| 2.1 Has required elements: nonspatial tables DataSources, DescriptionOfMapUnits, GeoMaterialDict; feature dataset GeologicMap with feature classes ContactsAndFaults and MapUnitPolys | PASS |
| 2.2 Required fields within required elements are present and correctly defined | PASS |
| 2.3 All MapUnitPolys and ContactsAndFaults based feature classes obey Level 2 topology rules: no internal gaps or overlaps in MapUnitPolys, boundaries of MapUnitPolys are covered by ContactsAndFaults | PASS |
| 2.4 All map units in MapUnitPolys have entries in DescriptionOfMapUnits table | PASS |
| 2.5 No duplicate MapUnit values in DescriptionOfMapUnit table | PASS |
| 2.6 Certain field values within required elements have entries in Glossary table | PASS |
| 2.7 No duplicate Term values in Glossary table | PASS |
| 2.8 All xxxSourceID values in required elements have entries in DataSources table | PASS |
| 2.9 No duplicate DataSources_ID values in DataSources table | PASS |
| 3.1 Table and field definitions beyond Level 2 conform to GeMS schema | PASS |
| 3.2 All MapUnitPolys and ContactsAndFaults based feature classes obey Level 3 topology rules: No ContactsAndFaults overlaps, self-overlaps, or self-intersections. | PASS |
| 3.3 No missing required values | PASS |
| 3.4 No missing terms in Glossary | PASS |
| 3.5 No unnecessary terms in Glossary | PASS |
| 3.6 No missing sources in DataSources | PASS |
| 3.7 No unnecessary sources in DataSources | PASS |
| 3.8 No map units without entries in DescriptionOfMapUnits | PASS |
| 3.9 No unnecessary map units in DescriptionOfMapUnits | PASS |
| 3.10 HierarchyKey values in DescriptionOfMapUnits are unique and well formed | PASS |
| 3.11 All values of GeoMaterial are defined in GeoMaterialDict. GeoMaterialDict is as specified in the GeMS standard | PASS |
| 3.12 No duplicate _ID values | PASS |
| 3.13 No zero-length, whitespace-only, or bad null values | PASS |
| MapUnit | DescriptionOfMapUnits | GeologicMap |
|---|---|---|
| Csy | X | X |
| Dw | X | X |
| Og | X | X |
| CZmgb | X | X |
| Cc | X | X |
| Dg | X | X |
| CZlo | X | X |
| Qc | X | X |
| Sp | X | X |
| Yb | X | X |
| CZum | X | X |
| CZloma | X | X |
| CZmgbf | X | X |
| CZs | X | X |
| CZg | X | X |
| Csq | X | X |
| Qal | X | X |
| CZmg | X | X |
| OBJECTID | Source | Notes | URL | DataSources_ID |
|---|---|---|---|---|
| 6 | Neuendorf, et al., eds., 2011 | modified from Neuendorf, K.K.E., Mehl Jr., J.P., and Jackson, J.A., eds. 2011. Glossary of Geology (Fifth Edition, Revised). Alexandria, VA. American Geological Institute. 783 p. | https://www.americangeosciences.org/pubs/glossary | AGI_2011 |
| 7 | Aleinikoff, et al., 2002 | Aleinikoff, J.N., Horton, J.W., Drake, A.A., and Fanning, C.M., 2002, SHRIMP and conventional U-Pb ages of Ordovician granites and tonalites in the central Appalachian Piedmont: Implications for Paleozoic tectonic events: American Journal of Science, v. 302, no. 1, p. 50–75. | https://pubs.usgs.gov/publication/70209291 | AJI_2002_302.1.50 |
| 22 | Sinha, et al., 2012 | Sinha, A.K., Thomas, W.A., Hatcher, R.D., and Harrison, T.M., 2012, Geodynamic evolution of the central Appalachian orogen: Geochronology and compositional diversity of magmatism from Ordovician through Devonian: American Journal of Science, v. 312, no. 8, p. 907–966. | https://ajsonline.org/article/61809 | AJI_2012_312.8.907 |
| 17 | Martin and Bosbyshell, 2019 | Martin, A.J., and Bosbyshell, H, 2019, Further detrital zircon evidence for peri-Gondwanan blocks in the central Appalachian Piedmont Province, USA: Canadian Journal of Earth Sciences, v. 56, no. 10, p. 1061-1076. | https://cdnsciencepub.com/doi/10.1139/cjes-2018-0253 | CJS_2019_56.10.1061 |
| 21 | Sawyer, 2008 | Sawyer, E., 2008, Atlas of Migmatites: Canadian Science Publishing, v. 9, 371p. | https://cdnsciencepub.com/doi/book/10.1139/9780660197876 | CSP_2008_v9 |
