Using the geologic map, assignment help

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U.S. DEPARTMENT OF THE INTERIOR
SCIENTIFIC INVESTIGATIONS MAP
U.S. GEOLOGICAL SURVEY
Obps
Osnr
25
63
Obs
50
75
58
70
50
80
40
40
25
L
16
68
75
88
55
|td
27
|td
Obs
Obrr
73
Obps
23
78
84
|e
6
19
74
34
25
60
81
Osnr
39
70
22
3
75
44
Obps
58
Obss
Obrr
Obs
16
35
87
9
81
31
53
82
35
50
20
47
30
45
45
25
64
55
60
Obss
70
45
30
86
45
26
68
60
25
Obs
45
|cb
35
26
77
O|c
|t
QTt
|ch
F
80
50
|ca
20
75
25
|cb
|t 5
70
|wact
|wac
|e
80
40
QTt
85
45
60
45
|ch
21
QTt
|ca
70
|cwo
18
30
|chs
45
40
24
Qa
27
50
80
45
52
|war
20
Qt
70
30
55
55
44
Qt
15
35
|cwo
58
|war
|ch
Qt
QTt
54
60
|ca
50
26
75
|chs
60
|ch
46
Ygt
Qcc
40
|cwo
44
40
15
22
57
|cwm
20
15
Qcc
Zcm
Zrc
60
Zcp
Zss
30
Zrd
70
Zmd
Ya
Qa
Ypb
Qa
Ylg
65
85
Ylg
70
Qa
Yc
53
36
72
70
45
60
45
Yq
65
Jd
15
30
47
Yp
Ygt
Ya
Zmd
Jd Ymc
25
Yp
Qa
Zmd
44
Zfsm
45
Base from U.S. Geological Survey, 1984
1983 North American datum
25,000-foot grid ticks based on Georgia coordinate system, west zone
10,000-meter Universal Transverse Mercator grid ticks, zone 16
J^tm
Ql
27
FAULT
OU
NTA
IN
QTt
11
44
27
Qt
65 Qt
|Zmg
Qa
^cbg
QTt S
Jdh
Jdc
Jd
^cbb
22
19
28
24
38
30
Jd
45
30
48
68
45
Qa
55
35
37
23
50
34
35
^cmp
Qa
45
Ob
78
|Zmm
60
50
|Zmg
|Zmg 67
Ob
80
|Zmm
Au
85
Qa
36
Qa
|Zmp
66
55
77
S
Qa
Oq
45
Odl
|Zn
80
SCALE 1:100 000
1
0
1
3
2
6
7
ET IC
N O R TH
TRUE NORTH
MAGN
0
1
3
2
4
5
6
7
10 KILOMETERS
9
8
VIRGINIA
CONTOUR INTERVAL 10 METERS
80
Qcf
Fine colluvium
Qcc
Coarse colluvium
Obrr
SEA LEVEL
Obps
Obrr
Om
|lu
45
67
|cb
O|c
85
Oc
Kps
Osnr
|wa
|cb
2000
3000
|ch |ca
|t
|ch
|ca
|tb |tf
|td
|e
|tbh
Zcm
Ybg
Obps
Zmd
Zrd
Yg
|cwm
|ch
Zcm
|clp
|cwb
^cmp ^cmt
|wa
|ca
|ar
|clp
|uq |uq |uq
|Zsb
|e
|Zsmp
|Zmbq
|Zmbs
|Zms
|Zmbs
STATE ROUTE 97
PLUMMERS ISLAND FAULT
|Zsmp
|Zsb
|u
|uq
|Zsq
|Zsb |Zip
|Zss
|fr
|Zmg
|Zmp
SEA LEVEL
|Zu
|Zsb
|Zsc
|wa
Undivided—Shown in cross section only
Tomstown Formation (Lower Cambrian)
|tb
Zmd
Ymc
Zmd
SEA LEVEL
1000
|chs
|wac
|t
Ypg
|cwm
Yml
Zcma
Zfcr
Zfsm
Ypg
Jdh
J^tm
|Zmg
^cbb
|Zms
^cbb
Jdh
|Zmp
|s
|s
INTERSTATE ROUTE 495
Tomstown Formation (Lower Cambrian)
|cp
Carbonaceous phyllite (Lower Cambrian)
^cbb
^cmp
Zfsc
|Zmbs
^cmr
|Zmbs
Harpers Formation (Lower Cambrian)
|Zu
|s
Ogh
|s
Ok
|l
|lu
Metasandstone and schist
|fr
Rocky Springs Station Member
Fauquier Group
Zfcr
Ogp
Ob
1000
|lu
Swains Mountain Formation (Neoproterozoic)
Zfsm
Metamudstone
Zfsc
Boulder conglomerate
Zrc
Cobbler Mountain Alkali Feldspar Quartz Syenite of the Robertson
River Igneous Suite (Neoproterozoic)
Ypb
Megacrystic metagranite (Mesoproterozoic)
Ybg
Biotite granite gneiss (Mesoproterozoic)
Yml
Pink leucocratic metagranite (Mesoproterozoic)
Yg
Ogh
Quartzite
Garnetiferous metagranite (Mesoproterozoic)
Yqp
Quartz-plagioclase gneiss (Mesoproterozoic)
Ym
Marshall Metagranite (Mesoproterozoic)
|f
Undivided
|Zmp
|Zmt
|Zl
|Zn
Lower Cambrian
and (or)
Neoproterozoic
|Zlm
Ymc
Coarse-grained metagranite (Mesoproterozoic)
Ypg
Porphyroblastic metagranite (Mesoproterozoic)
Yhm
Hornblende monzonite gneiss (Mesoproterozoic)
Urbana Formation (Lower Cambrian?)
|um
Marble
|uq
Quartzite
Sugarloaf Mountain Quartzite (Lower Cambrian)
|squ
Upper member
|sqm
Middle member
|sql
Lower member
|sq
Undivided–Shown in cross section only
|Zw
Sams Creek Formation (Lower Cambrian? and Neoproterozoic?)
