OID_	MapUnit	Name	FullName	Age	Description	HierarchyKey	ParagraphStyle	Label	Symbol	AreaFillRGB	AreaFillPatternDescription	DescriptionSourceID	GeoMaterial	GeoMaterialConfidence	DescriptionOfMapUnits_ID
1	Qal	Alluvium	Alluvium	Quaternary	"Well to poorly sorted, reddish-brown to grayish-brown mixture of unconsolidated rounded pebbles, cobbles, boulders, sand, silt and clay. These deposits form in stream channels, and on the flood plain adjacent to streams. Thickness varies from thin veneer to up to 15 feet (5 m)."	01-01-01-01	DMUHeader1			254 249 194	no pattern	DS1	Alluvial sediment	High	DMU_1
2	Qc	Colluvium	Colluvium	Quaternary	"Unsorted, light-gray to reddish-gray, angular to subangular pebbles, cobbles, boulders and sand that accumulate on slopes below outcrops, in hillslope depressions, and are present at the foot of prominent mountain ridges. Formed by the slow downslope movement of weathered material. Thickness ranges from a thin veneer to more than 100 feet (30 m)."	01-01-01-02	DMUHeader1			248 215 147	no pattern	DS1	Colluvium and other widespread mass-movement sediment	High	DMU_2
3	Qr	Residuum	Residuum	Quaternary	"Mixture of moderate reddish brown soil and rounded to angular pebbles, cobbles, and locally blocks of grayish-pink to white quartz. Thickness ranges from a veneer to 10 feet (3 m)."	01-01-01-03	DMUHeader1			242 229 78	no pattern	DS1	Residual material	High	DMU_3
4	Qt	Terrace deposits	Terrace deposits	Quaternary	"Reddish-brown to light-brown, sandy and clayey mixture of rounded pebbles to cobbles of sandstone, vein quartz, and quartzite. Locally present on elevated low relief areas above creeks and drainages. Thickness ranges from a thin veneer to more than 10 feet (3 m)."	01-01-01-04	DMUHeader1			254 234 133	no pattern	DS1	Residual material	High	DMU_4
5	Mp	Purslane Formation	Purslane Formation	Mississippian	"Light-gray, tan and reddish-brown, coarse-grained to conglomeratic, thick-bedded to cross-bedded sandstone and thin beds of gray shale and coaly shale. The Purslane is more than 300 feet (90 m) thick in western Washington County."	02-01-01-01	DMUHeader1			204 235 255	no pattern	DS1	Clastic sedimentary rock	High	DMU_5
6	MDr	Rockwell Formation	Rockwell Formation	Mississippian-Devonian	"Interbedded, gray silty shale, light-gray to tan sandstone, and coaly and reddish shale. In Washington County, a reddish-brown to gray polymictic diamictite marks the base of the formation. The Rockwell Formation is more than 400 feet (120 m) thick in western Washington County."	02-01-01-02	DMUHeader1			128 179 222	no pattern	DS1	Sandstone and mudstone	High	DMU_6
7	Dh	Hampshire Formation	Hampshire Formation	Devonian	"Interbedded, reddish-brown to brownish-red, locally greenish-gray sandstone, reddish-brown siltstone, shale, and rooted claystone. The thickness of the Hampshire is more than 3,000 feet (900 m) in western Washington County."	02-01-01-03	DMUHeader1			179 179 255	no pattern	DS1	Mostly sandstone	High	DMU_7
8	Df	Foreknobs Formation	Foreknobs Formation	Devonian	"Interbedded, olive-gray medium- to coarse-grained, cross-bedded sandstone and greenish-gray to dusky-red, fossiliferous shale and siltstone. Thick (>30 feet) sandstone intervals occur near the base and near the top of the formation. The Foreknobs is more than 1,500 feet (460 m) in thickness in western Washington County."	02-01-01-04	DMUHeader1			204 204 255	no pattern	DS1	Mostly sandstone	High	DMU_8
9	Dhbs	Harrell-Brallier-Scherr Formations (undivided)	Harrell-Brallier-Scherr Formations (undivided)	Devonian	"The Harrell Shale is a dark-gray, fissile, calcareous, thinly laminated shale that weathers to thin, yellowish-gray shale chips. The base of the Harrell is marked by the black, very fissile Burket Shale Member. The Harrell grades eastward into the Brallier Formation. The Harrell Shale is up to 150 feet thick (45 m). The Brallier Formation is a succession of thinly interbedded, gray to olive-gray shale and siltstone and thin, fine-grained sandstone. The Brallier is 2,000 to 2,500 feet thick (600 – 760 m). The Scherr Formation is interbedded reddish-brown to grayish-brown shale, thin, gray siltstone, and fine-grained, bioturbated and fossiliferous sandstone. The thickness of the Scherr is indistinct in western Washington County."	02-01-01-05	DMUHeader1			166 179 242	no pattern	DS1	Mudstone	High	DMU_9
10	Dm	Mahantango Formation	Mahantango Formation	Devonian	"Medium-gray to olive-gray massive siltstone to fine-grained sandstone occurs near the base and top of the formation and is interbedded with siltstone, sandstone, with silty, hackly shale. Weathers brownish-gray to grayish-brown. The Mahantango Formation is approximately 1,400 feet (425 m) thick in western Washington County."	02-01-01-06	DMUHeader1			179 204 255	no pattern	DS1	Clastic sedimentary rock	High	DMU_10
11	Dnm	Needmore-Marcellus Shales	Needmore-Marcellus Shales	Devonian	"Medium to dark brownish gray to medium dark gray, calcareous, fossiliferous shale, with thin (30 cm) beds of dark-gray, argillaceous limestone. The upper Needmore Shale consists of approximately 35 feet (10 m) of interbedded, dark-gray, argillaceous limestone and black shale. The top of the Needmore Shale is marked by the Tioga Bentonite, a brown, tuffaceous claystone. The Needmore Shale is 150 feet thick in western Washington County (45 m). The Marcellus Shale consists of black, brittle, fissile shale in the lower 100 feet (30 m), thinly interbedded black limestone and shale in the middle, and very dark gray, fissile shale containing thin (1 to 2 cm) siltstone beds at the top. The Marcellus Shale is up to 500 feet (152 m) thick."	02-01-01-07	DMUHeader1			140 140 255	no pattern	DS1	Mostly mudstone	High	DMU_11
12	Do	Oriskany Sandstone	Oriskany Sandstone	Devonian	"Interbedded, medium- to dark-gray, siliceous shale and sandy and cherty limestone near the base (Shriver Shale Member), overlain by tan, fine-grained, calcareous sandstone, and then by light-gray, medium- to coarse-grained, thin- to thick-bedded, calcareous sandstone at the top (Ridgely Member). The Oriskany Formation is approximately 50 feet (15 m) thick in western Washington County."	02-01-01-08	DMUHeader1			191 179 242	no pattern	DS1	Mostly mudstone	High	DMU_12
13	DSkh	Keyser-Helderberg Formations (undivided)	Keyser-Helderberg Formations (undivided)	Devonian-Silurian	"The Keyser Limestone consists of light-gray, coarsely crystalline, crinoidal limestone in the lower 50 feet (15 m), becoming medium- to dark-gray, medium- to thick-bedded, nodular, fossiliferous limestone containing dark-gray chert nodules. The upper Keyser is thin-bedded, cherty, fossiliferous limestone. The Keyser is up to 300 feet (90 m) thick in western Washington County. The Helderberg Limestone consists of medium-gray, medium-bedded, cherty, crinoidal limestone (New Creek Member), overlain in western Washington County by a light-gray, cross-bedded calcareous sandstone (Elbow Ridge Sandstone), then a medium-gray fossiliferous limestone containing beds of brown-weathering chert (Corriganville Limestone), which is succeeded by interbedded, cherty, dark-gray limestone and calcareous shale (Licking Creek Member), and topped by a thin, black, brittle shale (Mandata Shale). The Helderberg Limestone is 150 to 180 feet (30 to 55 m) thick in western Washington County."	02-01-01-09	DMUHeader1			217 217 255	no pattern	DS1	Limestone	High	DMU_13
14	Sto	Tonoloway Formation	Tonoloway Formation	Silurian	"Medium- to light-gray, fine-grained, thinly laminated, mudcracked, dolomitic limestone with thin layers of medium-gray, fine-grained limestone, and tan laminated dolomite. The Tonoloway Limestone is approximately 400 feet thick (120 m)."	02-01-01-10	DMUHeader1			204 179 255	no pattern	DS1	Limestone	High	DMU_14
