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Quaternary Research 78 (2012) 363–372

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Quaternary Research

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Paleowind velocity and paleocurrents of pluvial Lake Manly, Death Valley, USA

Jeffrey R. Knott ⁎, Joanna M. Fantozzi, Kelly M. Ferguson, Summer E. Keller, Khadija Nadimi, Carolyn A. Rath, Jennifer M. Tarnowski, Michelle L. Vitale

Department of Geological Sciences, California State University Fullerton, 800 N. State College Blvd., Fullerton, CA 92834, USA article info abstract

Article history: Pluvial lake deposits are found throughout western North America and are frequently used to reconstruct re- Received 7 June 2011 gional paleoclimate. In Death Valley, California, USA, we apply the beach particle technique (BPT) of Adams Available online 24 July 2012 (2003), Sedimentology, 50, 565–577 and Adams (2004), Sedimentology, 51, 671–673 to Lake Manly deposits at the Beatty Junction Bar Complex (BJBC), Desolation Canyon, and Manly Terraces and calculate paleowind Keywords: velocities of 14–27 m/s. These wind velocities are within the range of present-day wind velocities recorded in Lake Manly the surrounding area. Sedimentary structures and clast provenance at Desolation Canyon and the Manly Ter- Paleogeography Quaternary geology races indicate sediment transport from north to south. Lake level, based on the elevation of constructional Paleowind features, indicates that the hill west of the BJBC was an island and that the BJBC spits formed during simple lake regression. The data are consistent with the hypothesis that the present wind regime (velocity and direction) formed the pluvial Lake Manly features. © 2012 University of Washington. Published by Elsevier Inc. All rights reserved.

Introduction (1991) had previously determined paleowind velocity there. The Des- olation Canyon and the Manly Terrace locations were selected Lake Manly, the pluvial lake that occupied Death Valley during because: 1) the pluvial lake deposits are formed from resistant volca- cooler, wetter climate conditions, is a key component in climate nic rocks that are more suitable for the beach particle technique (BPT) models of the western USA and subsequently the northern latitudes of Adams (2003, 2004) and determining paleowind velocity, 2) these (Fig. 1; e.g., Matsubara and Howard, 2009; Peterson et al., 2010). are the largest distribution of contiguous Lake Manly deposits, and However, at one of the best known and most accessible outcrops of 3) outcrops of Ordovician Eureka Quartzite there provide a unique Lake Manly—the Beatty Junction bar complex (BJBC)—the age rock type to study longshore transport. (Caskey et al., 2006; Machette et al., 2001; Owen et al., 2010) and We combine these data with observations elsewhere in Death Val- paleoshoreline configuration (Hunt and Mabey, 1966; Orme and ley (Blair, 1999; Knott et al., 2002), to infer that storm-generated Orme, 1991; Galvin and Klinger, 1996; Klinger, 2001) remain confus- west-southwest and topographically funneled north winds with ve- ing. The age of the BJBC is considered either Marine Isotope Stage locities and directions similar to present-day winds generated (MIS) 6 (186–120 ka; e.g., Phillips and Zreda, 1999; Owen et al., waves across ancient Lake Manly. These winds were topographically 2010) or MIS 2 (30–10 ka; e.g., Caskey et al., 2006; Owen et al., funneled and generated east- and south-propagating waves and 2010). Hunt and Mabey (1966) describe the BJBC as gravel bars that southerly longshore drift along the eastern shore of pluvial Lake formed on the east side of an island in Lake Manly. Orme and Orme Manly. Our study shows that the present-day wind regime is suffi- (1991) inferred that these bars formed by waves generated by cient to form the Pleistocene constructional lake forms. >31 m/s south winds across a transgressing Lake Manly eroded the same hill to the west. Galvin and Klinger (1996) also inferred forma- Background tion in a rising lake and erosion of the same hill, but that the BJBC formed by intermittent south winds that produced north- and east- Pluvial Lake Manly was located at the southwestern edge of the ward currents east of a projecting peninsula (Klinger, 2001). Great Basin in Death Valley, California, USA (Fig. 1). Unlike Lake In this study we present field observations at the BJBC, Desolation Lahontan or Lake Bonneville to the north, Lake Manly's history and for- Canyon and the Manly Terraces in an effort to determine the wave mation is more enigmatic (Machette et al., 2001). Evidence of Lake height and direction and, ultimately, wind speed that formed these Manly is found at isolated locations throughout Death Valley Lake Manly deposits. We selected the BJBC because Orme and Orme (Machette et al., 2001). In this study we focus on two of the larger, more accessible and better studied locations: the BJBC and the Desola- ⁎ Corresponding author. Fax: +1 657 278-7266. tion Canyon/Manly Terraces areas. Even though these deposits are E-mail address: [email protected] (J.R. Knott). 25 km apart, Owen et al. (2010) obtained similar cosmogenic

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o Oregon Idaho 42N 124W 114W42N 119oW 118oW 117oW 116oW

Nevada California Sierra Nevada Nevada Utah California 38oN Mono 38oN 37N 37N Las Vegas White DV

