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GS Field Trip: End of Summer 2016 GS191/291 (Miller, no Klemperer (went to Tibet), Lund Snee, Gottlieb) Listed as Fall Quarter class under Miller

Crossing the Cordillera: From the Colorado Plateau to the Sierra Nevada Field trip (1 credit), advanced ugrad to grad level, but all welcome

Dates: September 15 to Sept. 21 (T.A. Eric Gottlieb)

There is unprecedented controversy about the paleo-topographic evolution of the western United States. How thick and how high was the crust following Mesozoic crustal shortening? Did the region between the Sierra Nevada and the Colorado Plateau form a high plateau, the Nevadaplano, underlain by 60 km thick crust? When did this thick crust collapse to its present crustal thickness of only 30 km? Did extension happen as a result of, during and shortly after crustal thickening? Or did extension take place only in the Miocene, during formation of Basin and Range topography? How much stretching is represented by Basin and Range faulting? Can it account for thinning of crust by 30 km? This field trip will provide you with an exceptional opportunity to view a complete cross-section of the geology of the southern part of the North American Cordillera, from the undeformed Colorado Plateau on the east to Mount Whitney and the Mesozoic Sierra Nevada arc on the west. With these big questions in mind, our stops will focus on Mesozoic shortening, when the Cordillera is believed to have looked like the Andes, and on younger extensional structures (including a variety faults in Death Valley), with a critical view and discussion of age, geometry and offset along normal faults. Journal articles, field trip guidebooks and maps will be available before and during the trip. It will be quite hot but cooler in the evenings. Some of our camping is wilderness camping. Small tent, sleeping bag, etc., suggested.

Aerial view of the Cretaceous Keystone thrust system, outside of Las Vegas: thrust fault places grey Cambrian limestone on top of red and white Jurassic Aztec sandstone

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Introduction This trip will provide an exceptional opportunity to view a complete cross-section of the geology of the southern part of the North American Cordillera, from the Colorado Plateau to the Sierra Nevada. We will focus on the older Mesozoic history of shortening within the Cordillera, when it is believed to have looked like the Andes or southern British Columbia Rocky Mountain fold and thrust belt, as well as its younger history of Cenozoic extension and faulting, which has significantly chopped up and complicated our view of the older geology. Cenozoic normal faults are particularly controversial in terms of their style, geometry and amount of slip, and we will see faults that exhibit the observed range of geometries, dips, and slip amounts. Several of our stops in the western part of our transect will highlight metamorphic and igneous rocks of both Mesozoic and Cenozoic age to evaluate the roles and relationships between deformation, metamorphism and magmatism at deeper crustal levels of the Cordillera.

The following section provides thumbnail sketches of what we will be visiting. Approximate routes and mileages follow. Original descriptions and references (if available) are in in the Appendix at the rear of the guidebook. These descriptions are resurrected from hard-to-find field trip guides that still form an important part of the “grey literature” of the geology of the west. It’s work in progress!

Fig. 1. The “big picture”: Index geologic map of the western U.S.

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Fig. 2. Combined California and Nevada state geologic maps.

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Itinerary and Stops Day 1 (Sept. 15): Drive to campsite outside of Las Vegas in the Spring Mountains (Sites 1 and 2, Hilltop Campground, Spring Mountains National Recreation Area: 36.309345º, -115.607200º, Reservation numbers: 2-36397156 & 2-36397155, Contact: 888-448-1474). Directions from I-15 northbound, starting south of Vegas. Sept. 15 Thursday Day 1: Drive to campsite outside of Las Vegas in the Spring Mountains The Spring Mountains constitute a large intact structural block that was little-affected by Cenozoic faulting, so it’s a great place to study Paleozoic stratigraphy and Mesozoic thrust fault history. The Spring Mountains expose a series of thrust faults that carry increasingly thick sections of Paleozoic stratigraphy in their hanging walls.

Fig. 3. Tectonic sketch map of the Spring Mountains showing the various Mesozoic thrust plates, emplaced from NW to the SE (from Burchfiel et al., 1974).

