Preliminary Bedrock Geology of the Northern Portion of the ... · 47 49 33 48 35 24 25 65 25 71 37...
1
SOURCES OF DATA Shaw, 1966 Kopera (this study) Dixon and Goldsmith (unpublished data 1977-1978) ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Christian Hill Synform 52 5 36 41 20 63 52 84 41 34 44 50 55 57 35 17 60 40 63 36 26 48 40 36 58 74 52 54 45 30 45 30 60 61 22 38 41 82 44 47 74 24 33 48 47 49 24 35 25 65 25 71 37 13 63 59 37 55 40 34 46 44 10 51 79 76 46 35 78 35 58 45 55 31 40 20 13 20 40 35 60 60 40 45 35 35 70 40 35 20 15 40 30 20 85 15 50 40 40 80 75 55 60 75 65 65 55 45 88 82 85 60 38 40 32 28 40 24 38 38 57 88 85 70 40 ~60 88 40 50 23 5 46 36 41 20 15 17 35 30 28 11 24 34 18 30 21 40 10 82 63 60 68 28 23 25 30 23 20 22 32 32 35 58 23 30 ? ? ? ? ? Hornblende abundant within shear zone 61 32 60 42 70 50 82 Zba Zba Zba Zba Zbq Zbq Zngg Zngg Zngg Zmgr Zmgd Zmgd Zg Zg Zg Zg Zngg Zbq Zbq Zbq Zba Zba 71°30'0"W 71°30'0"W 71°32'30"W 71°32'30"W 71°35'0"W 71°35'0"W 71°37'30"W 71°37'30"W 42°7'30"N 42°7'30"N 42°5'0"N 42°5'0"N 283000 283000 284000 284000 285000 285000 286000 286000 287000 287000 288000 288000 289000 289000 290000 290000 291000 291000 292000 292000 293000 293000 4660000 4661000 4661000 4662000 4662000 4663000 4663000 4664000 4664000 4665000 4665000 4666000 4666000 4667000 (HOLLISTON) (MILFORD) (GRAFTON) (UXBRIDGE) (FRANKLIN) FOLDS Approximate trace of axial surface of antiform Approximate trace of axial surface of synform Approximate trace of axial surface of minor antiform, showing direction of plunge MAGNETIC NORTH APPROXIMATE MEAN DECLINATION, 1999 TRUE NORTH 15 / 1 2 MASS. QUADRANGLE LOCATION 1 Data Sources: Shaw, C.E., Jr., 1967, Geology and petrochemistry of the Milford area, Massachusetts: PhD dissertation, Brown University. Goldsmith, D., and Dixon, R., 1976-1978, Unpublished maps and data. Obtained from USGS Field Records Archive. Kopera, J.P., 2007 - Field mapping and reconnaisance Bedrock exposure compiled from sources above by Mary DiGiacomo-Cohen (USGS) as part of USGS Open File Report 2006-1260-D. Modified and additional outcrops added by J. Kopera, 2008. Compilation and Digital Cartography by J.P. Kopera, 2008 Topographic Base Information: Topographic base modified from U.S. Geological Survey, 1966. Polyconic projection. Re-projected into 1983 North American Datum. 1000-meter Universal Transverse Mercator grid ticks from 1983 North American Datum, zone 19 OMSG Open File Report No. 08-03 Preliminary Map: Bedrock Geology Northern Portion of the Blackstone Quadrangle 2008 Map last modified 8/20/2008 by Joseph P. Kopera 1 and Charles E. Shaw, Jr. 2 1 Office of the Massachusetts State Geologist, University of Massachusetts, Amherst, MA 2 Formerly U.S. Geological Survey, Reston, VA Preliminary Bedrock Geology of the Northern Portion of the Blackstone Quadrangle, Massachusetts O F F I C E O F T H E S T A T E G E O L O G I S T U N I V E R S I T Y O F M A S S A C H U S E T T S Office of the Massachusetts State Geologist University of Massachusetts, Amherst Address: 269 Morrill Science Center, 611 North Pleasant Street, Amherst, MA 01003 Phone: 413-545-4814 E-mail: [email protected] WWW: http://www.geo.umass.edu/stategeologist Comments to the Map User A geologic map displays information on the distribution, nature, orientation and age relationships of rock and deposits and the occurrence of structural features. Geologic and fault contacts are irregular surfaces that form boundaries between different types or ages of units. Data depicted on this geologic quadrangle map are based on reconnaissance field geologic mapping, compilation of published and unpublished work, and photogeologic interpretation. Locations of contacts are not surveyed, but are plotted by interpretation of the position of a given contact onto a topographic base map; therefore, the accuracy of contact locations depends on the scale of mapping and the interpretation of the geologist(s). Any enlargement of this map could cause misunderstanding in the detail of mapping and may result in erroneous