|Zsb
Metabasalt
|Zsf
Felsic schist
|Zsm
Marble
|Zshp
Hematitic phyllite
|Zsl
J^tm
High-titanium quartz-normative late cumulates
Granophyre
Thermally metamorphosed rocks (Lower Jurassic and Upper
Triassic)
Jms
Jmss
Jmt
Jmh
Jmhs
Jmmc
Turkey Run Formation (Lower Jurassic)
Conglomerate
Hickory Grove Basalt (Lower Jurassic)
Sandstone and siltstone
Midland Formation (Lower Jurassic)
J^ccg
Conglomerate
|clp
Phyllite
Zcm
Metabasalt
Zcs
Metasedimentary phyllite
Zcp
Tuffaceous phyllite
Zcr
Metarhyolite
4000
Zmd
Mount Zion Church Basalt (Lower Jurassic)
Catharpin Creek Formation (Lower Jurassic and Upper Triassic)
Goose Creek Member
Metarhyolite dike (Neoproterozoic)
Quartz-rich schist
|Zmg
Metagraywacke
|Zmm
Migmatite
|Zmp
Phyllonite
|Zmt
Metatuff
|Zsd
Soldiers Delight Ultramafite (Lower Cambrian and (or)
Neoproterozoic)
|Zu
Mafic and ultramafic rocks (Lower Cambrian and Neoproterozoic)
|Zg
Metagabbro and metapyroxenite (Lower Cambrian and
Neoproterozoic)
Potomac Formation (Lower Cretaceous)
EXPLANATION OF MAP SYMBOLS
Contact—Dotted where concealed
Metalimestone
Lake bed—Dotted where concealed
Quartzite interbedded with phyllite
|Zsq
Quartzite
|Zss
Metasiltstone
Thrust fault—Sawteeth on upper plate
|Zsc
Calcareous metasandstone
Normal fault—Ball and bar on downthrown side
FAULTS
(Dashed where inferred; dotted where concealed)
Reactivated fault—Open ball and bar on downthrown side of early
normal fault and sawteeth on upper plate of later thrust fault; shown in
cross section as a double-headed arrow
Ijamsville Phyllite (Lower Cambrian? and Neoproterozoic?)
|Zip
Phyllite
|Zib
Metabasalt
|Ziq
Quartzite
|Zim
Marble
Overturned thrust fault—Bar on upper plate; sawteeth show direction of
dip
Strike-slip fault—Arrows show relative movement
Unclassified
|Zil
Metalimestone
|Zic
Phyllitic conglomerate
Shear zone
|Zicm
Conglomeratic metagraywacke
|Zicp
Chloritic phyllite
PLANAR FEATURES
(May be combined with linear features; where features are combined,
intersection of symbols marks point of intersection)
Strike and dip of bedding
32
Marburg Formation (Lower Cambrian? and Neoproterozoic?)
|Zmbs
Metasiltstone
|Zmbg
Metagraywacke
|Zmbb
Metabasalt
|Zmbq
Quartzite
|Zp
Inclined
44
Overturned
Vertical
Horizontal
Strike and dip of Mesoproterozoic foliation including compositional
layering
77
Inclined
Prettyboy Schist (Lower Cambrian? and Neoproterozoic?)
|Zpb
Metabasalt
|Zpq
Quartzite
Vertical
Strike and dip of first-generation (S1) Paleozoic cleavage and (or)
schistosity
47
Inclined
Vertical
Potomac Terrane
Dp
Pegmatite (Late Devonian)
Dg
Guilford Granite (Late Devonian)
Oq
Quartz bodies (Ordovician)
^cbb
Balls Bluff Member
Ong
Quartz gabbro
^cbl
Leesburg Member
Onu
Ultramafic rocks
Ontr
Trondhjemite
Manassas Sandstone (Upper Triassic)
^cmp
Poolesville Member
^cmt
Tuscarora Creek Member
^cmr
Reston Member
Grove Formation (Lower Ordovician and Upper Cambrian)
O|gu
Upper member
O|gl
Lower member
Strike and dip of second-generation (S2) Paleozoic cleavage and (or)
schistosity
60
Inclined
Vertical
Strike and dip of mylonitic and phyllonitic foliation
75
Inclined
Norbeck Intrusive Suite (Late Ordovician)
Biotite-hornblende tonalite
Frederick Valley Synclinorium
Metadiabase dike (Neoproterozoic)
|Zms
Kps
Groveton Member
Marble
Mather Gorge Formation (Lower Cambrian and (or) Neoproterozoic)
COASTAL PLAIN PROVINCE
Ont
^cbg
Northwest Branch Formation (Lower Cambrian and Neoproterozoic)
Conglomerate
Chatham Group
Jcm
Semipelitic schist and meta-arenite
|Zlm
|Zsqp
Sander Basalt (Lower Jurassic)
Sandstone and siltstone
Upper part
Wakefield Marble (Lower Cambrian? and Neoproterozoic?)
Amphibolite (Mesoproterozoic)
High-titanium quartz-normative early cumulates
Laurel Formation (Lower Cambrian)
|Zn
Ya
Jdc
|l
Loch Raven Schist (Lower Cambrian and (or) Neoproterozoic)
|u
Muscovitic phyllite
Crystalline diabase
Sykesville Formation (Lower Cambrian)
|Zl
|Zsmp
Jd
|s
Oella Formation (Lower Cambrian and (or) Neoproterozoic)
Charnockitic granite (Mesoproterozoic)
Culpeper and Gettysburg Basins
Bear Island Granodiorite (Ordovician?)
|Zo
Yc
PIEDMONT PROVINCE
Ob
Araby Formation (Middle and Lower Cambrian)
Tuffaceous phyllite
Quartzite and quartz-sericite tectonite (Mesoproterozoic)
Muscovitic trondhjemite
|ar
|Zstp
Yq
Odt
|lu
Layered granitic gneiss (Mesoproterozoic)
Garnet-graphite paragneiss (Mesoproterozoic)
Leucocratic muscovite-biotite monzogranite
Cash Smith Formation (Upper and Middle Cambrian)
Ylg
Yp
Odl
|cs
Undivided
|clc
Zrd
X
Shale
Westminster Terrane
J^cc
Buzzard Knob Member
Zcma
Ob
White leucocratic metagranite (Mesoproterozoic)
Ygt
Catoctin Formation (Neoproterozoic)
3000
Jd
GEOLOGIC MAP OF THE FREDERICK 30′
Maryland Heights Member
Loudoun Formation (Lower Cambrian)
2000
Ogg
Carter Run Formation (Neoproterozoic)
|frs
Bull Run Formation (Upper Triassic)
2000
SEA LEVEL
|Zms
Ok
LINEAR FEATURES
(May be combined with planar features; where features are combined,
intersection of symbols marks point of intersection)
40
Ogh
Biotite-hornblende tonalite
Ogg
Quartz gabbro
Ogp
Metapyroxenite
Dalecarlia Intrusive Suite (Early Ordovician)
Biotite monzogranite and granodiorite
Bearing and plunge of axis of minor fold