15	Swc	Wills Creek Formation	Wills Creek Formation	Silurian	"Interbedded, greenish-gray to light-gray, calcareous shale and tan, dolomitic shale containing mud cracks, laminations, and salt and gypsum casts. The thickness of the Wills Creek is approximately 400 feet (120 m)."	02-01-01-11	DMUHeader1			179 153 235	no pattern	DS1	Mudstone	High	DMU_15
16	Sb	Bloomsburg Formation	Bloomsburg Formation	Silurian	"Interbedded, reddish-gray to brownish-gray, fine-grained sandstone and hackly shale to mudrock. The Bloomsburg Formation rarely exceeds 100 feet in thickness (30 m)."	02-01-01-12	DMUHeader1			204 153 255	no pattern	DS1	Mostly sandstone	High	DMU_16
17	Sm	McKenzie Formation	McKenzie Formation	Silurian	"Interbedded, greenish-gray, calcareous shale and medium- to dark-gray, thinly bedded, fossiliferous limestone. The McKenzie Formation is up to 300 feet thick (90 m)."	02-01-01-13	DMUHeader1			230 179 235	no pattern	DS1	Limestone	High	DMU_17
18	Sk	Keefer Sandstone	Keefer Sandstone	Silurian	"Light-gray to yellowish-gray, fine- to medium-grained sandstone that weathers light-gray to yellowish-tan. The unit is thin-bedded in the lower part and thick-bedded in the middle and upper part, with lumpy and irregular bedding planes. The Keefer is moderately fossiliferous with small brachiopods, crinoid debris, and Skolithus tubes. Because it is resistant to weathering, the Keefer Formation tends to form a prominent topographic ridge. It is about 30 feet (10 m) thick at maximum thickness."	02-01-01-14	DMUHeader1			217 199 255	no pattern	DS1	Conglomerate	High	DMU_18
19	Srh	Rose Hill Formation	Rose Hill Formation	Silurian	"Light-olive to pale reddish-gray, light-gray, greenish-gray, and deep purple shale, brownish-red sandstone, and thin reddish siltstone. The Rose Hill Formation is mostly fissile, papery shale, weathering to rusty chips. The shale is interbedded with thin, laminated, cross-bedded sandstone strata, especially in the lower portion of the formation. About 150 to 170 feet (45 to 50 m) above the base of the Rose Hill is the Cresaptown Ironstone, comprised of 20 to 30 feet (6 to 9 m) of reddish-brown, fine-grained, thin-bedded, hematitic sandstone. The Rose Hill Formation is a poorly exposed, easily weathered shale with the exception of the Cresaptown interval, which is resistant and commonly forms a topographic ridge. The thickness of the Rose Hill is estimated at 270 feet (80 m)."	02-01-01-15	DMUHeader1			235 204 255	no pattern	DS1	Clastic sedimentary rock	High	DMU_19
20	St	Tuscarora Sandstone	Tuscarora Sandstone	Silurian	"Light-gray, fine- to medium-grained, medium-bedded, dense sandstone. Locally, sandstone layers are interbedded with thin gray shale. The thickness of the Tuscarora Sandstone is less than 50 feet (15 m) in Washington County."	02-01-01-16	DMUHeader1			242 214 242	no pattern	DS1	Sandstone	High	DMU_20
21	Oj	Juniata Formation	Juniata Formation	Ordovician	"Interbedded, reddish-brown to brownish-red, fine- to medium-grained, medium- to thick-bedded, cross-bedded sandstone and micaceous siltstone and silty shale. The Juniata Formation is estimated at 200 feet thick (60 m)."	02-01-01-17	DMUHeader1			224 112 222	no pattern	DS1	Mostly sandstone	High	DMU_21
22	Om	Martinsburg Shale	Martinsburg Shale	Ordovician	"Medium- to dark-gray, fissile shale at the base, overlain by medium-gray, silty shale and thinly interbedded medium-grained sandstone, and then by thick-bedded, medium-grained, fining upward sandstone at the top of the formation. The Martinsburg is up to 5000 feet thick in Washington County (1500 m)."	02-01-01-18	DMUHeader1			255 128 222	no pattern	DS1	Clastic sedimentary rock	High	DMU_22
23	Omu	"Martinsburg Formation, upper member"	"Martinsburg Formation, upper member"	Ordovician	"Interbedded medium-gray shale and thin, light-gray to tan, silty sandstone at the base, grading upward into interbedded greenish-gray to medium-gray siltstone and silty shale with medium- to thick-bedded medium- to coarse-grained sandstone. Thickness estimated at 2000 to 3000 feet (610 to 915 m)."	02-02-01-01-01	DMUHeader1			242 140 230	no pattern	DS1	Sandstone and mudstone	High	DMU_23
24	Oml	"Martinsburg Formation, lower member"	"Martinsburg Formation, lower member"	Ordovician	"Predominately medium- to dark-gray, silty, fissile shale with thin (<0.5 inches) siltstone interbeds. Dark-gray to black shale at base is equivalent to the Utica Shale. Thickness estimated at 1500 to 2000 feet (457 to 610 m)."	02-02-01-01-02	DMUHeader1			235 128 204	no pattern	DS1	Mudstone	High	DMU_24
25	Oc	Chambersberg Formation	Chambersberg Formation	Ordovician	"Medium- to dark-gray, nodular- to medium-bedded, fossiliferous limestone. Nodular-bedded, shaly, highly fossiliferous limestone bearing the echinoderm Echinosphaerites occurs near the base of the formation. Top of the Chambersburg Formation is marked by sharp contact with the black shales of the overlying Martinsburg. Thickness is 250 feet (76 m)."	02-02-01-02	DMUHeader1			230 179 233	no pattern	DS1	Limestone	High	DMU_25
26	Osp	St. Paul Group (undivided)	St. Paul Group (undivided)	Ordovician	"Massive, light-gray lime mudstone containing fenestral fabric at the base (Row Park Limestone), overlain by interbedded, medium- to light-gray, medium-bedded limestone and laminated dolomitic limestone at the top (New Market Limestone). The thickness of the St. Paul Group is 300 feet (91 m)."	02-02-01-03	DMUHeader1			255 166 255	no pattern	DS1	Mudstone	High	DMU_26
27	Ops	Pinesburg Station Dolomite	Pinesburg Station Dolomite	Ordovician	"Light-gray to tan, medium-bedded, highly fractured, fine-grained dolomite. Weathers to a very light gray surface. Interbedded with very light gray, laminated dolomite. Thickness is 350 to 400 feet (107 to 122 m)."	02-02-01-04	DMUHeader1			255 204 255	no pattern	DS1	Dolomite	High	DMU_27
28	Orr	Rockdale Run Formation	Rockdale Run Formation	Ordovician	"Interbedded and cyclic limestone and dolomite, cherty in the lower 400 feet (120 m). Limestone intervals consist of medium- to light-gray, ribbony and thrombolitic to stromatolitic lime mudstone to boundstone. Locally, limestone layers are light-gray oolitic grainstone. Dolomite varies from light-gray to tan, laminated to massive and fractured, with wispy dolomitic laminae. The relative proportion of the limestone to dolomite varies up section. In the lower 600 feet, limestone is typically thicker than dolomite. The progressively changes upsection so that the upper 700 feet (215 m) is dominantly dolomitic with little limestone within individual cycles. Forms very little topographic expression; many horizons are very poorly exposed. Thickness up to 2500 feet (762 m)."	02-02-01-05	DMUHeader1			235 153 214	no pattern	DS1	Limestone	High	DMU_28
29	Osdf	Dam Five Member	"Stonehenge Formation, Dam Five Member"	Ordovician	"Medium- to dark-gray, medium-bedded, ribbony and oolitic, lime mudstone to packstone. Near the base of the member, ribbony lime mudstone predominates. Upsection, medium-gray, ribbony lime mudstone becomes interbedded with intervals of flat-pebble lime grainstone, and hummocky, thickly laminated lime packstone and oolitic lime packstone to grainstone. Locally, thin (< 3.0 feet, 0.9 m) algal thrombolites are present. This member commonly forms a persistent and mappable ridge and is frequently well exposed. Thickness is 500 to 750 feet (150 to 215 m)."	02-02-01-06-01	DMUHeader1			255 222 255	no pattern	DS1	Mostly carbonate rock	High	DMU_29
30	Osf	Funkstown Member	"Stonehenge Formation, Funkstown Member"	Ordovician	"The lower part of the member is composed of massive, medium-gray, algal lime boundstone with some layers up to 7 m thick. Grading upsection into interbedded medium- to dark-gray algal thrombolites 1.5 to 2.0 m thick and medium-gray, thinly bedded to ribbony, locally fossiliferous, lime wackestone to lime packstone. Several thin, tan dolomite beds occur near the middle of the unit. Thickness: 300 to 400 feet (90 to 100 m)."	02-02-01-06-02	DMUHeader1			245 186 250	no pattern	DS1	Limestone	High	DMU_30
