Minute Man National Historical Park: Geologic resources inventory report.
Thornberry-Ehrlich TL. 2017. Minute Man National Historical Park: Geologic resources inventory report.. Natural Resource Report. NPS/NRSS/GRD/NRR—2017/1523. National Park Service. Fort Collins, Colorado
The Geologic Resources Inventory (GRI) program provides geologic map data and pertinent geologic information to support resource management and science-informed decision making in more than 270 natural resource parks throughout the National Park System. The GRI is one of 12 inventories funded by the National Park Service (NPS) Inventory and Monitoring Program. The Geologic Resources Division of the NPS Natural Resource Stewardship and Science Directorate administers the GRI. This report synthesizes discussions from a scoping meeting held in 2007 and a follow-up conference call in 2016 (Appendix A). Sections of this report discuss the geologic setting, distinctive geologic features and processes within Minute Man National Historical Park, highlight geologic issues facing resource managers, describe the geologic history leading to the present-day landscape, and provide information about the previously completed GRI map data. Posters (in pocket) illustrate these data. The “shot heard ‘round the world” on April 19, 1775 was likely fired by a colonial farmer, or group of farmers, standing on floodplain alluvial deposits and sandy deposits of ancient glacial Lake Concord. They were confronting British soldiers at the North Bridge, over a narrow reach of the Concord River, just upstream of the Great Meadow, a great flanking wetland area. During the British retreat from the bridge, colonial militia hunkered behind stone walls made from glacial erratic boulders and outwash gravel, and outcrops of the Nashoba and Avalon bedrock terranes. The long human history of Minute Man National Historical Park played out on a glaciated landscape whose geologic features strongly influenced the early settlement of the area, the attraction of literary luminaries, as well as the tactics and ultimate outcome of the first battle of the American Revolution. The bedrock units in Minute Man National Historical Park reflect the assembly of eastern Massachusetts during Appalachian mountain-building orogenies hundreds of millions of years ago that eventually lead to the creation of the supercontinent Pangaea. A major boundary—the Bloody Bluff Fault (named after the battle fought nearby)— between two such rock “pieces,” or geologic terranes, which accreted to the edge of North America about 425 million years ago, runs through the eastern end of the Battle Road unit. This northeast-to-southwest trending fault separates metamorphic and igneous rocks of the Avalon terrane (geologic map units Zwm and ZSfhg) on the east from the Nashoba terrane (COm, Sgrm, DSag, DSaqd, and COnu) on the west. Nearly 200 million years of weathering and erosion whittled away the massiveppalachian mountain range to expose its core in New England. The most recent ice age glaciations over the past few hundreds of thousands of years then carved the bedrock landscape and left behind glacial till (Qt), outwash and glacial lake deposits (Qsdc and Qsdf), alluvium (Qal), and swamp deposits (Qsw) across the region. At Minute Man, the glacial outwash and lake deposits are related to glacial Lake Sudbury along Battle Road and Barretts Farm, as well as two levels of Lake Concord in the environs of North Bridge, Mill Brook, The Wayside, and the town of Concord. Rivers. Wind, and weather continue to rework these sediments today. Throughout more recent history, humans significantly modified the landscape by clearing forests, draining or filling wetlands, channeling streams, building roads, plowing fields, and other suburban development. One of the park goals is to reveal the battle-era landscape appearance while protecting and preserving this valuable natural area in the greater Boston area. The geologic foundation of the park is a major factor to these efforts because it played such a prominent role in the history and geologic processes can alter historic context.
- Type
- Published Report
- Authors
- Thornberry-Ehrlich, Trista
- Date of Issue
- 2017-09
- Publisher
- National Park Service
- Units
- GRD , GRI , MIMA , NETN , NRSS
- Keywords
- and Protection., Aquifers and Groundwater Availability, Bedrock Exposures, Disturbed lands and Mineral Extraction, Eolian Features, Erosion and Slope Movement Hazards and Risks, Faults and Shear Zones, Flooding and Wetlands, Fluvial Features and Processes, Geologic Features, Geologic Features and Processes, Geologic History, Geologic Processes, Geologic Resource Management Issues, Geologic Resources Division, Geologic Resources Inventory, Glacial Features, GRD, GRI, Map Units, Massachusetts, MIMA, Minute Man National Historical Park, Monitoring, National Park Service, NPS, Paleontological Resource Inventory, Resource Management, Seismic Activity Hazards and Risks, Wetlands
- Subjects
- Ecological Framework: Geology and Soils | Geomorphology | Windblown Features and Processes , Ecological Framework: Geology and Soils | Geomorphology | Glacial Features and Processes , Ecological Framework: Geology and Soils | Geomorphology | Hillslope Features and Processes , Ecological Framework: Geology and Soils | Geomorphology | Stream/River Channel Characteristics , Ecological Framework: Geology and Soils | Geomorphology | Lake Features and Processes , Ecological Framework: Geology and Soils | Subsurface Geologic Processes | Seismic Activity , Ecological Framework: Geology and Soils | Paleontology | Paleontology