| 5 | FGDC, 2006 | Federal Geographic Data Committee [prepared for the Federal Geographic Data Committee by the U.S. Geological Survey], 2006, FGDC Digital Cartographic Standard for Geologic Map Symbolization: Reston, Va., Federal Geographic Data Committee Document Number FGDC-STD-013-2006, 290 p., 2 plates. | https://ngmdb.usgs.gov/fgdc_gds/geolsymstd.php | FGDC-STD-013-2006 |
| 4 | definitions copied from GeMS, 2020 | U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020, GeMS (Geologic Map Schema)—A standard format for the digital publication of geologic maps: U.S. Geological Survey Techniques and Methods, book 11, chap. B10, 74 p., https://doi.org//10.3133/tm11B10. | https://pubs.usgs.gov/publication/tm11B10 | GeMS_2020 |
| 19 | Muth, et al., 1979 | Muth, K.G., Arth, J.G., and Reed, J.C., Jr., 1979, A minimum age for the high grade metamorphism and granite intrusion in the Piedmont of the Potomac River gorge near Washington, D.C.: Geology, v. 7, no. 7, p. 349-350. | https://pubs.geoscienceworld.org/gsa/geology/article-abstract/7/7/349/188229/A-minimum-age-for-high-grade-metamorphism-and?redirectedFrom=fulltext | GEOL_1979_7.7.349 |
| 16 | Martin, et al., 2015 | Martin, A.J., Southworth, C.S., Collins, J.C., Fisher, S.W., and Kingman, E.R., III, 2015, Laurentian and Amazonian sediment sources to Neoproterozoic–lower Paleozoic Maryland Piedmont rocks: Geosphere, v. 11, no. 4, p. 1042–1061. | https://pubs.geoscienceworld.org/gsa/geosphere/article/11/4/1042/132215/Laurentian-and-Amazonian-sediment-sources-to | GEOS_2015_11.4.1042 |
| 12 | Kearns, 2018 | Kearns, C.A., 2018. The Mineralogy and Mineral Chemistry of the Henryton Pegmatite, Patapsco State Park, Carroll County, Maryland. Doctoral dissertation, George Mason University, 266 p. | https://science.gmu.edu/media/ckearnspdf | GMU_DD_CAK_2018 |
| 25 | Wetherill, et al., 1966 | Wetherill, G., Tilton, G., Davis, G., Hart, S., and Hopson, C., 1966, Age measurements in the Maryland Piedmont: Journal of Geophysical Research, v. 71, no. 8, p. 2139–2155. | https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/JZ071i008p02139 | JGPR_1966_71.8.2139 |
| 13 | Jonas, A.I., 1928 | Jonas, A.I., 1928. Map of Carroll County showing the geological formations. Maryland Geological Survey, County Geologic Map, scale 1:62,500. | http://www.mgs.md.gov/publications/maps.html | MGS_CLGEO1928 |
| 24 | Singewald, 1946 | Singewald, Jr., J.T., 1946. Mineral Resources of Carroll and Frederick Counties. p. 132-162 in Physical Features of Carroll and Frederick Counties. Maryland Geological Survey County Report, 312 p. | http://www.mgs.md.gov/publications/report_pages/County_Reports.html | MGS_CR_CAFR1946_132 |
| 15 | Jonas and Stose, 1946 | Jonas, A.I., and Stose, G.W., 1946. Geology of Carroll and Frederick Counties, in Physical Features of Carroll and Frederick Counties: Maryland Geological Survey County Report, p. 11-138. | http://www.mgs.md.gov/publications/report_pages/County_Reports.html | MGS_CR_CLFR1946 |
| 3 | Brezinski, D.K., field observations | Brezinski, D.K., field data collection and interpretations | None | MGS_DKB |
| 18 | Muller, 1994 | Muller, P.D., 1994, Geologic map of the Finksburg Quadrangle, Carroll and Baltimore Counties: Maryland Geological Survey, scale 1:24,000. | http://www.mgs.md.gov/publications/maps.html | MGS_FINKS1994 |
| 14 | Jonas and Stose, 1938 | Jonas, A.I., and Stose, G.W., 1938a. Geologic map of Frederick County and adjacent parts of Washington and Carroll Counties: Maryland Geological Survey, scale 1:62,500. | https://ngmdb.usgs.gov/Prodesc/proddesc_90332.htm | MGS_FRWACL1938 |
| 9 | Cloos, et al., 1964 | Cloos, E., Fisher, G. W., Hopson, C. A., and Cleaves, E. T., 1964, The geology of Howard and Montgomery Counties: Maryland Geological Survey, 373p. | http://www.mgs.md.gov/publications/report_pages/County_Reports.html | MGS_HOWMO1964 |