OTHER FEATURES
Location of isotopically dated rock—Sample dated by U-Pb dating
techniques
Kensington Tonalite (Middle Ordovician)
Georgetown Intrusive Suite (Early Ordovician)
Odm
Vertical
L
Quarry or mine, active and inactive—Abbreviations are as follows: Ag,
silver; Au, gold; C, chromite; Cu, copper; D, diabase; F, hematite,
limonite, manganese, and iron ore; L, limestone; M, marble; Pb, lead;
S, building stone; Sl, slate; Zn, zinc
Radon in soil gas—Shown where greater than 200 pCi/L (Gunderson
and others, 1988)
Small sinkhole—Less than or equal to 50 m2 in diameter
Large sinkhole
60′ QUADRANGLE, MARYLAND, VIRGINIA, AND WEST VIRGINIA
By
Scott Southworth, David K. Brezinski, Avery Ala Drake, Jr., William C. Burton, Randall C. Orndorff, Albert J. Froelich, James E. Reddy, Danielle Denenny, and David L. Daniels
3
Zss
Owens Creek Member
|cwb
1000
|Zmt
2
Adamstown Member
Jmm
Metasandstone
|cwmq
NO VERTICAL EXAGGERATION
1
|fa
Jmtc
Antietam Formation (Lower Cambrian)
|cw
Silver Spring
|s
Ogh
|Zu
|Zms |Zmg
Jdc
|Zmm
|Zmp
|Zmm
|Zu
|ch
1000 meters = 3281 feet
Surficial deposits are not shown
^cbb
|Zmg
|Zu
|Zms |Zmg
|Zms
Cabin John Creek
WASHINGTON AND OLD
DOMINION RAILROAD
REGIONAL TRAIL
Broad Run
^cbg
Jd
^cmr
^cmp
J^tm
Jdg
J^ccg
^cbb
J^tm
LT
U
FA
|ca
Ylg
Yp
Yp
Yq
Yp
Jd
Jdh
VE
O
GR
4000
|cwo
Jdh
J^tm
T
|war
J^cc ^cbb
Phyllite
Jdg
|t
|cwm
METERS
3000
AN
|ch
J^cc J^ccg
Jcm
Jmm
J^tm
Yp
|ca
|wact
Zcm
Ym
Zcp
|cw
S
EA
PL
3000
Ylg
Yc
|t
2000
Zmd
Yml
|ch
O|c
Ym
Zmd
INTERSTATE ROUTE 495
Zmd
Ogh
ROCK CREEK SHEAR ZONE
Yq
Zmd
PLUMMERS ISLAND FAULT
Zss
STATE ROUTE 190
|cwb Zcm Zcp
STATE ROUTE 7
|cwm
|cwo
|ch
Zsp
Benevola Member
BLUE RIDGE PROVINCE
4000
INTERSTATE ROUTE 495
|t
|ca |chs
INTERSTATE ROUTE 270
|e
|ca
|war
|wac
|cb |wact
|e
|e |e
Lime Kiln Member
Jdh
3000
B’
J^tm
|Zmg |Zmm
Frederick Formation (Upper Cambrian)
|fl
Bolivar Heights Member
|cwo
Ogg
|Zms
Meriden Group
POTOMAC TERRANE
|Zmg
|Zg
Neoproterozoic
Marble
Dargan Member
Fort Duncan Member
|tf
1000
|Zp
|Zms
|Zmg
|Zu
Zsm
Diabase dikes and sills (Early Jurassic)
Weverton Formation (Lower Cambrian)
|Zmg
Swift Run Formation (Neoproterozoic)
2000
POTOMAC RIVER
|cb
J^cc
1,153±6 Ma
Elbrook Limestone (Upper and Middle Cambrian)
Chilhowee Group
Sugarland Run
1000
Zcm Zss
Goose Creek
CATOCTIN
MOUNTAIN
2000
BULL RUN MOUNTAIN FAULT
U.S. ROUTE 15
3000
Ylg*
Big Spring Station Member (Upper Cambrian)
|tbh
CULPEPER BASIN
Black Oak Ridge
4000
1,149±19 Ma
Conococheague Limestone (Lower Ordovician and Upper Cambrian)
Red Run Member
PIEDMONT PROVINCE
SHORT HILL FAULT
BLUE RIDGE
B
SHENANDOAH
RIVER
METERS
Yhm*
Stoufferstown Member
|chs
BLUE RIDGE-SOUTH MOUNTAIN ANTICLINORIUM
|Zo
|Zsd
Mesoproterozoic
Stonehenge Limestone (upper part) (Lower Ordovician)
|war
|ch
GREAT VALLEY SECTION
1,144±2 Ma
Rockdale Run Formation (Middle and Lower Ordovician)
Cavetown Member
4000
BLUE RIDGE PROVINCE
Ypg*
Pinesburg Station Dolomite (Middle Ordovician)
|wact
|ca
VALLEY AND RIDGE PROVINCE
|Zpb
|Zmbs
|Zmbq
|Zp
|Zsqp
|Zpq
|Zsq
Sugarloaf Mountain Anticlinorium and Bush Creek Belt
Chewsville Member
NO VERTICAL EXAGGERATION
1000 meters = 3281 feet
Surficial deposits are not shown
1,140 Ma
St. Paul Group (New Market and Row Park Limestones, undivided)
(Middle Ordovician)
|td
|s
|Zsb
Zcm Yhm
|Zmbg
Yq
|wac
|t
1000
|Zsb
|sq
Ymc*
Waynesboro Formation (Lower Cambrian)
METERS
2000
|Zsb
|sq
|Zmbb
Chambersburg Limestone (Middle Ordovician)
3000
|Zmbq
Zcm
|ca |ch
|cw
Monrovia
|Ziq
|Zip
|u
Yhm
|ch
BARNESVILLE-MONROVIA
THRUST FAULT
MARTIC FAULT
SUGARLOAF MOUNTAIN
ANTICLINORIUM
MARTIC FAULT
Monocacy River
INTERSTATE ROUTE 270
MARTIC FAULT
|Zip
|fa
|cw
|t
|t
Jd
|ar
^cbl
Zcm
|fr
|frs
|ca
|cwm
|cwb |clc
|cwb
|fa
|fr
POTOMAC TERRANE
PLEASANT GROVE FAULT
Zrd
INTERSTATE ROUTE 70
CATOCTIN MOUNTAIN
Catoctin Creek
SOUTH MOUNTAIN
Zsm
Yg
|cwo
Zcr
|cwm
|cwo
|wa
|e |cb
|cw
Zcm
|tbh
|e
O|c
|t
|ca
|frs
|fr
1,111±2 Ma to
1,112±3 Ma
Beekmantown Group
4000
HYATTSTOWN THRUST FAULT
|wac
|e
|wact
|war
|td
Obss
Obss
BLUE RIDGE
KEEDYSVILLE FAULT
Antietam Creek
Sharpsburg
|e
O|gl
O|gu |fl
|Zsmp
PROTEROZOIC
Martinsburg Formation (Upper and Middle Ordovician)
|cb
INTERSTATE ROUTE 70
|cb
O|c
|ch
Ym*
Great Valley Section
A’
|Zsb
1,077±4 Ma
Terrace deposit, high level (Pleistocene and Tertiary)
T
RN
Ogh
WESTMINSTER TERRANE
Bush Creek
Obs
|ca
|chs
|ch
|war
Ybg
Zss Zmd
Frederick
Oc
Om
Obs
4000
POTOMAC
RIVER
Rockymarsh Run
Osnr
Oc
Om
Obps
|e
1000
Obss
Yqp*
VALLEY AND RIDGE PROVINCE
Obrr
FREDERICK VALLEY SYNCLINORIUM
U.S. ROUTES 15 AND 340
|cb
O|c
Osnr
Oc
STATE ROUTE 67
|cb
O|c
|e
BULL RUN MOUNTAIN FAULT
1000
Opequon Creek
2000
Opequon Creek
3000
U.S. ROUTE 11
INTERSTATE
ROUTE 81
4000
MASSANUTTEN SYNCLINORIUM
A
STATE ROUTE 9
METERS
CULPEPER BASIN
1,077±4 Ma
Lag gravel (Holocene and Pleistocene)
|l
PIEDMONT PROVINCE
BLUE RIDGE-SOUTH MOUNTAIN ANTICLINORIUM
|Ziq |Zshp
|Zsl
Dp
O|c
GREAT VALLEY SECTION
Ygt*
Residuum (Holocene and Pleistocene)
Obss
BLUE RIDGE PROVINCE
1,060±2 Ma
Terrace deposit, low level (Holocene and Pleistocene)
Obs
VALLEY AND RIDGE PROVINCE
Yg*
Qt
QTt
MAP LOCATION
NATIONAL GEODETIC VERTICAL DATUM OF 1929
APPROXIMATE MEAN
DECLINATION, 2007
1,059±2 Ma
Alluvium (Holocene)
