OBJECTID,MapUnit,Name,FullName,Age,Description,HierarchyKey,ParagraphStyle,Label,Symbol,AreaFillRGB,AreaFillPatternDescription,DescriptionSourceID,GeoMaterial,GeoMaterialConfidence,DescriptionOfMapUnits_ID
1,Qal,Alluvium,Alluvium,Quaternary,"Poorly sorted, unconsolidated, tan, reddish-brown, to dark-gray mud, silt, sand, and pebbles. These deposits form in stream channels, and on the flood plain adjacent to the streams. Thickness estimated at 3 to 10 feet (1 to 3 m).",1-1,DMUHeader1,,,,no pattern,DS1,Alluvial sediment,High,DMU1
2,Qr,Residuum,Residuum,Quaternary,"Mixture of moderate reddish brown soil and pebbles to blocks of grayish pink to white angular, locally euhedral, quartz. Thickness ranges from a thin veneer to 10 feet.",1-2,DMUHeader1,,,,no pattern,DS1,Residual material,High,DMU2
3,Qc,Colluvium,Colluvium,Quaternary,"Unconsolidated and unsorted sand, cobbles, and boulders that accumulate on the slopes below outcrops of the sandstone and quartzite units, and move slowly downslope under the influence of gravity. Three types were recognized in the Myersville and Smithsburg quadrangles. The first type is composed predominately of angular boulders that overlie outcroppings of quartzites of the Weverton Formation on the flanks of the South Mountain. This type of colluvium appears to be the direct result of the mechanical breakdown of the quartzite ledges. The thickness was not determined. The second type of collusium is composed of reddish brown, rounded pebbles and cobbles of sandstone, quartzite, and vein quartz. This type of colluvium is present both at the western base of South Mountain, and as isolated patches overlying limestone bedrock of the Hagerstown Valley. The latter is far removed from the slopes of South Mountain and tends to be much more heavily weathered. The thickness of this type of colluvium ranges from a thin veneer less than 3 feet to more than 300 feet (1 to 100 m). A third type of colluvium is found on steep slopes and valleys underlain by the Catoctin Formation. This colluvium consists of large angular boulders of metabasalt or metarhyolite that have been created by frost action and have moved down steeper slopes and have come to rest in adjacent valley floors. The thickness of this colluvium is typically less than 10 feet (3 m).",1-3,DMUHeader1,,,,no pattern,DS1,Colluvium and other widespread mass-movement sediment,High,DMU3
5,,Conococheague Formation,Conococheague Formation,Cambrian,"Interbedded gray limestone and tan dolomite cycles. Bell (1993) mapped three members of the Conococheague Formation in the adjacent Hagerstown quadrangle. Only two of those members are exposed in the Myersville and Smithburg quadrangles. Total thickness ranges from 2,000 to 2,500 feet (600 to 750 m)",3,DMUHeader1,,,,,DS1,Carbonate rock,,DMU5
8,Ce,Elbrook Formation,Conococheague Formation - Elbrook Formation,Cambrian,"The Elbrook Formation can be subdivided into three informal subunits that are not mapped separately in the Myersville and Smithburg quadrangles. The lower 700 feet (210 m) of the formation is very poorly exposed and contains interbedded very light gray, thin-to thick-bedded limestone and tan platy dolomite, which frequently weather to shale chips. Intervals of medium-bedded, bioturbated, dark-gray limestones are also present. The middle part of the formation contrains dark-gray limestone and dolomitic limestonen and is up to 200 feet (60 m) thick. The thickest part of the formation is the upper 1,400 feet (425 m) which consists of cyclically bedded, gray thrombolitic limestone and ribbony to laminated limestone and dolomite. Total formation thickness ranges from 2,200 to 2,500 feet (700 to 800 m).",3-3,DMUHeader1,,,255 112 141,no pattern,DS1,Carbonate rock,High,DMU8
9,,Waynesboro Formation,Waynesboro Formation,Cambrian,Interbedded and cyclically bedded carbonates and clastics. Divided into three members by Brezinski (1992). Total thickness approximately 100 feet (300 m) ???,4,DMUHeader1,,,,,DS1,Mostly carbonate rock,High,DMU9
