LeMasurier 

Quarry

?

?

2007–1399

2007–1399

50

57

74

NS–187

407±4 Ma

NS–188A

375±3 Ma

NS–187

407±4 Ma

80

80

80

80

75 75

70

80

85

80

80

80

80

85

85

75

80

85

75

70

60

80

55 75 80

85

85

7585

80

75 80

70

80

75

80

80

85 60

80

65

80

75

75

70 65

75

70

85

75

80

70

80

70

65

7080

75

80

50 85

85

75

70

80

75

85

70

80

80 85

85

75 80

80 80

70

78

65 70

75

70

80 70

70

80 80

70

70

75

85 85

75

80

75

80

85

85

80

80

75

85

70

85

85

80

85 40

85

80

75

80

85

80

80

80

75

85

85

80

80

85

85

50

60

75

75

75

70

75 70

58

72

70

80

80

80

80

80

55

80

80

85

85

80

80

60

80

50 60 75

80

70

70

45 50

50

60

80

60

75

85

80

80

85

85

88

80

85

85

85

60

80

80

65

75

70

75

75 65

65

80

70

68

65

80

85

85

85

80

85

86

85 60

75

85

85

85

85

75

75

80

70

75

80

75

75

75

75

80

85

80

85

80

85

80

85

75

80

85

80

75

80 85

85 80

70 65

75

75

65

60

80 70

75

60

70

60 50 70

60

55

50

80

80

85

75

85

80

80

85

65

80

85 85

80

65

85

85

75

85

84

80

50

65 45

55

45

55

60

65

45

55

50

40 60

40

40

60

45

50

55

60

70

55 60

67

40

80

68

80

60

65

58

45 70 80 40 75

70

80 55

50

50

60

55

45

70

65

70

65

70

80 80 75

70

75

70

50 40

60 85

80

85

85

85

85 80

40

55

55

35

35

55

50

70

55 70

80 80

45 35

45

50

60

40

75

60

50

80 45

83

30

80

70

40

50

40 40

40

35

30

50 30

35

45

35

45

40

45 45

50

40

40

70 45

50

40 40

30

65

65 50

75

65

70

70 80

75

68

40

70

70 50

65

60

70 40

45

70

75

60

65

75 75

60

70

80

65

50

65

85

60

80

80

75 80

51

75

80

75

75 80

75 70

80 80

70

70

70

85

70

71

70

65

70

82

85

80

80

80

55

60

50

70

70

75

80

80 80

70

55

70

50

85

65

80

80

78

60

65

50

60

70

85 85 60

70

75 70

80

75

65

75 70

70

85

75

75 70

75 65

70

70

80

68

70

85

80

70

75

84 77

80

36

85

75

75

60

85

77

65 75

80

55

55

70

80

75

70

75

65

85

80

70

60

74

81 76

87

75

85

86

62

64

76 66

62

74

59

84

169

172

166

55

74

73

81 78

8

82

45

55

84

58

68

51

70

75 45

174

47

65

85

44

66

84 52 60 56

33 35

164

74

52

73 66

41

75 58

59

77

68

65

82

86

168

174

16

16

72

71

65

42

76 81 85

74

56 69

85

42

72

58

2

4

18

68

35

74 54

72 67

55

35

25

53

74

56

5

52

1

167

3

8

35

67 37

10

35

58

64

35

36

37

40

44

33 54

71

74

54

8

29

55

19

58

80

18

35

58

50

80

42 77

0 50

5

71

68

58

42 16

25

24

1

16

66 32

67

61

57 24

37

67

21

17 50

10

25 44

64

54

50

49 44 14 63

48

35 75

43

43

52

30

58

58

71 35

33

25

23 84

0

61

62

26

54

54

71

10 54

33

55

16 62

5

22

60

51