Ql
Geology mapped from 1989 to 1994
Digital compilation by James E. Reddy and Danielle Denenny
Geologic map editing by Elizabeth D. Koozmin
Digital cartography by D. Paul Mathieux
8 MILES
W. VA.
1
57
B’
MARYLAND
5
4
Yml*
83
60
80
25
FA
Jmh
101/2°
1,055±4 Ma
Qa
Qr
Dg
T
|lu
62
77
|Zmp Ogp
Dg
Dp
35
Ok
40
65
|Zl
38
Qa
Ogg
Oq Odm
80
Ybg*
Colluvium (Holocene and Pleistocene)
Dp
S
50
Ogp
|Zu
Ok
60
80
78
S
S
48
Ok
50
|Zmp Ogh
75
50
45
35
65
68
40
50
45
Oq
|Zmp
60
42
67
70
47
50
40
Ok
50
85
|Zmt
|Zms
|Zmg
50
80
|Zmm Qa
8
10
33
|Zmp
1,055±2 Ma
UNCONSOLIDATED SURFICIAL MATERIALS
25
Ok
Ont
75
45
15
77
65
45
35
Oq
80
|Zmp
65
60
Qa
55
67
3 65
43
25
|Zu
Ob
80
|Zu
|Zmp
Ob
85
Ogh
Ypb*
Qa
60
Ont
80
|s
40
65
70
Ong
57
722±3 Ma
[Map units are shown generally from west to east. For descriptions, please see
accompanying text pamphlet.]
Ok
55
Ont
|Zss
|Zw
|Zsb
|Zsc
|Zsf
Ya
Yp
30
70
Oq
Au
55
80
75
Ont
Ont
Zrc*
LIST OF MAP UNITS
60
52
78
80
60
|Zic |Zstp
Qa
60
40
70
83
70
|Zmg
80
Ok
|s
83
|Zmp
Stratified rocks
|Zsm
|lu
|Zl
Ont
43
55
80
60
Onu
68
80
73
|Zmg
36
|Zmm
Ont
80
75
|Zib
|Zil
Zrd*
|Zicm
|l
Yc
Ok
35
Ont
Ong
Qa
45
Au
70
7
40
Ont
42
60
|Zicp
|s
571.5±5 Ma
45
Ok
Oq
Odm
Oq
Ong
|Zmg
WESTMINSTER TERRANE
|sqm
50
Onu
Ong
|Zmp
78
65
85
27
37
40
J^tm
Jd
27
83
78
20
|Zu
8
33
^cbb
56
50 45
70
|s
80
22
40
Qa
77
|Zmm
|Zu
|Zms
40
45
15
^cmr
S
17
13
30
40
10
8
21
Ql
J^cc
73
Jd
Jd
Jdh
45
QTt
|Zu
Qa
80
70
32
43
17
25
24
50
55
47
Qa
QTt
12
22
75
|Zu
|Zmg
45
10
20
J^tm
35
43
20
37
Jmss
10
S S S
14
20
^cbb
77
Jd
QTt
Qa
Qt
|Zu
85
|Zms
30
Oq
S
42
45
20
50
7
Jdc
|Zmg
35
15
15
30
S
Jms
36
25
^cmr
Qcc
J^ccg
Qa
|cw
Zcp
Zcma
^cmp
85
Zss
Ont
80
65
81
Zsp
Zmd
45
35
75
70
Zsm
Zfsc
Zfsm
Stratified rocks
Intrusive rocks
16
Ont
Ong Odt
Qa
80
|Zmp
Zcp Zcr*
Zcma Zcm
Zfcr
|u
|Zip
|Zim
70
56
35
85
Qa
|Zmg
^cmr
8
14
30
Qt
Qa
16
Qa
24
Jdh
24
Jdg
Qcf
Jmtc
Ylg
Yp
13
6
J^tm
30
25
Qa
10
10
Jd
S
Qcc
22
9
13
37
55
30
Zmd
50
50
45
50
78
20
Ymc
Yq
74
45
Zfsc
Zfsc
28
D
38
|cw
Jmt
51
M
30
Zfsm
Ypg
15
70
57
Qt
25
J^cc
46
Zfcr
11
^cbb
45
43
80
50
Jmm
Jmmc
39
40
60
Qa 36
48
QTt
Jd
35
7
10
6
Zcs
Lower Cambrian
600 Ma
Ont
|s
80
|Zmp
15
Lower Ordovician
CAMBRIAN
|sql
54
60
Ont
70
65
80
47
84
|sq
20
70
|Zmm
80
Odt
Middle Cambrian
|squ
10
Ontr
|Zu
50
Cu
J^cc
24
Jd Jmhs
Zcma
8
82
|s
75
75
70
70
40
Jd
Ob
85
80
25
Jmh
Zcp
35
61
68
Jd
45
45
Zmd
15
65
65
80
Qt
16
79
Odl
|cwmq
|Zo
|Zlm
Oq
60 45
60
|Zmg
Ob
Odm*
478±6 Ma
Upper Cambrian
|cwm
75
65
70
38
36
5
83
Ob
|Zmg
25
28
^cmr
70
55
|Zg
^cbb
Qa
Jdg
70
13
16
J^tm
Jcm
48
15
65
Ong
Oq
80
Qa
Ob
Lower Ordovician
and Upper Cambrian
|uq
30
15
|Zu
60
|Zu
80
Qa
45
85
72
64
Oq
|Zu
|Zu
48
85
Qa
72
74
85
10
15
|Zms
Ont
Ont
39

47
10
76
Ogp
?
|um
|chs
|cw
|Zl
Fauquier
Group
Ont
65
ORDOVICIAN
52
70
64
Ogg
472±4 Ma
Middle Ordovician
Stratified rocks
35
53
65
|Zu
Oq
SUGARLOAF MOUNTAIN
ANTICLINORIUM AND
BUSH CREEK BELT
|clp
80
|Zmg
60
Ob
|frs
|clc
60
Oq
50
52
|Zmbg
21
4
D
D
20
35
60
6
Qt
Jdc
J^ccg
3
8
|Zu
Ogh*
|cwb
58
65
|Zu
88
58
64
45
Chilhowee
Group
|Zsd
80
Oq
85
60
70
70
71
Jd
^cmp
Jd
D
|cw
Yg
57
Yq
45
78
Yml
26
62
38
9
|cp
39
70
Qa
55
43
83
|tbh
|ch
Qa
83
?