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Day 2 (Sept. 16): Overview: We begin our tour with the stratigraphy of the “foreland” of the Cordillera, known as the “Grand Canyon sequence” a thin platformal sequence that covered the western portion of the North American continent after it rifted away from another continent > 600 Ma. This initial rifting led to the deposition of the Cordilleran passive margin sequence in the Paleozoic. The platformal sequence is exposed at Frenchman Mountain, east of Las Vegas, where we will see its basal unconformity above > 1.7 Ga metamorphic and igneous rocks of the North American craton. We will then examine some of the major Mesozoic thrust faults of the Sevier foreland fold and thrust belt. These emplace thicker stratigraphic sequences of the Cordilleran passive margin (subsiding continental shelf) eastward across the much thinner cratonic sequence. We will have ample opportunity to view and learn about the units of the Cordilleran passive margin and you will want of refer frequently to the stratigraphic columns included in this guide. We will discuss the timing of thrusting (Mesozoic) and proceed westwards through the thrust belt, looking at the Red Springs and Keystone thrust faults. Stop 1: The Great Unconformity at Frenchman Mountain. Driving: From Hilltop Campground (1.25 hr / 51 mi without traffic). East on Lake Mead Blvd to where the road passes over the northern part of Frenchman Mountain. Stop and hike to see basal unconformity and talk about the stratified units of the platform sequence and their thicknesses. Reference: Steve Rowland, Geology UNLV. http://geoscience.unlv.edu/pub/rowland/Virtual/virtualfm.html

Fig. 4. Location map to Frenchman Mountain.

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Fig. 5. Google image of Frenchman Mountain.

Fig. 6. The basal unconformity is defined by the Tapeats Sandstone (~ 500 Ma) that lies above the Vishnu Schist (1.7 Ga and older here). Reference: Steve Rowland, Geology UNLV,

http://geoscience.unlv.edu/pub/rowland/Virtual/virtualfm.html Looking south. Altogether the section above the unconformity is less than 5 km thick. Let’s compare that to the shelf sequences deposited to the west in the next

stops and on the next figures!

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The Great Unconformity is best known from dramatic exposures in the Inner Gorge of the Grand Canyon. The unconformity was named by Clarence Dutton in his 1882 book Tertiary History of the Grand Cañon District. People are sometimes surprised to learn that at Frenchman Mountain they can visit the Great Unconformity without taking a long hike down into a deep canyon. Thank you, Miocene Basin and Range faulting and tilting! Let’s estimate the tilt of units here and the probable geometry of the normal fault bounding Frenchman Mountain.

Fig. 7. Cross Section of Frenchman Mountain by James E. Faulds. Reference: Steve Rowland, Geology UNLV, http://geoscience.unlv.edu/pub/rowland/Virtual/virtualfm.html Note that the horizontal and vertical scales are the

same and that most of these faults (except for the range-bounding fault) have small displacements.

Questions: What do you think of the angles between faults and bedding? Does the Frenchman Mountain normal fault (which bounds the western side of Frenchman Mt.) bottom into a detachment fault with 80 km of net slip? Or does it merge at depth with the DBTZ and is motion compensated by flow of the crust below? The cartoon below illustrates one of the end-member interpretations of what happens to normal faults at depth. Here they are shown as merging into a brittle shallow angle detachment fault with a significant magnitude of slip, increasing to the west! The alternative end-member interpretation is that normal faults merge down into a brittle-ductile transition zone in the crust where their horizontal component of slip is matched by ductile stretching and flow beneath (e.g. the McKenzie pure shear model below):

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Fig. 8. Cartoon of the low angle brittle fault model of Wernicke (19XX) (top) from Steve Rowland, Geology UNLV, http://geoscience.unlv.edu/pub/rowland/Virtual/virtualfm.html, the classic uniform pure shear model of McKenzie (reference) (middle and a crustal scale cross section from the Sierra east by Surpless et al. (2002) illustrating the

Stanford view of normal faults.

