OBJECTID |
MapUnit |
Name |
FullName |
Age |
Description |
HierarchyKey |
ParagraphStyle |
Label |
Symbol |
AreaFillRGB |
AreaFillPatternDescription |
DescriptionSourceID |
GeoMaterial |
GeoMaterialConfidence |
_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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |