National Park Service U.S. Department of the Interior

Natural Resource Program Center

Monocacy National Battlefield Geologic Resource Evaluation Report

Natural Resource Report NPS/NRPC/GRD/NRR—2008/051

Monocacy National Battlefield Geologic Resource Evaluation Report

Natural Resource Report NPS/NRPC/GRD/NRR—2008/051

Geologic Resources Division Natural Resource Program Center P.O. Box 25287 Denver, Colorado 80225

September 2008

U.S. Department of the Interior Washington, D.C.

COVER: Visitor Center Creek, Monocacy National Battlefield INSIDE COVER: Thomas Farm Pond, Monocacy National Battlefield

NPS Photos by National Capital Region Network Staff The Natural Resource Publication series addresses natural resource topics that are of interest and applicability to a broad readership in the National Park Service and to others in the management of natural resources, including the scientific community, the public, and the NPS conservation and environmental constituencies. Manuscripts are peer-reviewed to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and is designed and published in a professional manner.

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.

Views, statements, findings, conclusions, recommendations and data in this report are solely those of the author(s) and do not necessarily reflect views and policies of the U.S. Department of the Interior, National Park Service. Mention of trade names or commercial products does 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 online from the Geologic Resource Evaluation Program website (http://www2.nature.nps.gov/geology/inventory/ gre_publications) and the Natural Resource Publication Management website (http:// www.nature.nps.gov/publications/NRPM/index.cfm) or by sending a request to the address on the back cover. Please cite this publication as:

Thornberry-Ehrlich, T. 2008. Monocacy National Battlefield Geologic Resource Evaluation Report. Natural Resource Report NPS/NRPC/GRD/NRR—2008/051. National Park Service, Denver, Colorado.

NPS D-78, September 2008

Table of Contents

List of Figures ...... iv

Executive Summary ...... 1

Introduction ...... 2 Purpose of the Geologic Resource Evaluation Program ...... 2 History of Monacacy National Battlefield ...... 2 Geologic Setting ...... 2

Geologic Issues...... 6 Erosion and Slope Processes...... 6 Sediment Load and Channel Storage...... 6 Water Issues...... 6 Recreational Demands ...... 8 Soil ...... 9 Paleontology...... 9 Geology Education and Research...... 9

Geologic Features and Processes...... 10 Geologic Setting and Military History of Monocacy National Battlefield...... 10 Flooding of the Monocacy River ...... 10 The Blue Ridge Anticlinorium and Frederick Valley...... 11 Caves and Karst Formation...... 11 Geology and Archaeology ...... 11 Historical Preservation...... 12

Map Unit Properties ...... 15 Map Unit Properties Table...... 16

Geologic History...... 17

Glossary...... 22

References...... 26

Appendix A: Geologic Map Graphic ...... 28

Appendix B: Scoping Summary...... 31

Attachment 1: Geologic Resource Evaluation Products CD

MONO Geologic Resource Evaluation Report iii List of Figures Figure 1. Map of Monocacy National Battlefield...... 4 Figure 2. Location of Monocacy National Battlefield relative to geologic features...... 5 Figure 3. Regional map of Confederate Troop movement in 1864...... 12 Figure 4. Map of Monocacy area showing troop movement during 1864 battle ...... 13 Figure 5. The Monocacy Aqueduct ...... 14 Figure 6. Monocacy Junction ...... 14 Figure 7: Geologic time scale...... 20 Figure 8. Evolution of the landscape in the Monocacy area...... 21

iv NPS Geologic Resources Division Executive Summary

This report accompanies the digital geologic map for Monocacy National Battlefield in Maryland, which the Geologic Resources Division produced in collaboration with its partners. It contains information relevant to resource management and scientific research.

Monocacy National Battlefield is preserved to to change the landscape. The need to balance historic commemorate the men who fought on its soil in 1864 and natural preservation and restoration with recreation during the American Civil War. The landscape reflects a makes resource management a challenge. unique geologic history that spans from the ancient Precambrian through the formation of the Appalachian The following issues have geologic significance for Mountains, and from the more recent Ice Age events to management of the park: the modern day. Every landscape is determined by its • Erosion and slope processes past and present underlying geologic structure. The landscape begins with the geology, and the processes that The relatively wet climate of the eastern United States, shaped today’s environments, history, and scenery. combined with severe storms, loose soils along slopes, and active streams at Monocacy National Battlefield, Knowledge of geologic resources can directly support creates a setting that is especially susceptible to resource management decisions that address geologic slumping, slope creep, and erosion of stream banks. issues, air and water quality, urbanization, flood risk, Increased runoff can dramatically alter the landscape, wildlife populations, invasive species, future scientific creating new hazardous areas in the process, and may research projects, and interpretive needs associated with also clog streams with excess sediment, which affects the park. hydrologic systems and aquatic life. • Sediment load and channel storage Geologic processes give rise to a landscape composed of Erosion of the landscape at Monocacy leads to rock formations, hills and valleys, waterfalls, and increases in the sediment carried by the rivers in the wetlands. This landscape played a prominent role in the park. Sediment loads and distribution affect aquatic movement of troops and battle locations during the Civil and riparian ecosystems (including drinking-water War. Local geology dictated the placement of bridges, supplies). Sediment loading can result in changes to fords, and railroads, which in turn informed military channel morphology and increased frequency of strategy. Today, geologic processes continue to develop a overbank flooding. Fine-grained sediments also serve landscape that influences human use patterns. The to transport contaminants in a water system. connection between history and geology inspires visitors, • and emphasis on geologic resources will enhance the Water issues visitor’s experience. Floods are a natural process along many rivers, creating fertile floodplains and washing away The rocks of central Maryland reflect the powerful accumulated debris. However, seasonal flooding of the tectonic forces responsible for the Appalachian Monocacy River threatens the historic context of the Mountains. Precambrian gneiss, metavolcanic rocks, and battlefield and surrounding areas. Protecting these younger (Paleozoic) quartzite and phyllite underlie the features and cultural resources along the banks of the hills visible to the west of Monocacy. The entire region river requires an understanding of the relationships was compressed during three separate tectonic events, between geology, the hydrologic system, and biology the Taconic, Acadian, and Alleghenian orogenies. throughout the park. Following this compression, a series of fault-bounded extension basins, such as Frederick Valley, developed in Other geologic parameters and issues, such as the Triassic. These basins filled with sediment shed from recreational demands, water issues, agricultural the mountains. pollution, and geologic education and research, have also been identified as critical management issues for Humans have significantly modified the landscape of Monocacy National Battlefield. These are described Monocacy by developing dams, trails, buildings and further in the Geologic Issues section of this report. farms, roads, bridges and streamworks, as well as polluting the air and water. Geologic processes continue

MONO Geologic Resource Evaluation Report 1 Introduction

The following section briefly describes the National Park Service Geologic Resource Evaluation Program and the regional geologic setting of Monocacy National Battlefield.

Purpose of the Geologic Resource Evaluation Program History of Monacacy National Battlefield The Geologic Resource Evaluation (GRE) Program is Monocacy National Battlefield is located in Frederick one of 12 inventories funded under the NPS Natural County, Maryland. It was established as a National Resource Challenge designed to enhance baseline Memorial Park on June 21, 1934, and redesignated a information available to park managers. The program National Battlefield on October 21, 1976, by an act of carries out the geologic component of the inventory Congress in order to preserve and commemorate the effort from the development of digital geologic maps to sacrifices made during the American Civil War. providing park staff with a geologic report tailored to a park’s specific geologic resource issues. The Geologic The name Monocacy comes from the Shawnee name for Resources Division of the Natural Resource Program the river “Monnockkesey” which means “river with Center administers this program. The GRE team relies many bends.” This winding river set the stage for the heavily on partnerships with the U.S. Geological Survey, battle fought there in 1864. The 1864 Battle of Monocacy Colorado State University, state surveys, and others in Junction was fought on the east bank of the Monocacy developing GRE products. River on July 9, 1864, along what is now Maryland Route 355. Union troops attempted to burn all bridges across The goal of the GRE Program is to increase the river, but the Confederates were able to cross late in understanding of the geologic processes at work in parks the day. and provide sound geologic information for use in park decision making. Sound park stewardship relies on The landscape of the park consists of rolling hills and understanding natural resources and their role in the river valleys. Brooks Hill provides a scenic view of much ecosystem. Geology is the foundation of park of the battlefield area (fig. 1). Over this hill the ecosystems. The compilation and use of natural resource Confederate attacks proceeded towards Union troops at information by park managers is called for in section 204 the Thomas Farm. The attack stretched from the of the National Parks Omnibus Management Act of 1998 Monocacy River almost to Baker Valley Road to the and in NPS-75, Natural Resources Inventory and southeast. Fighting continued over to Georgetown Pike, Monitoring Guideline. and the Union retreat crossed the Baltimore and Ohio (B&O) Railroad towards Baltimore. To realize this goal, the GRE team is systematically working towards providing each of the identified 270 The boundaries of the park have changed several times natural area parks with a geologic scoping meeting, a since its beginning. Though created in the 1930s, land digital geologic map, and a geologic report. These was not purchased until the 1980s and the park was not products support the stewardship of park resources and opened until 1991. The 1,647 acre park attracted 22,125 are designed for non-geoscientists. During scoping visitors in 2007. In addition to its rich historical context, meetings the GRE team brings together park staff and the park provides recreational opportunities and a geologic experts to review available geologic maps and sanctuary for many species in the urbanized Frederick discuss specific geologic issues, features, and processes. area.

The GRE mapping team converts the geologic maps Geologic Setting identified for park use at the scoping meeting into digital The geology affected the 1864 Battle of Monocacy geologic data in accordance with their innovative Junction on regional and local levels. Two large rivers, Geographic Information Systems (GIS) Data Model. the Monocacy and the Potomac, shaped the course of These digital data sets bring an exciting interactive military movements in the area before the battles. Safe dimension to traditional paper maps by providing river crossings were vital to military success during the geologic data for use in park GIS and facilitating the Civil War. incorporation of geologic considerations into a wide range of resource management applications. The newest The Monocacy River is the third largest tributary of the maps come complete with interactive help files. As a Potomac River. The free-flowing river is approximately companion to the digital geologic maps, the GRE team 93 km (58 mi) long and is fed by a drainage area of prepares a park-specific geologic report that aids in use 1,927 km2 (744 mi2). The river begins at the confluence of of the maps and provides park managers with an Marsh Creek and Rock Creek in Adams County, overview of park geology and geologic resource Pennsylvania, and ends at its confluence with the management issues. Potomac near Dickerson, Maryland. Tributaries of the river in the battlefield area include Furnace Branch, For additional information regarding the content of this Double Pipe Creek, and Stony Creek in Maryland and report and up to date GRE contact information please Tom’s Creek in Pennsylvania. refer to the Geologic Resource Evaluation Web site (http://www.nature.nps.gov/geology/inventory/).