| 23 | Singewald, 1928 | Singewald, Jr., J.T., 1928, Notes on feldspar, quartz, chrome, and manganese in Maryland: Maryland Geological Survey Reports, v. 12, p. 91–194. | http://www.mgs.md.gov/publications/reports.html | MGS_R_12.91 |
| 10 | Crowley, 1976 | Crowley, W.P., 1976, The Geology of the Crystalline Rocks near Baltimore and Its Bearing on the Evolution of the Eastern Maryland Piedmont: Maryland Geological Survey Report of Investigations 27, 40 p. | http://www.mgs.md.gov/publications/report_pages/RI_27.html | MGS_RI_27 |
| 2 | Kavage Adams, R., field observations | Kavage Adams, R., field data collection and interpretations | None | MGS_RKA |
| 1 | Kavage Adams, 2025 | Kavage Adams, R., 2025. Geologic Map of the Sykesville Quadrangle, Howard, Carroll and Baltimore Counties, Maryland. Maryland Geological Survey, Quadrangle Geologic Map, SYKES2025.1, scale 1:24,000. | http://www.mgs.md.gov/publications/maps.html | MGS_SYKES2025.1 |
| 8 | Aleinikoff, et al., 2004 | Aleinikoff, J.N., Horton, J.W., Jr., Drake, A.A., Jr., Wintsch, R.P., Fanning, C.M., and Yi, K., 2004, Deciphering multiple Mesoproterozoic and Paleo- zoic events recorded in zircon and titanite from the Baltimore Gneiss, Maryland: SEM imaging, SHRIMP U-Pb geochronology, and EMP analysis, in Tollo, R.P., Corriveau, L., McLelland, J., and Bartholomew, M.J., eds., Proterozoic Tectonic Evolution of the Grenville Orogen in North America: Society of America Memoir 197, p. 411–434. | https://www.usgs.gov/publications/deciphering-multiple-mesoproterozoic-and-paleozoic-events-recorded-zircon-and-titanite | SoA_2004_Mem197_411 |
| 20 | Pearre and Heyl, 1960 | Pearre, N.C., and Heyl, A.V., 1960, Chromite and other mineral deposits in serpentine rocks of the Piedmont upland, Maryland, Pennsylvania, and Delaware: U.S.Geological Survey Bulletin 1082-K, p. 707-833, plate 40, scale 1:125,000. | https://pubs.usgs.gov/publication/b1082K | USGS_Bull_1082K_707 |
| 11 | Drake, 1994 | Drake, A.A., Jr., 1994, The Soldiers Delight Ultramafite in the Maryland Piedmont: U.S. Geological Survey Bulletin 2076, p. A1–A14. | https://ngmdb.usgs.gov/Prodesc/proddesc_92817.htm | USGS_Bull_2076_A1 |
| OBJECTID | MapUnit | Name | FullName | Age | Description | HierarchyKey | ParagraphStyle | Label | Symbol | AreaFillRGB | AreaFillPatternDescription | DescriptionSourceID | GeoMaterial | GeoMaterialConfidence | DescriptionOfMapUnits_ID |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Qal | Alluvium | Alluvium | Quaternary | Poorly to well-sorted, stratified mixtures of unconsolidated clay, silt, sand, gravel, and cobbles underlying flood plains of nearly all rivers and tributaries. Channels of tributaries are incised into bedrock with alluvium covering and exposed along the banks. Thickness of alluvium is highly variable, and is a function of bedrock, topography, and land-use practices. Abundant deposits of alluvium are present along Benson Branch, the Little and Middle Patuxent Rivers, and the North and South Branches of the Patapsco River. | 01-01 | DMU Unit 1 | Qal | 40 | 255,255,179 | None | MGS_SYKES2025.1 | Alluvial sediment | High | DMU01 |
| 2 | Qc | Colluvium | Colluvium | Quaternary | Coarse cobbles, boulders and large blocks of quartzite, pegmatite, and granitic gneiss. Typically derived from massive Setters Formation, Sykesville Formation, and pegmatite lithologies that were transported by gravity. Abundant on steeper slopes in the Patapsco River valley. | 01-02 | DMU Unit 1 | Qc | 62 | 255,222,128 | None | MGS_SYKES2025.1 | Colluvium and other widespread mass-movement sediment | High | DMU02 |