51

21

6814

14

14 33

78

24

74

10 37

60 60 25

52

70

84

59

50 64

58

47

61

70

71

80

12

64

15

26 62

24 32

35

56 63

53

13

20

25 35

20

60

25 44

14 19

20 61

81

59

78

10

24

24

5

46

58

73

75

62

18

75

78

75 63

74

163

67

82

72

85

55 35

20 21

24

60

85

70

1B,10B

1C,D

1E

1F

2A

2B

3A

3B

NS–040

3B

NS–027

3C

4A

4B

4C,D

7A-E

10A

10C

11A

11B

13A

13B

13C

1A

3B

NS–095

3B

NS–020

Sb

Sb

Sb

Dcgr

Dcgr

Dadg

Dadg

Dadg

Sb

Sb

Dadp

Dad

SbDc

SbDc

SbDc

SbDc

Dadp

Sb

Dad

Dcgr

Dcgr Dadp

DSdi

Dadp

Dadg

Dadp

SbDc

DSdi

Dadg

Sb

Sb

Sb

Dadp

DSgn

Sb

Dadg

Sb

Dcgr

DSdi

Sb

Sb

Dcgr

Dadg

SbDc

SbDc

Jd

DSdi

Dcgr

Dcgr

Jd

Sb

Dcgr

Dadp

Dcgr

Dcfgr

Jd

Dadg

Dadp

Dadp

Jd

Dad

Sb

Sb

Dcgr

Sb

DSdi

Dcfgr

Sb

Dadp

Dadp

Dadp

DSdi

DSdi

Dadp

DSdi

Dp

DSgn

Dp

Sb

Dp

Dadg

Jd

Sb

DSgn

DSdi

Dcgr

Dp

Dadg

Sb

Sb

Sb

Dp

Dadp

Sb

Dadg

Dadg

Dcgr

DSdi

DSdi

Sb

Sb

Dcgr

DSdi

DSdi

Sb

Dp

Sb

Dp

Sb

A

A'

B

B'

NASHUA NORTH WINDHAM

SOUTH

MERRIMACK

PEPPERELL

AYER WESTFORD BILLERICA

NASHUA SOUTH LOWELL

NEW HAMPSHIRE

MASSACHUSETTS

CLINTON - NEWBURY FAULT

Hudson

pluton

Hollis pluton

Dracut 

pluton

Wb

WEKEPEKE FAULT

Rockingham anticlinorium

Nashua trough

C

DLP

Ayer

pluton

Chelmsford

pluton

71°37’30” 71°30’ 71°22’30” 71°15’

42°52’30”

42°45’

42°30’

42°37’30”

Nashoba zone

Index to adjacent 7.5-minute quadrangles

South Merrimack (Sriramadas, 1966)

Nashua North (Sriramadas, 1966)

Windham (Walsh and Clark, 1999)

Pepperell (Robinson, 1978, 1981)

Lowell (Jahns and others, 1959)

Ayer (Kopera, 2006)

Westford (Kopera and others, 2008)

Billerica (Alvord, 1975)

0 10 20 KILOMETERS

EXPLANATION

Worcester basin (Pennsylvanian)

Granite (Permian)

Merrimack Belt

Chelmsford Granite (Devonian)

Ayer Granodiorite (Devonian)

Diorite to gabbro (Silurian-Devonian)

Metasedimentary rocks of the Merrimack 

trough (Silurian)

Nashoba zone (lower Paleozoic)

Massabesic Gneiss Complex (Neoproterozoic)

Fault

Simplified tectonic map.—Modified after Lyons and others (1997) and Zen and others (1983). C, Clinton facies; 

DLP, Devens-Long Pond facies of the Ayer Granodiorite; Wb, Worcester basin.

C DLP

3000

2000

1000

SEA LEVEL

1000

2000

3000

4000

5000

FEET

B B'

3000

2000

1000

SEA LEVEL

1000

2000

3000

4000

5000

FEET

Lower Massapoag Pond

PINE HILL

OAK HILL

Sb Dcgr

U.S. ROUTE 3

Newfield Pond

Sb Dad Sb Sb Dad Sb Dadg Dadg

Dadg Dadg

Sb Dad

Dadp

DSdi

DSgn SbDc

Dadg

Dadp

Sb

Jd Jd SbDc Sb Sb

Sb

Dadp

AYER PLUTON CHELMSFORD PLUTON

SURFACE

SURFACE

NO VERTICAL EXAGGERATION 1000 feet = 305 meters

Surficial deposits not shown

Apparent dip of S1, S2, or composite S1/S2

Sb Sb Sb Dadp

Dadp

Sb

DSgn

DSgn

Sb

Sb Sb

Dadg

Dcgr

Sb

DSdi

DSdi

?