2 NPS Geologic Resources Division The area’s smaller streams played a significant role in the The eastward-sloping Piedmont Plateau was formed actual fighting at Monocacy by creating important through a combination of folding, faulting, uplift and topographic differences and tactical targets such as erosion. These processes resulted in an eastern landscape railroad bridges, crossings, gaps, gulleys, and protective of gently rolling hills starting at 60 m (200 ft) in elevation cover. On the gentle landscape of Monocacy, even the that becomes gradually steeper towards the western edge smallest swell or depression was utilized for tactical of the province at 300 m (1,000 ft) above sea level. The advantage. Piedmont Plateau is composed of hard, crystalline igneous and metamorphic rocks such as schist, phyllite, Monocacy National Battlefield is located east of the slate, gneiss, and gabbro. Catoctin Mountains, part of the northern end of the Blue Ridge, a physiographic subprovince of the Appalachian Within the Piedmont are a series of Triassic extensional Mountains (fig. 2). Forming the easternmost part of the basins formed by normal faults during crustal extension. Blue Ridge province of Maryland and northern Virginia, The faults opened basins (grabens) that were rapidly the Catoctin Mountains are a belt of Lower Cambrian filled with roughly horizontal layers of sediment. sediments and older metavolcanic rocks. The mountain Examples of these basins include the Frederick Valley, ridge extends 80 km (50 mi) along a discontinuous linear which hosts the park, and the Culpeper Valley of trend from Emmitsburg, Maryland to Leesburg, Virginia. northern Virginia. The park is in the Frederick Valley and is underlain by thick Triassic sediments just east of the Blue Ridge. The Blue Ridge Province downdropped Frederick Valley is bordered on the west The Blue Ridge Province extends from Pennsylvania to by a large normal fault. Georgia along the eastern edge of the Appalachian Mountains. It contains the highest elevations in the The following is a general description of several of the Appalachian Mountain system in North Carolina, near region’s physiographic provinces. Great Smoky Mountains National Park. Precambrian and Paleozoic igneous, sedimentary, and metamorphic Atlantic Coastal Plain Province rocks were uplifted during several mountain building The Atlantic Coastal Plain province is primarily flat events to form the steep, rugged terrain. Resistant terrain with elevations ranging from sea level to about Cambrian quartzite forms Blue Ridge, Bull Run 100 m (300 ft) in northern Virginia. It extends from New Mountain, South Mountain, and Hogback Ridge in York to Mexico. Sediments eroding from the Virginia (Nickelsen 1956). South Mountain and Catoctin Appalachian Highland areas to the west were Mountain, both anticlines, are two examples of the intermittently deposited on the Atlantic Coastal Plain pervasive folding in the Blue Ridge province. over the past 100 million years, forming a wedge-shaped sequence during periods of higher sea level. These Eroding streams have caused the narrowing of the deposits were then reworked by fluctuating sea levels northern section of the Blue Ridge Mountains into a thin and the continual erosive action of waves along the band of steep ridges, climbing to heights of coastline. approximately 1,230 m (4,000 ft). The Blue Ridge province is typified by steep terrain covered by thin, The Atlantic Coastal Plain province stretches from the shallow soils, resulting in rapid runoff and low ground- Fall Line east to the Chesapeake Bay and Atlantic Ocean. water recharge rates. The province continues as the submerged Continental Shelf province for another 120 km (75 mi) to the east. Valley and Ridge Province Atlantic Coastal Plain surface soils are commonly sandy The landscape of the Ridge and Valley physiographic or sandy-loams that are well-drained. Large streams and province is characterized by long, parallel ridges of rivers in the Atlantic Coastal Plain province, including resistant sandstone separated by valleys formed in more the James, York, and Potomac Rivers, are often easily eroded shale and carbonate rocks. This province influenced by tidal fluctuations. contains strongly folded and faulted sedimentary rocks in western Maryland. Piedmont Province The “Fall Line,” or “Fall Zone,” marks a transitional zone Areas dominated by carbonate formations exhibit karst where the softer, less-consolidated sedimentary rocks of topography. “Karst” is a term used to describe a region of the Coastal Plain to the east intersect the harder, more irregular topography characterized by sinks, resilient metamorphic rocks to the west to form an area underground streams, caves, and springs formed by of ridges and waterfalls and rapids. This zone covers water percolating through water-soluble rock. more than 27 km (17 mi) of the Potomac River from Little Falls Dam, near Washington, D.C., west to Seneca, The eastern part of the Ridge and Valley province is part Maryland. Examples of this transition are present in the of the Great Valley (Shenandoah Valley). It is connected Potomac Gorge of the Chesapeake and Ohio Canal to the Piedmont province by streams that cut through the National Historic Park. Encompassing the Fall Line, Blue Ridge Mountains. westward to the Blue Ridge Mountains, is the Piedmont physiographic province.

MONO Geologic Resource Evaluation Report 3

Figure 1. Map of Monocacy National Battlefield.

4 NPS Geologic Resources Division

Figure 2. Location of Monocacy National Battlefield relative to geologic features of the Blue Ridge Province in Maryland. Note also the locations of the Piedmont and Valley and Ridge physiographic provinces. Graphic adapted from a figure in Whitaker (1955).

MONO Geologic Resource Evaluation Report 5 Geologic Issues

A Geologic Resource Evaluation scoping session was held for Monocacy National Battlefield on April 30−May 2, 2001, to discuss geologic resources, address the status of geologic mapping, and assess resource management issues and needs. This section synthesizes the scoping results, in particular those issues that may require attention from resource managers.

Erosion and Slope Processes can result in changes to channel morphology and The topographic relief within and surrounding the park increase overbank-flooding frequency. is small. However, the likelihood of landslides and slumps increases with precipitation and undercutting of High suspended sediment load continues to be a slopes by streams, roads, trails, and other development. management problem at Monocacy National Battlefield. Landslide hazard models and maps could help park Seasonal floods and storms can increase sediment load to managers assess specific areas relative risk for landslide levels unsuitable for drinking-water suppliers, causing occurance. These tools use information about geology, occasional closure of drinking water-supplies upstream topology, and climate to identify hazardous areas. and increasing the need for chemical treatment in drinking water from the lower reaches of the watershed. Severe weather is difficult to predict. The Monocacy (http://www.acb-online.org/pubs/projects/deliverables- National Battlefield area of Maryland can receive large 150-4-2003.pdf [Accessed August 2008]). amounts of snow (e.g., 208 cm [82 in] in 1996) and is in a hurricane-affected zone. Periodic flooding of the However, fine-grained sediments are vital in the overall Monocacy River results from sudden, large inputs of fluvial transport of contaminants in a water system. precipitation. Extreme weather combined with moderate Channel storage of fine sediment (and the contaminants slopes and loose, unconsolidated soils and substrate can contained therein) follows a seasonal cycle. This cycle is lead to sudden, catastrophic slope failures. On slopes subject to hydrologic variability, with increased that lack stabilizing vegetation, rock and soil may availability during the high stands of spring and mobilize and slide downhill, resulting in a massive slump decreased availability during the low stands of autumn. or debris flow. In the vicinity of streams and rivers, this Fine-grained sediments do not travel downstream in a leads to shoreline erosion, increased sediment load, single pulse, but are often resuspended bottom material gullying, and the threat of destruction for trails, bridges, (Miller et al. 1984). This intermittent transport of and other features of interest. contaminants and fine-grained sediment increases the affected area and could pose a threat to the park if Increased erosion along the outer banks of bends in focused, severe contamination were to occur within the streambeds (where stream velocity is higher) causes the Monocacy River Basin in Maryland. bank to retreat, leading to undercutting and washout. Trees, trails, and other features along these banks are Inventory, Monitoring, and Research Suggestions for undermined. Trees fall across the stream, and trails are Sediment Load and Channel Storage washed out. Remedial structures such as cribbing, log • Study channel morphology of intense seasonal runoff. frame deflectors, jack dams, stone riprap, and/or log Consult professional geomorphologists about dams can shore up the bank, deflect the flow, and help to erosional processes. slow erosion (Means 1995). However, these same • Inventory morphological characteristics of channels structures may have deleterious effects when used at and monitor changes. inappropriate sites causing eddying and further degradation of the banks beyond the margins of the • Encourage reforestation along the Monocacy River to structures. act as a buffer to erosion and to filter incoming nutrients and pollution. Inventory, Monitoring, and Research Suggestions for Erosion and Slope Processes Water Issues • Monitor unstable slopes and streambanks for hazards In the humid eastern climate of Maryland, water seems to staff and visitors. present everywhere in streams, rivers, runoff, springs, and groundwater wells. Annual precipitation at • Monitor erosion rates at key sites using repeated ≈ profile measurements. Monocacy National Battlefield averages 97 cm (38 in) per year with almost half of the rain coming in the • Develop a landslide hazard map or model for the park. summer months during short intense storms. Because of the development of the surrounding areas, water Sediment Load and Channel Storage resources are under constant threat of contamination Erosion at Monocacy leads to increases in sediment and overuse. The most severe threats to park streams are carried by the park’s rivers. Sediment loads and from impacts of existing and future development in the distribution affect aquatic and riparian ecosystems and rapidly growing Frederick area. The population of the

6 NPS Geologic Resources Division Monocacy watershed increased 55% between 1970 and as parking lots, roads, and buildings. Sedimentation also 1990 alone (http://www.hood.edu/academic/biology/ increases due to clearing land for development and water monocacy/Watershed/monocacy_watershed.htm temperature increases because of the insulating nature of [Accessed July 2005]). impervious surfaces. However, base flows of streams decrease because impervious surfaces prevent infiltration Anthropogenic effects from road salts, runoff from into the aquifer. Thus, the difference between base and impervious surfaces, septic systems, tilled fields, peak streamflows typically increases as a consequence of agricultural and residential fertilizers, pesticides, and development in the absence of runoff mitigation herbicides, animal waste, overuse, and acid rain can measures, such as detention ponds. considerably alter groundwater chemistry (Trombley and Zynjuk 1985; Dyer and Logan 1995). As Where agricultural runoff, construction materials, and suburbanization of the entire region increases, a decrease other human pollutants are present, nitrogen (and other in agriculture and an increase in residential activites will contaminant) levels in the water may reach dangerous lead to growth in landscaping-derived chemical input (L. levels. Runoff from roadways commonly contains high McClelland 2005, personal communication). levels of oil and other car emissions that are carried into park waterways and seep into the soil. Salt used to keep The preservation of the integrity of the watershed is a roads clear of snow and ice in winter contaminates soil major management objective at Monocacy and for the along ditches. Knowledge of the chemicals used in City of Frederick (the Monocacy is the principal water regional agriculture and development, combined with an resource for the city) (www.cityoffrederick.com/ understanding of the hydrogeologic system, including departments/Planning [Accessed July 2005]). Local groundwater flow patterns, is essential to protect the groups advocating a Riverbank Buffer Plan have stirred ecosystem of the watershed for the park. controversy among landowners (Kunkle 2004). The movement of nutrients and contaminants through The integrity of the watershed is directly reflected in the the hydrogeologic system can be modeled by monitoring quality of the river water. Differences in water quality the composition of system inputs, such as rainfall, and stem from a variety of natural and non-natural sources. outputs, such as streamflow. Other input sources include For instance, major geochemical differences exist wind, surface runoff, ground-water transport, sewage between water sampled from areas underlain by different outfalls, landfills, and fill dirt. Streams in effect integrate lithologic units as controlled by hydrolysis, or the the surface runoff and ground-water flow of their process that controls the chemical composition of most watersheds. Thus, they provide a measure of the status natural waters (Bowser and Jones 2002). Studies stress forthe watershed’s hydrologic system. Consistent the importance of knowing the mineral compositions of measurement of these parameters is crucial to both the aqueous phase and the host rock. establishing baselines for comparison.

