Fletcher Granite Quarry (H. E. Fletcher Quarry; Chelmsford Grey Quarry), Westford, Middlesex Co., Massachusetts, USA
|Latitude & Longitude (WGS84):||42° 37' 58'' North , 71° 25' 3'' West|
|Latitude & Longitude (decimal):||42.63278,-71.41750|
An active granite quarry operated by Fletcher Granite Company. Opened in 1881. Located in the town of Westford near the Chelmsford line.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
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|Frasnian - Eifelian|
372.2 - 393.3 Ma
Age: Devonian (372.2 - 393.3 Ma)
Stratigraphic Name: Chelmsford Granite
Comments: Part of Merrimack Belt (Silurian, Devonian and Pennsylvanian Rocks). Secondary unit description per MA007 as reported in USGS Geologic Names lexicon (ref. MA024): Chelmsford Granite intrudes Berwick Formation, Ayer Granite, and Dracut Diorite northwest of Clinton-Newbury fault. Occurs as two elongate, northeast-striking bodies occupying an area of 60 sq km. Described as light colored and gneissic. Zartman and Naylor (1984) could not obtain a definitive age but believed Chelmsford was in same age range as Ayer because the age of the Chelmsford lay within margin of error for their age determinations. Devonian age shown on MA State geologic map is based on their Pb-Pb age of 389 +/-5 Ma (Wones and Goldsmith, 1991).
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.