?
|ca
73
60
60
78
70
|Zu
67
18
80
|t
|s
55
70
84
|Zu 75
Stratified rocks
|tf
58
|Zmg
|Zmp
30
80
|tb
75
75
80
85
75
20
24
32
60
|Zu
|Zu
57
50
72
80
|Zmg
78
80
|Zmbs
50
?
|td
75
67
|Zmg
Upper Ordovician
Ontr
|wact
85
70
75
58
75 76
65
Qa
Qa
55
83
12
25
^cbb
|Zmbq
|Zmbg
5
QTt
20
Cu
17
Qcc
Yg
35
J^tm
Jdg
15
47
Ym
84
78
Ya
27
50
87
62
40
Jdc
27
48
60
Ygt
Zmd
Yp
50
75
Qa
Zcp
60
Qa
60
68
85
40
Qa
10
65
15
58
Zss
5
15
Qcc
Qcc
Zcp
Zcr
60
56
|cwb
55
20
35
20
28
Ypg
31
50
75
Yp
^cbb
80
|Zmbq
QTt
Qa
80
8
18
65
80
20
47
80
Yp
22
36
42
Zmd
Zmd
Ypg
15
70
Zcp
25
56
|chs
40
34
4
10
45
Qa
Jd
52
54
Jd
20
55
Zcm
Zmd
23
Qcf
10
|Zmbq
20
Qt
22
88
25
19
16
|cwb
34
65
60
35
25
Jd
45
Zcp
65
58
20
QTt
75
|wa
80
43
|Zmg
80
70
|Zmbq
35
73
21
55
81
60
Qt
Jdh
Qcc
Yg
25
35
20
Yg
Ylg
Jd
Ymc
Yq
15
45
38
Qcc
15
47
70
Zcm
27
46
Yp
^cbl
82
QTt
Qt
16
15
Ym
10
32
78
25
Qcc
Zcma
50
53
Zmd
Ylg
74
15
35
Jd
QTt
80
80
Qa
15
^cbb
67
64
Qa
|Zmbq
24
14
78
70
70
Ql
Qt
45
35
40
Ygt
30
52
Zcp
Yg
|Zmbb
15
20
20
|Zmbq
|wac
|Zmg
80
DEVONIAN
|ar
Qa
Qa
|Zu
Upper Devonian
|war
75
81
|Zmbq
42
Qa
63
60
45
Onu
|cs
|e
55
Ob
Ob
|Zmg
|Zmm
53
50
32
Qa
|Zmbq
5
QTt
25
28
43
70
Zcr
6
86
36
16
10
68
|t
|ca
|cwb
66
|cwm
30
65
25
42
80
80
67
^cmr
Jd
62
70
64
80
Ong
362±3 Ma
|fa
|cwo
70
75
|Zmbq
73
83
QTt
30
Zss
47
Zcs
Qa
36
48
62
36
15
20
Yp
35
72
M
46
M
40
34
Qcc
Jd
Zsm
Zcm
35
Yp
30
Qcc
60
Qcc
62
40
70
88
46
Qa
12
Ql
13
Ql
80
80
5
|Zsb
88
25
27
20
43
56
Ypg
Yp
Zss
47
Ym
^cmp
QTt
Zsp
30
Qa
QTt
|Zmbq
78
|Zmbq
|Zsmp
55
70
|f
|fr
82
Qa
85
Qa
67
85
72
65
80
5
61
42
Jd
62
81
84
Ql
18
Zcp
Zsm
Zmd
25
Zss
53
Yp
35
45
|chs
45
35
58
46
Jd
16
Jd
18
82
77
44
10
^cbl
29
28
45
31
86
20
44
56
15
|t
QTt
|wact
Ylg
31
53
5
Yc
50
70
QTt
32
58
40
34
80
2
20
^cmp
^cbb
17
Qa
Qcc
Yp
QTt
11
10
Qa
Qa
63
Qa
78
O|gl
|cb
43
65
73
8
C
O|gu
72
37
Qa
80
Stratified rocks
78
|Zmm
80
54
Jd
85
T
UL
FA
|Zmp
61
80
Jd
67
78
72
82
74
88
52
Jd
26
Qcc
Zcs
Zss
37
Zcp
Qa
65
23
10
20
22
80
30
18
|wac
Qt
Qcc
Qt
Qcc Zcr
52
34
85
Zcp
Ygt
Yc
Yc
Yp
25
Qa
QTt
Qa Qt
75
85
|Zmp
|Zmg
75
Obs
O|c
30
|Zu
Ont*
Obrr
|t
85
75
87
83
86
75
|uq
12
27
22
17
53
Qa
Ybg
^cbl
QTt
|ca
Zcp
64
33
Zmd
31
Yp
58
33
35
21
64
10
QTt
10
Qcf
Zcs
Zmd
35
Ya
27
70
10
55
26
QTt
73
Qt
8
20
Qt
^cbl
25
53
22
Qt
Jd
|u
80
12
|Zsq
Oq
TRIASSIC
Intrusive rocks
449±7 Ma
Obss
Qa
87
67
|Zsmp
68
17
12
70
40
68
Qa
72
45
80
Beekmantown
Group
65
65
Qa
70
|Zib
|Ziq
58
85
|Zmbq
84
|Zms
44
^cmr
Dg*
FREDERICK VALLEY
SYNCLINORIUM
A’
74
78
|Zmbq
84
77
|Zmbq
|Zu
78
80
73
Qa
|Zg
75
|Zip
47
35
82
20
POTOMAC TERRANE
^cmp
Obps
|Zmp
|Zu
46
44
|Zmbq
29
52
^cmr
QTt
85
84
72
Jd
Ql
21
S
S
26
32
42
72
15
|Ziq
50
32
|uq
31
QTt
8
^cbb
30
10 75
Qa
12
16
48
23
36
82
Qt
|squ
12
25
20
Jd
^cmp
QTt
33
Qcc
Zcm
Ybg
Zmd
Zcp
34
Ym
Zmd
Ygt
27
10
42
44 |squ59
40
^cbl
Ok*
|Zmp
|Zu
|Zmg
75
^cbb
|fl
60
75
|Zmbq
J^ccg
463±8 Ma
67
80
70
87
80
83
65
83
80
|Zsb
74
71
78
67
32
16
75
82
82
|Zib
58
78
50
68
66
77
65
70
Qa
52
75
74
80
|Zmbq
79
25
|Zmbs
^cbg
J^cc
Osnr
50
75
67
60
|Zsq
30
80
81
30
72
47
30
16
73
78
38
60
|Zmbq
Upper Triassic
J^tm
Om
|Zms
80
20
75
Jmm
Oc
57
70
|Zsmp
|Zsq
|Zss
20
52
53
35
|u
45
|sqm
Qcc
S
12
|ca
|cp
|ch
Yg
49
Jd
Zmd
80
Qa
28
17
Qcc
|cwb
Zsm
65
Yhm
Ya
Zss
20
41
|tbh
80
85
65
50
31
25
32
5
Zcp
10
30
32
Zss
Yg
Ya Yp
35
S
|Zil
Qa
12
30
|Zib21
Jd
Qcf
72
12
25
QTt
13
60
30
50
64
40
Qt
86
12
86
77
QTt
75
14
Jd
65
40
79
72
50
36
Zss
62
42
20
36
42
10
|cwb
20
24
46
32
77
QTt
Qcc
|Zmbq
Jmmc
86
55
54
JURASSIC
201.2
201.2
±1.3 Ma ±1.3 Ma
Stratified rocks
Qa
78
82
55
51
|Zmbq
44
|um
|squ
|uq
50
48
|Zsb
52 Sl
44
55
30
50
52
Qt
17
|ca
|cp
25