Ground-water chemistry in silicate-dominated rocks Flooding Issues seems particularly sensitive to compositions of Much of Monocacy National Battlefield comprises plagioclase (albite), smectite (clay), and mafic minerals floodplains along the Monocacy River. The visitor center (mica, amphibole, and pyroxene), whereas the presence and surrounding fields are often flooded during sudden of quartz or potassium feldspar has very little effect and seasonal high stands. This flooding has damaged (Logan and Kivimaki 1998; Bowser and Jones 2002). foundations of buildings and electrical wiring and has Similarly, it was determined that vein calcite and affected crops in surrounding fields. The floodplain of dolomite contribute calcium to the system and that the Monocacy River is described in greater detail in the chlorite contributes magnesium (Logan and Dyer 1996). following Features and Processes section. Many of these minerals contributing to chemical variations of groundwater are present in the map units Agricultural Pollution within and surrounding Monocacy. The Monocacy River is categorized as a Maryland Wild The hydrogeologic system at Monocacy National and Scenic River (passed by the Maryland General Battlefield is dominated by a karst aquifer. Karst features Assembly in 1968, Monocacy River inclusion April 30, are formed by the dissolution of carbonate rocks such as 1974). However, it has one of the greatest non-point limestone and dolomite. Karst aquifers can be highly source pollution problems in the region, largely due to permeable. In tests of mass-balance models in the area, agricultural runoff. Agriculture combined with easily Field and Mose (1998) determined that the median eroded soil has the potential to degrade both surface and conduit apertures ranged from 1.16–1.24 m (3.80–4.07ft). groundwater. Median macrofissures (narrower than conduits) ranged from 5.53–5.88 cm (2.18–2.31 in.). This implies rapid flow By increasing nutrient levels such as nitrogen and of groundwater through the aquifer after rainstorms, phosphorous, introducing other agrichemicals, and reducing the capacity of the substrate to filter impurities increasing suspended sediment, agricultural practices from the groundwater. pose a serious threat to the Monocacy watershed and by extension the Potomac River and Chesapeake Bay The hydrogeologic system changes in response to systems. increased surface runoff as well. This increase is a result of the further development of impervious surfaces, such The Environmental Protection Agency rated the Monocacy watershed (Hydrologic Unit Code 2070009) a

MONO Geologic Resource Evaluation Report 7 3 overall on a scale of 1–6 for water quality. This score commonly has interconnected conduits, and water indicates moderately serious water-quality problems typically moves rapidly through the system. with aquatic conditions below state goals (http://www.hood.edu/academic/biology/monocacy/Wa Pilot programs in which farmers utilized BMPs have tershed/monocacy_watershed.htm [Accessed July produced promising results for the Monocacy 2005]). conservation projects. In 1991, 42 demonstration plots resulted in reduced soil erosion on land covering 3,500 As much as 60% of the watershed is dedicated to acres. Erosion was reduced by an average of 6 tons of soil agricultural use on the fertile soils of the Frederick per acre per year. This early work prevented nearly 5,600 Valley, including large areas of Monocacy National tons of sediment from flowing into the targeted streams Battlefield. About 33% remains forested (mixed-oak (Israel Creek, Piney/Alloway Creeks, and Linganore deciduous forest). Urban areas such as Frederick, Creek). More farmers are being invited to join the Maryland, complete the watershed. More than 3,500 incentives program. farms, dairies, and livestock operations contribute polluting runoff and eroded sediment to the system In 2007 the NPS Water Resources Division (WRD) (http://www.acb-online.org/pubs/projects/deliverables- completed a Water Resources Stewardship Report for 150-4-2003.pdf [Accessed August 2008]). Monocacy National Battlefield. The goal of this report is to develop comprehensive strategies for water resources The U.S. Department of Agriculture, as well as the that help the park achieve or maintain desired conditions Maryland Department of Agriculture, is addressing this using measurable and objective indicators. The report is problem in a water-quality demonstration project available on the Web (http://www.nature.nps.gov/water/ designed to help reduce degradation from agricultural planning/Stewardship_Reports/MONO_WRSR_final_pd operations. Improved water quality depends upon better f.pdf) (Accessed September 2008). farming techniques, termed Best Management Practices (BMPs), which should address nutrient and agrichemical Inventory, Monitoring, and Research Suggestions for Water use as well as soil conservation in the area. Issues • Work with the NPS WRD, the U.S. Geological Survey, Across the watershed, soil erosion from open fields and the Maryland Geological Survey to design and ranges from 2–35 tons of soil per acre per year. This implement appropriate monitoring programs in the affects the land surrounding Monocacy National watershed. Battlefield as well as the river flowing through it. The T- • value (a measure of how much soil can be eroded and Map and quantify subterranean recharge zones, still maintain agricultural productivity) is a mere 3 tons focusing specifically on karst-related conduits. per acre per year throughout the watershed. Erosion • Work with local officials to encourage development control is needed to improve productivity as well as and maintenance of a buffer zone along the river to preserve the watershed (http://www.acb- help protect the watershed by facilitating natural river online.org/pubs/projects/deliverables-150-4-2003.pdf processes. [Accessed August 2008]). • Prepare educational exhibits explaining the natural

processes of floods, including the benefits to soil Runoff from nearby farms combined with all septic fertility. systems enrich nutrients in the Monocacy watershed. Livestock operations produce nearly 1,119,400 tons of • Reference - the Water Quality Inventory for manure containing the equivalent of 4,400 tons of Watershed Monocacy at the following EPA site: nitrogen and 900 tons of phosphorous. Inorganic http://yosemite.epa.gov/water/adopt.nsf/c2e50050353 nitrogen fertilizer use has increased more than four-fold 1739e85256a71005550c8/4a7150b0ee01226e85256f9c0 since 1960. Pesticide use has tripled since 1964. Fecal 06c838c!OpenDocument (Accessed August 2008). coliform, an indicator of disease-causing organisms in • Reference - the Maryland Department of the water, has been a persistent problem for the section of Environment’s (MDE) list of documents regarding river below the Frederick Sewage Treatment plant, very various conservation, restoration, and monitoring close to Monocacy National Battlefield (http://www.acb- projects, as well as water quality, physical habitat online.org/pubs/projects/deliverables-150-4-2003.pdf condition, and other biological measures in the Lower [Accessed August 2008]). Monocacy River watershed: http://mddnr.chesapeakebay.net/wsprofiles/surf/prof/ Geologic and climatic factors play a significant role in the wsprof.cfm?watershed=02140302 (Accessed August overall condition and health of the watershed. 2008). Precipitation, slope, soil type, soil permeability, and water-recharge rates all significantly affect the amount of Recreational Demands nitrogen and other pollutants leached below plant root zones. The overall pollution problem is complicated by Monocacy National Battlefield provides numerous properties such as solubility and absorption rate. Once recreational possibilities, including Civil War study, the contaminant moves below the soil and into the hiking, fishing, bicycling, picnicking, and photography. underlying karst aquifer, little chance for filtering exists The park promotes activities that do not damage the in the highly permeable substrate. Karst terrane park’s resources or endanger other visitors.

8 NPS Geologic Resources Division The park receives many visitors, especially during the Paleontology summer months; visitors totaled 22,125 in 2007. Visitors Monocacy National Battlefield has not had a formal are placing increasing demands on the resources of the paleontological inventory and no paleontological park. Management concerns vary from trail erosion to material has been collected within the park. However, streambank erosion. there may be potential for future fossil discoveries within the fossiliferous geologic formations exposed within the Many trails wind through preserved biological, park (Kenworthy and Santucci 2004). historical, and geologic environments at the park. Many of these are especially fragile, and off-trail hiking The Araby Formation of early to mid Cambrian age, has promotes their degradation. The park encourages yielded fragments of trilobite fossils from a location recreation within designated trails and picnic areas. northeast of Monocacy National Battlefield. These are Prohibited use in non-designated areas increases the area considered significant because they are among the oldest of impact and places delicate ecosystems at risk. Piedmont fossils found in Maryland. The Rocky Springs Station Member of the Fredrick Formation (late The Monocacy River enhances the natural beauty of the Cambrian in age) has also produced trilobite fossils from park. As with hiking, overuse of certain areas can lead to a location northwest of the park (Kenworthy and contamination and degradation of the ecosystem and Santucci 2004). increased erosion of stream banks. The Works Progress Administration (WPA) built stone walls in the 1930s to Fossils are non-renewable resources that bring geologic combat flooding along the Monocacy River. These and history to life from an interpretive perspective and would other efforts by the park have attempted to protect require park protection if discovered. Scientific interest certain sensitive reaches of the river and locations near in the paleontology of Monocacy National Battlefield visitor areas. These supports are meant to reduce stream- may afford the park an opportunity to partner with bank erosion, but such measures are temporary. In researchers and develop interpretive programs and addition to the large river and local streams (Bush Creek, materials explaining this aspect of the parks geologic Harding’s Run, among other unnamed tributaries), there history. are two manmade ponds in the park (on the Gambrill and Thomas Farms) intended to provide water for Inventory, Monitoring, and Research Suggestions for livestock. Paleontology • Collaborate with the scientific community to Inventory, Monitoring, and Research Suggestions for investigate potential paleontological sites. Recreational Demands • • Design wayside exhibits to encourage responsible use Be aware of formations containing potential fossil of park resources. resources when planning infrastructure projects in the park. • Promote stabilizing vegetation along slopes at risk for slumping and erosion. Geology Education and Research • Promote topographic and geologic mapping in the Monocacy National Battlefield has the opportunity to park linked to recreational use patterns to determine improve geologic interpretation by educating park areas at high risk for resource degradation. visitors about role of geology in the environment and history. A detailed geologic map and a road or trail log, Soil along with a guidebook linking Monocacy National The Soil Resources Inventory (SRI) Program of the NPS Battlefield to the other parks in the Central Appalachian Geologic Resources Division partnered with the Natural region would enhance a visitor’s appreciation of the Resources Conservation Service (NRCS) to complete a geologic history and dynamic processes that created the soil survey for Monocacy National Battlefield in 2005. natural landscape and played a role in the Civil War The SRI Program provides user-friendly products to battle showcased at the park. Strategically placed park managers to facilitate effective resource wayside exhibits would also help explain the geology and management, as well as baseline information on soil the role that geology played in park history to visitors. resources for the Vital Signs Monitoring Program. Soil resource inventories equip parks with maps showing the Inventory, Monitoring, and Research Suggestions for locations and extent of soils; data about the physical, Geology Education and Research chemical, and biological properties of those soils; as well • Research the surficial geologic story at Monocacy and as information regarding potential uses and limitations of develop an interpretive program to relate the current each kind of soil type. The products also can be used for landscape, ecosystem, history, and biology to the park interpretive programs and to identify emerging Soil geology. Program needs.

MONO Geologic Resource Evaluation Report 9 Geologic Features and Processes

This section describes the most prominent and distinctive geologic features and processes in Monocacy National Battlefield.

