Map Unit Descriptions
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UTAH GEOLOGICAL SURVEY a division of Plate 2 Utah Geological Survey Map 230 Utah Department of Natural Resources Geologic Map of the Goshen Valley North Quadrangle MAP UNIT DESCRIPTIONS Md Deseret Limestone (Upper to Lower Mississippian) – Medium- to very thick bedded, GEOLOGIC SYMBOLS LITHOLOGIC COLUMN medium-dark-gray, variably sandy and fossiliferous limestone that contains distinctive QUATERNARY white calcite nodules and blebs and local brown-weathering chert nodules and locally Contact – Dashed where approximately located Alluvial deposits brown-weathering bands (case hardened surface); fossils include rugose corals, uncom- TIME- THICK- Normal fault – Dashed where approximately mon brachiopods, crinoids, bryozoans, and fossil hash; locally few thin interbeds of calcar- STRATI- MAP NESS Level-1 stream deposits (upper Holocene) − Moderately sorted sand, silt, clay, and pebble to located, dotted where concealed and MAP UNIT LITHOLOGY Qal1 eous sandstone. Lower part (about 100 feet [30 m]) is marked by slope-forming, light-red GRAPHIC SYMBOL Feet boulder gravel deposited in active stream channels and flood plains; locally includes small approximately located; bar and ball on UNIT (Meters) to dark-gray phosphatic shale and thin-bedded cherty limestone of the Delle Phosphatic down-dropped side alluvial-fan and colluvial deposits, and minor terraces up to about 10 feet (3 m) above Member. Formation occurs as folded strata in the Mosida Hills. Upper contact is conform- Mio. lower Mosida Basalt Tb 50-100 (20-30) 19.5 Ma Ar/Ar current base level; mapped in an ephemeral wash draining the southern Lake Mountains able and gradational and corresponds to a change from fossiliferous limestone (Deseret) to Normal fault, concealed – Inferred principally from Soldiers Pass Chimney Rock Unconformity gravity and other geophysical data (Brimhall and Eo. upper Tsc 10+ (3+) (Mosida Hills, unofficial name) (NE1/4 section 19, T. 8 S., R. 1 W.) and along Pinyon predominantly sandstone (Humbug). Age from Morris and Lovering (1961), and TERT. Formation Pass Tuff Mbr. 34.7 Ma Ar/Ar Creek (section 30, T. 9 S., R. 1 W.); typically less than 20 feet (<6 m) thick. others, 1976; Floyd, 1993; Cook and others, Major unconformity Sandberg and Gutschick (1984). Thickness is about 1000 feet (300 m) from cross section 1997); very approximately located; bar and ball construction; the Deseret is 1000 feet (300 m) thick in the East Tintic Mountains (Morris on down-dropped side Top not exposed Qaly Younger alluvial deposits (Holocene) – Moderately sorted sand, silt, clay, and local pebble and Lovering, 1979), about 700 to 750 feet (210-230 m) thick in the Lake Mountains 500+ Oblique-slip fault – Dotted where concealed and Humbug Formation Mh gravel deposited in stream channels and flood plains; mapped along some drainages on (Biek, 2004; Biek and others, 2006), and 765 feet (235 m) thick in West Mountain (Clark, (150+) margin of Goshen Valley; grades to young alluvial-fan deposits (Qafy); thickness probably approximately located; arrows, bar and ball, 2009). Previously mapped as the Pine Canyon limestone (Hoffman, 1951). and (toward) + (away) symbols show relative less than 20 feet (<6 m). direction of displacement Mg Gardison Limestone (Lower Mississippian) – Medium- to very thick bedded, medium-gray Upper Level-1 alluvial-fan deposits (upper Holocene) − Poorly to moderately sorted, non-stratified, Thrust or reverse fault – Dashed where Qaf1 to medium-dark-gray limestone, cherty limestone, and fossiliferous limestone. Chert is clay- to boulder-size sediment deposited principally by debris floods or clear-water floods approximately located, dotted where concealed Deseret Limestone Md 1000 (300) present as black, irregularly shaped nodules and thin, discontinuous beds; fossils include and approximately located; teeth on upper plate at the distal end of the piedmont slope and at the mouths of active drainages; equivalent to rugose and colonial corals, brachiopods, gastropods, and bryozoans replaced by white MISSISSIPPIAN the younger part of Qafy, but differentiated because its forms smaller, isolated fans; calcite. Formation occurs as folded strata in Mosida Hills; queried in exposure adjacent to Axial trace of anticline – Dashed where Delle Phosphatic probably less than 20 feet (<6 m) thick. approximately located; dotted where concealed Member Tintic Prince fault? where uncertain correlation. Upper contact appears conformable and 400+ and approximately located Gardison Limestone Mg gradational and generally corresponds to a break in slope, with ledgy, thicker bedded, Lower (120+) Base not exposed Qafy Young undifferentiated alluvial-fan deposits (Holocene) − Similar to level-1 alluvial-fan cherty limestone below and