| 3 | Dg | Guilford Granite | Guilford Granite | Devonian | Massive, light gray, fine- to medium-grained, equigranular granite with occasional xenoliths of biotite schist. Weathers into large, rounded boulders. U-Pb dating of zircon from the Guilford Granite yielded an age of 362±3 Ma (Aleinikoff et al., 2002). | 02-01 | DMU Unit 1 | Dg | 245 | 222,153,179 | None | MGS_SYKES2025.1|AJI_2002_302.1.50 | Fine-grained, felsic-composition intrusive igneous rock | High | DMU03 |
| 4 | Dw | Woodstock Granite | Woodstock Granite | Devonian | Massive, light gray, medium-grained, weakly foliated granite. Intrudes outcrops of the Baltimore Gneiss on the northeastern edge of the quadrangle. U-Pb dating of zircon from the Woodstock Granite yielded an age of 381±11 Ma (Sinha et al., 2012). | 03-01 | DMU Unit 1 | Dw | 234 | 222,179,204 | None | MGS_SYKES2025.1|AJI_2012_312.8.907 | Fine-grained, felsic-composition intrusive igneous rock | High | DMU04 |
| 5 | Sp | Pegmatite | Pegmatite | Silurian | Massive, very coarse-grained, gray (smoky) quartz, light pinkish to grayish white feldspar (microcline and albite; Kearns, 2018), and grayish green muscovite with accessory garnet. Large blocks and boulders commonly mantle hillslopes below outcrops. Two historic quarry wall exposures of light pink, fine grained aplite just west of Marriottsville Road are mapped with pegmatite. Forms 1 to 150 feet (0.3 to 50 m) wide, cross-cutting bodies in rocks of the Baltimore Gneiss, Setters Formation, Cockeysville Marble, and Loch Raven Schist that were quarried and mined for feldspar in the early 1900s (Singewald, 1928). The largest is the Henryton Pegmatite, 0.6 mi (1.0 km) west of Marriottsville. Rb-Sr dating of total feldspar from the Henryton pegmatite yielded an age of 425±20 Ma (Wetherill et al., 1966). | 04-01 | DMU Unit 1 | Sp | 479 | 179,000,102 | None | MGS_SYKES2025.1|GMU_DD_CAK_2018|MGS_R_12.91|JGPR_1966_71.8.2139 | Coarse-grained, felsic-composition intrusive igneous rock | High | DMU05 |
| 6 | Og | Granodiorite (Ordovician?) | Granodiorite | Ordovician | Light gray, fine-grained, muscovite-biotite granodiorite composed largely of plagioclase feldspar, with lesser quartz and mica. Forms 3 to 6 feet (1 to 2 m) thick, cross-cutting bodies in rocks of the Mather Gorge and Sykesville Formations. Minimum age is estimated at 469±20 Ma based on Rb-Sr dating (Muth et al., 1979). Seen in the northwest corner of the quadrangle near Piney Branch and on an old railroad cut west of the town of Sykesville. | 05-01 | DMU Unit 1 | Og | 1 | 255,235,255 | None | MGS_SYKES2025.1|GEOL_1979_7.7.349 | Fine-grained, felsic-composition intrusive igneous rock | High | DMU06 |
| 7 | Cc | Cockeysville Marble | Cockeysville Marble | Cambrian | White to yellowish gray, fine- to medium-grained, marble and metadolostone with interlayed bands of yellowish brown phlogopite. Outcrop exposure is limited to interlayered schistose marble with phlogopite. Float blocks of massive, homogenous, white marble are found near old quarries and kiln sites, and is presumed to underlie valleys between outcrops of the Setters Formation and schistose marble. Abundant meter-scale folding is visible in outcrops near the North and South Branch of the Patapsco and Middle Pautuxent Rivers. The thickness of the Cockeysville Marble is estimated at 350 ft (107 m) along the South Branch of the Patapsco River. This estimate is not equivalent to true stratigraphic thickness of the formation due to deformation. | 06-01 | DMU Unit 1 | _c | 603 | 128,204,255 | None | MGS_SYKES2025.1 | Meta-carbonate rock | High | DMU07 |