Geologic Setting and Military History of Monocacy During the battle, troops used natural features such as National Battlefield ridges, low valleys and depressions, shallow fords, The Confederate army’s 2nd Corps, under the command undercut banks, and other subtle topographic of Lieutenant General Jubal A. Early, set out with 10,000 expressions to their advantage and for defense. men, 4,000 cavalry, and 40 guns towards Washington, Interpretive materials could emphasize geologic controls D.C., from the Shenandoah Valley, crossing the Potomac during troop movements as a way of educating the public at Shepherdstown, in June of 1864 (fig. 3). They were about the interconnectedness between history and attempting to divert Union forces from the quagmire at science. A deeper understanding of the landscape would Petersburg. Union Major General Lewis Wallace also result from such information. traveled west with a small force (≈5,000 men) to meet the Confederates. His defensive position was east of the In cooperation with the Chesapeake & Ohio Canal Monocacy River, directly facing three bridges spanning Association, visitors may also be directed to the the river (http://usa-civil-war.com/Monocacy/ neighboring Monocacy Aqueduct, in nearby Chesapeake monocacy.html [Accessed August 2008]). & Ohio Canal National Historical Park (fig. 5). The aqueduct is one of eleven along the canal. It is more than On July 9, the Confederates began crossing the river at a 157 m (515 ft) in length and has seven arches constructed downstream ford to advance on the Union left flank (fig. of white and pink quartz sandstone quarried nearby at 4). The Battle of Monocacy Junction had begun. Sugarloaf Mountain. Construction began in 1829 and Approximately 2,400 men fell in the struggle also known ended in 1833. This feature is threatened by floods and as the “Battle that Saved Washington.” In the end, the large storms such as Hurricane Agnes in 1972 Confederates won the day, diverting Union attention (http://www.geocities.com/Yosemite/3524/monocacy.ht away from General Robert E. Lee’s forces at Petersburg, ml [Accessed August 2008]). Virginia. However, the battle delayed the Confederate advance on Washington, D.C. Although they reached Flooding of the Monocacy River Fort Stevens within the city’s boundaries by July 12, Floods bring to mind terrible disasters, lost property, and Early’s troops were forced to retreat by the arrival of lost resources. However, floods are a natural process and Union reinforcements to defenses around the capital city are vital to soil formation in fertile floodplain areas. (www.nps.gov/mono). Floodplains are defined as areas of land adjacent to rivers that are covered in water on a regular basis during river Geology played a vital role in military success and failure high stands. Much of the Monocacy Battle was fought on in the Battle of Monocacy Junction. In the area around the floodplain. In the 1800s most of the riverbank was Monocacy, the parallel valleys and ridges of the cleared of buffering trees for agriculture. Encourageing Piedmont, Blue Ridge, and Valley and Ridge native plant life along the river will help buffer the physiographic provinces directed troop and supply erosive nature of floods as well as absorb (in part) movement along predictable routes. Gaps such as potentially harmful nutrients, waste, and sediments from Thoroughfare Gap and Harper’s Ferry through the Blue nearby developments and fields. Ridge were often the only means of crossing the mountains from east to west. These were strategic points The U.S. Geological Survey measures the streamflow of to defend. Many early railroads and roads followed the the Monocacy at several locations. Hydrographs are trends of these natural geologic features. The confluence available at the following website: of several major roads and railroads at Monocacy http://md.water.usgs.gov/surfacewater/streamflow/ Junction made it a focal point of defense from a southern (Accessed August 2008). These hydrographs detail the approach towards Washington, D.C., or Baltimore. location, drainage area, gage, station type, peak streamflow, daily streamflow, and contact information. The Monocacy River, the third largest tributary of the Potomac River, was another obstacle to Confederate According to the National Oceanic and Atmospheric advancement. Union Major General Lew Wallace chose Administration (NOAA), from 1929–2001 there were 86 Monocacy Junction as the site of a battle to halt floods that reached a flood stage of 5 m (16 ft). This is Confederate troops. The Georgetown Pike to almost one per year with the potential to cause serious Washington, the National Road to Baltimore, and the damage to low-lying areas along the river’s edge Baltimore and Ohio (B&O) Railroad all crossed the river (http://www.erh.noaa.gov/marfc/Rivers/FloodClimo/M in the area. These, in addition to the natural Worthington onths/pot/FrederickPOT.pdf [Accessed August 2008]). A McKinney Ford, were strategic targets for the Union minor flood was defined as a crest from 5–5.2 m (16–17 army to defend. ft), a moderate flood as 5.2–6 m (17–20 ft), and a major flood as greater than 6 m (20 ft) above normal flow.

10 NPS Geologic Resources Division Near the park, the floodplain of the Monocacy River was rock dissolves in acidic meteoric water to form fissures. the site of the original Moravian settlement in With increased water flow and subsequent dissolution, Bethlehem. Many historic buildings are located on the these fissures can expand into passages and ultimately floodplain. As part of the New Deal program in the 1930s hollow caverns and rooms. Outside the park, north of the Works Progress Administration program erected Frederick, the Monocacy River Cave is developed in stonewalls along the Monocacy to prevent further flood thin-bedded Frederick Limestone. The cave is small, damage (http://home.moravian.edu/users/phys/mejjg01/ having an entrance 1.2 m (4 ft) wide and extending for geology/images/Flood_1955/bethlehem_flood_of_1955.h another 8 m (26 ft). The cave is located above the east tm [Accessed August 2008]). In addition to the park area, bank of the Monocacy River, east of Harrisonville. River the City of Frederick maintains areas of parkland along alluvium that covers the floor of the cave demonstrates the floodplain itself, but the entire area is poorly drained the role of the river in cave formation and prone to seasonal flooding. (http://www.mgs.md.gov/esic/features/cave/monoc.html [Accessed August 2008]). The Blue Ridge Anticlinorium and Frederick Valley The northern terminous of the Blue Ridge is north of The presence of even a small cave in nearby areas is Monocacy, in southern Pennsylvania. At this northern evidence of karst development in the geologic units end, the Blue Ridge consists of a northeast-plunging, beneath Monocacy National Battlefield. The dissolution asymmetric anticlinorium, locally referred to as the of carbonate rocks by ground water flowing through South Mountain anticlinorium (trending N20E) (Logan fissures, cracks, or joints creates karst terrain. The and Dyer 1996). It extends southwestward nearly 400 km presence of karst has had a dramatic effect on the (250 mi) to the Roanoke, Virginia, area (Mitra 1989). hydrogeology of the area. Because Frederick Limestone Monocacy National Battlefield is east of the eastern, underlies the Monocacy River basin almost entirely, its upright limb of the anticlinorium, also known as the hydrogeologic regime has probably been altered by the Catoctin Mountains. The normal, eastern limb of the dissolution of the carbonate below. Karst terrain can anticline at the Catoctin Mountains exhibits open folds include underground streams, springs, caves, sinkholes, that show uniform strains (Mitra 1976). and pinnacles. Sinkholes are developed throughout most of the carbonate rock formations in the area. The karst The entire anticlinorium is locally overturned to the features around Monocacy National Battlefield have not northwest. The west limb dips steeply southeast, the yet been inventoried. crest is broad and flat, and the east limb dips approximately 50 degrees southeast. The anticlinorium Karst landforms, like sinkholes and caves, occur exposes Grenville granodiorite and granitic gneiss in its elsewhere in the Frederick Valley area, including in the core and is flanked on each side by Precambrian and Great Valley, the Valley and Ridge, the Culpeper basin, Lower Paleozoic metasedimentary and metavolcanic and Westminster terrane in the western Piedmont rocks (Mitra 1989). The Swift Run (phyllite and province. These areas have abundant limestone, quartzite), Fauquier and Mechum River dolomite, and marble rock units (Southworth et al. (metamorphosed clastic sedimentary rocks), and 2001). Karst is rare in the Blue Ridge province to the west Catoctin (greenstone, metarhyolite, and metasediments) because marble occurs only as small bodies. Formations unconformably overlie the Precambrian gneissic rocks in central Maryland and northern Virginia. Karst occurs in three different sections of the Piedmont The structural style of the anticlinorium is continuous province. Kanawha Spring, just east of Point of Rocks, across the Great Valley and into the Valley and Ridge flows from the limestone of the Frederick Formation, province. The anticlinorium is associated with which underlies the flood plain. Limestone cobbles Alleghenian thrusting above a detachment that extends within the conglomerate of the Leesburg Member of the eastward into the Piedmont province (Onasch 1986). Balls Bluff Siltstone dissolve to form hummocky topography with abundant sinkholes and springs just The anticlinorium marks the easternmost extent of the southeast of Point of Rocks. In addition, marble and Blue Ridge province in Maryland. The structure at limestone rock units of the Westminster terrane Catoctin Mountain is truncated on the east by a Triassic (exposed along Monocacy River north of Indian Flats) border fault. The fault separates the early Paleozoic underlie linear valleys. These form abundant sinkholes to rocks to the west from the thick Triassic rocks filling the the north. Frederick Valley. The fault is largely covered by debris and sediments shed from the Catoctin Mountains Geology and Archaeology highlands (Whitaker 1955). The fault was likely active Long before Confederate and Union troops converged during the Triassic extension that was responsible for on the Monocacy area during the Civil War, people had many large, narrow, northeast-trending, down-faulted been using the area’s abundant natural resources for basins along the foothills of the Appalachians following hunting and farming. Hunting tools and animal the Alleghenian orogeny. The Culpeper Basin, south of (mastodon) teeth in Frederick County record local Catoctin Mountain in Virginia, is another example of a ancient Native American activity. Early settlers, in the Triassic extensional basin. mid 1600’s, reported an Indian hunting camp northwest of Frederick (Means 1995). The area provided the Native Caves and Karst Formation Americans with materials for tools, animals for food and Large carbonate deposits, including the Frederick clothing, and a variety of nuts, berries and other plants Limestone, underlie the Frederick Valley. Carbonate for gathering.

MONO Geologic Resource Evaluation Report 11 The thick, rich soils shed from the highlands to the west streams and gullies. Historic structures and subtle and deposited in the floodplains, as well as an abundant topographic features are all vulnerable to change due to annual water supply, attracted settlers and farmers to the the geologic processes of weathering and erosion. area. This interest continues today with local agricultural Erosion naturally diminishes higher areas and fills in the comprising the bulk of the Monocacy watershed. lower areas and in the process distorts the historical context of the landscape. The park’s goal of preserving Historical Preservation both the natural and historical context of the area is One of the major goals of the park is to preserve the constantly compromised by the continuous natural historical context of the area; this includes preserving processes of erosion and weathering as well as local and restoring old buildings and the landscape around urban development. them. Maintaining this landscape often means resisting natural geologic changes, which presents several Intense storms such as Hurricane Isabel in September management challenges. For example, a proposal for 2003 damaged many local historical features, including restoration of a historic building may consist of removing the Beatty-Kramer House, Derr House, the Visitor surrounding natural materials. The streams in the park Center at Monocacy National Battlefield, cabins at are also sometimes engineered to preserve fishing habitat Catoctin Mountain Park, and the Chesapeake and Ohio and protect trails, buildings, and streambanks from being Canal National Historical Park undercut. These efforts attempt to reverse many natural (www.marylandhistoricaltrust.net/isabel_event_FR.html geologic changes. [Accessed July 2005]).

Geologic slope processes such as landsliding, slumping, The history of the area is heavily influenced by its chemical weathering, and slope creep are constantly geology. The geology determined the local river changing the landscape at the park. Runoff erodes crossings and fords, and localized construction of sediments from any open areas and carries them down railroad grades (fig. 6).

Figure 3. Regional map showing the path that Lieutenant General Jubal A. Early’s troops followed towards Washington, D.C. in the summer of 1864.

12 NPS Geologic Resources Division

Figure 4. Map of Monocacy area showing troop movement during 1864 battle. Gray arrows indicate Confederate forces. Blue arrows indicate Union forces. Note location of Monocacy Junction, the Worthington McKinney Ford, and Gambrill’s Mill (modern Visitor Center).

MONO Geologic Resource Evaluation Report 13

Figure 5. The Monocacy Aqueduct, which carries the Chesapeake and Ohio Canal over the Monocacy River. Photograph by Robert Kroll (1964).

Figure 6. Monocacy Junction (circle). This was the center of the Union infantry skirmish line. Photograph courtesy of: http://usa-civil- war.com/Monocacy/monocacy.html.

14 NPS Geologic Resources Division Map Unit Properties

This section identifies characteristics of map units that appear on the Geologic Resource Evaluation digital geologic map of Monocacy National Battlefield. 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.