OV Arizona Los Angeles Sierra Nevada OW 32N 32N Mexico 124W 114W

37oN OC 37oN RV Funeral I n yo HM San Joaquin Valley BJBC MD Panamint OL MT PM LM Black LG 36oN FM 36oN

CL HTS SL

OM MH MRS 35oN 35oN 0 kilometers 100 119oW 118oW 117oW 116oW

Figure 1. Shaded relief map of southeastern California and southern Nevada showing major mountain ranges and the location of the Beatty Junction Bar Complex (BJBC) and Manly Terraces (MT) relative to the hypothesized pluvial lakes (hashured areas) of the Owens River system: Owens Lake (OL), Searles Lake (SL), Lake Gale (LG) and Lake Manly (LM) along with Mono Lake (Mono) (after Blackwelder, 1933, 1954). Wind roses represent wind direction and velocity from RAWS from the Five Mile (FM), Horse Thief Springs (HTS), Hunter Mountain (HM), Mojave River Sink (MRS), Mud Hills (MH), Oak Creek (OC), Opal Mountain (OM), Oriental Wash (OW), Owens Valley (OV) and Panamint Mountain (PM) weather stations from 2007 to 2010. The black arrow shows the dominant wind direction at Racetrack Playa (RV; Lorenz et al., 2011). The gray arrows indicate the annual wind ﬂow directions for the area (after Laity, 1987; Berry et al., 1981). Other locations are the China Lake Naval Air Weapons Station (CL) and the Mesquite Dunes (MD). Box in location map indicates approximate area of larger map.

radionuclide ages on both features, suggesting that these deposits B would have prevented the southerly waves from reaching the formed at the same time. lower elevation spit A (Galvin and Klinger, 1996). The BJBC is along the Beatty Cutoff Road about 2.5 km north of Desolation Canyon and the Manly Terraces are two other promi- California Route 190 junction (Blackwelder, 1954; Hunt and Mabey, nent Lake Manly deposits found at the north end of the Artists Drive 1966). Hunt and Mabey (1966) described the BJBC as bar deposits structural block (Fig. 3; Clements and Clements, 1953; Hunt and extending from a hill to the west (Fig. 2) that is composed of Pliocene Mabey, 1966; Knott and Machette, 2001). At Desolation Canyon, Lake (Wright and Troxel, 1993) conglomerate. Based on stratigraphic and Manly deposits form a spit and tombolo that are deposited around out- sedimentological data, Orme and Orme (1991) interpreted the BJBC crops of Tertiary andesite and basalt (Knott and Machette, 2001). The as transgressive barrier bars formed by south winds. They noted that Manly Terraces are 300 m wide and 850 m long with the shoreline the elevation of the crest of the highest bar decreased 4 m to the east angle incised into late Pliocene Funeral Formation conglomerate and over its 500 m length. They suspected that tectonism may be the basalt (Hunt and Mabey, 1966). The Manly Terraces overlie outcrops cause of the elevation change. In addition, they attributed the increase of brecciated white quartzite that Hunt and Mabey (1966; p. 25) hy- in pebble flatness to the east to greater wave energy away from the hill pothesized as either Cambrian Zabriskie Quartzite or Ordovician Eure- west of the BJBC rather than longshore drift from west to east. ka Quartzite. The bright white color, brecciated character and vitreous Galvin and Klinger (1996) and Klinger (2001) interpreted the BJBC luster is more consistent with the Eureka Quartzite, which we adopt as a sequence of spits that were developed by southerly wind-driven as the rock type. The nearest other outcrop of Eureka Quartzite is waves against the hill to the west of the BJBC in the transgressing Lake 25 km northwest (Hunt and Mabey, 1966). Manly. The four spits (A, B, C, and D) formed from north to south at Paleowind velocity is derived from wave competency as repre- elevations of 44.97 m, 45.97 m, 36.30 m and 33.78 m above mean sented by the maximum-size clasts moved by the waves. The sea level (asl), respectively (Galvin and Klinger, 1996; Klinger, 2001). maximum-size clasts reflect the basal shear stress generated by the Wright and Troxel (1993) and Klinger (2001) also noted the presence moving water. Orme and Orme (1991) derived paleowind velocities of another Lake Manly deposit at 19.1 m asl (Fig. 2)hereinnamedspit for the BJBC by calculating bottom velocities using the Sverdrup– E. According to Galvin and Klinger (1996), the paleogeography at the Monk–Bretschneider method that uses mean clast size. They conclud- BJBC was a peninsula that projected south into Lake Manly. This config- ed that present-day south winds of 9 m/s and 14 m/s measured in uration necessitates that spit A, which is to the north of and lower in Death Valley were insufficient to generate waves large enough to elevation than spit B, formed first; otherwise the higher elevation spit move the largest particles at the BJBC. They also concluded that to Author's personal copy