31	Oss	Stoufferstown Member	"Stonehenge Formation, Stoufferstown Member"	Ordovician	"Dark-gray, argillaceous, thinly bedded to ribbony, lime mudstone with thin beds of flat-pebble lime grainstone conglomerate and hummocky, discontinuous, laminated limestone. A single, 10-foot (3 m) interval of massive, dark-gray, thrombolitic, algal boundstone occurs approximately 30 feet (10 m) above the base of the member. This member weathers into thin brown and orange chips, which litter overlying soil. Forms a low, discontinuous ridge. Thickness varies from 230 to 295 feet (70 to 90 m)."	02-02-01-06-03	DMUHeader1			235 128 235	no pattern	DS1	Mostly carbonate rock	High	DMU_31
32	Ccsg	Shady Grove Member	"Conococheague Formation, Shady Grove Member"	Cambrian	"Interbedded, medium- to light-gray, ribbony lime mudstone that weathers to flaggy to platy beds, and arenaceous grainstones exhibiting edgewise and flat-pebble conglomerates. Locally, thin pastel blue and pink marble strata are developed. Black or gray chert fragments and brown-weathering quartz sandstone cobbles are frequently abundant in overlying soil. Thickness is 650 to 750 feet (200 to 230 m)."	02-02-01-07-01	DMUHeader1			255 217 230	no pattern	DS1	Mostly mudstone	High	DMU_32
33	Ccz	Zullinger Member	"Conococheague Formation, Zullinger Member"	Cambrian	"Predominantly cyclically bedded, medium- to dark-gray, thrombolitic limestone and gray, ribbony and laminated limestone and tan, laminated dolomite. Thrombolites range in thickness from 3 to 6 feet (1 to 2 m) within thrombolitic intervals to less than 1 foot (0.3 m) within the ribbony intervals. Several dark-gray, oolitic intervals are present in the upper part of this member. Thickness is 1500 to 1800 feet (460 to 550 meters)."	02-02-01-07-02	DMUHeader1			255 191 217	no pattern	DS1	Limestone	High	DMU_33
34	Ccb	Big Spring Station Member	"Conococheague Formation, Big Spring Station Member"	Cambrian	"Tan, massive dolomite interbedded with tan to light-gray, laminated dolomite; unit characterized by dark-brown weathering. At the type section on the western side of the Hagerstown Valley, this member is characterized by interbeds of light-gray, cross-bedded, calcareous, intraclastic, quartzarenitic sandstone approximately 3 feet (1 m) in thickness. Member becomes interbedded with gray, dolomitic thrombolite beds near the top. Thickness ranges from 200 to 300 feet (60 to 90 m)."	02-02-01-07-03	DMUHeader1			255 166 204	no pattern	DS1	Dolomite	High	DMU_34
35	Ce	Elbrook Formation	Elbrook Formation	Cambrian	"Lower part of the formation is very poorly exposed and contains interbedded tan, thin- to thick-bedded limestone and dolomite, which frequently weather shaly and are intercalated with medium-bedded, dark-gray limestone. Middle part of the formation contains cyclic, dark-gray limestone and dolomitic limestone. The upper part of the formation, and making up its greatest thickness, is cyclically bedded, gray, thrombolitic limestone and ribbony to laminated limestone and dolomite. Thickness ranges from 2200 to 2500 feet (670 to 760 m)."	02-02-01-08	DMUHeader1			255 153 179	no pattern	DS1	Limestone	High	DMU_35
36	Cwac	Chewsville Member	"Waynesboro Formation, Chewsville Member"	Cambrian	"Reddish-brown to chocolate-brown, silty shale, siltstone, and silty fine-grained sandstone, interbedded with white, calcareous, Skolithus-burrowed sandstone beds (2 to 6 cm thick) and tan to buff, medium-bedded, sandy dolostone. This unit usually is the most diagnostic of the Waynesboro lithologies and typically forms a ridge, which makes it easily traceable. Thickness estimated at 90 to 125 feet (30 to 45 m)."	02-02-01-09-01	DMUHeader1			255 171 222	no pattern	DS1	Clastic sedimentary rock	High	DMU_36
37	Cwak	Cavetown Member	"Waynesboro Formation, Cavetown Member"	Cambrian	"Medium- to thick-bedded, medium- to coarse-grained, intraclastic grainstone; tan, laminated dolostone and dolomitic limestone; and medium-gray, oolitic, lime grainstone, ribbony carbonates, and burrowed-mottled dolomitic limestone. This unit is typically poorly exposed, but makes up the greatest thickness of the formation. Thickness estimated at 600 to 750 feet (200 to 250 m)."	02-02-01-09-02	DMUHeader1			255 133 207	no pattern	DS1	Dolomite	High	DMU_37
38	Cwar	Red Run Member	"Waynesboro Formation, Red Run Member"	Cambrian	"Interbedded, tan-weathering, punky, fine-grained sandstones; green-gray shale; gray sandy limestone; and laminated dolostone. Locally thin (0.6 to 5 cm) layers of red siltstone and sandstone are present. Typically, this unit forms a low ridge somewhat lower in height than the Chewsville Member. Thickness estimated at 150 to 225 feet (60 to 75 m)."	02-02-01-09-03	DMUHeader1			255 110 163	no pattern	DS1	Mostly sandstone	High	DMU_38
39	Ct	Tomstown Formation	Tomstown Formation	Cambrian	"Predominantly buff-weathering, medium- to dark-gray dolomite, dolomitic limestone, and limestone. Divided into 4 members. Total thickness is 1,200 to 1,300 feet (366 to 396 m)."	02-02-01-10	DMUHeader1			204 128 153	no pattern	DS1	Dolomite	High	DMU_39
40	Ctd	Dargan Member	"Tomstown Formation, Dargan Member"	Cambrian	"Interbedded and cyclical dolomite and limestone. Cycles consist of alternations of dark-gray, bioturbated dolomite and medium- to dark-gray, laminated dolomite, or dark-gray dolomite or limestone and tan, laminated, silty dolomite. Cycles of thin-bedded limestone and tan dolomite are more prevalent near the top of the member. Thickness is approximately 700 feet (215 m)."	02-02-01-10-01	DMUHeader1			252 204 179	no pattern	DS1	Dolomite	High	DMU_40
41	Ctb	Benevola Member	"Tomstown Formation, Benevola Member"	Cambrian	"Light-gray to white, massive to poorly bedded, highly fractured, sugary dolomite. The Benevola Member varies from white to very light gray, on both fresh and weathered surfaces. Bedding is rarely evident, except within polished slabs where faint ghosts of crossbedding are common. Thickness is 100 to 150 feet (33 to 50 m)."	02-02-01-10-02	DMUHeader1			242 158 179	no pattern	DS1	Dolomite	High	DMU_41
42	Ctf	Fort Duncan Member	"Tomstown Formation, Fort Duncan Member"	Cambrian	"Medium- to dark-gray, thick-bedded, mottled dolomite with white, void-filling, sparry dolomite. Weathered surface characterized by irregular, clotted to anastomosing network of algae. Layers of the white, sparry dolomite, 0.5 to 1.5 inches wide, fill voids that are continuous in beds for up to several yards (several meters) and contrasts the darker mottled dolomite. Thickness ranges from 200 to 250 feet (60 to 75 m)."	02-02-01-10-03	DMUHeader1			217 102 128	no pattern	DS1	Dolomite	High	DMU_42
43	Ctbh	Bolivar Heights Member	"Tomstown Formation, Bolivar Heights Member"	Cambrian	"The Bolivar Heights Member is characterized by three stratigraphically stacked lithologies. The basal lithology is a tan, vuggy dolomite that is in contact with the underlying Antietam Formation. This dolomite ranges from 10 to 40 feet (9 to 12 m) in thickness, and is rarely exposed. Overlying the tan basal dolomite is an interval 40 to 50 feet (12 to 15 m) thick, comprised of very light gray, sheared, laminated, dolomitic marble (Keedysville marble bed). Above the Keedysville marble bed, the Bolivar Heights Member consists of about 200 feet (60 m) of thin- to medium-bedded, dark-gray, ribbony, burrow-mottled, lime mudstone that weathers light-gray in color. The number and density of burrows vary among beds, with very little burrowing in some layers and an anastomosing network of burrows in others. Thickness is 200 to 250 feet (60 to 75 m)."	02-02-01-10-04	DMUHeader1			255 191 166	no pattern	DS1	Dolomite	High	DMU_43