Geologic maps facilitate an understanding of Earth, its processes, and the geologic history responsible for its Southworth, S., and D. Denenny. 2006. Geologic map of formation. Hence, the geologic map for Monocacy the national parks in the National Capital Region, National Battlefield informed the “Geologic History,” Washington D.C., Virginia, Maryland and West “Geologic Features and Processes,” and “Geologic Virginia. Scale 1:24,000. Open-File Report OF 2005- Issues” sections of this report. Geologic maps are 1331. Reston, VA: U.S. Geological Survey. essentially two-dimensional representations of complex three-dimensional relationships. The various colors on Using ESRI ArcGIS software, the Geologic Resource geologic maps represent rocks and unconsolidated Evaluation team created a digital geologic map from this deposits. Bold lines that cross and separate the color source. GRE digital geologic-GIS map products include patterns mark structural features such as faults and folds. data in ESRI personal geodatabase and shapefile GIS Point symbols indicate features such as dipping strata, formats, layer files with feature symbology, FGDC sample localities, mine features, wells, and cave openings. metadata, a Windows HelpFile that contains all of the ancillary map information and graphics, and an ESRI Incorporation of geologic data into a geographic ArcMap map document file that easily displays the map, information system (GIS) increases the utility of geologic and connects the HelpFile directly to the map document. maps and clarifies spatial relationships to other natural resources and anthropogenic features. Geologic maps GRE digital geologic data are included on the attached are indicators of water resources because they show CD and are available through the NPS Data Store which rock units are potential aquifers and are useful for (http://science.nature.nps.gov/nrdata/). The surficial finding seeps and springs. Geologic maps do not show map units in the Monocacy National Battlefield area soil types and are not soil maps, but they do show parent include and overlie rocks of the western Piedmont material, a key factor in soil formation. Furthermore, province. These rocks include late Proterozoic and resource managers have used geologic maps to make Lower Cambrian metasedimentary rocks of the correlations between geology and biology. For instance, Chilhowee Group (Loudoun, Weverton, Harpers, and geologic maps have served as tools for locating Antietam Formations), which consist of threatened and endangered plant species. metaconglomerate, phyllite, quartzite, shale, and slate. Other map units in the area are Lower and Middle Although geologic maps do not show where future Cambrian metasedimentary rocks and Upper Cambrian earthquakes will occur, the presence of a fault indicates to Lower Ordovician carbonate rocks of the Frederick past movement and possible future seismic activity. Valley synclinorium, including the Tomstown Dolomite Geologic maps will not show where the next landslide, and the Frederick and Grove Limestones (Southworth rockfall, or volcanic eruption will occur, but mapped and Brezinski 2003). deposits show areas that have been susceptible to such geologic hazards. Geologic maps do not show The area is part of the Triassic extensional basin formed archaeological or cultural resources, but past peoples by down-dropped block faulting to the west. Upper may have inhabited or been influenced by various Triassic sedimentary rocks of the Newark Group and geomorphic features that are shown on geologic maps. early Jurassic diabase sills and dikes fill the basin. The As examples alluvial terraces may preserve artifacts, and Gettysburg Shale and New Oxford Formation lie within inhabited alcoves may occur at the contact between two several Triassic extensional basins as part of the Newark rock units. Group. The scant diabase sills and dikes are late remnants of tectonic extension and renewed igneous The features and properties of the geologic units in the activity in the area. following table correspond to the accompanying digital geologic data. Map units are listed from youngest to Lining river and stream valleys are unconsolidated high- oldest. Please refer to the geologic time scale (fig. 7) for and low-level alluvial terrace gravels, alluvial gravel, the age associated with each time period. This table sand, and silt, and residual gravel. Other recent deposits highlights characteristics of map units such as include colluvial slope deposits such as talus and slump susceptibility to hazards; the occurrence of fossils, deposits (Southworth and Brezinski 2003). These cultural resources, mineral resources, and caves; and the Quaternary units cover the landscape at Monocacy suitability as habitat or for recreational use. The National Battlefield. following are source data for the GRE digital geologic map:

MONO Geologic Resource Evaluation Report 15

Geologic History

This section describes the rocks and unconsolidated deposits that appear on the digital geologic map of Monocacy National Battlefield, the environment in which those units were deposited, and the timing of geologic events that created the present landscape.

Monocacy National Battlefield is located in the Formation, Harpers Formation, and Antietam Frederick extensional valley just east of the ridge that Formation) (Southworth et al. 2001). forms the boundary between the Blue Ridge and Piedmont physiographic provinces in central Maryland. Associated with the shallow marine setting along the As such, it contains features that are intimately tied with eastern continental margin of the Iapetus were large the long geologic history of the Appalachian Mountains deposits of sand, silt, and mud in near-shore, deltaic, and the evolution of the eastern coast of the North barrier-island, and tidal-flat areas. Some of these are American Continent. A regional perspective is presented present in the Chilhowee Group in Central Maryland, here to connect the landscape and geology of the park to including the Harpers Formation and the Antietam its surroundings. Formation (Schwab 1970; Kauffman and Frey 1979; Simpson 1991). In addition, huge masses of carbonate The recorded history of the Appalachian Mountains rocks, such as the Cambrian Tomstown Dolomite and begins in the Proterozoic (fig. 7). In the mid-Proterozoic, Frederick Limestone, as well as the Upper Cambrian to during the Grenville orogeny, a supercontinent formed Lower Ordovician Grove Limestone, were deposited that consisted of most of the continental crust in atop the Chilhowee Group. They record a grand existence at that time, including North America and platform thickening to the east that persisted during the Africa. Sedimentation, deformation, plutonism, and Cambrian and Ordovician Periods (545-480 Ma) and that volcanism are all manifested in the metamorphic granite forms the floors of Frederick and Hagerstown Valleys and gneiss in the core of the modern Blue Ridge (Means 1995). Mountains (Harris et al. 1997). Somewhat later, 540, 470, and 360 Ma, igneous These rocks formed over a period of a 100 million years granodiorite, pegmatite, and lamprophyre, respectively, and are more than a billion years old, making them intruded the sedimentary rocks. During several episodes among the oldest rocks known in this region. They were of mountain building and continental collision later uplifed and thus exposed to erosive forces for (described below) the entire sequence of sediments, hundreds of millions of years. Their leveled surface intrusive rocks, and basalt were deformed and forms a basement upon which all other rocks of the metamorphosed into schist, gneiss, marble, slate, and Appalachians were deposited (Southworth et al. 2001). migmatite (Southworth et al. 2000). At Monocacy National Battlefield, these ancient rocks are buried beneath the Catoctin Mountains to the west, Taconic Orogeny but they are exposed in the Blue Ridge south of the park From Early Cambrian through Early Ordovician time (Means 1995). orogenic activity along the eastern margin of the

continent began again. The Taconic orogeny (≈440−420 − The late Proterozoic, roughly 800 600 million years ago Ma in the central Appalachians) was a volcanic (Ma), brought extensional rifting to the area. The crustal arc−continent convergence. Oceanic crust and the extension created fissures through which massive volcanic arc from the Iapetus basin were thrust onto the volumes of basaltic magma were extruded (fig. 8A). This eastern edge of the North American continent. The volcanic activity lasted tens of millions of years and Taconic orogeny resulted in the closing of the ocean, alternated between flood-basalt flows and ash falls. The subduction of oceanic crust during the creation of volcanic rocks covered the granitic and gneissic volcanic arcs within the disappearing basin, and the basement in the Catoctin Mountains area. uplift of continental crust (Means 1995).

Because of the tensional tectonic forces, the Initial metamorphism of the igneous rocks of the supercontinent broke up and a sea basin formed that Catoctin Mountains (Catoctin Formation) into eventually became the Iapetus Ocean. This basin metabasalt and metarhyolite, as well as the Chilhowee subsided and collected many of the sediments that later Group Rocks into quartzite and phyllite, occurred during formed the Appalachian Mountains (fig. 8B). this orogenic event.

Some of the sediments were deposited as alluvial fans, In response to the overriding plate thrusting westward large submarine landslides and turbidity flows, which onto the continental margin of North America, the crust today preserve their depositional features. These early bowed downwards creating a deep basin that filled with sediments are exposed on Catoctin Mountain, Short mud and sand eroded from the highlands to the east (fig. − − Hill South Mountain, the Blue Ridge Elk Ridge, and in 8C) (Harris et al. 1997). This so-called Appalachian basin areas within and surrounding Monocacy as the was centered on what is now West Virginia. These Chilhowee Group (Loudoun Formation, Weverton infilling sediments covered the grand carbonate platform

MONO Geologic Resource Evaluation Report 17 and are today recorded by the shale of the Ordovician elevations of less than 600 m (2,000 ft) west of Monocacy Martinsburg Formation (Southworth et al. 2001). National Battlefield (Means 1995).

During the Late Ordovician, the oceanic sediments of the Triassic Extension to the Present shrinking Iapetus Ocean were thrust westward onto Following the Alleghenian orogeny, during the late other deep-water sediments of the western Piedmont Triassic, a period of rifting began as the deformed rocks along the Pleasant Grove fault. Sediments that later of the joined continents broke apart from about 230–200 became sandstone, shale, siltstone, quartzite, and Ma. The supercontinent Pangaea was segmented into limestone were then deposited in the shallow marine to roughly the same continents that persist today. This deltaic environment of the Appalachian basin. These episode of rifting, or crustal fracturing, initiated the rocks, now metamorphosed, currently underlie the formation of the current Atlantic Ocean and created Valley and Ridge province west of Monocacy National many block-fault basins with accompanying volcanism Battlefield (Fisher 1976). (fig. 8E) (Harris et al. 1997; Southworth et al. 2001).

Shallow marine to fluvial sedimentation continued for a The Newark Basin system is a large component of this period of about 200 million years during the Ordovician tectonic setting. Large streams carried debris shed from through Permian Periods, resulting in thick layers of the uplifted Blue Ridge and Piedmont provinces creating sediments. Their source was the highlands that were alluvial fans at their mouths. These were deposited as rising to the east during the Taconian orogeny non-marine mud and sand in fault-created troughs, such (Ordovician) and the Acadian orogeny (Devonian). as the Frederick Valley in central Maryland and the Culpeper basin in the western Piedmont of central Acadian Orogeny Virginia. Many of these rift openings became lacustrine The Acadian orogeny (≈360 Ma) continued the mountain basins and were filled with thick deposits of silt and sand. building of the Taconic orogeny as the African continent drifted toward North America (Harris et al. 1997). Large faults, such as the border fault west of Monocacy Similar to the preceding Taconic orogeny, the Acadian National Battlefield, running beneath Thurmont and event involved collision of land masses, mountain Catoctin Furnace, Maryland, formed the western building, and regional metamorphism (Means 1995). boundaries of the basins and provided an escarpment This event was focused north of central Maryland. that was quickly covered with eroded debris. Magma was intruded into the new sandstone and shale strata as sills Alleghenian Orogeny (sub-horizontal sheets) and nearly vertical dikes that extend beyond the basins into adjacent rocks. Following the Acadian orogeny, the proto-Atlantic

