Geodiversity refers to the full variety of natural geologic (rocks, minerals, sediments, fossils, landforms, and physical processes) and soil resources and processes that occur in the park. The NPS Geodiversity Atlas delivers information in support of education, Geoconservation, and integrated management of living (biotic) and non-living (abiotic) components of the ecosystem.
Series: National Park Service Geodiversity Atlas
NPS Geodiversity Atlas—Monocacy National Battlefield, Maryland
Geologic Features and Processes
The rocks of central Maryland reflect the powerful tectonic forces responsible for the Appalachian Mountains. Precambrian gneiss, metavolcanic rocks, and younger (Paleozoic) quartzite and phyllite underlie the hills visible to the west of Monocacy. The entire region was compressed during three separate tectonic events, the Taconic, Acadian, and Alleghenian orogenies. Following this compression, a series of fault-bounded extension basins, such as Frederick Valley, developed in the Triassic. These basins filled with sediment shed from the mountains.
The park is in the Frederick Valley and is underlain by thick Triassic sediments just east of the Blue Ridge. The downdropped Frederick Valley is bordered on the west by a large normal fault.
Geologic processes give rise to a landscape composed of rock formations, hills and valleys, waterfalls, and wetlands. This landscape played a prominent role in the movement of troops and battle locations during the Civil War. Local geology dictated the placement of bridges, fords, and railroads, which in turn informed military strategy. Today, geologic processes continue to develop a landscape that influences human use patterns. The connection between history and geology inspires visitors, and emphasis on geologic resources will enhance the visitor’s experience.
The geologic setting affected the 1864 Battle of Monocacy Junction on regional and local levels. Two large rivers, the Monocacy and the Potomac, shaped the course of military movements in the area before the battles. Safe river crossings were vital to military success during the Civil War.
The Monocacy River is the third largest tributary of the Potomac River. The free-flowing river is approximately 93 km (58 mi) long and is fed by a drainage area of 1,927 km2 (744 mi2). The river begins at the confluence of Marsh Creek and Rock Creek in Adams County, Pennsylvania, and ends at its confluence with the Potomac near Dickerson, Maryland. Tributaries of the river in the battlefield area include Furnace Branch, Double Pipe Creek, and Stony Creek in Maryland and Tom’s Creek in Pennsylvania. The area’s smaller streams played a significant role in the actual fighting at Monocacy by creating important topographic differences and tactical targets such as railroad bridges, crossings, gaps, gulleys, and protective cover. On the gentle landscape of Monocacy, even the smallest swell or depression was utilized for tactical advantage.
Cambrian limestone and dolostone in the park may contain trace fossils, burrows, and algal mats.
All NPS fossil resources are protected under the Paleontological Resources Preservation Act of 2009 (Public Law 111-11, Title VI, Subtitle D; 16 U.S.C. §§ 470aaa - 470aaa-11).
Cave and Karst
There are no known caves at Monocacy NB, but 92.3% of the Battlefield unit is considered karst. The Battlefield is underlain by the Frederick Formation, a thick Cambrian-age sequence of thin to medium bedded limestone and dolostone.
The hydrogeologic system underlying most of the Battlefield is a karst aquifer. Karst features are formed by the dissolution of carbonate rocks such as limestone and dolomite. There are at least 4 springs and several water wells within the Battlefield boundaries that tie to this aquifer.
The Quaternary alluvium in the Battlefield contains sinks where the alluvium has collapsed into the dissolved portions of the underlying limestone bedrock.
All NPS cave resources are protected under the the Federal Cave Resources Protection Act of 1988 (FCRPA)(16 U.S.C. § 4301 et seq.).
Geology Field Notes
Students and teachers of college-level (or AP) introductory geology or earth science teaching courses will find that each park's Geologic Resource Inventory report includes the Geologic History, Geologic Setting, and Geologic Features & Processes for the park which provides a useful summary of their overall geologic story. See Maps and Reports, below.
Monocacy National Battlefield is a part of the Piedmont Physiographic Province and shares its geologic history and some characteristic geologic formations with a region that extends well beyond park boundaries.
Geologic Resources Inventory
- Scoping summaries are records of scoping meetings where NPS staff and local geologists determined the park’s geologic mapping plan and what content should be included in the report.
- Digital geologic maps include files for viewing in GIS software, a guide to using the data, and a document with ancillary map information. Newer products also include data viewable in Google Earth and online map services.
- Reports use the maps to discuss the park’s setting and significance, notable geologic features and processes, geologic resource management issues, and geologic history.
- Posters are a static view of the GIS data in PDF format. Newer posters include aerial imagery or shaded relief and other park information. They are also included with the reports.
- Projects list basic information about the program and all products available for a park.
Related ArticlesMonocacy National Battlefield
National Park Service Geodiversity AtlasThe servicewide Geodiversity Atlas provides information on geoheritge and geodiversity resources and values within the National Park System. This information supports science-based geoconservation and interpretation in the NPS, as well as STEM education in schools, museums, and field camps. The NPS Geologic Resources Division and many parks work with National and International geoconservation communities to ensure that NPS abiotic resources are managed using the highest standards and best practices available.
For more information on the NPS Geodiversity Atlas, contact us.