10,Cwac,Chewsville Member,Waynesboro Formation - Chewsville Member,Cambrian,"The uppermost member of the Waynesboro Formation consists of reddish-gray to reddish-brown, silty shale, siltstone, and silty fine-grained sandstone, interbedded with white, calcareous, Skolithos-burrowed sandstone beds (2 to 6 cm thick), greenish-gray shale, and tan to buff fractured, medium-bedded, sandy dolostone. This unit usually is the most diagnostic of the Waynesboro lithologies and typically forms a well-defined topographic ridge, which makes it easily traceable. Thickness estimated at 90 to 125 feet (30 to 45 m).",4-1,DMUHeader2,,,255 135 205,no pattern,DS1,Sandstone and mudstone,High,DMU10
11,Cwak,Cavetown Member,Waynesboro Formation - Cavetown Member,Cambrian,"The middle member of the Waynesboro Formation consists of cycles of medium-to thick-bedded, medium-to coarse-grained, intraclastic grainstone and tan, laminated dolomite and dolomitic limestone interstratified with medium-gray, oolitic, lime grainstone, ribbony dolomitic limestone and laminated dolomitic carbonates. At the top and base of this member massive dolomitic limestone intervals, up to 45 feet (14 m) are present. Thickness is estimated at 600 to 750 feet (200 to 250 m).",4-2,DMUHeader2,,,255 88 181,no pattern,DS1,Mostly carbonate rock,High,DMU11
12,Cwar,Red Run Member,Waynesboro Formation - Red Run Member,Cambrian,"The basal member of the Waynesboro Formation is lithologically similar to the Chewsville Member. This member consists of interbedded, tan-weathering, punky, fine-grained, dolomitic sandstones; green-gray shale; gray sandy limestone; and laminated dolostone. Locally thin (0.25 to 2.0 inches; 0.6 to 5 cm) layers of red siltstone and sandstone are present. Thickness estimated at 150 to 225 feet (60 to 75 m).",4-3,DMUHeader2,,,255 62 119,no pattern,DS1,Mostly carbonate rock,High,DMU12
13,,Tomstown Formation,Tomstown Formation,Cambrian,"Predominately buff-weathering, medium-to dark-gray, dolomite, dolomitic limestone, and limestone. The Tomstown Formation is divided into four members (Brezinski, 1992). In previous mapping of the Smithsburg quadrangle (Brezinski, 1993) the formation was not subdivided, however, in the current map, the members are mapped separately. The total thickness of the formation is 1,200 to 1,300 feet (366 to 396 m).",5,DMUHeader1,,,,,DS1,Carbonate rock,,DMU13
14,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).",5-1,DMUHeader2,,,255 181 141,no pattern,DS1,Carbonate rock,High,DMU14
15,Ctb,Benevola Member,Tomstown Formation - Benevola Member,Cambrian,"Light-gray to white, massive, hightly fractured, sugary dolomite. The Benevola Member varies from white to very light gray, both on fresh and weathered surfaces. It is very chemically pure, containing very little silica or clays. Bedding is rarely evident and is largely confined to the uppermost 30 feet (9 m). In fresh surfaces and within polished slabs faint ghosts of cross-bedding are evident. Thickness is 100 to 150 feet (33 to 50 m).",5-2,DMUHeader2,,,240 118 141,no pattern,DS1,Dolomite,High,DMU15
16,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 anastamosing 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). The white, void-filling dolomite contrasts the darker mottled dolomite. Thickness ranges from 200 to 250 feet (60 to 75 m).",5-3,DMUHeader2,,,202 54 76,no pattern,DS1,Dolomite,High,DMU16
17,Ctbh,Bolivar Heights Member,Tomstown Formation - Bolivar Heights Member,Cambrian,"The Bolivar Heights consists of about 200 feet (60 m) of thin-to medium-bedded, dark-gray, ribbony, burrow-mottled, lime mudstone nthat 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. The Keedysville marble bed is present near the base of the member. Thickness is 200 to 250 feet (60 to 75 m).",5-4,DMUHeader2,,,255 160 120,no pattern,DS1,Mostly carbonate rock,High,DMU17
18,,Chilhowee Group,Chilhowee Group,Cambrian,,6,DMUHeader3,,,,,DS1,,,DMU18