interpretations. Site-specific conditions should be verified by detailed surface mapping or subsurface exploration. Topographic and cultural changes associated with recent development may not be shown. We recommend reading Reading Maps with a Critical Eye: Becoming an Informed Map Reader by the Maine Geologic Survey to make the best use of a geologic map (http://www.maine.gov/doc/nrimc/mgs/mapuse/informed/informed.htm). This Open-File map is a progress report of mapping in this area, and is preliminary in nature. Revision of the map is likely because of the on-going nature of work in the region. It has not been peer reviewed or edited to conform with editorial standards of the Massachusetts State Geologist or with the North American Stratigraphic Code. The contents of the report and map should not be considered final and complete until reviewed and published by the Office of the Massachusetts State Geologist. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the University of Massachusetts, Commonwealth of Massachusetts, and the United States Federal Government. This research was supported by U.S. Geological Survey, National Cooperative Geologic Mapping Program, under assistance Award No. 07HQAG0061. Citation: Kopera, J. P., and Shaw, C.E. Jr,, 2008, Preliminary bedrock geology of the northern portion of the Blackstone quadrangle, Massachusetts: Office of the Massachusetts State Geologist Open File Report 08-03. Scale 1:24,000. 1 sheet and digital product: Adobe PDF and ESRI ArcGIS database. This map was produced on request directly from digital files (PDF format) on an electronic plotter. A digital copy of this map (PDF format), including GIS datalayers, is available at http://www.geo.umass.edu/stategeologist Clinton- Newbury Fault I-395 I-495 NH-Maine Sequence (Merrimack Belt) Nashoba Terrane Avalon Terrane Narragansett Basin Location of quadrangle with respect to major geologic terranes of eastern Massachusetts Lake Char- Bloody Bluff Fault Zone Zone Rt. 3 I-90 I-495 Rt. 20 Rt. 1 Rt. 1 I-290 I-190 I-495 I-90 I-95 I-95 Rt 128 / I-95 I-93 North plunging folds of interlayered quartzite, schist and amphibolite of the Blackstone Group Zba Zbq Zg Zmgd Zmgr Zngg Strike and dip of foliation in all rocks. May be secondary foliation in some areas where primary foliation is not displayed. Strike of vertical foliation Strike and dip of secondary foliation parallel to axial plane of minor folds in Blackstone Group. Strike and dip of ductile fault or shear zone in outcrop Bearing and plunge of mineral lineation Bearing and plunge of secondary mineral lineation associated with local shear zones Bearing and plunge of minor fold axis Bearing and plunge of boudinage 80 80 Bedrock outcrops visited by authors Area of abundant small outcrops or shallow bedrock (within 3 meters of surface) Location of float used to determine lithology in areas of poor exposure (from Shaw, 1966) Contact Solid where location is certain, long dashed where approximate, short dash where inferred, dotted where gradational contact between igneous rocks. Queried where uncertain. Zone of sheared and cataclastic rocks EXPLANATION OF MAP SYMBOLS PLANAR FEATURES EXPOSURE STRUCTURAL DATA 80 80 80 80 80 EXPLANATION OF LITHOLOGIC UNITS Neo-Proterozoic Plutonic Rocks of the Avalon Zone (descriptions in part modified from Shaw, 1966) NORTHBRIDGE GRANITE-GNEISS Equivalent in part to the Ponagansett gneiss as mapped by Zen et al. (1983) and Walsh and Aleinikoff (in press) and the Scituate granite-gneiss as mapped by Zen et al. (1983). Also equivalent to the Northbridge granite gneiss as mapped by Barosh et al. (1977). Age: (604 ± 5 Ma) from Zcg equivalent (Zpcg) in Grafton quadrangle (Walsh and Aleinikoff, in press); (607 ± 5 Ma; SHRIMP U/Pb) from Zcgm equivalent (Zpg)in Grafton quadrangle (Walsh and Aleinikoff, in press). Zngg – BIOTITE GRANITE-GNEISS – Massive to strongly foliated, light to dark gray, medium- to coarse-grained quartz-oligoclase-biotite-magnetite ± epidote ± sphene ± apatite ± zircon granite and gneiss. Biotite is