Interim Geologic Map of the West Part of - Utah Geological Survey

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Eolian depositsQed Eolian dune sand (Holocene) − Grayish-pink to pale-red, well-sorted silt andfine-grained sand largely stabilized by vegetation; most of the sand consists oftiny clay pellets eroded from the Claron Formation and carried eastward by strongwinds and updrafts where it was deposited in the lee of the Cedar Breaksescarpment; typically less than 15 feet (5 m) thick.QesEolian sand (Holocene) − Yellowish-brown to reddish-brown, moderately wellsorted sand and silt derived from deflation of Little Salt Lake playa depositslocated to the south and west; forms thin sheets and poorly developed dunespartly covered by sparse vegetation; generally more saline than underlyingalluvium and so allows greasewood to flourish at the expense of sagebrush;description modified from Maldonado and Williams (1993b); typically less than 6feet (2 m) thick.Glacial depositsGlacial till and outwash are present east of Brian Head peak in the Castle Creek andLowder Creek drainages and in the greater Castle Valley area. These deposits are of thePinedale alpine glacial advance and an older glaciation of unknown Quaternary age(possibly the Bull Lake alpine glacial advance). Pinedale deposits in their type area inthe Wind River Range of Wyoming are about 12 to 24 ka (Imbrie and others, 1984) (withglacial maxima about 16 to 23 ka based on cosmogenic 26 Al and 10 Be dating; Gosse andothers, 1995), and are roughly coeval with the late Wisconsin glaciation, Last GlacialMaximum (LGM), and marine oxygen isotope stage 2 (MIS 2). Early Wisconsin glacialmoraines (MIS 4, about 59 to 71 ka; Imbrie and others, 1984) are not known in Utah(Laabs and Carson, 2005). Deposits of the Bull Lake alpine glacial advance in their typearea in the Wind River Range of Wyoming are about 128 to 186 ka (Imbrie and others,1984) (with glacial maxima about 140 to 160 ka; Gosse and Phillips, 2001; Sharp andothers, 2003), and are roughly coeval with the Illinoian glaciation or MIS 6.Qgtp Glacial till of Pinedale age (upper Pleistocene) – Non-stratified, poorly sorted,sandy pebble to boulder gravel in a matrix of sand, silt, and minor clay; clasts arematrix supported, subangular to subrounded, and were derived from the LeachCanyon, Isom, and Brian Head Formations and the Markagunt megabrecciaexposed in the headwaters of the Castle Creek and Lowder Creek drainage basins;terminal moraine at the west end of Castle Valley is at an elevation of about 9750feet (2973 m), whereas the terminal moraine of the smaller Lowder Creek basin isat Long Flat at an elevation of about 10,100 feet (3080 m); recessional and lateralmoraines and hummocky, stagnant ice topography are locally well developed, butsculpted bedrock is absent or inconspicuous, probably owing to the relativelysmall size and suspected short duration of the glaciers (Mulvey and others, 1984);well-developed terminal and recessional moraines are as much as 120 feet (37 m)thick, but till is much thinner elsewhere and locally consists only of scatteredboulders or a veneer of meltout till on bedrock.The Brian Head-Sidney Peaks area marks the southernmost occurrence oflate Pleistocene glaciation in Utah (Mulvey and others, 1984), which was firstbriefly described by Gregory (1950); Agenbroad and others (1996) interpreted5
glacial deposits and features that they attributed to their “Mammoth Summitglacier” at the southwest side of Brian Head peak and northern edge of CedarBreaks National Monument, but that we interpret as landslide deposits and inplaceBrian Head Formation, the latter partly covered by a lag of large blocks ofthe Isom Formation.Till is Pinedale age based on distinct, well-preserved morainalmorphology and relatively unweathered clasts, and minimum limiting age of14,400 ± 850 14 C yr B.P. from marsh deposits of the Lowder Creek bog thatoverlies the till (Mulvey and others, 1984; Currey and others, 1986; see alsoAnderson and others, 1999); Madsen and others (2002) identified the 14,300 14 Cyr B.P. Wilson Creek #3 ash (erupted from Mono Craters in California) in theLowder Creek bog; Marchetti and others (2005, 2007) reported 3 He cosmogenicages of 20.0 ± 1.4 to 23.1 ± 1.3 ka on basaltic andesite boulders on moraines ofthe main Pinedale advance on Boulder Mountain approximately 80 miles (130km) to the northeast; Weaver and others (2006) reported 3 He cosmogenic ages of21.1 ± 2.1 to 23.2 ± 3.7 ka on andesite boulders on moraines of the main Pinedaleadvance on the Fish Lake Plateau just northwest of Boulder Mountain; these agescoincide with the global LGM (21 ± 2 ka) and thus likely are the age of the mainPinedale moraines on the Markagunt Plateau; Marchetti and others (2005) alsoreported a smaller advance at 15.2 ± 0.5 to 16.8 ± 0.5 ka in the Fish Creekdrainage on Boulder Mountain.Qgop Glacial outwash of Pinedale age (upper Pleistocene) – Moderately to wellsorted,generally subrounded, clast-supported, pebble to boulder sand and gravel;clasts are typically little weathered and of the same provenance as glacial till(Qgtp); mapped on the east side of Castle Valley where the deposits likelyrepresent the waning stages of Pinedale glaciation; probably about 20 to 30 feet(6-9 m) thick.Qgtu Older glacial till of uncertain pre-Pinedale age (middle? Pleistocene) – Similarto glacial till of Pinedale age, but glacial landforms are poorly preserved orabsent; forms a low-relief, rubble-covered, locally hummocky surface bothnortheast and southwest of the Long Flat cinder cone (peak 10,392, thesouthernmost map unit Qblfc); the northeast flank of the cinder cone isconspicuously truncated, perhaps by this glacial advance; also forms low hillssouth of Castle Valley, in the southwest part of the Panguitch Lake 7.5’quadrangle, that are composed almost entirely of large blocks of Leach CanyonFormation, with minor blocks of Isom Formation and chalcedony, that we infer tobe deeply eroded remains of a medial or recessional moraine; Mulvey and others(1984) and Currey and others (1986) first suggested that glacial till older thanPinedale age may be present in the Brian Head quadrangle, west of Castle Valley;we sampled a sandy till exposed in a bluff northwest of the confluence ofMammoth and Crystal Creeks (map unit Qgtou) that yielded an OpticallyStimulated Luminescence (OSL) age of 48.95 ± 19.24 ka, suggesting that thedeposits may correspond to the MIS 3-4 advance; however, given the widespreadextent and degree of incision of Qgtou deposits, we interpret these glacial deposits6
Page 1 and 2: ! !! !!! ! ! !! ! ! ! !! ! !! !! !
Page 3 and 4: MAP UNIT DESCRIPTIONSQUATERNARYAllu
Page 5: Qafc Coalesced fan alluvium of Paro
Page 9 and 10: (Tbhv) and Dakota (Kd and Ktd) Form
Page 11 and 12: typically mapped where lava flows d
Page 13 and 14: that range in age from Miocene to H
Page 15 and 16: fronts (except at Dry Valley, immed
Page 17 and 18: the quadrangle; no fault that postd
Page 19 and 20: Qbw, QbwcWater Canyon lava flow and
Page 21 and 22: others, 2007); lava flow is typical
Page 23 and 24: Mahogany Hill, about 500 feet (150
Page 25 and 26: lava flow (Tbbm) that conceal the u
Page 27 and 28: TERTIARYpreserved in down-dropped b
Page 29 and 30: and Rowley and others (in preparati
Page 31 and 32: field (or possibly coeval batholith
Page 33 and 34: hidden by shadow; we tentatively as
Page 35 and 36: esistant crystal-poor rhyolite tuff
Page 37 and 38: thickness uncertain but outcrop pat
Page 39 and 40: divide between Red Creek and Little
Page 41 and 42: pyroxene (5%), and sanidine (trace)
Page 43 and 44: unconformityThe Leach Canyon Format
Page 45 and 46: unconformityMa (Best and others, 19
Page 47 and 48: interval, and a lower limestone int
Page 49 and 50: Figure 3. View northwest to North V
Page 51 and 52: dark-yellowish-orange, grayish-pink
Page 53 and 54: TKgc Grand Castle Formation, undivi
Page 55 and 56: track (the latter found by Eric Rob
Page 57 and 58:
noted by Moore and Straub (2001) an
Page 59 and 60:
shoreface, beach, lagoonal, and est
Page 61 and 62:
water deposits of Cenomanian age (N
Page 63 and 64:
62Figure 7. Cedar Mountain Formatio
Page 65 and 66:
leached white under the Cretaceous
Page 67 and 68:
ACKNOWLEDGMENTSThis geologic map is
Page 69 and 70:
Anderson, R.E., and Christenson, G.
Page 71 and 72:
Biek, R.F., Rowley, P.D., Hayden, J
Page 73 and 74:
field guide (The Mackin Volume): Ut
Page 75 and 76:
2001, Cretaceous and early Tertiary
Page 77 and 78:
Hacker, D.B., Rowley, P.D., Blank,
Page 79 and 80:
Kurlich, R.A., III, 1990, Geology o
Page 81 and 82:
Maldonado, F., and Moore, R.C., 199
Page 83 and 84:
Flagstaff-Green River basins [abs.]
Page 85 and 86:
elation to other igneous centers in
Page 87 and 88:
Schulman, E., 1956, Dendroclimatic
Page 89:
Van Kooten, G.K., 1988, Structure a
Page 92:
113°00'112°00'15BV20R i v e rCCNP
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Interim Geologic Map of the West Part of - Utah Geological Survey

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