19,Ca,Antietam Formation,Chilhowee Group - Antietam Formation,Cambrian,"The lower part of the formation is greenish-gray, highly cleaved, silty, 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 consists of light-to medium-gray, crossbedded, vuggy, coarse-grained granular sandstone to conglomerate. Thickness ranges from 500 to 800 feet (150 to 245 m).",6-1,DMUHeader1,,,231 95 120,no pattern,DS1,Sedimentary rock,High,DMU19
20,Ch,Harpers Formation,Chilhowee Group - Harpers Formation,Cambrian,"Predominately dark-greenish-gray, highly cleaved, phyllitic shale and siltstone with lesser amounts of metasandstones that may be quartzitic, locally. Shale and siltstone are dark-green-gray, dark-brown-gray to medium-gray in color and commonly containing thin 2-to 6-inch, fine-grained sandstone layers. The greenish-gray intervals weathers tan to light gray. Cleavage typically obscures bedding. Mappable metasandstone intervals [Chm] are up to 30 feet (9 m) thick and contain Skolithos burrows. In the Smithburg quadrangle these metasandstone layers may be southern extensions of the Mont Alto Member of the Harpers Formation in southern Pennsylvania. Owing to intense intraformational folding, determining the thickness of the formation was impossible. Estimates range from 1,500 to 3,00 feet (450 to 1,000 m).",6-2,DMUHeader1,,,247 196 222,no pattern,DS1,Sedimentary rock,High,DMU20
21,,Weverton Formation,Weverton Formation,Cambrian,"Primarily light-gray to gray quartzite, conglomerate, and medium-to dark-gray metagraywacke with intervals of dark-gray to black phyllite. Three members are recognized and mapped in the Myersville and Smithsburg quadrangles (Brezinski, 1992).",6-3,DMUHeader1,,,,,DS1,Sedimentary rock,,DMU21
22,Cwo,Owens Creek Member,Weverton Formation - Owens Creek Member,Cambrian,"Dark-gray to very dark gray, very coarse grained to conglomeratic, crossbedded metagraywacke. Commonly crossbedded, but the very coarse grained nature 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).",6-3-1,DMUHeader2,,,200 87 83,no pattern,DS1,Metasedimentary rock,High,DMU22
23,Cwm,Maryland Heights Member,Weverton Formation - Maryland Heights Member,Cambrian,"Interbedded, thin (less than 30 feet; 9 m), medium-to dark-gray quartzite and metagraywacke and 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).",6-3-2,DMUHeader2,,,255 222 209,no pattern,DS1,Metasedimentary rock,High,DMU23
24,Cwb,Buzzard Knob Member,Weverton Formation - Buzzard Knob Member,Cambrian,"The lowest member of the formation consists of two ledge-forming quartzites, which are often difficult to discern between. The lower ledge consists of light-to medium-gray quartzite with dark-gray argillaceous layers up to 4 cm thick, separating the quartzite beds. Crossbedding within individual quartzite strata is pervasive and is commonly accentuated by purplish or yellow-gold bands demarcating the individual crossbed foresets. The upper ledge-forming quartzite is composed of medium-to thick-bedded, very light green-gray, shaly quartzite. Crossbedding is much less common than in the lower ledge. This member is the main ridge-forming unit of the Maryland Blue Ridge. Thickness ranges from 125 to 175 feet (40 to 50 m).",6-3-3,DMUHeader2,,,255 222 209,no pattern,DS1,Quartzite,High,DMU24
25,CZl,Loudoun Formation,Loudoun Formation,Cambrian or Late Proterozoic,"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 20 to 150 feet (6 to 45 m) in the Myersville and Smithsburg quadrangles.",6-4,DMUHeader1,,,237 156 153,no pattern,DS1,Sedimentary rock,High,DMU25
26,,Catoctin Formation,Catoctin Formation,Late Proterozoic,"The Catoctin Formation is a suite of volcanigenic rocks that consists principally of metabasalt, metarhyolite, and tuffaceaous phyllites. Although these major rock types are mappable lithologic units, their stratigraphic relationships are not known.",7-1,DMUHeader1,,,,,DS1,Metaigneous rock,,DMU26