3000

2000

1000

SEA LEVEL

1000

2000

3000

4000

FEET

A A'

3000

2000

1000

SEA LEVEL

1000

2000

3000

4000

FEET

U.S. ROUTE 3

Merrimack River

DSdi

SURFACE

SURFACE

NO VERTICAL EXAGGERATION 1000 feet = 305 meters

Surficial deposits not shown

Apparent dip of S1, S2, or composite S1/S2

EXPLANATION OF MAP SYMBOLS

Contact—Approximately located; dotted where concealed by water

Fault—Dashed where inferred; queried where conjectural

Outcrops—Areas of exposed bedrock or closely spaced bedrock exposures examined in this study

PLANAR FEATURES

[Symbols may be combined; point of intersection shows location of measurement]

Strike and dip of bedding

Inclined, deformed

Inclined, overturned

Strike and dip of inclined granodiorite-tonalite dike or sill (Dad) 

(Devonian)

Strike and dip of pegmatite dike (Dp) (Devonian)

Inclined

Vertical

Strike and dip of granitic dike (Dcgr) (Devonian)

Inclined

Vertical

Strike and dip of quartz vein

Inclined

Vertical

Strike and dip of layer-parallel foliation in the Berwick Formation—S1

or composite S1/S2

Inclined

Vertical

Inclined, deformed

Strike and dip of dominant foliation of undetermined age in the 

Berwick Formation—S2 or composite S1/S2

Inclined

Vertical

Strike and dip of compositional banding interpreted as flow banding 

in the Chelmsford Granite—Locally deformed by F2 folds

Inclined

Vertical

Strike and dip of S2 penetrative cleavage or schistosity in the Berwick 

Formation or gneissosity in the foliated intrusive rocks

Inclined

Vertical

Strike and dip of axial surface of minor fold

Deformed early F1 fold parallel to layer-parallel foliation (S1)

Inclined

Vertical

F2 fold parallel to dominant foliation (S2) or penetrative cleavage (S2)

Inclined

Vertical

F3 fold parallel to nonpenetrative S3 cleavage

Inclined

Vertical

Inclined shear band associated with S3

LINEAR FEATURES

[Symbols may be combined; point of intersection shows location of measurement]

Bearing and plunge of lineations and fold axes

Lineations

L2 intersection lineation between dominant foliation and compositional layering (S0 or S1)

L3 intersection lineation between dominant foliation and younger S3

cleavage

L2 mineral lineation; grain lineation of aligned amphibole

Minor Folds

Deformed F1 fold axis

F2 fold axis

F3 fold axis

OTHER FEATURES

Quarry

Geochronology sample location showing SHRIMP U-Pb zircon age, 

in mega-annum (Ma)

Methane-yielding bedrock water well studied by Pierce and others 

(2007)

Site of photograph—Tip of arrow at point of observation; arrow shows 

direction of view; number keyed to figure in explanatory pamphlet; for 

figure 3B, sample numbers are shown

Trend of glacial striations or grooves

Apparent dip of dominant foliation on cross sections

64

33

25

60

35

23

54

166

1A

41

82

60

85

70

56

20

25

20

8

25

DESCRIPTION OF MAP UNITS

[Minerals listed in order of increasing abundance]

POST-METAMORPHIC INTRUSIVE ROCKS

Diabase dikes (Jurassic)—Black to dark-gray and greenish-black, 

brown-weathering, fine- to medium-grained, subophitic to porphyritic 

diabase dikes. Dikes range in thickness from several meters (m) to 

approximately 20 m. Locally contains phenocrysts of pyroxene and 

plagioclase; may contain accessory serpentine, chlorite, and magnetite. 

Dikes locally contain amygdules filled with calcite or dolomite. Where 

carbonate minerals are relatively abundant, the dikes weather to an 

earthy black residuum. Good exposures occur in the town of Dunstable 

along Lowell Street and at the junction of Main Street and Forest Street 

about 1 kilometer (km) east of the village center. Dikes are probably part 

of the Eastern North American dolerite province of McHone and 

Sundeen (1995) and represent a continuation of the HigganumHolden-Onway dike

SYN- TO POST-METAMORPHIC INTRUSIVE ROCKS

Rocks of the New Hampshire Plutonic Suite

Pegmatite (Permian(?) to Devonian)—Light-gray to white, very coarse 

grained +/-muscovite-biotite-quartz-plagioclase-microcline pegmatite and 

coarse- grained granitic pegmatite. Contains accessory tourmaline, 

apatite, and zircon. Locally contains garnet (almandine). Dikes vary from 

folded and weakly foliated irregular masses to tabular, unfoliated bodies. 