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200 To Beatty, NV

320

(150.8 ft.) sh 280 46 m ore160 line 240 120 200

80 A B C 4

200 6 40 D m Annual Wind (150

Direction 120 . 8

f sea level t . )

s h E 80 o re lin e 40 -40

Prevailing Wind sea level Direction at Panamint Mountain RAWS station

meters To Hwy 190 0 500 1000

Figure 2. Portion of the 7.5' Beatty Junction topographic quadrangle (contour elev. in feet) showing the location of the 46 m asl Lake Manly shoreline along with the Beatty Junction Bar Complex spits A, B, C, D and E (gray lines). Note that the shoreline elevation makes an island of the hill west of the spits. The gray arrows indicate the annual (from Laity, 1987) and prevailing wind directions from Panamint Mountain station. Black arrows indicate hypothesized wind-driven wave directions. Box shows the location of Fig. 5.

initiate particle motion a sustained wind speed of >31 m/s was re- clast measurements allowed for the estimation of the critical shear quired to form large enough waves to move clasts at the BJBC stress, average velocity, breaking wave height, deep-water wave (Orme and Orme, 1991, p. 344). height, wind stress factor, and ultimately the wind speed required to Adams (2003, 2004) calculated paleowind velocities at pluvial generate the waves that move the clasts. Lake Lahontan using the Beach Particle Technique (BPT). Similar to Determination of paleowind velocity also requires determination Orme and Orme (1991), Adams (2003) used maximum clast size to of fetch length. We constructed a hypothetical lake with an elevation infer wave height and wind velocity. In his study, Adams (2003) validat- of 45 m asl (Fig. 4). Lake Manly was elongated in a north–south direc- ed his method against modern bars formed in 1986–87 at the Great Salt tion and fetch length is dependent upon wind direction. The logical Lake, Utah. He calculated paleowind velocities at pluvial, late Pleisto- approach to determining fetch length is to begin with the present cene Lake Lahontan as between 9.7 m/s and 27.1 m/s. Adams (2003) wind direction; however, wind direction in the western Basin and noted along Great Basin pluvial lake shores that larger clasts are pro- Range is not simple. Based on the work of Laity (1987) and Sharp duced where basalt and andesite bedrock forms the shoreline. and Glazner (1997) our observations at the Manly Terraces and Des- olation Canyon, and our interpretation of the weather data (see Methods Discussion below), we assumed a westerly to southwesterly wind direction at the BJBC and a northwesterly wind direction at Desolation Clast dimensions were measured at multiple sites at the BJBC, Des- Canyon/Manly Terraces to determine the fetch length. With these olation Canyon, and the Manly Terraces. Because competence was the general directions, the maximum fetch length was determined visual- goal, the clasts that were measured represent the largest clasts that ly (Fig 4). The fetch was then rotated at 3° intervals to determine if a could be found. The location, general rock type, along with the a-, longer fetch was possible. b-, and c-axes lengths were recorded for each clast. Clast dimension The slope of the surface over which the particles are transported is listed are for the b-axis dimension (Table 1). At Desolation Canyon also critical. The surface slopes of Lake Manly features vary from hor- and the Manly Terraces, the distribution of Eureka Quartzite clasts izontal to 12°. The most frequent slope angles were between 3° and was also observed to determine longshore drift direction. 4°. For the calculations, we assumed a slope of 3° in order to separate Calculations of paleowind velocities were based on the BPT method wave-driven movement of clasts from gravity movement. Adams of Adams (2003, 2004) using the equations therein. The clast dimen- (2003) stated that for a 10–100 km fetch, wave periods range from sions are the most important measurement for the calculations. The 3 to 8 s under fetch-limited conditions. We assumed this range of Author's personal copy

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To Furnace Creek sea level -200 B lac Annual Wind k M o Direction u n

tains

Desolation Canyon n i

l F

spit and tombolo e a r u o lt

h Z s o n e

200 D UU

400 Eureka Quartzite Manly Terraces

600 -200

meters 0500 1000 To Badwater

Figure 3. Portion of the 7.5' Furnace Creek topographic quadrangle (contour elev. in feet) showing the paleoshoreline Lake Manly deposits and Eureka Quartzite at Desolation Can- yon and the Manly Terraces in central Death Valley relative to the Black Mountains Fault Zone. Note that the paleoshoreline here is based on outcrop and is at ~40 m asl due to tectonics. The gray arrow shows the annual wind direction (Laity, 1987). The black arrows show the direction of wind-driven waves and longshore drift derived from field observations. Box shows the location of Fig. 6. probable wave periods in our calculations along with a particle densi- exception to this is the Hunter Mountain RAWS station where there ty of 2.9 g/cm3 (Table 1). are no wind data between May 21, 2010 and August 1, 2010. We used two different sets of wind data. The first wind data set is The second set of wind data is hourly mean wind speed and direc- the daily wind summary data from Remote Automatic Weather Sta- tion from a National Oceanic and Atmospheric Administration tions (RAWS) predominantly operated by the Bureau of Land Man- (NOAA) station at the China Lake Naval Air Weapons Station (China agement and available from the Western Regional Climate Center Lake; Fig. 1). We selected data from China Lake for the calendar (http://www.raws.dri.edu). RAWS wind data for the period 1/1/ year 2007 to be consistent with Lorenz et al. (2011). Wind speed 2007–12/31/2010 is available as daily mean wind speed and wind di- was recorded at least hourly at China Lake with the exception of rection based on hourly observations. For simplicity, these data are June 23–27 when wind data was sporadically collected. These data represented by wind rose diagrams (Figs. 1 and 4). Lorenz et al. were used to determine wind events as defined by Adams (2003). (2011) found that RAWS data were representative of synoptic wind Other weather stations exist in the Death Valley area; however, direction and comparable to local, portable wind measurements at many of these are in close proximity to the stations shown (Fig. 1) Racetrack Valley in northwest Death Valley National Park (Fig. 1). with no significant difference in observations. A NOAA CRN weather Each of the above RAWS wind data sets has data gaps; however, station exists at Stovepipe Wells (http://gis.ncdc.noaa.gov) about these data gaps are incomplete hourly data rather than missing 25 km west of the BJBC, but the wind direction data are not archived. “days” of data. Each RAWS station has wind speed and direction ob- Two NOAA Cooperative Network (NOAA-COOP) weather stations servations for all 1461 days of the designated time frame. The exist at Cow Creek and Furnace Creek in central Death Valley (http://wrcc.dri.edu/coopmap); however, wind data are not archived from these stations either. Table 1 Calculated paleowind velocities for three locations in Death Valley. Calculations were done using the Beach Particle Technique of Adams (2003, 2004). Results

