|Latitude & Longitude (WGS84):||42° 16' 2'' North , 71° 9' 30'' West|
|Latitude & Longitude (decimal):||42.26722,-71.15833|
|Köppen climate type:||Dfa : Hot-summer humid continental climate|
A large open-pit crushed stone quarry, over 300 feet (91 meters) deep, primarily in coarse-grained Dedham granite. The quarry was opened in 1889 by Thomas F. Welch (b. 1855 West Roxbury, MA). The business was incorporated as West Roxbury Trap Rock Company in 1903.
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
20 valid minerals.
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.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
298.9 - 323.2 Ma
|Paleozoic sedimentary rocks|
Age: Pennsylvanian (298.9 - 323.2 Ma)
Comments: Narragansett And Boston Basins
Lithology: Sedimentary rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
|Ediacaran - Cryogenian|
541 - 720 Ma
Age: Neoproterozoic (541 - 720 Ma)
Stratigraphic Name: Dedham Granite
Description: Light grayish-pink to greenish-gray, equigranular to slightly porphyritic, variably altered, granite south and west of Boston. Includes dioritic rock near Scituate and Cohasset and Barefoot Hills Quartz Monzonite of Lyons (1969) and Lyons and Wolfe (1971). Intrudes Zdi, Zgb, Zb, Zv. Extensive calc-alkaline plutons separated by Boston basin have long been mapped as Dedham. Those to the north of Boston and studied in this report, are referred to as Dedham North. Crystallization ages for the Dedham North suite (based on titanites and zircons) have been determined at 607+/-4 Ma, while ages for the Lynn are slightly younger at 596+/-3 Ma. Both are clearly part of the Late Proterozoic magmatic event. Dates on two samples from Sheffield Heights indicate that the diorite and granite are part of the Dedham North suite. The Dedham south and west of Boston has been dated at 630+/15 Ma (Zartman and Naylor, 1984). Dedham North Granite has a compositionally highly variable suite ranging from leucogranites to granodiorites, tonalites, and quartz diorite. The granites originated by partial melting of a sedimentary protolith, while the intermediate members show a mixing of granitic magma and mafic magma (Hepburn and others, 1993).
Comments: Part of Milford-Dedham Zone (Tertiary and Older Rocks). Secondary unit description per MA018.Proterozoic Z age of Dedham is based on the following isotopic dates: . 1. 630 +/-15 Ma by U/Pb methods on zircon (Zartman and Naylor, 1984) from Dedham Granite. 2. 595 +/-17 Ma by Rb/Sr whole rock methods (Kovach and others, 1977) from Dedham Granite north of Boston. 3. 640 +/-14 Ma by K/Ar methods on hornblende (Zartman and Naylor, 1984) per MA007.
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.