Iapetus Ocean closed during the Late Paleozoic as the After this magma was emplaced approximately 200 Ma, North American and African continents collided. This the region underwent a period of slow uplift and erosion. collision formed the Pangaea supercontinent and the The uplift was in response to isostatic adjustments within Appalachian mountain belt still evident today. This the crust, which forced the continental crust upwards mountain-building episode, termed the Alleghenian and exposed it to erosion. orogeny (≈325−265 Ma), is the last major orogeny that affected the Appalachians (fig. 8D) (Means 1995). The Thick deposits of unconsolidated gravel, sand, and silt rocks were deformed by folds and faults producing the were shed from the eroded mountains. These were Sugarloaf Mountain anticlinorium and the Frederick deposited at the base of the mountains as alluvial fans Valley synclinorium in the western Piedmont, the Blue and spread eastward becoming part of the Atlantic − Ridge South Mountain anticlinorium (including the Coastal Plain (Duffy and Whittecar 1991; Whittecar and Catoctin Mountains), and the numerous folds of the Duffy 2000; Southworth et al. 2001). The amount of Valley and Ridge province (Southworth et al. 2001). material that was deposited has been inferred from the now-exposed metamorphic rocks to have been immense. During this orogeny, rocks of the Great Valley, Blue Many of the rocks exposed at the surface must have been Ridge, and Piedmont provinces were transported along at least 20 km (≈10 mi) below the surface prior to the North Mountain fault as a massive block (Blue regional uplift and erosion. Today, the Potomac, − Ridge Piedmont thrust sheet) westward onto younger Rappahannock, Rapidan, and Shenandoah Rivers and rocks of the Valley and Ridge. The amount of crustal tributaries continue to erode the Coastal Plain sediments, shortening was very large. Estimates of 20−50 percent lowering the mountains, and depositing alluvial terraces shortening would amount to 125–350 km (80−220 mi) along the rivers, as they sculpt the present landscape. (Harris et al. 1997). Since the breakup of Pangaea and the uplift of the Deformed rocks in the eastern Piedmont were also Appalachian Mountains, the North American plate has folded and faulted, and existing thrust faults were continued to drift toward the west. Isostatic adjustments reactivated as both strike-slip and thrust faults during the that uplifted the continent after the Alleghanian orogeny Alleghenian orogeny (Southworth et al. 2001). continued at a lesser rate throughout the Cenozoic Paleoelevations of the Alleghenian Mountains are Period (Harris et al. 1997). estimated at approximately 6,000 m (20,000 ft), analogous to the modern-day Himalaya Range in Asia. The landscape and geomorphology of the greater These mountains have been beveled by erosion to Potomac and Rappahannock River valleys are the result

18 NPS Geologic Resources Division of erosion and deposition from about the middle of the terminus was in northeastern Pennsylvania), the colder Cenozoic Period (≈5Ma) to the present. The distribution climates of the Ice Ages played a role in the formation of of flood plain alluvium and ancient fluvial terraces of the the landscape at Monocacy National Battlefield. The rivers and adjacent tributaries reflect the historical periglacial conditions that must have existed near the development of both drainage systems. There is little or glaciers intensified weathering and other erosional no evidence that the rivers migrated laterally across a processes (Harris et al. 1997). Glacially influenced broad, relatively flat region. It seems the rivers have cut landforms and deposits are probably late Tertiary to downward through very old, resistant rocks, Quaternary, when a wetter climate, sparse vegetation, overprinting their early courses (Southworth et al. 2001). and frozen ground caused increased precipitation to run into the ancestral river channels, enhancing downcutting Though glaciers from the Pleistocene Ice Ages never and erosion by waterways (Means 1995; Zen 1997a and reached the central Maryland area (the southern 1997b).

MONO Geologic Resource Evaluation Report 19

Figure 7: Geologic time scale; adapted from the U.S. Geological Survey (http://pubs.usgs.gov/fs/2007/3015/). Red lines indicate major unconformities between eras. Included are major events in life history and tectonic events occurring on the North American continent. Absolute ages shown are in millions of years(Ma, or mega-annum).

20 NPS Geologic Resources Division

Figure 8. Evolution of the landscape in the area of Monocacy National Battlefield from the Precambrian through the present. Graphic adapted from Means (1995). Drawings not to scale.

MONO Geologic Resource Evaluation Report 21 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. active margin. A continental margin where significant cleavage (rock). The tendency of rock to break along volcanic and earthquake activity occurs; commonly a parallel planes that correspond to the alignment of convergent plate margin. platy minerals. alluvial fan. A fan-shaped deposit of sediment that concordant. Strata with contacts parallel to the attitude accumulates where a high-gradient stream flows out of of adjacent strata. a mountain front into an area of lesser gradient, such conglomerate. A coarse-grained sedimentary rock with as a valley. clasts larger than 2 mm in a fine-grained matrix. alluvium. Stream-deposited sediment that is generally continental crust. The type of crustal rocks underlying rounded, sorted, and stratified. the continents and continental shelves; having a angular unconformity. An unconformity where the strata thickness of 25−60 km (16−37 mi) and a density of above and below are oriented differently; generally approximately 2.7 grams per cubic centimeter. caused by structural deformation and erosion prior to continental drift. The concept that continents have deposition of the upper bed. shifted in position over Earth (see and use “plate anticlinorium. A composite anticlinal structure of tectonics”). regional extent composed of lesser folds. continental rise. Gently sloping region from the foot of aquifer. Rock or sediment that are sufficiently porous, the continental slope to the abyssal plain. permeable, and saturated to be useful as a source of continental shelf. The shallowly submerged part of a water. continental margin extending from the shoreline to the ash (volcanic). Fine pyroclastic material ejected from a continental slope with water depths of less than 200 m volcano (also see “tuff”). (656 ft). asthenosphere. Weak layer in the upper mantle below continental shield. A continental block of Earth’s crust the lithosphere where seismic waves are attenuated. that has remained relatively stable over a long period basement. The undifferentiated rocks, commonly of time and has undergone only gentle warping igneous and metamorphic, that underlie the rocks of compared to the intense deformation of bordering interest. crust basin (structural). A doubly-plunging syncline in which continental slope. The relatively steep slope from the rocks dip inward from all sides (also see “dome”). outer edge of the continental shelf down to the more basin (sedimentary). Any depression, from continental gently sloping ocean depths of the continental rise or to local scales, into which sediments are deposited. abyssal plain. bed. The smallest sedimentary strata unit, commonly convergent boundary. A plate boundary where two ranging in thickness from one centimeter to a meter or tectonic plates are moving together (i.e., a zone of two and distinguishable from beds above. subduction or obduction). bedding. Depositional layering or stratification of craton. The relatively old and geologically stable interior sediments. of a continent (also see “continental shield”). bedrock geology. The geology of underlying solid rock cross-bedding. Uniform to highlyvaried sets of inclined as it would appear with the sediment, soil, and sedimentary beds deposited by wind or water that vegetative cover stripped away. indicate distinctive flow conditions. block (fault). A crustal unit bounded by faults, either cross section. A graphical interpretation of geology, completely or in part. structure, and/or stratigraphy in the third (vertical) braided stream. A stream, clogged with sediment that dimension based on mapped and measured geological forms multiple channels that divide and rejoin. extents and attitudes depicted in an oriented vertical calcareous. A rock or sediment containing calcium plane. carbonate. crust. The outermost compositional shell of Earth, 10−40 carbonaceous. A rock or sediment with considerable km (6−25 mi) thick, consisting predominantly of carbon, especially organics, hydrocarbons, or coal. relatively low-density silicate minerals (also see cementation. Chemical precipitation of material into “oceanic crust” and “continental crust”). pores between grains that bind the grains into rock. crystalline. Describes the structure of a regular, orderly, chemical sediment. A sediment precipitated directly repeating geometric arrangement of atoms from solution (also called “nonclastic”). debris flow. A rapid and often sudden flow or slide of chemical weathering. The dissolution or chemical rock and soil material involving a wide range of types breakdown of minerals at Earth’s surface via reaction and sizes. with water, air, or dissolved substances. deformation. A general term for the process of faulting, clastic. Rock or sediment made of fragments or pre- folding, shearing, extension, or compression of rocks existing rocks. as a result of various Earth forces. clay. Clay minerals or sedimentary fragments the size of delta. A sediment wedge deposited at a stream’s mouth clay minerals (>1/256 mm). where it flows into a lake or sea.

22 NPS Geologic Resources Division dike. A tabular, discordant igneous intrusion. karst topography. Topography characterized by dip. The angle between a structural surface and a abundant sinkholes and caverns formed by the horizontal reference plane measured normal to their dissolution of calcareous rocks. line of intersection. lacustrine. Pertaining to, produced by, or inhabiting a disconformity. An unconformity at which the bedding of lake or lakes. the strata above and below are parallel. lamination. The finest stratification or bedding as seen in discordant. Having contacts that cut across or are set an shale and siltstone (syn: lamina or laminae) or the angle to the orientation of adjacent rocks. formation of laminae. divergent boundary. A tectonic plate boundary where landslide. Any process or landform resulting from rapid the plates are moving apart (e.g., a spreading ridge or mass movement under relatively dry conditions. continental rift zone). lava. Magma that has been extruded out onto Earth’s drainage basin. The total area from which a stream surface, both molten and solidified. system receives or drains precipitation runoff. levees. Raised ridges lining the banks of a stream; may be eustatic. Relates to simultaneous worldwide rise or fall natural or artificial. of sea level in Earth’s oceans. limbs. The two sides of a structural fold on either side of evaporite. Chemically precipitated mineral(s) formed by its hingeline. the evaporation of solute-rich water under restricted lineament. Any relatively straight surface feature that can conditions. be identified via observation, mapping, or remote exfoliation. The breakup, spalling, peeling, flaking, etc., sensing, commonly representing tectonic features. of layers or concentric sheets from an exposed rock lithification. The conversion of sediment into solid rock. mass due to differential stresses resulting from thermal lithology. The description of a rock or rock unit, changes or pressure unloading. especially the texture, composition, and structure of extrusion. The emission of relatively viscous lava onto sedimentary rocks. the Earth’s surface; also, the rock so formed. lithosphere. The relatively rigid outmost shell of Earth’s extrusive. Of or pertaining to the eruption of igneous structure, 50−100 km (31−62 mi) thick, that material onto the surface of Earth. encompasses the crust and uppermost mantle. facies (metamorphic). The pressure-temperature regime loess. Silt-sized sediment deposited by wind, generally of that results in a particular, distinctive metamorphic glacial origin. mineralogy (i.e., a suite of index minerals). mafic. A rock, magma, or mineral rich in magnesium and facies (sedimentary). The depositional or environmental iron. conditions reflected in the sedimentary structures, magma. Molten rock generated within the Earth that is textures, mineralogy, fossils, etc. of a sedimentary the parent of igneous rocks. rock. mantle. The zone of Earth’s interior between crust and fault. A subplanar break in rock along which relative core. movement occurs between the two sides. matrix. The fine-grained interstitial material between formation. Fundamental rock-stratigraphic unit that is coarse grains in porphyritic igneous rocks and poorly mappable and lithologically distinct from adjoining sorted clastic sediments or rocks. strata and has definable upper and lower contacts. meanders. Sinuous lateral curves or bends in a stream fracture. Irregular breakage of a mineral; also any break channel. in a rock (e.g., crack, joint, fault) mechanical weathering. The physical breakup of rocks frost wedging. The breakup of rock due to the expansion without change in composition (syn: physical of water freezing in fractures. weathering). geology. The study of Earth including its origin, history, member. A lithostratigraphic unit with definable contacts physical processes, components, and morphology. that subdivides a formation. igneous. Refers to a rock or mineral that originated from metamorphic. Pertaining to the process of molten material; one of the three main classes or metamorphism or to its results. rocks—igneous, metamorphic, and sedimentary. metamorphism. Literally, “change in form.” intrusion. A body of igneous rock that invades older Metamorphism occurs in rocks through mineral rock. The invading rock may be a plastic solid or alteration, genesis, and/or recrystallization from magma that pushes its way into the older rock. increased heat and pressure. island arc. A line or arc of volcanic islands formed over mid-ocean ridge. The continuous, generally submarine, and parallel to a subduction zone. seismic, median mountain range that marks the isostasy. The process by which the crust “floats” at an divergent tectonic margin(s) in the world’s oceans. elevation compatible with the density and thickness of mineral. A naturally occurring, inorganic crystalline solid the crustal rocks relative to underlying mantle. with a definite chemical composition or compositional isostatic adjustment. The shift of the lithosphere of the range. Earth to maintain equilibrium among units of varying mud cracks. Cracks formed in clay, silt, or mud by mass and density; excess mass above is balanced by a shrinkage during subaerial dehydration. deficit of density below, and vice versa. nonconformity. An erosional surface preserved in strata joint. A semi-planar break in rock without relative in which crystalline igneous or metamorphic rocks movement of rocks on either side of the fracture underlie sedimentary rocks. surface. normal fault. A dip-slip fault in which the hanging wall moves down relative to the footwall.