Stops 2 and 3: Red Rock Canyon Scenic area Driving Directions from the Las Vegas Strip south of Russell Road: Get on to the I-15 south Take exit 36 for Russell Road/215 west Keep left at the fork, follow signs for Interstate 15 south Keep right at the fork, follow signs for 215 west and merge onto 215 west for 13.5 miles Take exit 26 for Charleston Boulevard and turn left Continue onto State Route 159/ West Charleston Boulevard for 5.5 miles. Turn right into the entrance of Red RockCanyon National Conservation Area

Driving Directions from State Route 160:Get on to the I-15. Take exit 33 toward State Route160 west /Blue Diamond Road. Keep right at the fork and merge onto State Route 160 west /Blue Diamond Road for 10.5 miles. Turn right onto State Route 159 east/Charleston Boulevard (opposite the gas station) drive for 10.5 miles. Turn left into the entrance of Red Rock Canyon.

Fig. 9. Driving to Red Rock Canyon

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Fig. 10. Stratigraphic sections of the Spring Mountains and adjacent Frenchman Mountain. Note the addition of units along unconformities and the thicker sections to the west and in higher thrust plates (from Burchfiel and Davis,

1988).

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Fig. 11. Simplified geologic map of the Keystone thrust (K) showing structural blocks of the underlying, older and enigmatic “Red Springs Thrust” beneath the main Keystone thrust. The Red Springs thrust is cut by a series of

normal or strike-slip faults that are all truncated by the more continuous Keystone thrust. (The Red Springs thrust moved across its own debris that includes an ash dated at 150 ± 10 Ma (Carr, 1980; Axen, 1987) and thus is about

that age or slightly younger.

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Stop 2: Climb around and photo ops of giant cross-beds in the Aztec Sandstone along the north side of the Scenic Loop Drive. Stop 3 (From Axen,1987, his Site 3, Fig. 3): Here we will look at a part of the Red Springs thrust and see evidence that it rode over the ground surface, burying debris derived from the erosion of the moving thrust plate that became structurally buried in its footwall. Directions: Take Loop Drive to intersection with W hite Rock Spring Road and turn right (northwest). 23.9 38.4 End of W hite Rock Spring Road; park here. Cross the wash to the right (northeast) and walk cross-country toward the black hill for about 660 ft (200 m) until you meet an abandoned Jeep trail. W alk north on the Jeep trail, around the northwest end of the black hill to the Aztec Sandstone outcrop on the northeast side, to Site 3. A llow 15-20 minutes for the walk, 1.5 hours from the time you leave the parking area until you return. Driving to the parking spot from Stop 2 should take ~10 minutes (~1.7 mi). As one walks from the parking area to the site, the buried trace of the La Madre fault is crossed. Here the La Madre fault has about 3.6 mi (6 km) of right-lateral separation, or about 4,290 ft (1,300 m) of northeast-side-down separation, and bounds the northeast side of a large horst(?) formed by the Aztec Sandstone cliffs to the southwest. Drive out the scenic loop and get on I-15 South. Optional Stop 4 (historical). Take Exit and drive to Goodsprings to check out the historic bar. (>1 hr (57 mi) from Stop 3). Stop 5. Pachalka Thrust (equivalent to the Winters Pass thrust). Spectacular exposure of knife-sharp contact between Precambrian gneisses in hanging wall and Cambrian clastic rocks in the footwall. Short hike up wash (Burchfiel and Davis stop 2.8) or along road (see their description below). This is a good example of higher thrust sheets carrying hotter metamorphic rocks in their hanging walls. See index map and Google images. How to get there: Cima Road intersects 15 at exit 272. Take it to the north (called Excelsior Mine or Kingston Road in that direction). At a very slight bend, there is a small road to the east, to Pachalka Springs. Take that. Drive north to a poorly graded dirt road that leads eastward toward Pachalka Spring on the west flank of the Clark Mountains. The turnoff lies not far to the north of a round metal water tank on the east side of the road. Stop 2-8 Pachalka Spring road: the Pachalka thrust (Figure below). Google directions to Pachalka Spring from Goodsprings (~1.25 hr without traffic / 53 mi from Goodsprings; 2 hr without traffic / 96 mi from Stop 3 at Red Rocks):

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Fig. 12. Google images of Pachalka thrust stop. Red lines are equivalent to 1 km for scale.