Field site Fetch Probable Clast size Calculated location period (s) wind speed Paleowind velocity (UTM) Length Direction Median Max (m/s) (mph) (km) (cm) (cm) The dimensions of 191 clasts were measured from Lake Manly deposits at the BJBC, Desolation Canyon, and the Manly Terraces. Clasts Beatty Bar 24 NW–SE 8 11 20 14 32 24 NW–SE 3 11 20 21 49 ranged from oblate to equant with the highest percentage of oblate Desolation 42 NW–SE 8 13 29 17 39 (most rounded) clasts found at the BJBC. The median length of the in- Canyon 42 NW–SE 3 13 29 27 60 termediate clast dimension at the Manly Terraces was 15.2 cm (n= – Manly 42 NW SE 8 15 27 15 35 21) whereas the same dimension at the BJBC was 10.9 cm (n=99) Terraces 42 NW–SE 3 15 27 23 52 and Desolation Canyon (n=71) was 12.7 cm. Using the BPT method Author's personal copy

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37oN Funeral Range

36o50’ 42 24

BJBC 36o40’ regional wind Three Bare Hills

36o30’

Death Valley Desolation Canyon Manly Terraces

Black Mountains 36o20’

Panamint Range

36o10’ 46 m (150 ft) amsl shoreline amsl ft) (150 m 46 Mormon Point 36oN

Warm Springs Fan Shoreline Butte 0 km 10

117o10’ 117oW 116o50’ 116o40’

Figure 4. Shaded relief map of Death Valley showing the 46 m (150 ft) m asl Lake Manly shoreline (dotted line), location of the Beatty Junction Bar Complex (BJBC), Desolation Canyon and Manly Terraces; bounding mountain ranges; regional wind direction (gray arrow) from Laity (1987) and the wind rose from the Panamint Mountain RAWS station. Black arrows indicate wave directions determined in this study and by others. Solid white lines indicate fetch length and direction for BJBC; dashed lines indicate fetch length and direction for Desolation Canyon. Dotted area is the location of Mesquite Flat dune ﬁeld. Boxes outline approximate locations of Figs. 2 and 3. of Adams (2003, 2004), the calculated paleowind velocities required to Mabey (1966). The area between spit A and spit B is covered by Qg2 move clasts of these dimensions ranged from 14 to 27 m/s (Table 1). and Qg3 deposits. In a stream cut at its east end, spit B is overlain by ﬁne-grained deposits interpreted as a playa. These playa deposits are Wind direction and longshore drift overlain by alluvial fan deposits with a well-developed desert pavement that are equivalent to the Qg2 deposits of Hunt and Mabey (1966). We completed a geologic map of the BJBC to elucidate the stratigraph- Clast imbrications in the roadcut and stream cut were generally ic relations among spits A, B, C and D (Fig. 5). Our mapping shows that trending north–south, as described previously by Orme and Orme spits B, C and D form a contiguous deposit. In contrast, we found that (1991). However, acceptable outcrops of Lake Manly deposits were the east end of spit A is overlain by alluvial fan deposits with a subdued limited to the highest bar (spit B of Galvin and Klinger, 1996) where bar-and-swale topography equivalent to the Qg3 deposits of Hunt and the best incisions and cuts through the bar are oriented north– Author's personal copy

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Qg3 spit A Qg4 Qg 36o 37.0’ N 3 Qlm

Qg2 Qg4

spit B Qlm 36o 36.8’ N Qg Qg2 2 Qg4 spit C Tfcc spit D

kilometers 0 0.5 1

36o 36.6’ N 116o57.0’ W 116o56.75’ W 116o56.5’ W

Qg4 Active alluvial fan: poorly sorted breccia to sand with little varnish on clasts and bar and swale topography

Intermediate alluvial fan: breccia to sand with subdued bar-and-swale topography and moderately varnished clasts Qg3

Older alluvial fan: breccia to sand with well-developed desert pavement and well varnished clasts Qg2

Qlm Lake Manly deposits: bimodally sorted, poorly cemented, equant to platey clasts with spits A, B, C & D labeled.