| 8 | Csq | Setters Formation | Setters Formation | Cambrian | Light gray, fine to medium-grained quartzite and interlayered schist (quartz-feldspar-muscovite-tourmaline). Quartzite layers are typically 0.5 to 3 in (2 to 6 cm) thick, parting on thin schistose bands covered in medium to coarse-grained muscovite and tourmaline. Quartzite of the Setters Formation commonly splits into flaggy slabs. Currently and historically quarried in the Marriottsville area (Singewald, 1946). Portions of the formation are predominantly schist with minor quartzite but are poorly exposed in the map area. The overall thickness of the formation in the map area ranges from 10 to 500 ft (3 to 160 m), the lower limit due to lack of exposure. Antiformal and synformal folds from 20 to 4000 ft amplitude are observable in outcrops and topography, respectively, of the Setters Formation. U-Pb dating of detrital zircon from the Setters Formation west of the Woodstock Gneiss dome yielded a maximum depositional age of 1 Ga (Martin et al., 2015). The thickness of the Setters Formation is estimated at 460 ft (140 m) along the South Branch of the Patapsco River. This estimate is not equivalent to true stratigraphic thickness of the formation due to deformation. | 07-01 | DMU Unit 1 | _sq | 52 | 255,222,153 | None | MGS_SYKES2025.1|MGS_CR_CAFR1946_132|GEOS_2015_11.4.1042 | Quartzite | High | DMU08 |
| 9 | Csy | Sykesville Formation | Sykesville Formation | Lower Cambrian | Variegated, olive to pinkish gray, granitic-looking matrix containing abundant small 0.04 to 2 inch (1 mm to 5 cm) fragments of quartz and dark gray schist. Weathers into massive, rounded outcrops and boulders. Locally contains coarse, angular fragments of metagraywacke, quartz-rich schist, amphibolite and banded schist ranging from 2 inches to 30 feet (5 cm to 9 m) in size. Felsic veins with sharp to diffuse boundaries commonly surround and cross-cut dark gray fragments of schist. Clast shape and orientation is heterogeneous in some outcrops and aligned with foliation in others. Strongly developed foliation and lineation comprised of dark gray schist and light gray felsic banding from 0.08 to 0.4 inch (2 mm-1 cm) in thickness, often with gneissic appearance, abundant 0.4 to 1.2 inch (1 to 3 cm) stretched quartz clasts with that form “eyes”. Exposed in the northwest corner of the quadrangle in Piney Branch and marked with a lineated pattern as seen in the lower half of the symbol. U-Pb dating of detrital zircon of the Sykesville Formation from the town of Sykesville yielded a maximum depositional age of 550 Ma (Martin et al., 2015). The thickness of the Sykesville Formation is estimated at 14,850 ft (4,526 m) along the South Branch of the Patapsco River. Apparent thickness is not equivalent to the true stratigraphic thickness of the formation due to deformation. | 08-01 | DMU Unit 1 | _sy | 121 | 235,235,222 | None | MGS_SYKES2025.1|GEOS_2015_11.4.1042 | Metasedimentary rock | High | DMU09 |
| 10 | CZmg | Mather Gorge Formation | Mather Gorge Formation | Lower Cambrian and (or) Neoproterozoic | Quartz-rich schist and quartzitic metagraywacke interbedded in layers ranging from 0.1 inch to 3 feet thick (2.5 mm to 1 m). Schist is very fine grained and greenish gray to gray, with muscovite, chlorite, plagioclase, epidote, magnetite ± garnet. Metagraywacke is light to dark olive gray, fine- to medium-grained. Equivalent to the Peters Creek Schist of Jonas and Stose (1946), the Wissahickon Formation, Western Sequence, psammatic rocks of Cloos et al. (1964), and the Morgan Run Formation of Muller (1994). U-Pb dating of detrital zircon from the Mather Gorge Formation at Hoods Mill yielded maximum depositional ages of 540 and 550 Ma (Martin et al., 2015; Martin and Bosbyshell, 2019). | 09-01 | DMU Unit 1 | _Zmg | 185 | 235,153,077 | None | MGS_SYKES2025.1|MGS_CR_CLFR1946|MGS_HOWMO1964|MGS_FINKS1994|GEOS_2015_11.4.1042|CJS_2019_56.10.1061 | Schist and gneiss, of sedimentary-rock origin | High | DMU10 |