44	Ca	Antietam Formation	Antietam Formation	Cambrian	"The lower part of the formation is greenish-gray, highly cleaved, slaty, phyllitic shale and siltstone interbedded with white, Skolithos-burrowed, and fine-grained sandstone. These lower strata grade upsection into medium-bedded, white, bioturbated and crossbedded, fine- to medium-grained sandstone in the middle of the formation. The uppermost strata of the formation consist of light- to medium-gray, crossbedded, vuggy, coarse-grained granular sandstone to conglomerate. Thickness ranges from 500 to 800 feet (150 to 245 m)."	03-01-01-01	DMUHeader1			235 128 153	no pattern	DS1	Sandstone and mudstone	High	DMU_44
45	Ch	Harpers Formation	Harpers Formation	Cambrian	"Brownish-gray to dark greenish gray, silty phyllitic shale to highly sheared phyllitic siltstone with intervals of brownish-gray, medium-grained, silty sandstone. On Catoctin Mountain: light brownish gray to light olive gray, sheared, muscovite(?)-sericite phyllite weathering to pale red, moderate reddish brown, and yellowish-brown. Approximate formation thickness 1,000 to 1,500 feet (300 to 450 m). On South Mountain: Primarily light olive gray and dark greenish gray, highly cleaved phyllitic siltstone. Interbeds of medium-grained, medium-gray sandstone and quartzite occur locally. Estimated formation thickness greater than 2500 feet (760 m)."	03-01-01-02	DMUHeader1			247 196 222	no pattern	DS1	Clastic sedimentary rock	High	DMU_45
46	Chm	"Harpers Formation, metasandstone"	"Harpers Formation, metasandstone"	Cambrian	"Commonly thin (1 inch to 16 feet; 3 cm to 5 m), dark green gray, fine to medium-grained, highly argillaceous metasandstones containing Skolithus burrows, especially near the top of the formation. Mappable metasandstone intervals are up to 30 feet (10 m) thick."	03-01-01-02-01	DMUHeader1			217 110 159	no pattern	DS1	Metasedimentary rock	High	DMU_46
47	Chma	Mont Alto Member	"Harpers Formation, Mont Alto Member"	Cambrian	"Light-to medium-gray, coarse grained to conglomeratic, crossbedded quartzite, commonly less than 30 feet (10 m) in thickness."	03-01-01-02-02	DMUHeader1			255 176 231	no pattern	DS1	Quartzite	High	DMU_47
48	Cwo	Owens Creek Member	"Weverton Formation, Owens Creek Member"	Cambrian	"Dark to very dark gray, very coarse grained to conglomeratic, crossbedded graywacke. Although commonly crossbedded, the very coarse grained nature of this unit makes recognition of crossbedding difficult. Large (1 to 3 cm) white and pink quartz pebbles are characteristic of this member, although they are only locally common. Thickness ranges from 150 to 180 feet (50 to 60 m)."	03-01-01-03-01	DMUHeader1			212 120 120	no pattern	DS1	Metasedimentary rock	High	DMU_48
49	Cwm	Maryland Heights Member	"Weverton Formation, Maryland Heights Member"	Cambrian	"Thin (less than 33 feet; 10 m), medium- to dark-gray quartzite and graywacke interbedded with very dark gray, highly cleaved siltstone and phyllitic shale. Shales and siltstones are very poorly exposed and individual quartzites and graywackes are only locally traceable. Thickness ranges from 150 to 350 feet (50 to 115 m)."	03-01-01-03-02	DMUHeader1			247 153 153	no pattern	DS1	Metasedimentary rock	High	DMU_49
51	Cwb	Buzzard Knob Member	"Weverton Formation, Buzzard Knob Member"	Cambrian	"Light-gray to medium-gray, medium-bedded quartzite with dark-gray, argillaceous layers up to 4 cm thick separating the quartzite beds. Crossbedding within individual quartzite strata is pervasive. The Buzzard Knob Member has an estimated thickness of 50 to 150 feet (15 to 45 m)."	03-01-01-03-03	DMUHeader1			255 222 209	no pattern	DS1	Quartzite	High	DMU_51
52	CZl	Loudoun Formation	Loudoun Formation	Late Proterozoic? Cambrian?	"Medium- to dark-gray, medium-bedded conglomerate and black, tuffaceous phyllite. Lithology is very variable, ranging from a crossbedded quartz-pebble conglomerate to a highly cleaved polymictic conglomerate with a matrix of flattened phyllite pebbles. The localized distribution and rapid thickness variations of this formation may be the result of the original deposition patterns. The Loudoun Formation ranges in thickness from 30 to 200 feet (9 to 60 m)."	03-01-01-04	DMUHeader1			240 179 179	no pattern	DS1	Clastic sedimentary rock	High	DMU_52
53	CZlc	"Loudoun Formation, conglomerate"	"Loudoun Formation, conglomerate"	Late Proterozoic? Cambrian?	"Medium-bedded, medium light gray, grayish yellow green or dusky blue conglomerate that weathers light-gray and greenish-gray or dusky blue. Contains oval pebbles of quartz, quartzite, rhyolite, and granite(?) that are 0.5 to 4.0 cm long, and flattened, dark-colored phyllite fragments, 1.5 to 3.0 cm long; matrix is a medium- to coarse-grained graywacke. Conglomerate beds are intercalated with cross-laminated, thin- to medium-bedded, medium- to coarse-grained, pebbly graywacke and thin intervals of very dusky purple, dusky blue, or very dusky red phyllites and quartz phyllites. Unit grades upward into pebbly quartzites. Conglomerate member ranges from 0 to 50 feet (0 to 15 m) in thickness."	03-01-01-04-01	DMUHeader1			219 168 168	no pattern	DS1	Conglomerate	High	DMU_53
54	Zcr	"Catoctin Formation, metarhyolite"	"Catoctin Formation, metarhyolite"	Late Proterozoic	Undifferentiated bluish-gray metarhyolite in which no single variety is dominant.	03-01-01-05-01	DMUHeader1			193 135 77	no pattern	DS1	Meta-felsic and intermediate rock	High	DMU_54
55	Zcra	"Catoctin Formation, aphanitic metarhyolite"	"Catoctin Formation, aphanitic metarhyolite"	Late Proterozoic	"Aphanitic, bluish-gray metarhyolite that is massive and dense, and exhibits a conchoidal fracture. Rare phenocrysts, where present, comprise less than 1 percent of the rock. Weathers bone white to very light gray."	03-01-01-05-02	DMUHeader1			232 219 204	no pattern	DS1	Meta-felsic and intermediate rock	High	DMU_55
56	Zcrb	"Catoctin Formation, metarhyolite breccia"	"Catoctin Formation, metarhyolite breccia"	Late Proterozoic	"Dusky blue-gray, metarhyolite breccia with angular to subrounded clasts that weather to a lighter color than the felsic matrix."	03-01-01-05-03	DMUHeader1			143 110 89	no pattern	DS1	Meta-felsic and intermediate rock	High	DMU_56
57	Zcrf	"Catoctin Formation, flow banded metarhyolite"	"Catoctin Formation, flow banded metarhyolite"	Late Proterozoic	"Flow-banded, bluish-gray metarhyolite containing nearly planar, locally convoluted flow bands 0.12 to 0.4 inch (3 to 10 mm) thick. Laminae are discontinuous and most prominent on weathered surfaces. Phenocrysts constitute less than 2 percent of the rock."	03-01-01-05-04	DMUHeader1			191 138 102	no pattern	DS1	Meta-felsic and intermediate rock	High	DMU_57
58	Zcrp	"Catoctin Formation, porphyritic metarhyolite"	"Catoctin Formation, porphyritic metarhyolite"	Late Proterozoic	"Porphyritic, bluish-gray metarhyolite with conspicuous very light gray to very pale orange or pinkish-gray feldspar laths. Phenocrysts are up to 0.2 inches (6 mm) long and make up 2 to 5 percent of the rock."	03-01-01-05-05	DMUHeader1			179 130 110	no pattern	DS1	Meta-felsic and intermediate rock	High	DMU_58
59	Zcrr	"Catoctin Formation, red metarhyolite"	"Catoctin Formation, red metarhyolite"	Late Proterozoic	"Grayish-red to dusky reddish purple, porphyritic metarhyolite. Phenocrysts make up 3 to 5 percent of the rock and are predominately euhedral, pink to light-gray feldspar and reddish quartz. Estimated thickness 200 to 300 feet (20 to 90 m)."	03-01-01-05-06	DMUHeader1			204 150 128	no pattern	DS1	Meta-felsic and intermediate rock	High	DMU_59
60	Zcdf	"Catoctin Formation, felsic dikes"	"Catoctin Formation, felsic dikes"	Late Proterozoic	"Massive, light-gray to medium-gray felsite; weathers light orange brown. Contains very few small feldspar phenocrysts."	03-01-01-05-07	DMUHeader1			242 89 140	no pattern	DS1	"Fine-grained, felsic-composition intrusive igneous rock"	High	DMU_60
