton, 

David Russ 

(USGS - 

Reston), Mark 

Nellis (USGS - 

Denver), USDA, 

EPA, USGS - 

NAWQA 

Riparian areas, 

Wetlands 

Change in 

soil 

surface 

elevation 

and 

horizontal 

dimension

s 

Land 

engineering 

resulting in 

changes to 

deposition and 

erosion, 

dredging, 

dumping, 

creation of 

impoundments 

and dams 

Disruption to 

the 

wetland/riparia

n ecosystems, 

change in storm 

water flow 

rates, vegetation 

change, wildlife 

change, change 

in stream bed 

characteristics 

High 4 

High resolution 

riparian/ wetland 

elevation 

monitoring, 

vegetation 

monitoring, 

sediment budget, 

changes in size of 

wetland area 

Changes in wetland 

extent - aerial photo 

analysis. Change in 

topography - 

LIDAR, GPS. 

Changes in 

sedimentation - 

bedload analysis, 

storm water event 

sampling, total 

suspended solids, 

light penetration in 

water column. 

Condition of 

wetland - changes 

in wetland plant 

species, multiband 

aerial photography. 

Use survey and 

analysis methods 

to evaulate 

changes in 

topography, 

sediment loading 

and water flow 

rates. 

Rebecca 

Beavers (NPS - 

GRD), Wayne 

Newell, Nancy 

Simon, Pete 

Chirico (USGS 

- Reston), 

Richard 

Lowrance 

(USDA/ARS), 

EPA - Office of 

Water and 

ORD, USGS - 

NAWQA, 

Loren Setlaw 

(?), Doug Curtis 

(NPS - CUE), 

Don Weeks 

(NPS - Denver)
 WOTR Geologic Resource Evaluation Report 39

Table 1. Priority threats, vital signs, and monitoring goals and objectives for geological resources in the NCN. 

Threats (in priority 

order) Vital Sign Monitoring Goal Monitoring Objectives 

Nutrient and chemical 

contamination 

Changes in soil and 

groundwater chemistry. 

Use an input/output 

approach to understand 

nutrient and contaminant 

cycling in the ecosystem. 

(1) Measuring nutrient inputs from 

sources pertinent to each park unit. (2) 

Measuring contaminant inputs from 

sources pertinent to each park unit. (3) 

Tie information from numbers 1 and 2 

to the hydrologic cycle, flood history, 

flood effects, and flood impacts. 

Erosion and 

sedimentation 

Changes in topography, 

sediment loading and 

deposition, shoreline 

change, wetland extent 

and condition. 

Use survey and analysis 

methods to evaluate changes 

in topography, sediment 

loading, and flow rates. 

(1) Measure loss of soil, growth of 

gullies, changes in streambanks.... (2) 

Track sedimentation history, effects, 

and impacts (including streams and 

ponds, hillslopes and gullies). 

Lack of understanding 

of urban soils and 

engineered lands 

Compaction, runoff, 

chemical composition, 

soil profile and 

structure, biodiversity. 

To understand the 

functioning and components 

of urban soils engineered 

landscapes and their effects 

upon resident biota. 

Components include: highly 

impacted soil (compaction in 

and around trails, visitor 

centers), landfills, engineered 

soil, etc. 

(1) Measure changes to physical 

components of urban soils and 

engineered lands and correlate with 

changes in resident biota (and exotic 

species). (2) Measure contaminant 

outflow from landfills, abandoned 

mines, etc. 

Shoreline change 

Inundation of wetlands, 

erosion and 

sedimentation 

processes. 

Use mapping or survey 

methods to track shoreline 

change and depositional 

patterns. 

(1) Measure shoreline change using 

aerial photos, LIDAR and survey 

methodologies and correlate changes 

to development, when possible. (2) Use 

sediment coring and historical data to 

understand long- term flood histories. 

Geo- hazard 

Physical failure, rock 

falls, landslides, 

sinkhole collapse. 

Use observation and 

assessment to provide an 

early warning of physical 

failure to protect the 

resource, visitors, and park 

infrastructure. 

(1) Monitor areas of potential hazard 

due to unstable slopes, rockfalls, etc. (2) 

Monitor for changes in unstable 

engineered sites or areas that are 

geologically active (e.g. Potomac 

Gorge). (3) Document and monitor 

areas underlain by swelling clays. 
 NPS Geologic Resources Division 40 

Appendix D: Geoindicators Notes 

NCR Geoindicators Meeting May 20, 2002 

Attendees: 

NPS 

Christine Wright, Data Manager, CUE 

Marcus Koenen, Monitoring Coord., CUE 

Pat Toops, Nat. Res. Chief, NCR 

Bob Higgins, GRD - Denver 

Sid Covington, GRD - Denver 

Lindsay McClelland, GRD - Washington 

Rijk Morawe, Nat. Resources Mgt. Specialist, GEWA 

USGS 

Nancy Simon, WRD 

Marty Gurtz, Water Quality Program 

Bill Bartlett, Water Quality Program 

Owen Bricker, WRD (Geochem./Hydrology) 

Wayne Newell 

Scott Southworth 

Peter Chirico 

Vital Signs Network - Marcus Koenen 

1. National Capital Region (NCR) began monitoring about 3 years ago. 

2. Planning process will help determine what the important issues are; what specific indicators need to be 

monitored. 

