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Bedrock geologic map of the Littleton and Lower Waterford quadrangles, Essex and Caledonia Counties, Vermont, and Grafton County, New Hampshire

Open-File Report 2018-1087
Prepared in cooperation with the State of Vermont, Vermont Agency of Natural Resources, Vermont Geological Survey, and the State of New Hampshire, Department of Environmental Services, New Hampshire Geological Survey
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Abstract

The bedrock geologic map of the Littleton and Lower Waterford quadrangles covers an area of approximately 107 square miles (277 square kilometers) north and south of the Connecticut River in east-central Vermont and adjacent New Hampshire. This map was created as part of a larger effort to produce a new bedrock geologic map of Vermont through the collection of field data at a scale of 1:24,000. A large part of the map area consists of the Bronson Hill anticlinorium, a post-Early Devonian structure that is cored by metamorphosed Cambrian to Devonian sedimentary, volcanic, and plutonic rocks. The northwestern part of the map is divided by the Monroe fault which separates Early Devonian rocks of the Connecticut Valley-Gaspé trough from rocks of the Bronson Hill anticlinorium.

The Bronson Hill anticlinorium is the apex of the Middle Ordovician to earliest-Silurian Bronson Hill magmatic arc that contains the Ammonoosuc Volcanics, Partridge Formation, and Oliverian Plutonic suite, and extends from Maine, down the eastern side of the Connecticut River in New Hampshire, to Long Island Sound. The deformed and partially eroded arc is locally overlain by a relatively thin Silurian section of metasedimentary rocks (Clough Quartzite and Fitch Formation) that thickens to the east. The Silurian section near Littleton is disconformably overlain by a thicker, Lower Devonian section that includes mostly metasedimentary rocks and minor metavolcanic rocks of the Littleton Formation. The Bronson Hill anticlinorium is bisected by a series of northeast-southwest trending Mesozoic normal faults. Primarily among them is the steeply northwest-dipping Ammonoosuc fault that divides older and younger units (upper and lower sections) of the Ammonoosuc Volcanics. The Ammonoosuc Volcanics are lithologically complex and predominantly include interlayered and interfingered rhyolitic to basaltic volcanic and volcaniclastic rocks, as well as lesser amounts of metamorphic and metasedimentary rocks. The Ammonoosuc Volcanics overlies the Albee Formation that consists of interlayered feldspathic sandstone, siltstone, pelite, and slate.

During the Late Ordovician, a series of arc-related plutons intruded the Ammonoosuc Volcanics, including the Whitefield pluton to the east, the Scrag granite of Billing (1937) in the far southeastern corner of the map, the Highlandcroft Granodiorite just to the west of the Ammonoosuc fault, and the Joslin Turn tonalite (just north of the Connecticut River). To the east of the Monroe fault lies the late Silurian Comerford Intrusive Complex, which consists of metamorphosed gabbro, diorite, tonalite, aplitic tonalite, and crosscutting diabase dikes. Abundant mafic dikes of the Comerford Intrusive Complex intruded the Albee Formation and Ammonoosuc Volcanics well east of the Monroe fault.

This report consists of a single geologic map sheet and an online geographic information systems database that includes contacts of bedrock geologic units, faults, outcrops, and structural geologic information.

Suggested Citation

Rankin, D.W., 2018, Bedrock geologic map of the Littleton and Lower Waterford quadrangles, Essex and Caledonia Counties, Vermont, and Grafton County, New Hampshire: U.S. Geological Survey Open-File Report 2018–1087, 1 sheet, scale 1:24,000, https://doi.org/10.3133/ofr20181087.

ISSN: 2331-1258 (online)

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Table of Contents

  • Correlation of Map Units
  • Description of Map Units
  • Explanation of Map Symbols
  • References Cited

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Bedrock geologic map of the Littleton and Lower Waterford quadrangles, Essex and Caledonia Counties, Vermont, and Grafton County, New Hampshire
Series title Open-File Report
Series number 2018-1087
DOI 10.3133/ofr20181087
Year Published 2018
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Eastern Geology and Paleoclimate Science Center
Description Sheet: 36.00 x 45.82 inches; Geologic Map: ArcGIS 10.5 zip; Geodatabase; Metadata; Base Map
Country United States
State New Hampshire, Vermont
County Caledonia County, Grafton County, Essex County
Other Geospatial Littleton Quadrangle, Lower Waterford Quadrangle
Online Only (Y/N) Y
Additional Online Files (Y/N) N