61	Zcm	"Catoctin Formation, metabasalt"	"Catoctin Formation, metabasalt"	Late Proterozoic	"Medium to dark greenish gray, chloritic, locally amygdaloidal, epidote-rich metabasalt. Some areas are composed of highly sheared chlorite schist. Epidote occurs as light-green veins and nodules. Thickness estimated at greater than 1000 feet by Fauth (1977)."	03-01-01-05-08	DMUHeader1			222 204 179	no pattern	DS1	Meta-mafic rock	High	DMU_61
62	Zcmp	"Catoctin Formation, porphyritic metabasalt"	"Catoctin Formation, porphyritic metabasalt"	Late Proterozoic	"Greenish-gray to bluish-green rock that weathers bluish-gray to dark greenish gray. Very prominent white to very light gray, randomly oriented lath-shaped feldspar (albite?) phenocrysts. Individual crystals or aggregates may range in length from 1 to 25 mm and make up about 2 to 7 percent of the rock."	03-01-01-05-09	DMUHeader1			186 153 128	no pattern	DS1	Meta-mafic rock	High	DMU_62
63	Zcp	"Catoctin Formation, phyllite"	"Catoctin Formation, phyllite"	Late Proterozoic	Light-to medium-gray phyllite containing highly elongated light-gray flecks and blebs. Thickness of this unit appears to be less than 100 feet.	03-01-01-05-10	DMUHeader1			204 179 128	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_63
64	Zcp1	"Catoctin Formation, phyllite unit 1"	"Catoctin Formation, phyllite unit 1"	Late Proterozoic	"Poorly exposed, lustrous, light-gray to medium dark gray, olive-gray phyllite, or mottled yellowish-gray and medium-gray phyllite. Commonly contain numerous light-colored, flattened and elongate blebs from 1x10 to 10x20 mm in size. Unit thickness is estimated to be between 50 and 100 feet (15 to 30 m)."	03-01-01-05-11	DMUHeader1			153 128 89	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_64
65	Zcp2	"Catoctin Formation, phyllite unit 2"	"Catoctin Formation, phyllite unit 2"	Late Proterozoic	"Light greenish gray, moderate greenish gray and very light gray streaked phyllite; may be silicified. Weathered surfaces commonly soft and soapy. Lithologically similar to parts of the lavender phyllite exposed in adjacent parts of the Myersville 7.5-minute quadrangle (Fauth, 1977). Estimated thickness between 30 and 50 feet (9 and 15 m)."	03-01-01-05-12	DMUHeader1			214 201 158	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_65
66	Zcp3	"Catoctin Formation, phyllite unit 3"	"Catoctin Formation, phyllite unit 3"	Late Proterozoic	"Medium dark gray, medium bluish gray, or light-gray phyllite containing blebs 2 to 4 mm long. Weathers to light-colored, flat or platy fragments up to 15x40 cm in size. Estimated thickness between 30 and 60 feet (9 and 15 m)."	03-01-01-05-13	DMUHeader1			191 166 128	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_66
67	Zcpl	"Catoctin Formation, lavender phyllite"	"Catoctin Formation, lavender phyllite"	Late Proterozoic	"Pale purple to grayish red-purple or very light gray phyllite. Locally, color is mottled with red quartz grains and light-gray to yellowish-gray porphyroblasts of feldspar. Estimated thickness of 30 to 50 feet (9 to 15 m)."	03-01-01-05-14	DMUHeader1			217 196 184	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_67
68	Zcb	"Catoctin Formation, basaltic dike"	"Catoctin Formation, basaltic dike"	Late Proterozoic	"Dark greenish gray, locally phyllitic and chloritic basalt. Commonly has strongly developed cleavage. These bodies are present in the basement gneiss complex and appear to represent dikes that once contacted the main Catoctin outcrop belt."	03-01-01-05-15	DMUHeader1			204 179 179	no pattern	DS1	Extrusive igneous material	High	DMU_68
69	Zcd	"Catoctin Formation, mafic dikes"	"Catoctin Formation, mafic dikes"	Late Proterozoic	"Typically dark greenish gray to grayish olive green, fine- to medium-grained metadiabase or metabasalt. Commonly occurs as dikes and sills(?) intruding rocks of basement gneiss complex. Crosscutting relationships with older, gneissic structure discernible in several outcrops. Dikes range in width from several inches up to 40 feet (12 m). Thicker dikes may show chilled margins; thinner dikes usually have been altered to chlorite phyllite or schist. Individual dikes may be traceable and mappable for distances ranging from a few hundred to thousands of feet (about 100 m to more than 1000 m)."	03-01-01-05-16	DMUHeader1			191 77 115	no pattern	DS1	Meta-mafic rock	High	DMU_69
70	Zsr	Swift Run Formation	Swift Run Formation	Late Proterozoic	"Medium gray brown, silty sandstone with intervals of very light gray, foliated, micaceous marble. Marble locally quarried for agricultural purposes. Thickness estimated at 0 to 200 feet (0 to 60 m)."	03-01-01-06	DMUHeader1			204 128 179	no pattern	DS1	Meta-carbonate rock	High	DMU_70
71	Zsrp	"Swift Run Formation, phyllite"	"Swift Run Formation, phyllite"	Late Proterozoic	"Very light gray, dusky yellow green and very light greenish gray, lustrous quartz sericite(?) phyllite that weathers grayish-orange to very light gray. Quartz occurs as medium to coarse detrital grains either uniformly disseminated throughout the rock or concentrated in thin bands or lenses. Estimated thickness ranges from 0 to 75 feet (0 to 23 m)."	03-01-01-06-01	DMUHeader1			217 166 191	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_71
72	Zsrq	"Swift Run Formation, quartzite"	"Swift Run Formation, quartzite"	Late Proterozoic	"Very light gray, thin-bedded, laminated and cross-laminated sericitic quartzite that weathers light greenish gray to light-gray; and medium light gray, thick-bedded, coarse-grained, laminated quartzite, weathering light-gray. Locally, a white to very light gray, graded, fine- to coarse-grained, friable feldspathic sandstone that weathers yellowish-gray and grayish-orange. Estimated thickness ranges from 0 to 90 feet (0 to 27 m)."	03-01-01-06-02	DMUHeader1			236 206 218	no pattern	DS1	Quartzite	High	DMU_72
73	Ygl	"Basement gneiss complex, leucocratic gneiss"	"Basement gneiss complex, leucocratic gneiss"	Middle Proterozoic	"Fine- to medium-grained, tan to very light gray, massive, finely banded to indistinctly foliated chlorite-quartz-microcline-plagioclase gneiss. Very light gray to yellowish-gray granitic rock weathers very pale orange, grayish-pink, and grayish-orange to pale brown."	03-01-01-07-01	DMUHeader1			161 189 138	no pattern	DS1	"Medium and high-grade regional metamorphic rock, of unspecified origin"	High	DMU_73
74	Ygt	"Basement gneiss complex, garnet gneiss"	"Basement gneiss complex, garnet gneiss"	Middle Proterozoic	"Fine- to medium-grained, very light gray, finely banded to indistinctly foliated quartz-microcline-plagioclase gneiss. Similar to leucocratic gneiss, but with scattered garnets. Weathers light-gray to yellowish."	03-01-01-07-02	DMUHeader1			199 215 158	no pattern	DS1	"Schist and gneiss, of sedimentary-rock origin"	High	DMU_74
75	Ygb	"Basement gneiss complex, biotite gneiss"	"Basement gneiss complex, biotite gneiss"	Middle Proterozoic	"Fine- to medium-grained, very light gray to yellowish-gray granitic rock that weathers very pale orange, grayish-pink, and grayish-orange to pale brown. Usually massive, but a faint foliation is commonly discernible. Quartz occurs in prominent grayish-blue grains. Biotite, the principal varietal mineral, is brownish-black to greenish-black. In places, the gneiss is interlayered with thin, irregular bands or zones of biotite schist."	03-01-01-07-03	DMUHeader1			179 204 128	no pattern	DS1	"Fine-grained, felsic-composition intrusive igneous rock"	High	DMU_75