42
Zss
30
3
26
38
Zmd
Ya
Zmd
20
|clp
54 57
L
86
QTt
43
28
35
26
|cwm
|td 55
|tb
|tf
|wact
|war
80
30
80
Qt
15
Zcr
29
20
10
30
Yp
30
80
40
34
Zcma
Ybg
35
45
Yp
45
Zrd
25
22
65
Ygt
Qcc
8
16
QTt
Qa
78
25
27
86
20
55
36
45
50
70
Qcc
23
30
60
Zsp
20
25
35
30
Yp
10
Qcf ^cbl
15
Qcc
89
45
36
30
|sql
46
|Ziq
|Zib
|uq
78
82
14
Jd
67
70
81 84
49
60
25
30
|um
|ar |fr
Qa
20
|um
70
|Zmg
87
78
81
72
50
12
Lower Jurassic
Jdg*
GREAT VALLEY SECTION
85
89
80
70
65
80
10
45
50
29
83
81
40
75
45
34
76
73
60
80
72
|Zip
33
45
43
35
^cmr
80
25
15
34
11
68
S
44
42
Qcc
50
48
28
60
21
40
60
75
20
|uq
32
|um
Jd 45
|squ 58 68
15
|um
32
65
64
Jd
F |Zil
Qa
|frs
QTt
16
70
53
Zsm
70
22
Qcc
15
Zcr
16
29
33
52
Yp
Ya
Jd
Yhm
45
Zss
Zsm
67
35
65
25
Zmd
|cwb
Qcc
48
Zss
Zcr
Zcp
11
67
|wac
15
Zcr
22
57
F
35
15
56
Qa
10
Jd
Yg
Zmd
26
Jd
28
50
Ya
22
32
75
13
25
34
|uq
60
12
80
|uq
60
35
52
70
|Zmbq
|Zp
5
12
54
85
15
83
80
|Zmbq
78
|Zsb
|Zsf
52
39
75
CRETACEOUS
Dp
75
60
75
83
|Zsb
48 62
74
60
80
31
74
|Zsq
28
|Zss 62
|Zim
70
56
84
35
42
Qt
20
85
72
|frs
32
10
F 27
62
|f
FF
F
88
Jd
Ygt
42
45
Zcr
45
17
18
Zn
40
QTt
45
80
12
25
17
5
17
15
70
|t
25
55
26
30
70
67
QTt
45
18
20
26
58
42
40
67
L
39
L F
Qcc
Zcma
Yp
50
|t
68
|clp
28
78
QTt
F |ca
39
67
F
|ar
82
37
82
Jd
40
|Zib
62
Jd
84
|frs
|fr
11
33
30
|ar
|Zsq
10
53
|Zip
|fr
75
Qr
|u
60
75
50
72
83
42
62
82
60
60
25
6
|fr
27
^cmp
|cwb
58
45
Jd
49
Jd
Ya
Yqp
Yp
78
F
19
30
|uq
65
|Zss
|Zsq
40 |Zsc
|Zsq
45
|Zsb
42
40
47
|Zsc
|Zip |Ziq
|Zss
45
|Zsq
38
56
Sl |u
53
60
15
82
75
|Zmbq
28
72
61
|Zsq
45
69
46
41
30
40
80
75
70
|fa
72
Jd
Sl
Qt
Qt
QTt
57
21
^cmt
22
35
23
Jd
Zsm
32
41
F
L |tbh
23
|wac
24
22
6
F
L
60
64
Zcr
Yqp
23
44
Zmd
Zcm
Zcr
25
Qr
25
36
30
80
16
Zmd
|cwb
30
24
70
45
L
75
|war
28
50
50
82
|wact
Yc
Jd
20
45
46
38
15
|tf
2
36
45
12
16
Qcc
73
L
35
34
77 66
50
60 52
56
36
Zcr
Yg
|clp
89
Qa
Ybg
29
50
12
56
F
78
O|gl
21
60
45
85
75
68
51
78
Sl
Sl
|um
Jd
17
75
55
|fr
QTt
Qr
55
30
76
Qcc
37
Yg
30
42
28
75
88
|td F
|tb
40
60
Yhm
19
Zmd
25
|cwm
|cwo
|ch
32
Qt
24
21
Zmd
58
7
Qr
62
50
46
77
27
53
48
85
25
44
35
Ybg
Qa
7
|frs
QTt
75
|ar
78
|fl
Jd
11
|t
|ca
60
Ybg
40
Jd
Zss
Zcr
Qa
21
14
15
20
18
35
32
|ch 51
|cwm
|t
QTt
80
35
QTt
16
24
55
40
F
F
F
10
56
74
65
82
QTt 45
|e
29
55
Qa
25
50
36
60
|fr
57
Qcc
65
QTt
Yg
18
66
36
50
|clp
30
87
33 5
63
83
70
B
|ca
36
50
75
70
60
62
73
70
Zcma
QTt
Qt
32
|frs
17
|ch
QTt
37
44
32
62
^cbl
Qa
Yqp
Yp
32
Zcp
35
|cwb
78
20
47
20 20
67
26
30
20
Yqp
60
Zss
Yg
60
Yp
Zmd
48
|clc
Qcc
85
21
22
Zrd
62
55
50
29
10
QTt
86
30
Zmd
32
36
15
|cb
33
56
|cwb
|cwm
QTt
|tf
|tbh
62
Oc
53
|ca
|wac
50
35
58
88
35
Obss
L
|wact
28
67
Obs
33
56
44
20
46
Ybg
40
QTt
QTt
Ybg53
47
28
^cmt
Qcf
|cwb
Zmd
37
Jd
|cwb50
Zrd
Zcp
Zss
Qcc
Yqp
41
32
52
56
Ygt
35
56
Zss
|clp
|clc
Qa
Jd
Jd
36
58
|ch
68
|ch
Yp
Qa
|tb 15
50
Osnr
L
25
58
Obs
10
Qcc
70
20
Qa
10
|cwo
36
20
32
Ygt
Qt
36
66
Qt
L 81
66
^cmp
11
60
Zrd
Zrd
12
Qcc
|clp
Yml
Qt
49
27
47
45
45
Ya
Jd
M
25
70
26
17
50
Zcr 40Yp
15
|war
O|c
62
40
43
QTt
5
71
70
32
28
42
Obss
72
Oc
Oc
Obrr
23
Ybg
Ya
70
5
45
Jd
50
13
77
73
47
31
Yml
Zmd
|cwm
|cwo
2
42
35
30
Qr
Jd
|ca
|t
11
82
82
21
BRIN
KLOW T
HRUS
T FAUL
T
65
53
54
55
38
35
53
47
20
47
45
81
|ch
45
Qcc
|cwb
Yhm
22
Zcm
L
61
53
72 |um
53
11
75
M |Zsmp
85
82
74
Jmhs
^cmt
UL
35
21
59
Qt
22
32
50
|chs
Qcc
45
80
|ar
75
71
48
42
20
78
75
57
|Zsm
|uq |Zim
|Zic
|Zip
74
M
|Zsb
Chatham
Group
ZO
NE
13
38
Obrr
36
25
25
54
Zmd
Jd
Yqp
61
F
|frs
76
32
25
Lower Cretaceous
Jcm
80
52
80
F
88
MILLS
30
L
65
Om
45
85
25
|ca
Zcp
34
42
23
41
5
QTt
|fr
75
87
56
50
|Zsl
32
83
50
ND
71
|e
38
16