Occurs as outcrop- and map-scale dikes that range from several 

centimeters thick to kilometer-scale intrusions. Larger mapped units 

generally represent sills that are roughly concordant to the dominant 

foliation. Red strike and dip symbols show the location and orientation of 

tabular outcrop-scale dikes that crosscut the foliation or sills that are 

generally concordant with the foliation. Good exposures crop out in the 

town of Nashua at roadcuts near Interchange 1 on U.S. Route 3 and at 

outcrops west of the interchange in an apartment complex south of Spit 

Brook Road

Chelmsford Granite (Late Devonian)

Medium-grained two-mica granite—Light-gray to white, tan- to 

white-weathering, medium- to coarse-grained, foliated muscovite-biotitequartz-plagioclase-microcline monzogranite to syenogranite and granitic 

pegmatite. Locally contains small (≤5 millimeter, mm) anhedral, zoned 

megacrysts of white feldspar, with myrmekitic rims. Feldspar megacrysts 

are interpreted as porphyroblasts of albite-oligoclase or microcline and 

orthoclase (Currier, 1937). Contains trace amounts of chlorite, opaques, 

apatite, titanite, epidote, clinozoisite, saussurite, and zircon. Locally 

contains trace amounts of garnet (almandine). Contains folded flow 

banding consisting of alternating dark-gray syenogranite and light-gray 

monzogranite layers, the latter of which contain relatively less biotite and 

muscovite. Dikes vary from folded, foliated irregular masses to tabular, 

weakly foliated bodies. Occurs as outcrop- and map-scale dikes that 

range from several centimeters thick to kilometer-scale intrusions. 

Light-red strike and dip symbols show the location and orientation of 

tabular outcrop-scale granite dikes or sills. A SHRIMP U-Pb zircon age of 

375±3 Ma (sample NS–188A) indicates a Late Devonian age. Good 

exposures crop out in the town of Westford at the abandoned quarry at 

Oak Hill and the active quarries along Ledge Road and Groton Road

Fine-grained two-mica granite—Light-gray, tan- to white-weathering, 

fine-grained, weakly foliated muscovite-biotite-quartz-plagioclase-microcline 

monzogranite. Contains trace amounts of opaques, apatite, and 

clinozoisite. Exposed at two places in the town of Tyngsborough: on the 

southwestern side of Abrams Hill along U.S. Route 3 and 1 km 

southwest of Hayward Corner

Migmatitic Berwick Formation (Devonian and Silurian)—A zone of rock 

around the Chelmsford pluton, as much as 1 km wide, consisting of 

metasedimentary rocks of the Berwick Formation with abundant injected 

foliation-parallel granite and pegmatite sills. The unit consists of 50 to 75 

percent granitic rock 

Ayer Granodiorite (Early Devonian)

Devens-Long Pond facies 

Biotite granodiorite—Medium-grained, light-gray to gray, generally 

equigranular, microcline-quartz-biotite-plagioclase granodiorite to quartz 

monzodiorite. Locally the rock is inequigranular where the rock contains 

trace amounts of deformed microcline megacrysts as much as 1 cm long; 

in these places the rock resembles the Dadp unit. Similar to the Dad unit 

but contains no hornblende. Plagioclase is altered to saussurite, 

K-feldspar is altered to sericite, and biotite is altered to chlorite. Contains 

as much as 3 percent muscovite. Contains trace amounts of chlorite, 

titanite, zircon, and apatite. A typical exposure crops out in the town of 

Tyngsborough at a roadcut on Patriot Drive (road is not on the base 

map), 0.4 km southeast of Scribner Hill

Porphyroblastic biotite granodiorite—Light-gray- to gray-weathering, black 

and white, inequigranular, medium- to coarse-grained, well-foliated 

biotite-microcline-quartz-plagioclase granodiorite to quartz monzodiorite 

with white feldspar megacrysts. Feldspar megacrysts are porphyroblasts 

of microcline and minor plagioclase (Gore, 1976). Discontinuous 

segregations of biotite define a gneissosity that wraps around and cuts 

through granular aggregates of quartz and feldspar. The aggregates are 

locally cored by anhedral to subhedral megacrysts of microcline that 

locally display Carlsbad twinning but lack well-formed crystal faces. 