76	Ygh	"Basement gneiss complex, hornblende gneiss"	"Basement gneiss complex, hornblende gneiss"	Middle Proterozoic	"Medium-grained, granular, massive or poorly foliated biotite-hornblende-plagioclase gneiss that weathers light olive gray, pale olive, or greenish-gray. May contain prominent greenish-black hornblende porphyroblasts 5 to 10 mm long. Hornblende, grayish-black biotite, and dusky green to dusky yellow green chlorite contrast with very light gray to light greenish gray plagioclase feldspar."	03-01-01-07-04	DMUHeader1			204 204 153	no pattern	DS1	"Medium and high-grade regional metamorphic rock, of unspecified origin"	High	DMU_76
77	Ygp	"Basement gneiss complex, paragneiss"	"Basement gneiss complex, paragneiss"	Middle Proterozoic	"Fine- to medium-grained, tan to rusty red, highly foliated micaceous-quartz-garnet paragneiss to schist. Weathers to a yellowish-brown or very pale orange, schistose rock."	03-01-01-07-05	DMUHeader1			204 235 153	no pattern	DS1	"Medium and high-grade regional metamorphic rock, of unspecified origin"	High	DMU_77
78	Jd	Jurassic Dikes	Jurassic Dikes	Jurassic	"Medium- to dark-gray, medium- to fine-grained diabase, weathering to rusty orange-brown spheroidal boulders and cobbles. Diabase dike(s) range in thickness from 3 to 15 feet (1 to 5 m)."	04-01-01-01	DMUHeader1			255 77 0	no pattern	DS1	"Fine-grained, intermediate-composition intrusive igneous rock"	High	DMU_78
79	JTrtm	Thermally metamorphosed rocks	Thermally metamorphosed rocks	Triassic	"Medium- to olive-gray, hard, brittle, and fractured hornfels and meta-arkose, adjacent to diabase intrusions. Includes dark-gray to olive-black hornfels in contact metamorphic zones that are a few feet wide adjacent to narrow dikes but may be hundreds of feet thick adjacent to thick sills."	04-01-01-02	DMUHeader1			140 167 189	no pattern	DS1	Contact-metamorphic rock	High	DMU_79
80	Trg	Gettysburg Formation	Gettysburg Formation	Triassic	"Reddish-brown to reddish-gray, locally greenish-gray, medium-grained siltstone, claystone, mudstone, and fine-grained sandstone. Sandstone beds exhibit sharp bases, shale pebble-lag conglomerates, and fining upward character. Claystone intervals are thoroughly root-mottled and contain light-gray caliche nodules. Thickness is estimated at up to 8000 feet (2440 m)."	04-02-01-01	DMUHeader1			158 209 209	no pattern	DS1	Clastic sedimentary rock	High	DMU_80
81	Trgc	"Gettysburg Formation, conglomerate"	"Gettysburg Formation, conglomerate"	Triassic	"Limestone conglomerate marks the western edge of the Gettysburg Basin in Maryland and is similar in appearance and position to the Leesburg Formation in the Culpeper Basin. Thickness is in question, but may be as much as 2438 m (8000 feet)."	04-02-01-01-01	DMUHeader1			194 232 232	no pattern	DS1	Conglomerate	High	DMU_81
82	Trgh	Heidlersburg Member	"Gettysburg Formation, Heidlersburg Member"	Triassic	"Interbedded gray calcareous siltstone and shale; laminated, mudcracked, and brecciated limestone; and dark grayish brown to reddish-brown siltstone and shale. Bedding is defined by cycles of gray siltstone and shale grading upward into gray, laminated limestone followed by reddish siltstone. The Heidlersburg Member is 400 to 500 feet thick in the Maryland part of Emmitsburg Quadrangle."	04-02-01-01-02	DMUHeader1			27 183 222	no pattern	DS1	Mostly mudstone	High	DMU_82
83	Trn	New Oxford Formation	New Oxford Formation	Triassic	"Brownish-red to dark reddish brown, argillaceous to silty sandstone and micaceous siltstone with subordinate interbedded silty shale and mudstone. Some reddish-gray to gray arkosic sandstone also occurs. Claystone intervals are thoroughly root-mottled and contain light-gray caliche nodules. Throughout the region, the siltstone-shale-arkose unit overlies a basal quartz-pebble conglomerate. The formation may be as thick as 10,000 feet (3048 m)."	04-02-01-02	DMUHeader1			153 245 240	no pattern	DS1	Sandstone and mudstone	High	DMU_83
84	Trns	"New Oxford Formation, sandstone"	"New Oxford Formation, sandstone"	Triassic	"Interbedded, light reddish gray to reddish-brown sandstone. Sandstones exhibit sharp bases with shale-pebble lag conglomerates, and fining upward character."	04-02-01-02-01	DMUHeader1			128 235 224	no pattern	DS1	Sandstone	High	DMU_84
85	Trni	Irishtown Member	"New Oxford Formation, Irishtown Member"	Triassic	"Light reddish gray, subangular to subrounded, quartz and limestone conglomerate. Clasts are predominately gray limestone, tan dolostone, or quartz pebbles with a matrix of reddish-brown, calcareous mudstone. Poorly exposed, and thickness is in question (Brezinski, 2004)."	04-02-01-02-02	DMUHeader1			102 207 204	no pattern	DS1	Conglomerate	High	DMU_85
86	Trl	Leesburg Formation	Leesburg Formation	Triassic	"Light-gray to light reddish gray, very thickly bedded, boulder conglomerate. Clasts are mainly subangular to subrounded limestone and dolostone of Cambrian and Ordovician age, but locally Triassic age siltstone and sandstone are prevalent. Thickness ranges from 100 to 3000 feet (30 to 910 m)."	04-02-02-01	DMUHeader1			102 191 204	no pattern	DS1	Conglomerate	High	DMU_86
87	Trb	Balls Bluff Siltstone	Balls Bluff Siltstone	Triassic	"Brownish-red to reddish-brown, argillaceous, massive siltstone with thin fine-grained sandstone interbeds. Thickness is estimated at 200 to 4500 feet (61 to 1372 m)."	04-02-02-02	DMUHeader1			140 217 230	no pattern	DS1	Sandstone and mudstone	High	DMU_87
88	Trmp	Poolesville Member	"Manassas Formation, Poolesville Member"	Triassic	"Reddish-brown to reddish-gray, locally greenish-gray, medium-grained sandstone and reddish, variegated claystone. Sandstone beds exhibit sharp, convex-down bases, shale-pebble lag conglomerates, and fining-upward character. Claystone intervals are thoroughly root mottled and contain light-gray caliche carbonate nodules. The thickness of this member is estimated at 500 to 3000 feet (152 to 914 m)."	04-02-02-03-01	DMUHeader1			166 204 230	no pattern	DS1	Sandstone and mudstone	High	DMU_88
89	Trmps	"Poolesville Member, sandstone beds"	"Manassas Formation, Poolesville Member, sandstone beds"	Triassic	"Medium-grained sandstone beds exhibiting sharp, convex-down bases, shale-pebble lag conglomerates and fining upward character."	04-02-02-03-01-01	DMUHeader1			102 166 204	no pattern	DS1	Sandstone	High	DMU_89
90	Trmt	Tuscarora Creek Member	"Manassas Formation, Tuscarora Creek Member"	Triassic	"Light-gray to light reddish gray, subangular to subrounded, limestone and dolomite conglomerate. Clasts are predominately tan dolostone, but locally reddish siltstone, sandstone, and some limestone clasts are prevalent. Matrix is a reddish-brown calcareous mudstone to reddish clayey carbonate. Thickness ranges from a feather edge to 100 feet (30 m)."	04-02-02-03-02	DMUHeader1			189 219 235	no pattern	DS1	Carbonate rock	High	DMU_90
91	Ogw	Woodsboro Member	"Grove Formation, Woodsboro Member"	Ordovician	"Thin-bedded, dark-gray, fine-grained limestone interbedded with medium-bedded, bioturbated, dark-gray, fine-grained limestone, and thin, wavy bedded limestone with tan, dolomitic partings. Top of Woodsboro Member not exposed because it is covered by the Triassic New Oxford Formation. Thickness is 500 feet (152 m)."	04-02-03-01-01	DMUHeader1			255 204 255	no pattern	DS1	Limestone	High	DMU_91
92	Ogf	Fountain Rock Member	"Grove Formation, Fountain Rock Member"	Ordovician	"Very thickly bedded, medium light gray, locally sandy, thrombolitic and stromatolitic algal limestone and medium-gray, laminated dolomitic limestone and olive-gray dolomite. Thickness is in question, but may range from 1000 to 3300 feet (305 m to 1006 m) in central Frederick County."	04-02-03-01-02	DMUHeader1			255 179 255	no pattern	DS1	Limestone	High	DMU_92
93	Ogfs	"Fountain Rock Member, sandstone"	"Grove Formation, Fountain Rock Member, sandstone"	Ordovician	Two cross-bedded sandstone units recognized in the middle of the formation were identified and traced.	04-02-03-01-02-01	DMUHeader1			255 153 255	no pattern	DS1	Sandstone	High	DMU_93