present as distinctive 1-cm diameter mats and, in areas of strong foliation, streaks on foliation surfaces (Photo 1). Biotite content is commonly 5-10%, but locally may be present in amounts up to 20-30%. Magnetite is common. Locally grades into biotite-hornblende schist towards contacts with the Milford granite (Zmgr) and rocks of the Blackstone group. Concordant and discordant seams of quartz-epidote rock, approximately 1 cm-thick, are common. Abundant megacrysts of beige-weathering feldspar up to 1-cm in diameter are common. Where strongly foliated or sheared rock is equivalent to Zplcg of Walsh and Aleinkoff (in press). MILFORD GRANITE Age: ~ 606 Ma (206Pb/238U) (Margeret Thompson, written communication, 2007, Holliston quadrangle) from Zmgr. Zmgr – UNDIFFERENTED GRANITE AND GRANODIORITE – Bright-pink to gray, massive to weakly foliated, medium-grained quartz-plagioclase-microcline-biotite±epidote granite. Biotite content is commonly 3-5%, though locally is as much as 10% or more, and occurs in distinctive fine-grained clots up to 1cm in diameter. Secondary muscovite is common. Commonly known as “Milford-Pink”. Dikes and masses of Zmgd are common. Unit as mapped may contain up to 50% Zmgd. Zmgd – BIOTITE GRANITE AND GRANODIORITE – Light to dark gray, weakly to moderately foliated, medium to coarse grained, locally porphyritic oliglase-quartz-biotite granite to granodiorite to quartz-diorite. Biotite content is typically 15-20% or more, and is evenly disseminated throughout the rock. Phenocrysts of oligoclase are common. Isolated, distinctive masses, enclaves, and pillows of fine-grained, biotite-hornblende diorite and gabbro are common. Commonly occurs as dikes and sills intruding Zmgr. Schleiren and flow banding are common near contacts with Zmgr. UNDIFFERENTIATED GRANITIC ROCKS Zg – UNDIFFERENTIATED GRANITIC ROCKS – Light to dark grey to pink weathering, massive and foliated granite, alaskitic granite, quartz monzonite, and gneiss with varying amounts of biotite from 5- 20%. Locally includes lithologies similar to Zmgr, Zmgd, and Zngg. Neo-Proterozoic Meta-sedimentary and Volcanic Rocks of the Avalon Zone (descriptions in part modified from Shaw, 1966) BLACKSTONE GROUP (after Zen et al. 1983) Zba – AMPHIBOLITE AND SCHIST – Black to dark gray to gray-green amphibolite, locally massive or foliated, fine- to coarse-grained epidote-plagioclase-hornblende±biotite±garnet amphibolite (Photo 6) and amphibolite-schist. Locally contains randomly oriented hornblende needles up to 2 cm in length near contacts with Zbq. May be equivalent to Hunting Hill Greenstone of Quinn (1971). Intruded by Zngg. Zbq – QUARTZITE AND SCHIST – White to buff, fine- to medium-grained, sugary-textured quartzite and feldspathic quartzite (Photo 5) with minor schistose layers. Contains layers and lenses of biotitic quarztite, muscovitic quartzite, and biotite-muscovite schist. Bedding and/or foliation are generally absent. In northern part of quadrangle, correlative with Hopedale quartzite of Shaw (1966). CITED REFERENCES Barosh, P.J., Fahey, R.J., and Pease, M.H., 1977, Preliminary compilation of the bedrock geology of the land area of the Boston 2-degree sheet, Massachusetts, Connecticut, Rhode Island and New Hampshire: U.S. Geological Survey, Open-File Report OF-77-285, scale 1:125000. Quinn, A.W., 1971, Bedrock Geology of Rhode Island: U.S. Geological Survey Bulletin 1295, 68 p. Shaw, C.E., Jr., 1967, Geology and petrochemistry of the Milford area, Massachusetts: PhD dissertation, Brown University. Walsh, G.J., and Aleinikoff, J.N., in press Bedrock Geologic Map of the Grafton Quadrangle, Worcester County, Massachusetts: U.S. Geological Survey Scientific Investigations Map. 2 Sheets. Zen, E.A., Goldsmith, R., Ratcliffe, N.M., Robinson, P., Stanley, R.S., Hatch, N.L., Jr., Shride, A.F., Weed, E.G.A., and Wones, D.R., 1983, Bedrock geologic map of Massachusetts: U.S. Geological Survey, Scale 1:250,000
Transcript of Preliminary Bedrock Geology of the Northern Portion of the ... · 47 49 33 48 35 24 25 65 25 71 37...