26 F
23
35
18 25
Yg
|fa
|fr
|frs
Qa
SH
EA
R
59
Obss
L
70
Ygt
51
12
Qcf
Yg
Ygt
80
4
72
|Zstp
62
|Ziq 86
|Zsq
|Ziq
|uq
36
Newark
Supergroup
79
86
BU
Obps
30
60
43
L
22
Qcc
47
Qt
55
80
34
Ql
22
24
Qt
42
Qa
Kps
Jmt
Jmh
67
Jdh*
Jdc
200 Ma
Jmss
Jmtc
Meriden
Group
36
PLU
MM
ER
S IS
LA
Obs
22
41
51
Osnr
80
10
62
Yhm
Ybg
40
37
42
|fa
22
11
16
Zcr
Qr
22
Sl
10
77
|Zpq
85
10
CR
EE
K
72
25
Om Oc
35
45
37 45
78
|cwb
Qa 54
30
36
Zcm
Zcp 20
35
67
86
85
69
15
ROCK
21
53
|ch
|tf
22
55
41
30
83
6
3
25
67
Qa
O|gl
O|gu
55
78
86
50
LT
42
Zcp
Qt
49
32
Jd
30
36
20
5
27
35
32
|ar
82
15
53
52
85
55
F
67
7 76
25
45
FA
U
Qt
31
3
Ygt
78
30
33
Zss
67
32
32
|t
89
78
42
88
15
Jms
70
50 82
70
83
70
82
|Zsl
|Zsb
18
|Zsm
M
45
M
Qa
Jd*
Stratified rocks
55
85
65
VE
Oc
66
85
77
15
|tbh
|td
|tb
5
83
Zrd Yp
Yqp
Ybg
Zcp
73
50
M
M
M
50 82
19
Jd
40
60
M
81
CULPEPER AND GETTYSBURG BASINS
Unconformity
|Zpb
85
81
RO
O|c
80
|wact
F |chs
74
80
32
43
74
62
20
33
|Zim
68
40
73
70
43
L
|Zmbq
55
|Zmbs
25
COASTAL PLAIN
PROVINCE
PIEDMONT PROVINCE
|Zmbq
63
QUATERNARY
Pleistocene
Intrusive rocks
85
82
L
|Zsm
Qa
26
70
Ql
Tertiary
BLUE RIDGE PROVINCE
73
Qa
G
Oc
50
67
L
72
22
32
20
19
F
48
77
81
53
27
75
79
L
48
82
36
67
85
83
|Zmbq
L
|Zsl
|Zsb
|Zsm
40
|Zsq
40
78
59
47
55
L
80
6
71
|Zmbq
VALLEY AND RIDGE
PROVINCE
65
|Zmbq
T
30
71
68
58
|war
L
50
|cb
77
Qcc
21
57
26
Yp
Qa
Zmd
82
33
43
Jd
60
62
|Zstp
|Zsq
16
36
M
30
Cu,
Au,Ag
50
35
42
32
Qa
85
68
77
15
83
N
34
63
Qt
68
57
36
57
32
Ya
31
^cbl
44
75
34
55
55 60
|Zsqp
82
52
43
19
65 73
45
|fl
62
Qa
81
32
32
37
35
80
50
|Zsq
47
80
80
88
Qr
Qcc
QTt
|Zmbq
72
Qcf
Qt
67
|Zmbq
Holocene
80 80
58
|Zsm
77
50
|Zsm
25
35
25
60
20 62
|Zshp
49
|Zsb 45
38
82
63
86
|Zmbq
34
12
72
Qa
18
SA
50
70
L
75
|ca
L
Zss
Jd
41
Qr
50
60
47
|Zil
80
25
62
|Zshp
78
UNCONSOLIDATED SURFICIAL MATERIALS
46
33
|Zpb
80
|Zmbq
32
Qr
74
M
63
|Zpb
EA
15
38
49
Oc
20
41
O|c
9
70
L
41
41
^cmt
60
Qr
L
35
40
Qa
55
68
77 71
56
M
M
Qa
30
58
78
PL
85
34
Qcc
44
32
39
L
22
37
31
^cmp
43
78
|fr
O|gl
47
35
33
75
Zcr
43
23
61
77
81
65
45
42
23
Zmd
24
Zmd
34
|Zstp
57
74
28
54
72
86
|fa
21
|ca
|fl
82
|Zsq
44
81
45
74
34
49
Zcp
^cmt
52
52
73
55
ISLA
ND F
AULT
50
|wac
15
73
Ygt
Yp
31
Yqp
21
|ch
Qa
Zsm
35
30
50
Zss
Zcm
Qcc Zmd
Yg
40
|fr
55
|fa
Qr
Jd
|frs
72
82
40
Qt
|Zp
65
PLU
MM
ERS
15
38
35
L
Obss
|chs
30
39
35
Zcp
Zss
17
Jd
Qcc
70
Zmd
31
Qt
43
38
|Zsm
22
60
|Zsq
|Zw
(Units with an asterisk have been dated)
28
Jd
Jd
86
|Zsl
68
28
70
76
3
Qcf
81
82
46
55
68
|Zsmp
|Zsb
64
|Zsl
67
F
F
52
FA
UL
T
80
86
75
Yhm
Ygt
23
23
18
65
52
2
86
40
Zss
Zmd
Ya
Ya
Yq
Ygt
16 19
46
Au
QTt
30
52
L
81 70
65
80
32
30
30
70
60
Qa
5
80
CORRELATION OF MAP UNITS
37
|Zp
|Zsq
M
86
|Zsq
25
86
46
66
|Zicm
|Zip
47
|fr
32
72
36
82
20
37
62
28
35
F
86
80
83
|Zsb
|Zsm
|Zsb
|Zsm
85
M
|Zsb
E
Qt
Qa
38
20
28
30
81
Yqp
Yqp
30
Zcp
73
43
Zsm
30
22
85
|cwo
Qcc
31
45
33
Jd
35
69
72
26
3
Qt
|Zsq
OV
88
68
L
Obs
40
8
|tbh
77
Obs
80
47
31
|cwb
|clp
Zrd
74
Zsm
Qa
Zmd
Qcc
32
Jd
|Zicp
|Zsb
Cu
Cu,Ag 54
58
Pb
86
75
|Zsb
Qa
|Zsmp
75
44
GR
80
|cwb
21
29
Yp
Yqp Qa
63 Zrd
35
81
52
10
56
Jd
35
83
63
|Zstp
58
|Zstp
|Zsm
NT
Obss
40
19
42
Zmd
Ybg
28
32
Zcr
Zcr
83
Zss
Jd
|cwb
|clc
44
29
Qa
40
33
40
Zss
22
|tb
|tbh
78
8
47
38
Om
73
28
Zcr
49
38
QTt
20
Zcm
42
Zss
52
35
21
82
42
30
|Zsm
|Zicm
Qa
36
75
48
SA
Oc
Osnr
23
7
Zcm
10
Qcc
Qcc
|cwo
46
79
|cwo
73
|clc
^cmp
46
Qa
32
|ar
|fr
85
42
85
50
47
29
70
72
EA
12
Obss
|tf
25 38
40
41
35
50
30
|Zsq
29
82
40
FA
UL
T
63
79
Qa
13
20
|ch
|cwm
QTt
54
82
|frs
Qr
38
70
Zsm
Zss Zsm
33 Jd
Qa Yg
33
Zsm
Zsm 27 35
Zrd
L
Qr
Qt
31
25
73
14 11
8
43
25
20
61