94	Ogc	Ceresville Member	"Grove Formation, Ceresville Member"	Ordovician	"Medium light gray to medium-gray, thick-bedded and cross-bedded, arenaceous limestone and sandy, dolomitic limestone with thin interbeds (1 ft or 0.3 m) of medium light gray, sandy, thrombolitic dolomite. Thickness is approximately 150 to 200 feet (46 to 61 m)."	04-02-03-01-03	DMUHeader1			255 128 255	no pattern	DS1	Limestone	High	DMU_94
95	Cfu	"Frederick Formation, undivided"	"Frederick Formation, undivided"	Cambrian	"Medium- to dark-gray, thin- to medium-bedded, pyritic, argillaceous limestone and shaly limestone. Contains intervals of tan-weathering dolomitic shale and sandy brecciated limestone. In the Emmitsburg Quadrangle, the Frederick Formation is highly sheared and highly deformed. Thickness in the Emmitsburg Quadrangle is estimated at 500 to 1000 feet (50 to 305 m)."	04-02-03-02	DMUHeader1			255 145 114	no pattern	DS1	Limestone	High	DMU_95
96	Cfa	Adamstown Member	"Frederick Formation, Adamstown Member"	Cambrian	"Thinly interbedded, medium dark gray to dark-gray, argillaceous, fine-grained limestone and dusky yellow to medium dark gray, silty dolomite. Limestone beds range from 0.1 to 2.0 inches (0.3 to 5.1 cm) in thickness. Several thin (6.0 to 30 feet or 1.8 to 9.1 m), dark greenish gray to greenish-black, light olive brown weathering, silty, calcareous shale intervals are present throughout the member. The top of the member is mapped at the base of the lowest medium to thick bed of sandy or algal limestone. Thickness is approximated at 1000 feet (305 m)."	04-02-03-02-02	DMUHeader1			255 204 204	no pattern	DS1	Limestone	High	DMU_96
97	Cfl	Lime Kiln Member	"Frederick Formation, Lime Kiln Member"	Cambrian	"Interbedded, thinly laminated to thinly bedded, dark-gray, fine-grained limestone, calcareous shale, and medium-bedded, fine-grained limestone near the base, becoming more thickly interbedded toward the top with medium dark gray, fine-grained limestone with wavy bedding and stromatolitic algal beds. Near the top, the member becomes interbedded with cross-bedded, sandy, medium light gray limestone. Thickness is 700 feet (213 m)."	04-02-03-02-01	DMUHeader1			240 153 166	no pattern	DS1	Limestone	High	DMU_97
98	Cfr	Rocky Springs Station Member	"Frederick Formation, Rocky Springs Station Member"	Cambrian	"Interbedded dark-gray, thinly bedded, lime mudstone and black dolomitic shale, massive, medium-gray polymictic breccias, medium-gray sandy limestone, and dark-gray, flaggy lime mudstone. Top of the member is mapped at the top of the stratigraphically highest polymictic breccia or sandstone interval. Thickness is approximated at 1200 feet (425 m) on the eastern flank, but is likely much thicker on the western flank."	04-02-03-02-03	DMUHeader1			255 166 140	no pattern	DS1	Clastic sedimentary rock	High	DMU_98
99	Cfrb	"Rocky Springs Station Member, breccia"	"Frederick Formation, Rocky Springs Station Member, breccia"	Cambrian	"Massive, medium-gray, polymictic breccias on the western flank of the synclinorium but are not evident on the east flank."	04-02-03-02-03-01	DMUHeader1			255 120 120	no pattern	DS1	Clastic sedimentary rock	High	DMU_99
100	Cfm	Monocacy Member	"Frederick Formation, Monocacy Member"	Cambrian	"Thickly interbedded, black, platy shale, rubbly, dolomitic breccia, laminated lime mudstone, and black shale. A laterally continuous black shale marks the top of the member. Thickness of this member is approximately 200 feet (61 m)."	04-02-03-02-04-02	DMUHeader1			255 143 133	no pattern	DS1	Clastic sedimentary rock	High	DMU_100
101	Cfms	"Monocacy Member, shale bed"	"Frederick Formation, Monocacy Member, shale bed"	Cambrian	Black shale that marks the top of the Monocacy Member and is more than 50 feet (15 m) thick.	04-02-03-02-04-01	DMUHeader1			255 179 128	no pattern	DS1	Clastic sedimentary rock	High	DMU_101
102	Car	Araby Formation	Araby Formation	Cambrian	"Thickly bedded, greenish-black to grayish-black, very fine grained to fine-grained, burrow-mottled silty sandstone, interbedded with medium-gray to grayish-black, phyllitic shales 1 to 3 m thick. Top of the formation consists of grayish-black phyllitic shale 50 to 66 feet (15 to 20 m) thick. The Araby Formation is present on the eastern side of the Frederick Valley synclinorium. Thickness of the Araby Formation is estimated at 300 feet (100 m)."	04-02-03-03	DMUHeader1			255 166 184	no pattern	DS1	Sandstone	High	DMU_102
103	CZi	Ijamsville Phyllite	Ijamsville Phyllite	Late Proterozoic? Cambrian?	"Dusky blue, grayish-blue, very dusky red-purple, greenish-gray to pale olive phyllite, phyllonite, and minor slate. Phyllite contains mostly muscovite and chlorite. Lustrous sheen from mica and dark color results from abundant hematite dust."	04-03-02-03	DMUHeader1			235 173 194	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_103
104	CZiq	"Ijamsville Phyllite, quartzite"	"Ijamsville Phyllite, quartzite"	Late Proterozoic? Cambrian?	"Yellowish-gray, fine- to medium-grained, sericitic quartzite locally intervenes between phyllite and metabasalt."	04-03-02-03-01	DMUHeader1			191 128 128	no pattern	DS1	Quartzite	High	DMU_104
105	CZib	"Ijamsville Phyllite, metabasalt"	"Ijamsville Phyllite, metabasalt"	Late Proterozoic? Cambrian?	"Dark-green and schistose metabasalt composed of chlorite, epidote, and quartz. Rare pillows locally preserved. Mapped as thin unit east of Martic thrust fault contact with Urbana Formation; one small body mapped in fault slice near confluence of Potomac and Monocacy Rivers (Southworth et. al., 2008)."	04-03-02-03-02	DMUHeader1			189 190 129	no pattern	DS1	Meta-mafic rock	High	DMU_105
106	CZic	"Ijamsville Phyllite, conglomeratic metagraywacke"	"Ijamsville Phyllite, conglomeratic metagraywacke"	Late Proterozoic? Cambrian?	"Light-gray and green, medium- to coarse-grained metagraywacke with white quartz pebbles, variegated phyllite, and green chloritic matrix."	04-03-02-03-03	DMUHeader1			217 140 166	no pattern	DS1	Metasedimentary rock	High	DMU_106
107	CZil	"Ijamsville Phyllite, metalimestone"	"Ijamsville Phyllite, metalimestone"	Late Proterozoic? Cambrian?	"Light bluish gray to medium light gray, thin-bedded, laminated, carbonaceous and argillaceous metalimestone; and minor, medium dark gray, finely laminated, carbonaceous phyllite. Thin unit mapped from confluence of Potomac and Monocacy Rivers for about 5 km to the southeast. Small body located above flood plain of Linganore Creek, east of Frederick, Md."	04-03-02-03-04	DMUHeader1			151 127 102	no pattern	DS1	Meta-carbonate rock	High	DMU_107
108	CZim	"Ijamsville Phyllite, marble"	"Ijamsville Phyllite, marble"	Late Proterozoic? Cambrian?	"Light olive gray, sandy limestone and dusky red, calcareous quartzite occurs within phyllite locally."	04-03-02-03-05	DMUHeader1			204 140 179	no pattern	DS1	Limestone	High	DMU_108
109	CZip	Ijamsville Chlorite Phyllite	Ijamsville Chlorite Phyllite	Late Proterozoic? Cambrian?	"Light olive gray and greenish-gray, chlorite phyllite and metasiltstone."	04-03-02-03-06	DMUHeader1			209 153 163	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_109
110	CZmb	Marburg Formation	Marburg Formation	Late Proterozoic? Cambrian?	"Buff to light olive green quartz-muscovite phyllite with subordinate silvery gray quartz-paragonite-muscovite-chlorite phyllite and muscovite-quartz phyllite. Contains abundant limonite cubes, up to 2 cm across, that are pseudomorphs after pyrite. Hematite and tourmaline are common accessory minerals. Very poorly exposed; weathers easily into thick, resistant saprolite containing abundant chips of phyllite. Underlies broad, gently sloping hills. Corresponds to select parts of the Ijamsville muscovite phyllite of Fisher (1978)."	04-03-02-04	DMUHeader1			191 153 179	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_110