| 11 | CZmgb | banded schist with interlayered metagraywacke | Mather Gorge Formation, banded schist with interlayered metagraywacke | Lower Cambrian and (or) Neoproterozoic | Interbedded quartz-mica schist and quartzitic metagraywacke with intermittent zones of banded schist. The banded schist contains mm to cm-scale light gray to white and dark gray to black layers interpreted as in-situ leucosome (light layers) and melanosome (dark layers) produced by partial melting of the parent material (Sawyer, 2008). Metagraywacke remains similar in appearance to CZmg but is often surrounded by cm-scale zones of light gray to white quartz. Weathering form of outcrops with banded schist is more massive and rounded than CZmg, and foliation is less apparent. | 09-01-01 | DMU Unit 2 | _Zmgb | 186 | 235,128,077 | None | MGS_SYKES2025.1|CSP_2008_v9 | Schist and gneiss, of sedimentary-rock origin | High | DMU11 |
| 12 | CZmgbf | banded schist with metagraywacke fragments | Mather Gorge Formation, banded schist with metagraywacke fragments | Lower Cambrian and (or) Neoproterozoic | Banded, light gray to white and dark gray to black, commonly contorted, schist. Metagraywacke fragments, similar in appearance to CZmg, 1 to 3 feet (0.3 to 1 m) long, are surrounded by banded schist. Also contains 0.25 to 1 foot (10 to 40 cm) thick, felsic bands containing abundant small schist clasts, similar in appearance to Csy. Interpreted to be produced by partial melting of quartz-mica schist and quartzitic metagraywacke (Sawyer, 2008). Cross-cutting, cm-scale, bands are white to very pale orange and comprised of mm-cm size crystals of plagioclase feldspar, quartz, and muscovite. These felsic bands sometimes contain clasts of schist and metagraywacke and are interpreted as in-situ or in-source leucosome (Sawyer, 2008). | 09-01-02 | DMU Unit 2 | _Zmgbf | 187 | 235,102,077 | None | MGS_SYKES2025.1|CSP_2008_v9 | Schist and gneiss, of sedimentary-rock origin | High | DMU12 |
| 13 | CZlo | Loch Raven-Oella Formation, undifferentiated | Loch Raven-Oella Formation, undifferentiated | Cambrian | Light to medium gray, medium- to coarse-grained, schist containing biotite-plagioclase-muscovite-quartz ± euhedral garnet, staurolite, and kyanite. Garnet is locally 0.5 in (1 cm) in size and covers foliation surfaces. The thickness of the Loch Raven-Oella Formation is estimated at 1,930 ft (588 m) along the South Branch of the Patapsco River. This estimate is not equivalent to true stratigraphic thickness of the formation due to deformation. | 09-02 | DMU Unit 1 | _Zlo | 546 | 153,128,179 | None | MGS_SYKES2025.1 | Schist and gneiss, of sedimentary-rock origin | High | DMU13 |
| 14 | CZloma | meta-arenite | Loch Raven-Oella Formation, meta-arenite | Cambrian | Light gray, fine-grained quartzite with fine bands of biotite every 0.3 to 0.6 in (1 to 2 cm), ranging from 0.1 inch to 1.5 feet thick (2.5 mm to 0.5 m). Interlayered with dark gray, medium-grained schist. Similar in appearance to CZmg but occurs east of Soldiers Delight ultramafite. Equivalent to the Peters Creek schist of Jonas and Stose (1946), Wissahickon Formation, Eastern Sequence, psammatic rocks, of Cloos et al. (1964), and portions of the Oella Formation of Crowley (1976). | 09-02-01 | DMU Unit 2 | _Zloma | 122 | 235,222,222 | None | MGS_SYKES2025.1|MGS_CR_CLFR1946|MGS_HOWMO1964|MGS_RI_27 | Schist and gneiss, of sedimentary-rock origin | High | DMU14 |
| 15 | CZum | Ultramafic rocks | Ultramafic rocks | Lower Cambrian and (or) Neoproterozoic | Greenish gray to black, occur as large bodies or smaller blocks within rocks of the Mather Gorge, Sykesville, and Loch Raven-Oella undifferentiated Formations. The cores of the bodies are comprised of dark green to black, medium-grained serpentinite with a rounded, often light gray, fractured weathering surface. The margins are typically magnesian schist. The largest of these is the Soldiers Delight ultramafite (Drake, 1994), which transects the quadrangle from NE to SW and is estimated at 2,350 ft (716 m) thickness at Marriottsville Road #2. This estimate is not equivalent to true stratigraphic thickness of the formation due to deformation. May include magnesian schist (CZs) and metagabbro (CZg) lithologies. | 10-01-01 | DMU Unit 1 | _Zum | 440 | 179,255,179 | None | MGS_SYKES2025.1|USGS_Bull_2076_A1 | Meta-ultramafic rock | High | DMU15 |