3. Final plan should be completed by Spring 2004. 

Geology Overview 

by Scott Southworth 

1. Antietam National Battlefield and Monocacy National Battlefield. 

a. Share similar geology. 

b. Underlain by carbonates; karst topography. 

2. Catoctin Mountain Park. 

a. Quaternary alluvium. 

b. Debris flows. 

c. Few slope hazard issues. 

d. Completely clear- cut by mid- 30s. 

3. Rock Creek; George Washington Mem. Parkway; Wolf Trap Farm; Prince William Forest. 

a. Share similar geology and issues. 

b. Similar land use, but different surfaces. 

c. Landscape has been extremely modified and altered (esp. Rock Creek). 

4. Prince William Forest. 

a. Acid mine drainage. 

b. Heavily forested; highly altered. 

5. General. 

a. Ground water is an issue in almost all the NCR parks. 

b. Data on river pollution should become available on a CD ROM. 

c. Need to look at processes along the strike of faults, esp. in Piedmont and Blue Ridge provinces. 

d. Potomac Conservancy Plan - developed by the NPCA; common link among geologic provinces. 

e. Lithochemical studies - study the path of nutrients through various rock lithologies (McClelland). 

f. Rates of erosion are increasing from the incising effects of runoff. 

Soils 

1. The chemistry of soils is based on the geology; how and from what rock type are the soils derived. 

2. Look at the "geochemical landscape". 

3. Soil studies are needed at Catoctin Mt.; can be used as an example. 

4. Partnering needed with the Natural Resources Conservation Service (NRCS). 

5. Biologists are most interested in soils developed from ultramafic rocks. 

6. Need long- term monitoring: 

a. Atmospheric stations to see what is coming in from the air (for example, acid deposition). 

b. Streamflow site monitoring. 
 WOTR Geologic Resource Evaluation Report 41

c. Suite of biological components to monitor change. 

7. Need to monitor what comes into the system, what is in the system, and what leaves the system. 

George Washington Birthplace (Nancy Simon) 

1. Maybe less altered; looking at "natural" processes: sediment transport from pastures fertilized with sewage 

sludge from sewage treatment plants. 

2. Compare with areas not using sludge, using GEWA as a reference site. 

3. Very good watershed to study; use as a baseline (also Oxon Run estuary, rather than Anacostia). 

4. Draw in surrounding people (landowners) to interpret study. 

5. Arboretum - has funding been cut? 

6. Need to look at: 

a. "Natural" (such as Catoctin) v. changing areas (such as George Washington Parkway). 

b. Parks with geologic similarities and compare with vegetation (Toops); similar vegetation areas may 

vary geologically along strike. 

c. A larger, more inclusive perspective - areas outside the parks that have similar characteristics. 

d. Water quality (w/NAQWA) and effects of urbanization. 

e. Certain indicator parks at different stages: 

(1) Unaltered ("natural"). 

(2) Slightly or moderately altered. 

(3) Greatly altered. 

(4) Altered, but recovering. 

f. Historical forestation (or deforestation); example: conditions during the Civil War (Chirico). 

Geoindicators Worksheet 

1. Surface Water 

a. Stream channel morphology: 

(1) C & O Canal (no jurisdiction of channel). 

(2) Antietam Creek. 

(3) Catoctin Mt. 

(4) Manassas - Bull Run Creek. 

(5) Rock Creek - greatly affected by urbanization; removing barriers to herring spawning. 

(6) George Washington Parkway and Great Falls – urbanized. 

b. Need to look at tributaries as well as major streams. 

c. Human impacts on surface water flow (Chirico). 

(1) What was the topography prior to human impact? Some streams have been filled 20- 30 

meters with coal ash, brick, dirt fill; Tiger Creek is now the Red Metro line. 

(2) What do we monitor from now on? 

(3) Streams have been converted to wastewater and stormwater discharges. 

(4) Some trend exists to "daylight" streams - reopening streams that were buried, exposing the 

stream bed down to the drainage pipes. 

(4) Much of the urbanized land that was cleared has been stripped and moved down into 

stream valleys; this can be studied by coring (Bricker). 

(5) There has been a flattening out of the topography by removing hills and filling in the 

streams; changes in slope affect channel morphology; between 1888 and today, the amount of 

material removed is equivalent to the material deposited by Mount St. Helens in 1980. 