SOURCES OF DATA
Shaw, 1966
Kopera (this study)Dixon and Goldsmith(unpublished data 1977-1978)
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52
5
364120 63
5284
41 34
44 5055
57
3517
60 4063 362648
40 36587452 5445 30
45306061
22
38 41 82
44 477424
33 4847 49
2435
25 6525 71
37
1363
5937
55
4034
464410
51
7976
463578
3558
45
5531
40
20
13
20
40
35
6060
40
45
35
35
70
40
35
20
15
40
30
20
85
1550
40
40
80
75
55
60
75
65
65
55
45
88
8285
60
38
40
3228
40
24
38
38
5788
85
70
40
~60
88
40
50
23
5
46
36
41
20
15
17
35
30
28
11
24
3418
30
21
40
10
82
63
60
68
28
23
25
3023
20
22
32
32
35
58
23
30
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Hornblende abundantwithin shear zone
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32 60
42
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Zba
Zba
Zba
Zba
ZbqZbq
Zngg
Zngg
Zngg
Zmgr
Zmgd
Zmgd
Zg
Zg
Zg
ZgZngg
Zbq
Zbq
Zbq
Zba
Zba
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W71
°30'
0"W
71°32'30"W
71°32'30"W
71°35'0"W
71°35'0"W
71°3
7'30
"W71
°37'
30"W
42°7'30"N 42°7'30"N
42°5'0"N 42°5'0"N
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(HOLL
ISTON)
(MILFORD)
(GRAFTON)
(UX
BR
IDG
E)
(FR
AN
KLI
N)
FOLDS
Approximate trace of axial surface of antiform
Approximate trace of axial surface of synform
Approximate trace of axial surface of minor antiform, showing direction of plunge
�MA
GN
ETIC N
OR
THAPPROXIMATE MEANDECLINATION, 1999
TR
UE
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15 / 1 2
MASS.
QUADRANGLE LOCATION
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Data Sources:
Shaw, C.E., Jr., 1967, Geology and petrochemistry of the Milford area, Massachusetts: PhD dissertation, Brown University.
Goldsmith, D., and Dixon, R., 1976-1978, Unpublished maps and data. Obtained from USGS Field Records Archive.
Kopera, J.P., 2007 - Field mapping and reconnaisance
Bedrock exposure compiled from sources above by Mary DiGiacomo-Cohen (USGS) as part of USGS Open File Report 2006-1260-D. Modified and additional outcrops added by J. Kopera, 2008.
Compilation and Digital Cartography by J.P. Kopera, 2008
Topographic Base Information:
Topographic base modified from U.S. Geological Survey, 1966. Polyconic projection. Re-projected into 1983 North American Datum.
1000-meter Universal Transverse Mercator grid ticks from 1983 North American Datum, zone 19
OMSG Open File Report No. 08-03Preliminary Map: Bedrock Geology
Northern Portion of the Blackstone Quadrangle 2008
Map last modified 8/20/2008
by Joseph P. Kopera1 and Charles E. Shaw, Jr.21 Office of the Massachusetts State Geologist, University of Massachusetts, Amherst, MA
2 Formerly U.S. Geological Survey, Reston, VA
Preliminary Bedrock Geology of the Northern Portion of the Blackstone Quadrangle, Massachusetts
OFF
ICE O
F THE STATE GEOLOGIST
UN
IVERS ITY OF MAS SACHUSETTS
Office of the Massachusetts State GeologistUniversity of Massachusetts, AmherstAddress: 269 Morrill Science Center, 611 North Pleasant Street, Amherst, MA 01003Phone: 413-545-4814 E-mail: [email protected]: http://www.geo.umass.edu/stategeologist
Comments to the Map User
A geologic map displays information on the distribution, nature, orientation and age relationships of rock and deposits and the occurrence of structural features. Geologic and fault contacts are irregular surfaces that form boundaries between different types or ages of units. Data depicted on this geologic quadrangle map are based on reconnaissance field geologic mapping, compilation of published and unpublished work, and photogeologic interpretation. Locations of contacts are not surveyed, but are plotted by interpretation of the position of a given contact onto a topographic base map; therefore, the accuracy of contact locations depends on the scale of mapping and the interpretation of the geologist(s). Any enlargement of this map could cause misunderstanding in the detail of mapping and may result in erroneous interpretations. Site-specific conditions should be verified by detailed surface mapping or subsurface exploration. Topographic and cultural changes associated with recent development may not be shown.