Megacrysts of white to gray feldspar (mostly microcline) are as much as 3 

cm long, but are more typically 1 to 2 cm long. Where strongly foliated, 

megacrysts are aligned in the plane of the gneissosity, and the rock is an 

augen gneiss. Contains 1 to 5 percent muscovite. Plagioclase is altered to 

saussurite, K-feldspar is altered to sericite, and biotite is altered to 

chlorite. Contains trace amounts of chlorite, opaques, clinozoisite, 

titanite, hematite, and apatite. A SHRIMP U-Pb zircon age of 407±4 Ma 

(sample NS–187) indicates an Early Devonian age. Good exposures 

occur in the town of Tyngsborough at roadcuts on Alpine Way (road is 

not on the base map), 0.8 km southeast of Scribner Hill

Hornblende-biotite granite to tonalite—Medium-grained, locally coarsegrained, gray to black and white, largely equigranular hornblende-biotite 

granite to hornblende-biotite tonalite. Locally the rock is inequigranular 

where the rock contains trace amounts of deformed microcline 

megacrysts as much as 1.2 cm long; in these places the rock resembles 

the Dadp unit. The granite is a hornblende-quartz-plagioclasebiotite-microcline rock, and the tonalite is a hornblende-quartz-biotiteplagioclase rock with trace amounts of K-feldspar. Plagioclase is altered 

to saussurite, K-feldspar is altered to sericite, and biotite is altered to 

chlorite. Hornblende shows blue-green to light-brown pleochroism. A 

heterogeneous unit locally containing well-layered leucocratic layers 

alternating with darker more mafic layers containing more hornblende 

and biotite; layering is approximately 10 to 20 cm thick. Garnet as much 

as 1 cm in diameter occurs in a dike exposed on U.S. Route 3; the dike 

is shown by a yellow strike and dip symbol. Contains trace amounts of 

titanite, zircon, apatite, epidote, clinozoisite, and opaques. Unit is well 

exposed in the town of Tyngsborough along Appaloosa Circle (road is 

not on the base map), 0.75 km northwest of Hayward Corner, and in 

downtown Chelmsford in cuts along the Boston and Maine Railroad

Diorite–gabbro suite (Early Devonian to Late Silurian)

Fine-grained diorite-gabbro—Equigranular, fine- to medium-grained, 

weakly foliated, very dark green to black or gray and white, salt and 

pepper textured biotite-hornblende-plagioclase (oligoclase-andesine) 

metadiorite. Contains relict subhedral granular texture. Contains a few 

percent to trace amounts of quartz (as much as 6 percent), sulfides, 

magnetite, epidote, allanite, titanite, apatite, and hematite. Plagioclase is 

saussuritized. Similar to DSgn unit but fine grained. Good exposures 

crop out in a residential neighborhood north of Groton Road and west of 

Scribner Road. Good exposures also crop out in the town of Pelham, 

along the jeep trail section of Spaulding Road

Dcfgr

Dadg

Dadp

Dad

Dp

SbDc

Medium- to coarse-grained diorite-gabbro—Equigranular, medium- to 

coarse-grained, weakly foliated, very dark green to black or gray 

biotite-plagioclase-hornblende metadiorite to metagabbro. Contains relict 

subhedral granular texture. Contains a few percent to trace amounts of 

quartz (as much as 9 percent). Hornblende has largely pale-green to 

bluish-green and light-brown pleochroism, and actinolite is pale green. 

Uralite occurs locally as very fine grained alteration of relict pyroxene. 

Biotite occurs as reaction rims in and around amphibole. Biotite is locally 

chloritized. Contains trace amounts of opaques, titanite, epidote, 

clinozoiste, apatite, and serpentine. Opaques (sulfides-magnetiteilmenite) occur as lamellae within biotite and amphibole, and as anhedral 

masses. Plagioclase is saussuritized. Similar to DSdi unit but coarser 

grained. Good exposures crop out in the town of Tyngsborough at Fox 

Ledge, in the town of Dunstable under the power lines west of Pond 

Street and southeast of Lower Massapoag Pond, and in Nashua, west of 

Conant Road

METASEDIMENTARY ROCKS OF THE MERRIMACK BELT

Berwick Formation (Late Silurian)

Biotite-plagioclase-quartz granofels with minor schist and calc-silicate 

rocks—Purplish-gray, grayish-green, and light-gray to dark-gray, locally 

sulfidic and rusty-weathering, fine- to medium-grained biotiteplagioclase-quartz granofels, muscovite-biotite-quartz schist, and 

intercalated purplish-gray to pale-green, white-weathering, dark-greenspotted±garnet(grossular)±calcite±dolomite-epidote-clinozoisitequartz±diopside-actinolite±hornblende-plagioclase calc-silicate gneiss or 

granofels. The biotite-plagioclase-quartz granofels contains trace to 

accessory amounts of epidote, diopside, actinolite, and hornblende and 

accessory muscovite, chlorite, magnetite, titanite, apatite, and garnet 

(grossular). The percentage of calc-silicate rock varies within the unit 

from approximately 5 percent, or less, up to about 30 percent. Calcite 

and dolomite are present in trace amounts. Calc-silicate rock locally 

occurs as distinct layers up to 30 cm thick or as disarticulated, 

boudinaged lenses and pods within the psammitic granofels. 