(6) Surface streams have been converted to groundwater channels; comparisons of surface 

drainage from 1888 to 1999 shows very little similarity; difficult to compare. 

(7) Look at old studies and publications: Leopold, Walden, Hack. (Newell). 

d. Need better topography data: 

(1) Topographic data for Catoctin Mt. is very poor. 

(2) Counties are doing better work and producing better maps than the GS. Sometimes the data 

are available but not to the Federal agencies; may need to purchase. 

e. What kind of data is needed for streamflow? Not much baseline data; need cross sections; not much 

streamflow data in D.C. metro area; how important are streams to a particular unit? 

f. Maybe need to look at the geoindicator table as, for example, what factors affect stream morphology? 

g. Need "event sampling" - sample streams during flood or high water events (Simon). 

h. Streamflow is more than just monitoring; need index of hydrologic alteration (Nature Conservancy); 

how has streamflow changed? look at historical versus today's conditions; TNC has added predictability 

and looks at it slightly differently than the GS; need to look at historical data; in some cases, we have the 

information but no analysis of the data (Gurtz). 
 NPS Geologic Resources Division 42 

2. Sediment Influx 

a. Oxon Run; GW Parkway below National AP (Dike Marsh); Anacostia; C&O Canal (effects of locks 

and channelization); Piscataway Creek (Newell). 

b. What does park management want the parks to look like? Need to know where you want to go; for 

example, should we be looking at the morphology of Bull Run Creek at Manassas? (Toops) 

c. Look at what will happen if we further alter a stream (Gurtz). 

3. Wetlands 

a. Not a major issue. 

b. Anacostia has recreated/is recreating wetlands. 

c. Some studies done by the D.C. Dept. of Health and USGS MD District. 

d. NOAA studies mostly water quality. 

4. Groundwater 

a. Groundwater level: 

(1) Level in Maryland is dropping, wells are running dry; vegetation is probably changing; 

moratorium on new home construction in Frederick Co., Md., due to low groundwater level. 

(2) Drought and growth have made ground water a big issue; removal is outpacing recharge 

(surface water is still sufficient for now; Potomac is heavily used for water and for sewage, runoff and sewage treatment recharge). 

(3) Maryland has a network of 17 monitoring wells. 

b. Groundwater quality: 

(1) Does the NPS need to drill monitoring wells to monitor level and quality and impact on 

biota (especially plants, amphibians)? 

(2) Manassas, Antietam, Catoctin, and Anacostia all need monitoring wells (Newell and 

Chirico). 

(3) Aquifers (except in the Coastal Plain) are fairly small and isolated in fault blocks, lithology, 

and fractures; no large aquifers like in the Midwest. 

5. Karst 

a. Karst topography at Antietam, C&O Canal, and Harpers Ferry. 

b. Seeps and springs are important to some parks: C&O Canal has streams that flow into underground 

karst and seep out into the Potomac. 

c. Southworth has done some mapping in the C&O Canal/Antietam area. 

d. C&O has 8 abandoned mines and 14 caves; no active cave interpretation; some of the caves are open, 

but not a major resource to the park. 

e. Problems with contamination from pesticides, fertilizers, sewage, run- off, others. 

6. Hazards 

a. Colluvial rock slides an issue at Harpers Ferry. 

7. Relative Sea Level 

a. Most shorelines are armored (see: Andy Miller, USGS, Rates of erosion around the Potomac area). 

b. George Washington Birthplace (GEWA). 

(1) Mouth of Popes Creek has an accreting delta derived from eroded material at GEWA. 

(2) Cores from Popes Creek show agricultural influx from about 1650 on; can see effects of land 

clearing, tobacco farming, and other agricultural uses in cores. 

(3) Need PMIS statement for coring. 

c. Need to document changes in shoreline both historically and from recent events. 

d. What are the impacts of armoring, and what would be the impacts of further armoring? 

e. Piscataway Park - shoreline erosion. 

f. Shorelines around the NCR coastal parks have been greatly altered. 

8. Soils (Redux) 

a. Soils are derived from a variety of basement rocks: limestones, saprolites, red shales, and quartzites. 

b. Coastal Plain - stripped of sediment and soils since Colonial time (~1650); soil dumped into streams. 

c. Beavers have become an important factor by retarding the loss of sediment. 

d. Indicators: Change in acidity; Ca and Mg replaced by Al. 

e. Monitor acid deposition (PMIS?); where? 
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. 

Wolf Trap National Park for the Performing Arts 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2008/041 

NPS D-43, June 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 

Chief • Dave Steensen 

Planning Evaluation and Permits Branch Chief • Carol McCoy 

Credits 

Author • Trista Thornberry- Ehrlich

Review • Lindsay McClelland and Carol McCoy 

Editing • Lorna Carter and Melanie Ransmeier 

Digital Map Production • Stephanie O'Meara 

Map Layout Design • Andrea Croskrey
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