We recommend reading Reading Maps with a Critical Eye: Becoming an Informed Map Reader by the Maine Geologic Survey to make the best use of a geologic map (http://www.maine.gov/doc/nrimc/mgs/mapuse/informed/informed.htm).
This Open-File map is a progress report of mapping in this area, and is preliminary in nature. Revision of the map is likely because of the on-going nature of work in the region. It has not been peer reviewed or edited to conform with editorial standards of the Massachusetts State Geologist or with the North American Stratigraphic Code. The contents of the report and map should not be considered final and complete until reviewed and published by the Office of the Massachusetts State Geologist. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the University of Massachusetts, Commonwealth of Massachusetts, and the United States Federal Government.
This research was supported by U.S. Geological Survey, National Cooperative Geologic Mapping Program, under assistance Award No. 07HQAG0061.
Citation:Kopera, J. P., and Shaw, C.E. Jr,, 2008, Preliminary bedrock geology of the northern portion of the Blackstone quadrangle, Massachusetts: Office of the Massachusetts State Geologist Open File Report 08-03. Scale 1:24,000. 1 sheet and digital product: Adobe PDF and ESRI ArcGIS database.
This map was produced on request directly from digital files (PDF format) on an electronic plotter.
A digital copy of this map (PDF format), including GIS datalayers, is available at http://www.geo.umass.edu/stategeologist
Clinto
n-N
ewbu
ry
Fault
I-395
I-495
NH-Maine Sequence(Merrimack Belt)
Nasho
ba Terr
ane
Avalon Terra
ne
Narragansett Basin
Location of quadrangle with respect to major geologic terranes of eastern Massachusetts
Lake C
har-
Bloody BluffFa
ult
Zone
Zone
Rt. 3
I-90
I-495
Rt. 2
0
Rt. 1
Rt. 1
I-290
I-190
I-495
I-90
I-95
I-95
Rt 1
28 /
I-95
I-93
North plunging folds of interlayered quartzite, schist and amphibolite of the Blackstone Group
Zba
Zbq
Zg
Zmgd
Zmgr
Zngg
Strike and dip of foliation in all rocks. May be secondary foliation in some areas where primary foliation is not displayed.
Strike of vertical foliation
Strike and dip of secondary foliation parallel to axial plane of minor folds in Blackstone Group.
Strike and dip of ductile fault or shear zone in outcrop
Bearing and plunge of mineral lineation
Bearing and plunge of secondary mineral lineation associated with local shear zones
Bearing and plunge of minor fold axis
Bearing and plunge of boudinage
80
80
Bedrock outcrops visited by authors
Area of abundant small outcrops or shallow bedrock (within 3 meters of surface)
Location of float used to determine lithology in areas of poor exposure (from Shaw, 1966)
ContactSolid where location is certain, long dashed where
approximate, short dash where inferred, dotted where gradational contact between igneous rocks.
Queried where uncertain.
Zone of sheared and cataclastic rocks
EXPLANATION OF MAP SYMBOLS
PLANAR FEATURES
EXPOSURE
STRUCTURAL DATA
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EXPLANATION OF LITHOLOGIC UNITS
Neo-Proterozoic Plutonic Rocks of the Avalon Zone(descriptions in part modified from Shaw, 1966)
NORTHBRIDGE GRANITE-GNEISS
Equivalent in part to the Ponagansett gneiss as mapped by Zen et al. (1983) and Walsh and Aleinikoff (in press) and the Scituate granite-gneiss as mapped by Zen et al. (1983). Also equivalent to the Northbridge granite gneiss as mapped by Barosh et al. (1977).
Age: (604 ± 5 Ma) from Zcg equivalent (Zpcg) in Grafton quadrangle (Walsh and Aleinikoff, in press); (607 ± 5 Ma; SHRIMP U/Pb) from Zcgm equivalent (Zpg)in Grafton quadrangle (Walsh and Aleinikoff, in press).