Tfcc Furnace Creek Formation: poorly to moderately cemented, poorly sorted conglomerate and sandstone

Figure 5. Geologic map of the Beatty Junction Bar Complex. Base is a Google Earth image. Geologic units after Hunt and Mabey (1966) and Wright and Troxel (1993). south; alternately oriented cuts or incisions are poor, which effective- p. 69) noted that the hill west of the BJBC was an island when the ly prevented determination if clasts are imbricated in any other direc- spit was built. In contrast, Galvin and Klinger (1996) hypothesized tion (i.e., east–west) or if the north–south imbrication is an apparent that the hill to the west was part of a south-projecting peninsula. trend direction. This peninsula configuration means that spit A (44.97 m asl) must AttheDesolationCanyonspit(Fig. 3), foreset beds were found to dip have formed before spit B (45.97 m asl) because spit B and the penin- south and climb to the south (Fig. 6). The crest of the tombolo to the sula prevented waves generated by southerly winds from reaching west of this spit is oriented north–south and is convex to the west. spit A (Galvin and Klinger, 1996). Klinger (2001) supported this hy- Clasts composing the Desolation Canyon spit and tombolo are a mixture pothesis with a cross section showing superposition of the spits of the Tertiary andesite and basalt that crop out north of these lake fea- with spit A overlying spit B. tures. Both the spit and tombolo are north of outcrops of the Eureka We could not confirm the superposed relations between spits A and Quartzite; no quartzite clasts were observed in the spit or tombolo. B(Fig. 5). The few outcrops between spits A and B are alluvial-fan de- The Manly Terraces, which are south of the Desolation Canyon spit posits with no outcrops of lake deposits. Plotting the 45.97-m and tombolo (Fig. 3), are incised by active stream channels allowing (150.8-ft) contour of the spit B highstand on a topographic map of the the observation that foreset beds dip to both the east and south. Clasts BJBC shows that the hill to the west would be an island rather than a were dominantly equant in shape and a mixture of Tertiary basalt and peninsula (Fig. 2). We entertained the alternative hypothesis that the Eureka Quartzite; Eureka Quartzite clasts were found only east and neck of the Lake Manly peninsula was subsequently eroded; however, south of the bedrock outcroppings. we dismissed this hypothesis because erosion of the peninsula neck would result in erosion of spit A also and the spit is clearly present. Discussion Based on the topography and spit crest elevations from Klinger (2001), our hypothesis is that the hill to the west was an island, as Beatty Junction Bar Complex Hunt and Mabey (1966) inferred. An island configuration would allow waves around the north side where spit A (44.97 m asl) There is some confusion regarding the shoreline configuration formed. Thus, spit A is not required to form before spit B (45.97 m when the BJBC spits were formed (Fig. 2). Hunt and Mabey (1966, asl). Spit A could have formed during either lake regression or Author's personal copy