| 16 | CZs | Magnesian schist | Magnesian schist | Lower Cambrian and (or) Neoproterozoic | Soft, very light gray to dark greenish gray, fine- to coarse-grained talcose schist with occasional euhedral biotite, actinolite, and tremolite from 0.1 to 0.4 inch (3 mm to 1 cm) in length. 0.1 to 0.2 inch (3 to 5 mm) euhedral magnetite grains can occur in abundance. The weathering surface appears foliated. Found within Sykesville Formation and comprises part of the Soldiers Delight Ultramafite. Historically quarried for soapstone and talc near Marriottsville (Singewald, 1946; Perre and Heyl, 1960). | 10-01-02 | DMU Unit 1 | _Zs | 310 | 204,255,235 | None | MGS_SYKES2025.1|MGS_CR_CAFR1946_132|USGS_Bull_1082K_707 | Meta-ultramafic rock | High | DMU16 |
| 17 | CZg | Metagabbro and amphibolite | Metagabbro and amphibolite | Lower Cambrian and (or) Neoproterozoic | Very light gray and dark gray to black, medium- to coarse-grained plagioclase feldspar, hornblende, epidote. Weathering form is massive. Found within the Sykesville Formation and comprises part of the Soldiers Delight Ultramafite. | 10-01-03 | DMU Unit 1 | _Zg | 443 | 179,204,179 | None | MGS_SYKES2025.1 | Meta-mafic rock | High | DMU17 |
| 18 | Yb | Baltimore Gneiss | Baltimore Gneiss | Mesoproterozoic | Light gray to white and dark gray to black, alternating felsic and mafic bands of biotite, feldspar, quartz, and plagioclase typically 0.1 to 1 in (3 mm to 2 cm) in thickness. Thicker light gray felsic bands (2 to 5 in / 5 to 10 cm) are present parallel to and cross cutting thinner banding. 1 to 3 ft (0.3 to 1 m) layers of dark gray schist with bands of light gray, stretched quartz feldspar lenses (augen or eyes) 0.5 to 1 in (1 to 2 cm) occur. 1 to 3 ft (0.3 to 1 m) thick, friable-weathering, layers of dark-gray to black hornblende-biotite schist occur intermittently in outcrops in the Patapsco River between Woodstock and Marriottsville. Where visible they define folds and faults. U-Pb dating of zircon from the Baltimore Gneiss yielded an age of 1.25 Ga (Aleinikoff et al., 2004). | 11-01 | DMU Unit 1 | Yb | 653 | 128,204,153 | None | MGS_SYKES2025.1|SoA_2004_Mem197_411 | Metaigneous rock | Medium | DMU18 |
| OBJECTID | Term | Definition | DefinitionSourceID | Glossary_ID |
|---|---|---|---|---|
| 10 | bedding | Formed, arranged, or deposited in layers or beds, or made up of or occurring in the form of beds; esp. said of a layered sedimentary rock, deposit, or formation. The term has also been applied to nonsedimentary material that exhibits depositional layering, such as the "bedded deposits" of volcanic tuff alternating with lava in the mantle of a stratovolcano. | AGI_2011 | GLO10 |
| 1 | certain | Identity of a feature can be determined using relevant observations and scientific judgment; therefore, one can be reasonably confident in the credibility of this interpretation. | FGDC-STD-013-2006 | GLO01 |
| 11 | cleavage | A locally planar fabric in an unmetamorphosed or weakly metamorphosed, fine-grained rock defined by either the tendency of a rock to split in a particular direction, a preferred orientation of crystal planes in mineral grains, or a preferred orientation of inequant grain shapes; it is a product of deformation or metamorphism. | AGI_2011 | GLO11 |
| 9 | contact | A plane or irregular surface between two different types or ages of rock, sediment or other geologic and stratigraphic units. | AGI_2011 | GLO09 |