111	CZmbq	"Marburg Formation, quartzite"	"Marburg Formation, quartzite"	Late Proterozoic? Cambrian?	Tan to reddish quartzite. Beds of quartzite 15 to 60 cm thick (6 to 24 inches) interbedded with muscovite and chlorite phyllites. Very resistant to weathering. Corresponds to the parts of the Ijamsville quartzite of Fisher (1978) that are associated with phyllite now included in the Marburg Formation.	04-03-02-04-01	DMUHeader1			149 152 128	no pattern	DS1	Quartzite	High	DMU_111
112	CZscb	"Sams Creek Formation, metabasalt"	"Sams Creek Formation, metabasalt"	Late Proterozoic? Cambrian?	"Dark greenish gray to medium bluish gray, aphanitic to porphyritic, massive to schistose metabasalt composed of chlorite, epidote, quartz, altered plagioclase, actinolite, hornblende, and albite; igneous texture is locally preserved and pods of epidosite are common; includes some metaconglomerate composed of greenstone pebbles and cobbles, local pillow structures, and hyaloclastite."	04-03-02-02-01	DMUHeader1			151 182 221	no pattern	DS1	Meta-mafic rock	High	DMU_112
113	CZschp	"Sams Creek Formation, hematite phyllite"	"Sams Creek Formation, hematite phyllite"	Late Proterozoic? Cambrian?	"Bluish-purple, hematite-rich phyllite, resembles Ijamsville Phyllite (Southworth et. al, 2008)."	04-03-02-02-02	DMUHeader1			162 178 196	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_113
115	CZscm	"Sams Creek Formation, marble"	"Sams Creek Formation, marble"	Late Proterozoic? Cambrian?	"Brownish-gray to grayish reddish purple, massive to thin-bedded, calcitic and dolomitic marble containing quartz sand. Includes minor calcareous metasiltstone."	04-03-02-02-04	DMUHeader1			120 136 197	no pattern	DS1	Meta-carbonate rock	High	DMU_115
116	CZscmp	Sams Creek Muscovite Phyllite	Sams Creek Muscovite Phyllite	Late Proterozoic? Cambrian?	"Light bluish gray, dusky yellow, and moderate orange pink, muscovite-chlorite phyllite containing albite porphyroblasts, quartz, and hematite dust. Contains minor metasiltstone. Lithologically distinct from rocks of the Ijamsville Phyllite and Marburg Formation."	04-03-02-02-05	DMUHeader1			208 205 207	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_116
117	CZscq	"Sams Creek Formation, quartzite"	"Sams Creek Formation, quartzite"	Late Proterozoic? Cambrian?	"Light-gray to grayish-green, medium-grained, thin-bedded to massive quartzite and minor calcareous sandstone. Contains detrital plagioclase, orthoclase, and polymictic quartz. Bedding is defined by concentrations of heavy minerals. Light-gray, medium- and coarse-grained quartzite, locally calcareous and cross-bedded also present."	04-03-02-02-06	DMUHeader1			162 119 169	no pattern	DS1	Quartzite	High	DMU_117
118	CZscqp	"Sams Creek Formation, quartzite within phyllite subunit"	"Sams Creek Formation, quartzite within phyllite subunit"	Late Proterozoic? Cambrian?	Light-tan to light grayish green to light silvery gray. The micas and chlorite are typically segregated into prominent pinstripe laminations spaced 0.4 to 1.2 inches (1 to 3 cm) apart and parallel to cleavage. Resistant to weathering; crops out extensively and commonly forms low ridges capped by a thin sandy soil. Corresponds to the Ijamsville mica-chlorite-quartz phyllite of Fisher (1978) and to the Gillis Formation of Edwards (1986).	04-03-02-02-07	DMUHeader1			167 145 187	no pattern	DS1	Metasedimentary rock	High	DMU_118
119	CZscs	"Sams Creek Formation, metasiltstone"	"Sams Creek Formation, metasiltstone"	Late Proterozoic? Cambrian?	"Metasiltstone, phyllite, quartzite, and metagraywacke, undifferentiated. Light-brown metasiltstone interbedded with quartzite and calcareous metasandstone. Bedding can be recognized except where transposed in shear zones adjacent to faults. Muscovite phyllite containing albite porphyroblasts and elongate blebs of chlorite is interpreted to be a metatuff."	04-03-02-02-08	DMUHeader1			141 130 159	no pattern	DS1	Metasedimentary rock	High	DMU_119
120	CZscsr	Silver Run Limestone Member	"Sams Creek Group, Silver Run Limestone Member"	Late Proterozoic? Cambrian?	"Medium to dark bluish gray, fine-grained, thin-bedded to laminated, siliceous to argillaceous or micaceous limestone, interbedded with minor amounts of black to silvery gray phyllite. Bedding ranges from 1/4 inch to 4 inches (0.5 to 10 cm) in thickness and exposures exhibit tight internal folding and strong penetrative cleavage. Thickness of unit is estimated to range between 10 to 100 feet (3 and 30 meters)."	04-03-02-02-09	DMUHeader1			217 217 217	no pattern	DS1	Limestone	High	DMU_120
121	CZsctp	"Sams Creek Formation, tuffaceous phyllite"	"Sams Creek Formation, tuffaceous phyllite"	Late Proterozoic? Cambrian?	"Grayish red-purple and bluish-gray, variegated, vesicular phyllite with light-gray streaks and blebs of tuffaceous phyllite."	04-03-02-02-10	DMUHeader1			209 219 244	no pattern	DS1	"Slate and phyllite, of sedimentary-rock origin"	High	DMU_121
122	CZwm	Wakefield Marble	Wakefield Marble	Late Proterozoic? Cambrian?	"Predominately white to gray, massive to banded or bedded crystalline marble, but also contains dark-gray, bluish-gray, pale green, and purple marble and interbeds of green and purple phyllite. Some zones or layers of the marble are made up primarily of calcite, whereas others are primarily of dolomite. Zones of complex internal folding, boudinaged layers, and purple brecciated zones occur through the unit. Thickness is estimated to range between 3 to 500 feet (1 to 150 meters)."	04-03-02-01	DMUHeader1			199 207 237	no pattern	DS21	Meta-carbonate rock	High	DMU_122
123	Cu	Urbana Formation	Urbana Formation	Cambrian	"Predominately moderate olive brown to light olive gray, calcareous metagraywacke and metasiltstone. Poorly sorted, graded, cross-bedded, and ripple marked. Contains light olive gray and light brownish gray very calcareous metasandstone and quartzite. Fine- to coarse-grained, thin- to medium-bedded, crossbedded, pitted, friable, lensoidal and discontinuous. Interbedded with light-brown, laminated metasiltstone. Also contains light-gray to greenish-gray, thin-bedded, crystalline marble. Laminated beds of indeterminate thickness are marked by seams of sericite and chlorite. Poorly exposed; produces distinctive reddish-orange soil."	04-03-01-01	DMUHeader1			255 191 191	no pattern	DS1	Metasedimentary rock	High	DMU_123
124	Cuq	"Urbana Formation, quartzite"	"Urbana Formation, quartzite"	Cambrian	"Light olive gray and light brownish gray, coarse-grained, thin- to medium-bedded, cross-bedded, pitted, vuggy, friable, lensoidal, and discontinuous quartzite."	04-03-01-01-01	DMUHeader1			255 166 166	no pattern	DS1	Quartzite	High	DMU_124
125	Csq	Sugarloaf Mountain Quartzite	Sugarloaf Mountain Quartzite	Cambrian	"Pinkish-gray to white, fine-to medium-grained granular quartzite. Medium-bedded to massive, well-sorted, graded, crossbedded and ripple marked. Quartzite, interbedded with seldom-exposed moderate-brown quartzose metasiltstone and dusky blue laminated metasiltstone similar to that of the conformably overlying Urbana Formation, underlies topographic swales. Lower, middle, and upper members (informal) are not separately mapped based on topographic expression of ridge-forming units since the quartzites are virtually identical; total thickness is approximately 2000 feet (600 m)."	04-03-01-02	DMUHeader1			255 184 209	no pattern	DS1	Quartzite	High	DMU_125
127	CZscl	"Sams Creek Formation, metalimestone"	"Sams Creek Formation, metalimestone"	Late Proterozoic? Cambrian?	"Light-gray, thinly layered, argillaceous metalimestone (Southworth et. al, 2008)."	04-03-02-02-03	DMUHeader1			144 153 177	no pattern	DS4	Meta-carbonate rock	High	DMU_127