MONO Geologic Resource Evaluation Report 23 obduction. The process by which the crust is thickened regression. A long-term seaward retreat of the shoreline by thrust faulting at a convergent margin. or relative fall of sea level. oceanic crust. Earth’s crust formed at spreading ridges relative dating. Determining the chronological that underlies the ocean basins. Oceanic crust is 6−7 placement of rocks, events, fossils, etc. from geological km (3−mi) thick and generally of basaltic composition. evidence. o orogeny. A mountain-building event, particularly a well- reverse fault. A contractional, high-angle (>45 ), dip-slip recognized event in the geological past (e.g., the fault in which the hanging wall moves up relative to the Laramide orogeny). footwall (also see “thrust fault”). outcrop. Any part of a rock mass or formation that is rift valley. A depression formed by grabens along the exposed or “crops out” at Earth’s surface. crest of an oceanic spreading ridge or in a continental overbank deposits. Alluvium deposited outside a stream rift zone. channel during flooding. ripple marks. The undulating, subparallel, usually small- paleogeography. The study, description, and scale ridge pattern formed on sediment by the flow of reconstruction of the physical geography from past wind or water. geologic periods. rock. A solid, cohesive aggregate of one or more minerals paleontology. The study of the life and chronology of or mineraloids. Earth’s geologic past based on the phylogeny of fossil roundness. The relative amount of curvature of the organisms. “corners” of a sediment grain, especially with respect Pangaea. A theoretica, single supercontinent that existed to the maximum radius of curvature of the particle. during the Permian and Triassic Periods (also see sandstone. Clastic sedimentary rock of predominantly “Laurasia” and “Gondwana”). sand-sized grains. parent (rock). The original rock from which a scarp. A steep cliff or topographic step resulting from metamorphic rock or soil was formed. vertical displacement on a fault or by mass movement. passive margin. A tectonically quiet continental margin seafloor spreading. The process by which tectonic plates indicated by little volcanic or seismic activity. diverge and new lithosphere is created at oceanic pebble. Generally, small, rounded rock particles from 4 ridges. to 64 mm in diameter. sediment. An eroded and deposited, unconsolidated permeability. A measure of the ease or rate that fluids accumulation of lithic and mineral fragments. move through rocks or sediments. sedimentary rock. A consolidated and lithified rock plateau. A broad, flat-topped topographic high of great consisting of detrital and/or chemical sediment(s). extent and elevation above the surrounding plains, sequence. A major informal rock-stratigraphic unit that canyons, or valleys (both land and marine landforms). is traceable over large areas and defined by a major sea plate tectonics. The theory that the lithosphere is broken level transgression-regression sediment package. up into a series of rigid plates that move over Earth’s shale. A clastic sedimentary rock made of clay-sized surface above a more fluid aesthenosphere. particles that exhibit parallel splitting properties. pluton. A body of intrusive igneous rock. silt. Clastic sedimentary material intermediate in size plutonic. Describes igneous rock intruded and between fine-grained sand and coarse clay (1/256−1/16 crystallized at some depth in the Earth. mm). porosity. The proportion of void space (cracks, siltstone. A variablely lithified sedimentary rock interstices) in a volume of a rock or sediment. composed of silt-sized grains. Principal of Original Horizontality. The concept that slickenside. A smoothly polished and commonly striated sediments are originally deposited in horizontal layers surface representing deformation of a fault plane. and that deviations from the horizontal indicate post- slope. The inclined surface of any geomorphic feature or depositional deformation. rational measurement thereof (syn: gradient). Principle of Superposition. The concept that sediments slump. A generally large, coherent mass movement with are deposited in layers, one atop another, i.e., the rocks a concave-up failure surface and subsequent backward on the bottom are oldest with the overlying rocks rotation relative to the slope. progressively younger toward the top. soil. Surface accumulation of weathered rock and progradation. The seaward building of land area due to organic matter capable of supporting plant growth and sedimentary deposition. commonly overlying the parent rock from which it provenance. A place of origin. The area from which the formed. constituent materials of a sedimentary rock were spring. A site where water flows out at the surface due to derived. the water table intersecting the ground surface. radioactivity. The spontaneous decay or breakdown of strata. Tabular or sheetlike masses or distinct layers (e.g., unstable atomic nuclei. of rock). radiometric age. An age in years determined from stratigraphy. The geologic study of the origin, radioisotopes and their decay products. occurrence, distribution, classification, correlation, recharge. Infiltration processes that replenish age, etc. of rock layers, especially sedimentary rocks. groundwater. stream. Any body of water moving under gravity flow red beds. Sedimentary strata composed largely of and confined within a channel. sandstone, siltstone, and shale that are predominantly strike. The compass direction of the line of intersection red due to the presence of ferric oxide (hematite) that an inclined surface makes with a horizontal plane. coating individual grains. strike-slip fault. A fault with measurable offset where the relative movement is parallel to the strike of the fault.

24 NPS Geologic Resources Division subduction zone. A convergent plate boundary where topography. The general morphology of Earth’s surface oceanic lithosphere descends beneath a continental or including relief and location of natural and oceanic plate and is carried down into the mantle. anthropogenic features. subsidence. The gradual sinking or depression of part of trace (fault). The exposed intersection of a fault with Earth’s surface. Earth’s surface. suture. The linear zone where two continental trace fossils. Sedimentary structures, such as tracks, landmasses become joined due to obduction. trails, burrows, etc., that preserve evidence of syncline. A fold of which the core contains the organisms’ life activities, rather than the organisms stratigraphically younger rocks; it is generally concave themselves. upward. transgression. Landward migration of the sea due to a synclinorium. A composite synclinal structure of regional relative rise in sea level. extent composed of lesser folds. trend. The direction or azimuth of elongation of a linear tectonic. Relating to large-scale movement and geological feature. deformation of Earth’s crust. type locality. The geographic location where a tectonics. The geological study of the broad structural stratigraphic unit is well displayed, is formally defined architecture and deformational processes of the as a typical section, and derives its name. lithosphere and aesthenosphere (also see “structural unconformity. A surface within sedimentary strata that geology”). marks a prolonged period of nondeposition or terraces (stream). Step-like benches surrounding the erosion. present floodplain of a stream due to dissection of uplift. A structurally high area in the crust, produced by previous flood plain(s), stream bed(s), and/or valley movement that raises the rocks. floor(s). volcanic. Related to volcanoes; describes igneous rock terrane. A region or group of rocks with similar geology, crystallized at or near Earth’s surface (e.g., lava). age, or structural style. water table. The upper surface of the saturated (phreatic) terrestrial. Relating to Earth or Earth’s dry land. zone. theory. A hypothesis that has been rigorously tested weathering. The set of physical, chemical, and biological against further observations or experiments to become processes by which rock is broken down in place. a generally accepted tenet of science. 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.

MONO Geologic Resource Evaluation Report 25 References

This section lists references cited in this report as well as a general bibliography that may be of use to resource managers. A more complete geologic bibliography is available from the National Park Service Geologic Resources Division.

Blomquist, J. D., and G. T. Fisher. 1994. Nitrogen sources Kulp, R. R., and R. O. Hughes III. 1999. The existence of and nitrate loads in major watersheds of the upper olivine in several exposures of Pennsylvania York Potomac River basin. Eos, Transactions, American Haven type diabase. Geological Society of America Geophysical Union 75 (16, Suppl.): 165. Abstracts with Programs 31 (7): 165.

Bowser, C. J., and B. F. Jones. 2002. Mineralogic controls Kulp, R. R., and R. O. Hughes III. 2001, Xenoliths of the on the composition of natural waters dominated by Triassic Passaic Formation in the Monocacy Hill silicate hydrolysis. American Journal of Science 302 (7): diabase intrusion, Amity Township, Berks County, 582−662. Pennsylvania. Geological Society of America Abstracts with Programs 33 (6): 375. Duffy, D. F., and G. R. Whittecar. 1991. Geomorphic development of segmented alluvial fans in the Kunkle, F. 2004, Riverbank buffer plan angers Shenandoah Valley, Stuarts Draft, Virginia. Geological landowners. Washington Post, May 23. Society of America Abstracts with Programs 23 (1): 24. Logan, W. S., and L. J. Dyer. 1996. Influence of mineral Dyer, L. J., and W. S. Logan. 1995. Water-rock weathering reactions, road salt and cation exchange on interaction and anthropogenic effects within the groundwater chemistry, Catoctin Mountain, central western Catoctin Mountain watershed, western Maryland. Geological Society of America Abstracts with Maryland. Geological Society of America Abstracts with Programs 28 (7): 31−32. Programs 27 (2): 51. Logan, W. S., and K. W. Kivimaki. 1998. Mass-balance Field, M. S., and D. G. Mose. 1998. Estimating subsurface modeling of dissolved solutes in groundwater of fissure apertures in karst aquifers from equilibrium metasediments and basin fill sediments, eastern activities. Environmental & Engineering Geoscience 4 Catoctin Mountain, west-central Maryland. Geological (2): 145−159. Society of America Abstracts with Programs 30 (7): 375.

Fisher, G. T. 1995. Selected herbicides in major streams Matthews, E. D. 1960. Soil survey of Frederick County, in the Potomac River basin upstream from Maryland. U.S. Department of Agriculture Soil Washington, D.C. Fact Sheet FS 95-107. Reston, VA: Conservation Service. U. S. Geological Survey. Means, J. 1995. Maryland’s Catoctin Mountain parks; an Fisher, G. T., and T. M. Lewis. 1990. Estimation of interpretive guide to Catoctin Mountain Park and drainage density and overland flow length using digital Cunningham Falls State Park. Blacksburg, VA: cartographic data. In Application of geographic McDonald & Woodward Publishing Company. information systems, simulation models, and knowledge- based systems for land use management. coordinator J. Miller, A. J., J. A. Smith, and L. L. Shoemaker. 1984. P.Mason. 111−120. Blacksburg, VA: Virginia Channel storage of fine-grained sediment in the Polytechnic Institute and State University. Monocacy River basin. Eos, Transactions, American Geophysical Union 65 (45): 888. Fisher, G. W. 1976. The geologic evolution of the northeastern Piedmont of the Appalachians. Geological Mitra, G. 1989. Day four; The Catoctin Mountain−Blue Society of America Abstracts with Programs 8 (2): Ridge anticlinorium in northern Virginia. In 172−173. Metamorphism and tectonics of eastern and central North America; Volume 2, Geometry and deformation Harris, A. G., E. Tuttle, and S. D. Tuttle. 1997. Geology of fabrics in the Central and Southern Appalachian Valley National Parks. [place of publication]: Kendall/Hunt and Ridge and Blue Ridge, ed. P. M. Hanshaw, 31−44. Publishing Company. Collection Field Trips for the 28th International Geological Congress. Kauffman, M. E., and E. P. Frey. 1979. Antietam sandstone ridges; exhumed barrier islands or fault- Mitra, S. 1976. A quantitative study of deformation bounded blocks? Geological Society of America mechanisms and finite strain in quartzites. Abstracts with Programs 11 (1): 18. Contributions to Mineralogy and Petrology 59: 203-226.

Nickelsen, R. P. 1956. Geology of the Blue Ridge near Harpers Ferry, West Virginia. Geological Society of America Bulletin 67 (3): 239−269.