slope-forming shale and thin-bedded limestone (Delle) above. Axial trace of syncline – Dashed where deposits (Qaf1), but forms coalesced apron of post-Bonneville sediment shed off the East Age from Morris and Lovering (1961). Base not exposed in quadrangle. Thickness is 500 approximately located; dotted where concealed and approximately located Tintic Mountains area (west of quadrangle); also includes coalesced fans emanating from feet (150 m) in East Tintic Mountains (Morris and Lovering, 1961), about 500 to 650 feet streams draining the plain of lacustrine mud (Qlmp) adjacent to Utah Lake; upper parts of (150-200 m) thick in Lake Mountains (Biek, 2004; Biek and others, 2006), and 620 feet Shorelines of the Bonneville lake cycle – Mapped fans are locally deeply incised; thickness unknown, but likely as much as several tens of (190 m) thick in West Mountain (Clark, 2009). The Gardison Limestone and underlying at the top of the wave-cut platform of erosional feet thick. Fitchville Formation were previously mapped as the Gardner dolomite (Hoffman, 1951). shorelines and top of constructional bars and barrier beaches; may coincide with geologic contacts; Bonneville shoreline not present in Spring Deposits PREVIOUS WORK AND ACKNOWLEDGMENTS quadrangle Other transgressive shorelines Qsm Spring and marsh deposits (Holocene) – Silt and clay with local sand; present in low-lying Harold J. Bissell, Brigham Young University (BYU), conducted the first geologic mapping areas of Goshen Valley where seeps, springs, and marshy areas exist within areas of of surficial deposits in this area as part of his Ph.D. dissertation (1948), later published as Provo shoreline younger lacustrine deposits (Qlmy); thickness probably 0 to 10 feet (0-3 m). part of a USGS Professional Paper (1963). He advised BYU graduate students Hoffman Other regressive shorelines (1951) and Williams (1951) on mapping projects within and adjacent to the quadrangle, Lacustrine deposits respectively. The late Paul Proctor, Brigham Young University, mapped the adjacent Crest of Lake Bonneville barrier beach or spit 2006, in press) Refer to table 1 for ages and elevations of major shorelines of Lake Bonneville and Utah Allens Ranch quadrangle under contract to the Utah Geological Survey (UGS) (Proctor, Utah Lake shorelines – (Solomon and Lake. 1985). This area also served as a training ground for field classes led by Eric H. Christian- Biek, 2008) sen at BYU, and several recent BYU undergraduate students contributed to the under- Utah Lake highstand and contact between Qlmy Qlmy Younger lacustrine silt and clay deposits (Holocene to upper Pleistocene) − Silt, clay, and standing of the southern Lake Mountains, Fox Hills, and Mosida Hills. Baxter and others and other surficial deposits minor fine-grained sand deposited along the margin of Utah Lake; locally organic rich, and (2005) and Christiansen and others (2007) recently conducted petrologic, geochemical, Other Utah Lake shorelines locally includes pebbly beach gravel; locally includes small areas of spring and marsh and geochronologic analyses on the Tertiary volcanic rocks of the area. UGS staff Barry deposits (Qsm) and mixed lacustrine and alluvial deposits (Qla) difficult to map at this Solomon, Grant Willis, and Robert Ressetar reviewed this map, while Kent Brown set up Strike and dip of bedding in sedimentary rocks scale; probably 0 to 10 feet (0-3 m) thick. 2009) the digital photogrammetry, and Jim Parker and Lori Douglas prepared the drawings for Inclined plate 2. Qlsy Younger lacustrine sand and silt deposits (Holocene to upper Pleistocene) − Sand, silt and Inclined – approximate minor gravel deposited in low linear ridges south of Utah Lake; locally organic rich; REFERENCES Vertical mapped within areas of younger lacustrine silt and clay (Qlmy); probably beach deposits formed from fluctuations at and near the Utah Lake highstand; probably 0 to 10 feet (0-3 Prospect Baxter, N., Ward, T., Chandler, M.R., Zobell, E.A., Christiansen, E.H., Dorais, M.J., and m) thick. Kowallis, B.J., 2005, Cenozoic extension and volcanism in the southern Lake Mountains, Sand and gravel pit central Utah [abs.]: Geological Society of America Abstracts with Programs, vol. 37, no. Deposits of the regressive (Provo) phase of the Bonneville lake cycle (Currey and Oviatt, Line of cross section 7, p. 72. 1985; Oviatt and others, 1992) are identified with the last map symbol letter “p,” and deposits of the transgressive (Bonneville) phase of the Bonneville lake cycle are identified Biek, R.F., 2004, Geologic maps of the Cedar Fort and Saratoga Springs quadrangles, Utah with the last map symbol letter “b.” County, Utah: Utah Geological Survey Maps 201 and 202, 3 plates, scale 1:24,000. Lacustrine gravel and sand (upper Pleistocene) − Moderately to well-sorted, moderately