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Fig. 13. From Burchfield and Davis (1988) showing the various Mesozoic thrust sheets and their names in both the

Spring and Clark Mountains. For details of the Clark Mountains, see Figure 15.

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Fig. 14. Relevant age and facies transect of older part of shelf sequence from Las Vegas to Death Valley, showing the addition of thick Precambrian to Cambrian clastic units to the west (Stewart, 1980).

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Fig. 15. Simplified geologic map of the Clark Mountains showing the location of the exposure of the Pachalka Springs/Winters Pass thrust (Burchfiel and Davis, 1988).

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Proceed to Tecopa Pass campsite for night 2. Note: There are 2 Tecopa Passes. One is in the Kingston Range and is near a campground. Seems like a much better place to camp. The other is further west, slightly east of the town of Tecopa, with no campground. We could camp at either one but the campground near the eastern one, in the Kingston Range, is more logical after a long day (closer to Stops 5 and 6). Location: 35°46'35.5"N 115°51'49.4"W. From either Pachalka Spring or Winters Pass, continue northwest on Excelsior Mine Road. Go 14.3 miles northwest on Excelsior Mine Road from the turnoff to Winters Pass (Optional Stop 6), or 20.8 miles from the turnoff to Pachalka Pass (Stop 5). Where Excelsior Mine Road begins to turn left (SW), make slight right on unnamed road and go 0.2 mi NE into campground. http://www.blm.gov/ca/st/en/fo/needles/horse_thief_camp.html Day 3 (Sept. 17): Onward to Death Valley! The Death Valley region exposes some of the youngest and most impressive extensional deformation in the Basin and Range province- mostly began post-13–10 Ma and is ongoing now. The spectacular relief and 100% exposure make this an ideal natural laboratory for the study of the geometry and kinematics of extensional fault systems. Given that the geology is laid out on the table here, it is surprising how much controversy there has been over how these fault systems work. Drive north through Shoshone and west on CA 178. Drive: 1.75 hr / 51 mi from Tecopa Pass, Kingston Range, campground to Bradbury Wash. Stop 1. Amargosa chaos at Bradbury Wash. (Troxel and Wright, 1988; stop a, their Fig. 4 and accompanying text). Early on, no one had any idea what this “chaos” was. They knew it was unusual. They noted the intense deformation (brecciation) and that the slivers of strata were in the right order but extremely thin. They thought the deformation was thrust-related, but the intimate association with Cenozoic sedimentary and volcanic rocks suggested the age of deformation was Miocene. This is a quick stop to see how messed up these rocks are, basically brecciated sheets of rocks. Later on this trip we will stop and see some in good sedimentary relationship with alluvial fan sediments. Stop 2. Badwater. Lowest point in the USA! High angle faults bound the Black Mountains. Wineglass canyons, alluvial fan size and shape etc. 1 hr / 37 mi from Stop 1. Directions from Stop 1 to Badwater: Continue west on Jubilee Pass Rd / Hwy 178 for 7.5 mi. Turn right (north) onto Badwater Rd and drive for 29.3 miles to Badwater. Stop 3. Natural Bridge Arch (on range front). Tertiary fanglomerates deposited along major normal fault. Discuss interpretations. 9 min / 5 mi from Badwater. Directions from Badwater: Drive north on Badwater Rd for 3.5 mi. Turn right (east) onto Natural Bridge Road.

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Fig. 16. Google overview image of the Black Mountains and adjacent Panamint Range to the west.

Fig. 17. Google image of Badwater range front and Badwater fan. Red line is 1km for scale.