27,Zcm,Massive metabasalt,Catoctin Formation - massive metabasalt,Late Proterozoic,"Characteristically a dark-green, dark-greenish-gray, or dark-bluish-green, medium-grained, metabasalt (Fauth, 1981). Textures vary greatly between exposures. Most commonly rock consists of massive to highly cleaved aphanitic metabasalt. Locally metabasalt is amygdaloidal, porphyoblastic, porphyritic, or banded. Porphyroclasts commonly are epidote, plagioclase feldspar, or chlorite. Amygdules are commonly oval-shaped vesicles filled with epidote. Porphyroblastic rock contains flattened and elongated grains or aggregates of chlorite, actinolite (?), or epidote, ranging between 10 and 25 mm (0.4 to 1 inch) in length. Primary layering is present in many exposures. Prominent veins and nodular masses of epidote and quartz are widely distributed throughout the unit. Thickness of the entire metabasalt unit is estimated at approximately 1,000 to 2,000 feet (300 to 700 m).",7-1-1,DMUHeader2,,,222 204 179,no pattern,DS1,Meta-mafic rock,High,DMU27
28,Zcrr,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).",7-1-2,DMUHeader2,,,195 120 89,no pattern,DS1,Meta-volcaniclastic rock,High,DMU28
29,,Blue to bluish-gray metarhyolite,Catoctin Formation - blue to bluish-gray metarhyolite,Late Proterozoic,"Blue to gray, aphanitic metarhyolite that weathers to medium-dark-gray to light-grayish-blue. Five separate units differentiated and mapped on the basis of texture. These metarhyolite subunits were identified as Units A through E by Fauth (1981) and are here identified (and coded) by textural name following the protocol on the adjacent quadrangle map (Brezinski and Fauth, 2005). Minimum aggregate thickness is estimated at 500 to 800 feet (150 to 240 m).",7-1-3,DMUHeader2,,,,,DS1,Meta-volcaniclastic rock,,DMU29
30,Zcr,"Blueish-gray metarhyolite, undifferentiated","Catoctin Formation - blue to bluish-gray metarhyolite - blueish-gray metarhyolite, undifferentiated",Late Proterozoic,Undifferentiated bluish-gray metarhyolite in which no single variety is dominant.,7-1-3-1,DMUHeader4,,,198 143 94,no pattern,DS1,Meta-volcaniclastic rock,High,DMU30
31,Zcrf,Flow-banded bluish-gray metarhyolite,Catoctin Formation - blue to bluish-gray metarhyolite - flow-banded blueish-gray 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.",7-1-3-2,DMUHeader4,,,185 122 80,no pattern,DS1,Meta-volcaniclastic rock,High,DMU31
32,Zcrp,Porphyritic bluish-gray metarhyolite,Catoctin Formation - blue to bluish-gray metarhyolite - porphyritic bluish-gray 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.",7-1-3-3,DMUHeader4,,,190 131 129,no pattern,DS1,Meta-volcaniclastic rock,High,DMU32
33,Zcra,Aphanitic metarhyolite,Catoctin Formation - blue to bluish-gray metarhyolite - aphanitic metarhyolite,Late Proterozoic,"Aphanitic, bluish-gray metarhyolite that is massive and dense, and exhibits a concoidal fracture. Rare phenocrysts, were present, comprise less than 1 percent of the rock. Weathers bone white to very light gray.",7-1-3-4,DMUHeader4,,,230 210 185,no pattern,DS1,Meta-volcaniclastic rock,High,DMU33
34,Zcrb,Metarhyolite breccia,Catoctin Formation - blue to bluish-gray metarhyolite - metarhyolite breccia,Late Proterozoic,"Dusky blue-gray, metarhyolite breccia with angular to subrounded clasts that weather to a lighter color than the felsic matrix.",7-1-3-5,DMUHeader4,,,123 74 46,no pattern,DS1,Meta-volcaniclastic rock,High,DMU34
35,Zcpl,Lavender phyllite,Catoctin Formation - lavender phyllite,Late Proterozoic,Pale purple to grayish red-purple or very light gray phyllite. Locally color mottled with red quartz grains and light gray to yellowish gray porphyoblasts of feldspar. Estimated thickness of 30 to 50 feet (9 to 15 m).,7-1-4,DMUHeader2,,,211 179 158,no pattern,DS1,"Lower-grade metamorphic rock, of unspecified origin",High,DMU35
36,Zcp1,"Phyllite, unit 1","Catoctin Formation - phyllite, unit 1",Late Proterozoic,Medium-light-gray to dark-gray phyllite with very light gray elongate feldspathic porphyoblasts. Locally exhibits fine banding or laminations which appear to be a shear fabric. This unit is equivalent to the gray phyllite (Zcpg) of Fauth (1981). Estimated thickness 50 to 100 feet (15 to 30 m).,7-1-5,DMUHeader2,,,143 111 67,no pattern,DS1,"Lower-grade metamorphic rock, of unspecified origin",High,DMU36