26 NPS Geologic Resources Division Onasch, C. M. 1986. Structural and metamorphic Southworth, S., C. Fingeret, and T. Weik. 2000. Geologic evolution of a portion of the Blue Ridge in Maryland. Map of the Potomac River Gorge: Great Falls Park, Southeastern Geology 26 (4): 229−238. Virginia, and Part of the C & O Canal National Historical Park, Maryland. Open-File Report OF 00- Schwab, F. L. 1970. Origin of the Antietam Formation 264. Reston, VA: U.S. Geological Survey. (late Precambrian?, lower Cambrian), central Virginia. Journal of Sedimentary Petrology 40 (1): 354−366. Southworth, S., and D. K. Brezinski. 2003. Geologic map of the Buckeystown Quadrangle, Frederick and Schwartz, S. S. 1987. A conceptual model of sediment Montgomery counties, Maryland, and Loudoun County, transport and delivery for the Monocacy River sub- Virginia. Scale 1:24,000. Geologic Quadrangle Map GQ basin of the Potomac River basin. Report number 87- [series number here]. Reston, VA: U.S. Geological 11. [place of publication]: [publisher]. Survey.

Showstack, R. 1998. Real-time monitoring and warning Trombley, T. J., and L. D. Zynjuk. 1985. Hydrogeology for natural hazards can provide real-time benefits. Eos, and water quality of the Catoctin Mountain National Transactions, American Geophysical Union 79 (28): 329, Park area, Frederick County, Maryland. Water 33. Resources Investigations [series number here]. Reston, VA: U.S. Geological Survey. Simpson, E. L. 1991. An exhumed Lower Cambrian tidal- flat; the Antietam Formation, central Virginia, U.S.A. Werner, H. J. 1966. Geology of the Vesuvius Quadrangle, In Clastic tidal sedimentology. eds. D. G. Smith, B. A. Virginia. Report of Investigations. Charlottesville, VA: Zaitlin, G. E. Reinson, and R. A. Rahmani. Canadian Virginia Division of Mineral Resources. Society of Petroleum Geologists Memoir 16:123−133. Whitaker, J. C. 1955. Geology of Catoctin Mountain, Southworth, S., and D. K. Brezinski. 1996. Geology of the Maryland and Virginia. Geological Society of America − Harpers Ferry Quadrangle, Virginia, Maryland, and Bulletin 66 (4): 435 462. West Virginia. Bulletin B-2123. Reston, VA: U.S. Geological Survey. Whittecar, G. R., and D. F. Duffy. 2000. Geomorphology and stratigraphy of late Cenozoic alluvial fans, Augusta Southworth, S., and D. K. Brezinski. 2003. Geologic map County, Virginia, U.S.A. In Regolith in the Central and of the Buckeystown Quadrangle, Frederick and Southern Appalachians, eds. G. M Clark, H. H. Mills, Montgomery counties, Maryland, and Loudoun County, and J. S. Kite. Southeastern Geology 39 (3−4): 259−279. Virginia. Scale 1:24,000. Geologic Quadrangle Map GQ [series number here]. Reston, VA: U.S. Geological Zen, E-an. 1997a, The Seven-storey river: Survey. Geomorphology of the Potomac River channel between Blockhouse Point, Maryland, and Southworth, S., D. K. Brezinski, R. C. Orndorff, P. G. Georgetown, District of Columbia, with emphasis on Chirico, and K. M Lagueux. 2001. Geology of the The Gorge complex below Great Falls. Open-File Chesapeake and Ohio Canal National Historical Park Report OF 97-60. Reston: VA: U.S. Geological Survey. and Potomac River Corridor, District of Columbia, Maryland, West Virginia, and Virginia. CD-ROM Zen, E-an. 1997b. Channel geometry and strath levels of (Disc 1: A, geologic map and GIS files; Disc 2: B, the Potomac River between Great Falls, Maryland, and geologic report and figures). Open-File Report OF 01- Hampshire, West Virginia. Open-File Report OF 97- 0188. U.S. Geological Survey. 480. Reston, VA: U.S. Geological Survey.

MONO Geologic Resource Evaluation Report 27 Appendix A: Geologic Map Graphic

The following page is a snapshot of the geologic map for Monocacy National Battlefield. 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://www.nature.nps.gov/geology/inventory/gre_publications).

28 NPS Geologic Resources Division Appendix B: Scoping Summary

The following excerpts are from the GRE scoping summary for Monocacy National Battlefield. 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.

project leader and main contact. The original PMIS Executive Summary (Project Management Information Systems) statement is Geologic Resource Evaluation (GRE) workshops were available as number 60900; of note is that portions of it held for National Park Service (NPS) Units in the need to be changed to reflect that the source of funding National Capital Region (NCR) over April 30-May 2, will be Inventory and Monitoring funds and not NRPP. 2001. The purpose was to view and discuss the park’s geologic resources, to address the status of geologic -Desired Enhancements mapping for compiling both paper and digital maps, and To better facilitate the geologic mapping, Scott to assess resource management issues and needs. Southworth would like to obtain better topographic Cooperators from the NPS Geologic Resources Division coverage for each of the NCR units. Tammy Stidham (GRD), Natural Resources Information Division knows that some of these coverages are already available (NRID), individual NPS units in the region, and the and will supply them to Scott and the USGS. In general, United States Geological Survey (USGS) were present for anything in Washington, D.C., proper has 1-meter the workshop. topographic coverage, and Prince George's county has 1:24,000 coverage. This involved half-day field trips to view the geology of Catoctin Mountain Park, Harpers Ferry NHP, Prince Notes on Monocacy National Battlefield William Forest Park, and Great Falls Park, as well as Monocacy (MONO) is lumped with Antietam; should another full-day scoping session to present overviews of have topographic coverage soon. Have occasional flood the NPS Inventory and Monitoring (I&M) program, the problems. GRD, and the ongoing GRE. Round-table discussions involving geologic issues for all parks in the National Digital Geologic Map Coverage Capital Region included the status of geologic mapping The USGS will supply digital geology in ArcInfo format efforts, interpretation, paleontologic resources, sources for all of the NCR parks. GRE staff will take this data and of available data, and action items generated from this add the Windows help file and NPS theme manager meeting. capability to the digital geology and will supply to the region to distribute to each park in NCR. Geologic Mapping - Existing Geologic Maps and Publications Other Desired Data Sets for NCR After the bibliographies were assembled, a separate Soils search was made for any existing surficial and bedrock Pete Biggam (GRD Soil Scientist) supplied the following geologic maps for the National Capital Region parks. information in reference to soils for parks: The bounding coordinates for each map were noted and entered into a GIS to assemble an index geologic map. National Capitol Parks - Central is covered by the Separate coverages were developed based on scales "District of Columbia" Soil Survey (State Soil Survey (1:24,000, 1:100,000, etc.) available for the specific park. Area ID MD099). It has been mapped, and is currently Numerous geologic maps at varying scales and vintages being refined to match new imagery. An interim digital cover the area. Index maps were distributed to each product is available to us via NRCS, but the "final workshop participant during the scoping session. certified" dataset most likely will not be available until FY03. - Status The index of published geologic maps is a useful National Capitol Parks - Eastern is covered by portions reference for the NCR. However, some of these maps are of three soil survey areas; "District of Columbia dated and are in need of refinement, and in other places, (MD099),” "Charles County, Maryland (MD017),” and there is no existing large-scale coverages available. The "Prince George's County, Maryland (MD033).” Both USGS began a project to map the Baltimore-Washington, Charles County and Prince George's County are D.C., area at 1:100,000 scale, and as a result it was currently being updated, with Charles County scheduled brought to their attention that modern, large-scale to be available sometime in calendar year 2002, and geologic mapping for the NCR NPS areas would be Prince George's County sometime within calendar year beneficial to NPS resource management. 2003.

Because of this, the USGS developed a proposal to re- Paleontology map the NCR at large scale (1:24,000 or greater) and to Greg McDonald (GRD Paleontologist) would like to see supply digital geologic databases to accompany this an encompassing, systematic paleontological inventory mapping. Scott Southworth (USGS-Reston, VA) is the for the NCR describing the known resources in all parks

MONO Geologic Resource Evaluation Report 31 with suggestions on how to best manage these resources. Geologic Report In addition to the parks containing paleo resources in A stand-alone encompassing report on each park’s NACE, according to his current database, the following geology is a major focus of the GRE. As part of the USGS are considered "paleo parks" in the NCR: proposal to map the NCR, they will be summarizing the • Chesapeake & Ohio Canal NHP major geologic features of each park in a report to accompany their database. • George Washington Memorial Parkway • Manassas NBP It was suggested hoped that after the individual reports are finished a regional physiographic report will be • Prince William Forest Park completed for the entire NCR. • Harpers Ferry NHP

List of Attendees for NPS National Capital Region Workshop

NAME AFFILIATION PHONE E-MAIL Joe Gregson NPS, NRID (970) 225-3559 [email protected] Tim Connors NPS, GRD (303) 969-2093 [email protected] Bruce Heise NPS, GRD (303) 969-2017 [email protected] Lindsay McClelland NPS, GRD 202-513-7185 [email protected] Scott Southworth USGS (703) 648-6385 [email protected] Pete Chirico USGS 703-648-6950 [email protected] Pat Toops NPS, NCR 202-342-1443, ext. 212 [email protected] James Voigt NPS, CATO 301-416-0536 [email protected] Marcus Koenen NPS, NCR 202-342-1443, ext. 216 [email protected] Ellen Gray NPS, NCR 202-342-1443, ext. 223 [email protected] Dale Nisbet NPS, HAFE 304-535-6770 [email protected] Suzy Alberts NPS, CHOH 301-714-2211 [email protected] Dianne Ingram NPS, CHOH 301-714-2225 [email protected] Bill Spinrad NPS, CHOH 301-714-2221 [email protected] Debbie Cohen NPS, ANTI 301-432-2243 [email protected] Ed Wenschhof NPS, ANTI/MONO 301-432-2243 [email protected] Ann Brazinski NPS, GWMP 703-289-2541 [email protected] Melissa Kangas NPS, GWMP 703-289-2542 [email protected] Barbara Perdew NPS, GWMP 703-285-2964 [email protected] Barry Wood NPS, GWMP 703-289-2543 [email protected] Marie Sauter NPS, CHOH 301-714-2224 [email protected] Carol Pollio NPS, PRWI 703-221-2176 [email protected] Duane Donnelly- [email protected] NPS, PRWI 703-221-6921 Morrison Diane Pavek NPS-NRS 202-342-1443, ext. 209 [email protected] Chris Jones NPS-WOTR 703-255-1822 [email protected] Doug Curtis NPS-NCR-NRS 202-342-1443, ext.228 [email protected] Brent Steury NPS-NACE 202-690-5167 [email protected] Dave Russ USGS 703-648-6660 [email protected] Tammy Stidham NPS-RTSC 202-619-7474 [email protected] Dan Sealy NPS-GWMP 703-289-2531 [email protected] Sue Salmons NPS-ROCR 202-426-6834, ext. 33 [email protected]

32 NPS Geologic Resources Division Monocacy National Battlefield Geologic Resource Evaluation Report

Natural Resource Report NPS/NRPC/GRD/NRR—2008/051 NPS D-78, September 2008

National Park Service Director • Mary A. Bomar

Natural Resource Stewardship and Science Associate Director • Bert Frost

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 • Diane Lane Digital Map Production • Stephanie O'Meara and Trista Thornberry-Ehrlich Map Layout Design • Andrea Croskrey

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. National Park Service U.S. Department of the Interior

Geologic Resources Division Natural Resource Program Center P.O. Box 25287 Denver, CO 80225

http://www.nature.nps.gov/geology/inventory/ (303) 969-2090

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