Centimeter-scale quartz veins and white-weathering calc-silicate and 

quartz segregations, both syn- and post-deformational, cut the granofels. 

Locally, finely laminated (2–3 mm thick) plagioclase-quartz layers 

alternate with thin planes of biotite and (or) calc-silicate minerals to 

produce a pinstripe texture within Sb. Locally, light-gray granofels 

displays thicker (0.5–1.5 cm thick) biotite-plagioclase-quartz laminations 

separated by 0.5-mm-thick, biotite-rich or calc-silicate partings. Unit is 

well exposed in the town of Nashua at large roadcuts along U.S. Route 3 

at Interchanges 1 and 3

DSgn

DSdi

Sb

Jd

Dcgr

CORRELATION OF MAP UNITS

Rocks of the

Merrimack Belt

INTRUSIVE ROCKS METASEDIMENTARY ROCKS

Post-Metamorphic 

Intrusive Rocks

Syn- To Post-Metamorphic 

Intrusive Rocks

407±4 Ma

375±3 Ma 

Jd

Dp

Dcfgr

Dcgr

Dadg

Dadp

Dad

DSdi

DSgn

SbDc

Sb

New Hampshire 

Plutonic Suite

JURASSIC

DEVONIAN

SILURIAN

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

Prepared in cooperation with the

COMMONWEALTH OF MASSACHUSETTS, Massachusetts Geological Survey and the

STATE OF NEW HAMPSHIRE, New Hampshire Geological Survey

SCIENTIFIC INVESTIGATIONS MAP 3200

Explanatory pamphlet accompanies map

Geology mapped by G.J. Walsh, 2006, and compiled from unpublished 

mapping by R.H. Jahns, 1939–40 (Mass.) and 1951 (N.H.)

Geochronology by J.N. Aleinikoff, 2007–08

Digital compilation by G.J. Walsh

1000 0 1000 2000 3000 4000 5000 6000 7000 FEET

1 .5 0 1 KILOMETER

SCALE 1:24 000

1 1/ 2 0 1 MILE

CONTOUR INTERVAL 10 FEET

Base from U.S. Geological Survey, 1965 

Photorevision as of 1979

Polyconic projection. 1927 North American Datum

10,000-foot grid ticks based on Massachusetts coordinate 

system, mainland zone, and New Hampshire coordinate system

1,000-meter Universal Transverse Mercator grid ticks,

zone 19, shown in blue

MAGNETIC NORTH

APPROXIMATE MEAN

DECLINATION, 2012 TRUE NORTH

15°

MAP LOCATION

MASS.

N.H.

BEDROCK GEOLOGIC MAP OF THE NASHUA SOUTH QUADRANGLE, HILLSBOROUGH COUNTY, NEW HAMPSHIRE

AND MIDDLESEX COUNTY, MASSACHUSETTS

By

Gregory J. Walsh,1 Richard H. Jahns,2 and John N. Aleinikoff3

1U.S. Geological Survey, Montpelier, VT 05601. 2U.S. Geological Survey and Stanford University, deceased. 3U.S. Geological Survey, Denver, CO 80225.

2013

Any use of trade, product, or firm names in this publication is for descriptive purposes 

only and does not imply endorsement by the U.S. Government

For sale by U.S. Geological Survey, Box 25286, Denver Federal Center, Denver, CO 

80225; http://store.usgs.gov; 1–888–ASK–USGS (1–888–275–8747)

Suggested citation: Walsh, G.J., Jahns, R.H., and Aleinikoff, J.N., 2013, Bedrock 

geologic map of the Nashua South quadrangle, Hillsborough County, New Hampshire, 

and Middlesex County, Massachusetts: U.S. Geological Survey Scientific Investigations 

Map 3200, 1 sheet, scale 1:24,000, 31-p. pamphlet