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Figure 6. Photograph of the Desolation Canyon spit showing foreset beds dipping and climbing to the south. People atop the spit for scale. transgression or at the same time as spit B. Adams and Wesnousky of this working hypothesis is that spit A formed before spit B during (1998) found that constructional, highstand features formed at the lake transgression as waves moved around the island to the west or at Lake Lahontan highstand had up to 2.6 m in elevation difference. thesametimeasspitB. If our hypothesis that the hill to the west was an island when the BJBC formed is correct, then we infer that the simplest explanation of Wind velocity the BJBC spits is that they formed as Lake Manly regressed rather than We calculated wind velocities of 14 to 27 m/s using the BPT method the complex sequence previously proposed to form and preserve the of Adams (2003, 2004). Orme and Orme (1991; p. 344) calculated that BJBC. Orme and Orme (1991) did not consider spit A; however, they the winds required to make waves high enough to initiate clast move- inferred that Lake Manly receded rapidly in order to preserve spits ment at the BJBC were >31 m/s. The calculated wind velocity differ- C and D. If spits A, C, D and E formed during lake regression from ences might be attributable to calculation method. Orme and Orme the elevation of spit B, then it is not necessary for rapid lake recession (1991) measured 90 rocks at two locations along spit B at the BJBC to occur and the lower-elevation features are preserved as lake level where clasts are reworked from sedimentary rock and found a mean drops. At Lake Lahonton, a pluvial lake in west-central Nevada north b-axis diameter of 1.6–6.4 cm. In contrast, we measured clasts at spits of Death Valley, Adams and Wesnousky (1998) noted that many of A–D and used a maximum b-axis diameter of 20 cm at the BJBC. We the preserved surficial nearshore features formed during lake reces- also found larger clasts at Desolation Canyon and the Manly Terraces, sion with only a few transgressive features preserved. which should logically have resulted in higher wind velocities than In a more complex process dependent upon the presence of a pen- those calculated by Orme and Orme (1991); however, our wind velocity insula, Galvin and Klinger (1996) implied that Lake Manly transgressed was less. This difference is likely due to the calculation methods where to 44.97 m asl to first form spit A along its north paleoshoreline. Then, the BPT method uses both median and maximum dimensions to ac- the water level rose an additional ~1 m to 45.97 m and formed spit B count for grain pivot whereas the Sverdrup–Monk–Bretschneider offshore rather than at the paleoshoreline, thereby preserving spit A. method used by Orme and Orme (1991) uses mean grain size only. Lake Manly subsequently receded with pauses to form spits C, D and The question remains, however, are these velocities reasonable? E(Fig. 2). With the hypothesized island configuration, spits A and B Are wind velocities 14 to 27 m/s in Death Valley today and how may have formed simultaneously as waves wrapped around the island often do they occur? Wind direction and velocity in the southern (Fig. 2) or as Lake Manly rose or receded. The southwesterly to wester- Basin and Range is difficult to characterize due to the steep, north– ly winds shown by the present-day wind roses would also drive waves south trending, topographic relief that is counter to the east–west around the north side of the island and facilitated formation of spit A. synoptic wind regime—and Death Valley is no exception (Fig. 1). Galvin and Klinger (1996) hypothesized that the spits formed Adams (2003) was fortunate to have wind velocity and direction during transgression as waves easily eroded sediment from the hill data from stations located within the limits of pluvial Lake Lahontan. to the west. Subsequently, this erodible sediment was lacking during Wind data from within Death Valley itself is not archived at RAWS or regression. We found the conglomerate that composes the hill to the NOAA climate data sites in the valley leaving regional wind data as west (Fig. 5) remarkably homogeneous and poorly cemented. Thus, proxies for wind direction and velocity. Within the suspected time the sediment deficit hypothesis may still be true; however, we did frame of Lake Manly (ca. 180 ka or ca. 30 ka), the present topography not find the induration or composition conditions that might support has not changed appreciably, so large-scale topographic changes that this hypothesis. would impact wind regime need not be considered. In summary, our observations support the hypothesis that Lake Regional winds are generally westerly in the southwestern US Manly rose to an elevation near 45.97 m asl, making the hill to the (Fig. 1) with the highest velocity winds during the spring (Laity, west of the BJBC an island. Lake Manly then receded with significant 1987 after Berry et al., 1981). Winds in Death Valley vary seasonally pauses at 44.97 m, 36.30 m, 33.78 m and 19.1 m to form spits A, C, D with lower velocity, southerly winds during the summer months and E, respectively (Fig. 2). Funneled north winds and west-southwest and higher velocity, northerly winds during the spring and winter winds drove waves around the island to form spit A. Another variation months (Laity, 1987). Laity (1987) characterized the annual wind Author's personal copy