47
Qcc
24
44
|ca
|ch
31
|clp
38
Zcr
O|gu
63
52
62
Qr
35
33
Jd
Zcp
Qa
21
Qcc
Zss
|fa
|fl
87
PL
Qa
Obs
|e
8
30
30
|fr
37
^cmp
32
39
Qr
47
F
RU
ST
Obrr
30
18
|td
Zsm
35
Qcf
86
O|gl
|Zsmp Cu,Zn |Zsb
|Zsm
|Zsb
|Zsm
|Zsq
TH
Oc
|td
QTt
|cb
65
79
20
20
40
23
QTt
65
80
40
Qt
80
L
47
40
85
50
42
22
4
Zss 36
Zcp
18
16
|cwmq
38
26
15
|cwb
Qa
38
34
Zcr
QTt
^cmt
50
RU
NM
25
54
Obps
QTt
Qt
L
18
Zcm
34
21
|clc
25
35
Qcc
|cwo
|fl
BA
RN
ES
VIL
LE
-M
ON
RO
VIA
THR
UST
FAULT
HY
AT
TS
TO
W
N
51
Qa
50
|e
24
33
Osnr
Obps
Obrr
Oc
78
38
|cwm
17
Zcr
35
Zcp
Jd
Zcp
47
|ch
Zcp
Zmd Zcr
15
68
Qa
20
12
23
32
|cwm
|war
|tb
|tf
|wac
15
21
58 62
28
|cwo Qcc
20
22
37
BU
LL
Obs
7
|chs
Qcc
Zcr
24
LT
Obs
35
41
|tbh
|ca
Qcc
Zcr
Qa
Zcp
19
2
27
37
22
4
67
|ch
30
Qcc
Zcp |clp
Zcp
Zcr
|cwb
70
Qcc
59
20
46
45
Qcc
12
33
85
O|c
33
57
51
60
Obrr
|cb
62
25
5
|wact
60
82
QTt
20
43
32
FAU
L
Obss
69
Oc
L
50
48
Oc
L
L
40
75
27
60
83
60
8
45
37
51
34
45
|tb
|td
4
15
26
57
|cwb |cwm
37
25
Zcp
Zcp
TA
IN
L
Osnr
Obss
Oc
45
Qt
57
Qa
32
37
51
20
Qcc
38
Zcp
52
UN
30
Obps
Obrr
35
25
62
|tf
F
13
85
Obs
42
Qt
72
Qa
52
47
Obps
Obrr
66
QTt
23
62
L
28
21
56
L
49
Oc
63
60
Om
34
29
F
|e
|war
|td
35
18
MO
30
QTt
Obss
Obss
52
Obps
Osnr
Oc
60
30
Qa
|tbh
|tf
65
|tb
|cwb
|clc
N
60
L
50
O|c
Qt
77
60
40 Obs
Qa
50
Obps
67
O|c
15
|cwo
RU
|cb
|e
O|c
QTt
12
86
55
27
L
89
Qa
QTt
|tf
|tb
|Zshp
|cs
|ar 72
37
12
BUL
35
Obs
Qa
70
23
12
80
FAUL
T
Osnr
Oc
Obps
|e
Om
78
55
70
Qa
58
67
KEE
DYS
VILL
E
27
80
LT
Obrr
65
Osnr
HI
LL
78
28
82
60
20
QTt
FAU
80
22
RT
|cb
35
L
SHO
A
|e
SIM 2889
Explanatory pamphlet accompanies map
1
1
4
U.S. Geological Survey, Reston, Va. 2Maryland Geological Survey, Baltimore, Md. 3U.S. Geological Survey, Retired. 4Deceased.
1
2007
1
1
3
This map is available for sale by U.S. Geological Survey, Information Services,
Box 25286, Denver Federal Center, Denver, CO 80225
For product and ordering information:
World Wide Web: http://www.usgs.gov; Telephone: 1-888-ASK-USGS
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
Printed on recycled paper
Using the geologic map of Virginia, answer the following questions:
1.Is the region in the extreme northwest corner to the Potomac River strongly folded or strongly
faulted?
2.Is the region from the southeast corner to Harrison Island along the Potomac strongly folded or
strongly faulted?
3.In the southwestern part of the map, along the Shenandoah River, the sediments are only Quaternary
in age, yet they are surrounded by much older Cambrian sediments. How do you explain this?
4.In the southeastern corner of the map, locate Rockville and Gaithersburg. Notice that they are
separated by the Plummer’s Island Fault. Is Rockville moving atop Gaithersburg or is Gaithersburg
moving atop Rockville?
5.Find Martinsburg, WV, in the extreme northwest corner. Now locate Martinsburg, MD, which is just to
the to the east of Harrison Island and Mason Island along a bend in the Potomac in the south central
area of the map. Which is surrounded by the older rock?
6.Locate Long Marsh Run just south of the West Virginia/ Virginia border on the southwestern side of
the map. Which way is it flowing?
How many different ages of rock would you encounter along its course?
7.In the middle image at the bottom, to the far right, you see that the younger Prettyboy Schist lies
beneath the older Mather Gorge Formation. How can older rock be found atop younger rock?
8.Locate the oval, brown rocks near the center of the map. What geologic feature is this?

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