Zngg – BIOTITE GRANITE-GNEISS – Massive to strongly foliated, light to dark gray, medium- to coarse-grained quartz-oligoclase-biotite-magnetite ± epidote ± sphene ± apatite ± zircon granite and gneiss. Biotite is present as distinctive 1-cm diameter mats and, in areas of strong foliation, streaks on foliation surfaces (Photo 1). Biotite content is commonly 5-10%, but locally may be present in amounts up to 20-30%. Magnetite is common. Locally grades into biotite-hornblende schist towards contacts with the Milford granite (Zmgr) and rocks of the Blackstone group. Concordant and discordant seams of quartz-epidote rock, approximately 1 cm-thick, are common. Abundant megacrysts of beige-weathering feldspar up to 1-cm in diameter are common. Where strongly foliated or sheared rock is equivalent to Zplcg of Walsh and Aleinkoff (in press).
MILFORD GRANITE
Age: ~ 606 Ma (206Pb/238U) (Margeret Thompson, written communication, 2007, Holliston quadrangle) from Zmgr.
Zmgr – UNDIFFERENTED GRANITE AND GRANODIORITE – Bright-pink to gray, massive to weakly foliated, medium-grained quartz-plagioclase-microcline-biotite±epidote granite. Biotite content is commonly 3-5%, though locally is as much as 10% or more, and occurs in distinctive fine-grained clots up to 1cm in diameter. Secondary muscovite is common. Commonly known as “Milford-Pink”. Dikes and masses of Zmgd are common. Unit as mapped may contain up to 50% Zmgd.
Zmgd – BIOTITE GRANITE AND GRANODIORITE – Light to dark gray, weakly to moderately foliated, medium to coarse grained, locally porphyritic oliglase-quartz-biotite granite to granodiorite to quartz-diorite. Biotite content is typically 15-20% or more, and is evenly disseminated throughout the rock. Phenocrysts of oligoclase are common. Isolated, distinctive masses, enclaves, and pillows of fine-grained, biotite-hornblende diorite and gabbro are common. Commonly occurs as dikes and sills intruding Zmgr. Schleiren and flow banding are common near contacts with Zmgr.
UNDIFFERENTIATED GRANITIC ROCKS
Zg – UNDIFFERENTIATED GRANITIC ROCKS – Light to dark grey to pink weathering, massive and foliated granite, alaskitic granite, quartz monzonite, and gneiss with varying amounts of biotite from 5-20%. Locally includes lithologies similar to Zmgr, Zmgd, and Zngg.
Neo-Proterozoic Meta-sedimentary and Volcanic Rocks of the Avalon Zone(descriptions in part modified from Shaw, 1966)
BLACKSTONE GROUP(after Zen et al. 1983)
Zba – AMPHIBOLITE AND SCHIST – Black to dark gray to gray-green amphibolite, locally massive or foliated, fine- to coarse-grained epidote-plagioclase-hornblende±biotite±garnet amphibolite (Photo 6) and amphibolite-schist. Locally contains randomly oriented hornblende needles up to 2 cm in length near contacts with Zbq. May be equivalent to Hunting Hill Greenstone of Quinn (1971). Intruded by Zngg.
Zbq – QUARTZITE AND SCHIST – White to buff, fine- to medium-grained, sugary-textured quartzite and feldspathic quartzite (Photo 5) with minor schistose layers. Contains layers and lenses of biotitic quarztite, muscovitic quartzite, and biotite-muscovite schist. Bedding and/or foliation are generally absent. In northern part of quadrangle, correlative with Hopedale quartzite of Shaw (1966).
CITED REFERENCES
Barosh, P.J., Fahey, R.J., and Pease, M.H., 1977, Preliminary compilation of the bedrock geology of the land area of the Boston 2-degree sheet, Massachusetts, Connecticut, Rhode Island and New Hampshire: U.S. Geological Survey, Open-File Report OF-77-285, scale 1:125000.
Quinn, A.W., 1971, Bedrock Geology of Rhode Island: U.S. Geological Survey Bulletin 1295, 68 p.
Shaw, C.E., Jr., 1967, Geology and petrochemistry of the Milford area, Massachusetts: PhD dissertation, Brown University.
Walsh, G.J., and Aleinikoff, J.N., in press Bedrock Geologic Map of the Grafton Quadrangle, Worcester County, Massachusetts: U.S. Geological Survey Scientific Investigations Map. 2 Sheets.
Zen, E.A., Goldsmith, R., Ratcliffe, N.M., Robinson, P., Stanley, R.S., Hatch, N.L., Jr., Shride, A.F., Weed, E.G.A., and Wones, D.R., 1983, Bedrock geologic map of Massachusetts: U.S. Geological Survey, Scale 1:250,000