370 J.R. Knott et al. / Quaternary Research 78 (2012) 363–372 direction in Death Valley as from the north (Fig. 1). Northerly winds 19 m/s in February. A total of 83 wind events occurred at China in Death Valley are consistent with the 2007–2010 winds recorded Lake in 2007 with at least one wind event each month. In comparison, at the Oriental Wash RAWS site (Fig. 1), which is located in a valley Adams (2003) identified 58 wind events at the Salt Lake City airport bottom north of Death Valley. In addition, Sharp and Glazner (1997) during the two-year period of 1986–87 (29 events/year) and 203 point out that the sand source for the Mesquite Flat dune field wind events at Fallon Naval Air Station in the 8 yr from 1992 to (Fig. 1) is from the dry lake sediments to the north—indicating 1999 (25 events/year). Clearly, it's windier in the Death Valley region. dominant north winds. The Mesquite Flat dunes, however, are a star As Adams (2003) observed, however, a wind event may not cap- dune suggesting that wind direction is variable and funneled westerly ture the full picture of the wind regime. For example, three wind winds are common as illustrated by the Hunter Mountain wind data events occurred during a 36-hour period from February 25 to 26 (Fig. 1). The dominant wind direction at the Panamint Mountain (Fig. 7). During that time, 74 wind velocity measurements were station is west-southwest or parallel to the orientation of the valley made with only three measurements below the 9 m/s threshold and where the station is located. The same relations exist between wind the median wind velocity was 12 m/s. Between 13:56 and 19:56 on direction and valley orientation for the Hunter Mountain and Oriental February 25 and between 03:12 and 07:56 on February 26, the wind Wash stations (Fig. 1) suggesting topographic funneling of winds in velocity was >14 m/s. In effect, the wind exceeded 9 m/s for nearly the Death Valley region. 36 h with a maximum velocity of 19 m/s. Racetrack Valley, northwest of Death Valley, is a 4-km-wide, Regional weather stations near Death Valley recorded monthly north–south trending valley with 630 m of relief (Fig. 1) where maximum wind velocities ranging from 11 to 34 m/s. Eighty-three Lorenz et al. (2011) collected local wind, temperature and precipita- sustained wind events where wind velocity exceeded 9 m/s occurred tion data using portable automated weather stations. They found at China Lake during 2007 with a maximum velocity of 19 m/s. These that the local wind direction and velocity were from the south but average and discrete wind velocities are within the range of the wind were generated by westerly winds topographically funneled by local velocities that we calculated (14 to 27 m/s). Thus, we infer that the topography. They concluded that, in spite of the topographic condi- wind velocities present today could have formed the Lake Manly tions, the data from the surrounding RAWS stations were useful and features. similar to the local climate data they collected with portable weather In contrast, Orme and Orme (1991) found that present-day winds stations. If we accept the conclusions of these studies (Laity, 1987; were insufficient to move Lake Manly clasts. In their study, they state Sharp and Glazner, 1997; Lorenz et al., 2011) that wind direction that winds of 9 and 14 m/s were recorded by the National Park Service and speed is strongly influenced by topography and variable in the for predominantly southerly winds (SSE–SSW) in Death Valley. They Death Valley region (Fig. 1) but that RAWS and other regional stations assumed that these values were representative of the Death Valley may be used to represent regional wind condition, then we can com- wind conditions. Based on Lorenz et al.'s (2011) conclusion that region- pare our calculated wind speed of 14 to 27 m/s to regional weather al RAWS data was representative of local (i.e., Death Valley) wind re- station data. gimes, we infer that the more temporally and spatially comprehensive Average wind velocities during 2007–2010 at the five RAWS stations data set from the RAWS stations that surround Death Valley is an equiv- near Death Valley (Panamint, Hunter Mountain, Oriental Wash, Horse alent, if not improved, representation of the Death Valley wind regime Thief Springs, and Mojave River Sink) ranged from 0.6–4.1 m/s with and sufficient to move Lake Manly clasts. maximum wind speeds ranging from 34.8 m/s (Panamint Mountain) to 11.6 m/s (Hunter Mountain). These maximum wind speeds repre- Wind direction sent the average speed over 1 h. Adams (2003) suggested that Orme and Orme (1991), who focused on southerly present-day wind-generated waves that move clasts must be sustained and require winds, observed that high-velocity southwesterly winds might pro- “wind events” that he defined as three consecutive hours when hourly duce 1.8-m-high, short-period waves that may have moved clasts at wind speed exceeded 9 m/s. the BJBC. As a result, they posed the question of whether or not the Do sustained wind events occur in the Death Valley region? The wind direction was different when the BJBC was formed. Wind direc- closest weather station where hourly wind velocity is archived is at tions in the western Basin and Range are highly influenced by topog- China Lake about 100 km west of Death Valley. The hourly wind ve- raphy as the wind roses show (Fig. 1) and as observed by Lorenz et al. locity archived from China Lake showed that during 2007 the month- (2011). West of Death Valley (Panamint and Hunter Mountain), wind ly maximum wind velocity ranged from 11 m/s in November to direction is dominantly from the south and southwest; however,