| 8 | cross section line | A plane or polyline along which a diagram is drawn showing the transected subsurface and topographic features and geology; specifically a vertical section drawn at right angles to the longer axis of a geologic feature. | AGI_2011 | GLO08 |
| 19 | desktop analysis | Data added to the digital geologic map through desktop methods for the purpose of clarification or to indicate general locations of objects or places. | MGS_SYKES2025.1 | GLO19 |
| 5 | DMU Unit 1 | Formation style, bolded title, 11pt Times New Roman font. This format is used for both formal and major informal units that are mapped at the surface, and may or may not contain subunits. | MGS_SYKES2025.1 | GLO05 |
| 6 | DMU Unit 2 | Informal formation or subunit style, bolded title, 11pt Times New Roman font. This format is used for visible map units that are informal units or are subunits of another visible map unit. | MGS_SYKES2025.1 | GLO06 |
| 12 | fault | A discrete surface or zone of discrete surfaces separating two rock masses across which one mass has slid past the other. | AGI_2011 | GLO12 |
| 13 | fold axis | A line which, when moved parallel to itself, traces out a folded surface. It applies only in the case of cylindrical folds. | AGI_2011 | GLO13 |
| 14 | foliation | A general term for a planar arrangement of textural or structural geatures in any type of rock, esp. the locally planar fabric in a rock defined by a fissility, a preferred orientation of crystal planes in mineral grains, a preferred orientation of inequant grain shapes, or from compositional banding. In igneous rocks, planar parallelism of flaky or tabular minerals and mineral aggregates, slabby xenoliths, or flattened vesicles as well as compositional layering. In metamorphic rocks, planar parallelism of flaky minerals and compositional layering. | AGI_2011 | GLO14 |
| 3 | High | The selected term in the GeoMaterial field (and its definition) adequately characterizes the overall lithologic nature of rocks and (or) sediments in the map unit. | GeMS_2020 | GLO03 |
| 15 | joint | A planar fracture, crack, or parting in a rock, without shear displacement. | AGI_2011 | GLO15 |
| 16 | lineation | A general, nongeneric term for a locally linear structure or facric in a rock, e.g. flow lines, scratches, striae, slickensides or slickenfibers on a single surface; linear arrangements of components in sediments; or axes of folds. Lineation in metamorphic rocks includes aligned rod-shaped and/or elongate mineral grains, crenulation fold axes, and the lines of intersection between bedding and cleavage or any two sets of oriented surfaces. | AGI_2011 | GLO16 |
| 4 | Medium | The selected term in the GeoMaterial field (and its definition) generally characterizes the overall lithologic nature of rocks and (or) sediments in the map unit, but one or more significant but minor lithologies are not adequately described by the selected term. | GeMS_2020 | GLO04 |
| 7 | neatline | Map Outline | MGS_SYKES2025.1 | GLO07 |
| 2 | questionable | Identity of a feature cannot be determined using relevant observations and scientific judgment; therefore, one cannot be reasonably confident in the credibility of this interpretation. For example, IdentityConfidence = questionable is appropriate when a geologist reasons "I can see some kind of planar feature that separates map units in this outcrop, but I cannot be certain if it is a contact or a fault." | FGDC-STD-013-2006 | GLO02 |
| 18 | recreational GPS | Data collected using Apple iPad using GIS software such as ESRI Field Maps or IGIS with settings of 30 ft point accuracy. | MGS_SYKES2025.1 | GLO18 |
| 17 | shear zone | A parallel-sided zone of localized shearing displacement, which may be recognized by sigmoidal mineral-filled veins, locally well-developed cleavage or foliation, wholesale grain-size reduction or mylonitization, or some combination of these features. | AGI_2011 | GLO17 |