25 290 Velocity Azimuth 270 20

250 15 230

210 10 9 m/sec

190 Velocity (m/sec) Azimuth (degrees) 5 170 February 25, 2007 February 26, 2007 150 0 00 0740 1200 1900 2000 2100 0200 0600 1800 1200 2200 Time (hours)

Figure 7. Time series plot of wind velocity and direction during the February 25–26, 2007 storm at the China Lake Naval Air Weapons Station (CL on Fig. 1). Note that there are only 3 non-consecutive velocity measurements below the 9 m/s wind-event threshold velocity of Adams (2003). Author's personal copy

J.R. Knott et al. / Quaternary Research 78 (2012) 363–372 371 north and east of Death Valley (Oriental Wash and Horse Thief bar crest and the position of the deposit behind prominent hills may Spring), the dominant wind direction is from the north (Fig. 1). explain the unusual configuration and foreset dip; however, we did These varying wind directions are expressed by the Mesquite Flat not explore this location and this is an obvious object of future work. dunes at the northern end of the Panamint Mountains (Fig. 4). Sharp and Glazner (1997) inferred that the source for the dunes is the Conclusions playa surface north of the dune, implying north winds; however, the Mesquite Flat dunes are a star dune complex, which forms by variable Wind direction and velocity in the western Basin and Range are wind directions. Thus, the wind direction in Death Valley is variable. strongly influenced by topography (Fig. 1) and storm movement The 36-hour high wind storm described above also illustrates the (Fig. 7). We used the BPT method to determine wind velocity on con- variability of wind direction during a storm event (Fig. 7). During that structional landforms of Lake Manly. The largest, wave-rounded clasts storm, initial winds were 13 m/s from 280°. At the end of this partic- were found at the Manly Terraces where the substrate consists of Ter- ular storm, when wind velocity dropped below 9 m/s, 36 h later, the tiary basalt. At the BJBC, the smaller clasts were reworked from the wind direction had shifted 70° toward the south to 210°. As a result, adjoining Tertiary conglomerate. Based on the BPT method, wind speeds these data support the hypotheses put forth by Orme and Orme required to generate waves that moved clasts on constructive Lake (1991) and Galvin and Klinger (1996) that occasional strong winds Manly features in Death Valley were 14–27 m/s. These velocities are from the south may have formed the BJBC. Imbrication directions at within the range of average maximum wind velocities (11–34 m/s) the BJBC might help resolve wind direction, however, we found the from 2007 to 2010 and wind event velocities at China Lake during outcrops at the BJBC where Orme and Orme (1991) and Galvin and 2007. Adams (2003) calculated Pleistocene wind velocities of 9–27 m/s Klinger (1996) made their observations limited and therefore cannot at Lake Lahonton to the north of Death Valley. Thus, we infer that the fi eliminate other wind directions or con rm a single wind direction. wind velocities that formed the Lake Manly deposits were similar to Orme and Orme (1991) observed that the crest of spit B at the BJBC the present-day wind velocities in the region and that Death Valley is fl decreased in elevation by 4 m from west to east and that pebble at- windier. ness increased to the east. They explained the elevation difference as Orme and Orme (1991) calculated an initiation velocity of >31 m/s tectonic tilting and the shape change as higher wave energy away using the Sverdrup–Monk–Bretschneider method that used mean clast from the hill to the west. The most active and closest fault to the size. The BPT method uses both median and maximum clast size to ac- BJBC is the Northern Death Valley fault zone, which is 2 km to the count for clast shape. This methodology difference may account for the southwest (Wright and Troxel, 1993). Here the fault is dominantly lower wind velocity that we calculated. b strike slip with scarps at the fault of 1 m high with the adjoining We explain the difference in clast sizes between our study and hills only a few meters high (Brogan et al., 1991). Thus, it is unlikely Orme and Orme (1991) as differing clast source (reworked conglom- that the BJBC is tectonically tilted 4 m at a distance of 2 km from the erate vs. basalt) and number of clasts measured. At Desolation Canyon fault. If the tilting of spit B is not tectonically tilted, then the elevation and the Manly Terraces, sedimentary structures and the southerly change of spit B may just as easily be due to easterly longshore drift. transport of Eureka Quartzite clasts (Fig. 3) infer wave propagation fl The attening of the clasts to the east is just as reasonably due to from the north-northwest and west with a longshore drift to the reworking of clasts from west to east, which would be consistent south, which is consistent with other observations of wave transport with an elevation decrease in that direction. in southern Death Valley (Fig 4). We propose an alternative hypothesis and interpretation that the Plotting of the surveyed crest elevation (45.97 m asl) of the highest fl decrease in elevation from west to east of spit B and the attening of spit (spit B) as the water level of Lake Manly indicates that the hill to clasts in that same direction indicates west-to-east reworking of clasts the west of the BJBC was an island. Hunt and Mabey (1966) made in the BJBC. Reworking and moving of clasts to the east would require this same observation. The island configuration would allow waves more southwesterly to westerly winds. This westerly-southwesterly around the north end and formation of spit A at 44.97 m asl. Spits A wind direction is consistent with present-day wind directions and B could have formed synchronously or as Lake Manly receded or recorded at the Panamint Mountain RAWS station and the variable rose. Because the elevation difference between spits A and B is only wind directions forming the Mesquite star dune complex. A more a meter, we hypothesize that spits A and B formed synchronously. westerly wind direction would also explain the formation of spit A We hypothesize that the remaining spits (C, D and E) simply formed by wind-driven waves around the north end of an island (Fig. 2). as Lake Manly receded rather than during shoreline transgression, as Outcrops and observations at both Desolation Canyon and the required if the hill to the west was a peninsula. Manly Terraces indicate that north-to-south and west-to-east waves transported Eureka Quartzite clasts with longshore drift to the south Acknowledgments (Figs. 3 and 4). The west-to-east transport direction is consistent with the hypothesized westerly wind direction at the BJBC. The This study is the product of a graduate course in Quaternary Geol- north-to-south longshore drift at the Manly Terraces and north to ogy at California State University Fullerton taught by Knott. Support south wave direction is also consistent with the northerly annual for this study was, in part, from grants to Knott from the Petroleum winds (Laity, 1987) topographically funneled to the south. Research Fund (43505-B and 46581-UFS) as well as California State Topographically funneled winds from the north are also consistent University Fullerton. We thank Dr. Ken Adams of the Desert Research with Blair's (1999) description of south-dipping foresets in Lake Institute for assistance and discussions on paleowind calculations. Re- Manly deposits at Warm Springs Canyon (Fig. 4). At Mormon Point, views of an earlier version by Dr. Adams and two anonymous reviews foresets dip south and nearshore gravels are also transported to the greatly improved the manuscript. south (Knott et al., 2002). In addition, north winds are consistent with the putative wave-cut benches at Shoreline Butte in southern Death Valley (Noble, 1926). These benches face north and it seems References unlikely that these benches would form by south-to-north waves Adams, K.D., 2003. Estimating palaeowind strength from beach deposits. Sedimentolo- driven by south winds (Fig. 4). gy 50, 565–577. A marked anomaly in our hypothesis is the Lake Manly deposits at Adams, K.D., 2004. Estimating palaeowind strength from beach deposits — reply. Sed- the Three Bare Hills about 5 km southeast of the BJBC (Fig. 4). There, imentology 51, 671–673. Adams, K.D., Wesnousky, S.G., 1998. Shoreline processes and the age of the Lake Hunt and Mabey (1966, p. 69) described foreset beds dipping 10° Lahontan highstand in the Jessup embayment, Nevada. Geological Society of Amer- northwest and a bar crest that arcs over 90°. This wide sweep of the ica Bulletin 110, 1318–1332. Author's personal copy

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