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Fig. 18. Google image of Natural Bridge Canyon area and Black Mountain range front. Red line is 1 km. Drive through lovely Artist’s Drive for scenery toward Furnace Creek. (0.75 hr / 20.8 mi from Natural Bridge to Furnace Creek via Artist’s Drive.) Directions from Natural Bridge: Turn around and head back down Natural Bridge Road. Turn right onto Badwater Road and go northwest for 4.4 mi. Turn right on Artists Drive. After 8.8 miles, Artists Drive connects back onto Badwater Road. Turn right to go north and drive for 4.8 mi. Turn left onto Hwy 190 westbound and drive into Furnace Creek. Stop at Furnace Creek for anything? Continue N on Hwy 190 toward Beatty Junction. Stop 5. Lake Manly shorelines Continue to Beatty Junction; turn right on dirt jeep track road toward Chloride Cliffs (before Daylight Pass). Take dirt road to a Y, take right down Monarch Canyon to camp. If time permits, we will take a look at the Boundary Canyon detachment before camping. Otherwise tomorrow morning.

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Fig. 19. Google images of Monarch Canyon, the Boundary Canyon detachment fault, and the Chloride Cliff fault. Draw them!

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Day 4 (Sept. 18). Death Valley. Stop 1. Pack up camp and hike down Monarch Canyon. High-grade metamorphic rocks. Kyanite-staurolite bearing, peak metamorphism is Cretaceous. Disagreement as to the age of deformation in this Canyon. Discuss history of thought and work done. Back to cars and up canyon to see amazing differences in rheologic behavior during deformation and put your finger on the exposure of the Cenozoic Boundary Canyon normal fault. All information discussed at this stop is from Mattinson et al. (2007)—A Stanford contribution to the grand debates here! Return to the paved road, continue N to Junction 374, head SW to Stovepipe Wells. Stop 2. Mosaic Canyon. Highly deformed metasedimentary rocks in the footwall of the Mosaic Canyon “detachment” fault, northern Panamint Range. Noonday Dolomite. Hanging wall consists of late Precambrian clastic rocks. Wernicke et al’s. (1986) Stop 6. Return to highway and continue S, taking Emigrant Canyon turnoff (we need to check and see if road is open again). Take turnoff to Auguereberry Point for final view stop: Stop 3: Auguereberry Point: Looking down into Death Valley and the normal fault mosaic of Paleozoic and Cenozoic rocks above the Mosaic Canyon detachment fault. Wernicke et al’s (1986) Stop 2.

Fig. 20 (above). Tectonic sketch map of the northern Panamint Range showing the major normal faults. See Figure

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Fig. 21. Geology of the Augueberry Point region. Augueberry Point is the white region, underlain by the Zabriskie Quartzite. Notice the Cenozoic lavas that dip east with the rest of the section.

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Fig. 22 (below). Stratigraphy and formation names of the Precambrian and Cambrian strata of Death Valley (exposed at Augueberry Point)

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Camp at Wildrose (or if intrepid at Mohogany flats at 10K feet). If road is closed out of Wildrose maybe could also go back and camp at the little campground called Immigrant Springs? See map and info in driving information section. Day 5 (Sept. 18). The transition into the Sierra Nevada batholith. Drive out of Death Valley on Hwy 190. Stop 1. (only if time permits) Emigrant normal fault in Emigrant Canyon. Here we will examine a segment of the range front fault (Emigrant Fault) on the west side of the Panamints where it places east-tilted Pliocene fanglomerates and basalts of the Nova Formation on highly sheared late Precambrian Kingston Peak Fm and Cretaceous 2 mica granite. Refs Wernicke et al. 1986, Stop 3 (6.8 miles from Auguereberry, their Figure 2) Continue N to 190 head west onto the Darwin Plateau. Stop 2. Short stop at Father Crowley overlook to look back onto the highly extended Death Valley region from the much less extended Darwin Plateau. There is an active controversy about very low-angle normal faults beneath the intervening valley here. Continue W on 190 and then turn N on dirt road to Talc City Hills Stop 3. (Dunne 1986 stop 11, their figs 7, 10.) The early to mid-Jurassic Talc City thrust fault. This thrust and several others in the area are thought to be among the oldest of the Mesozoic crustal shortening related structures. Here the Talc City thrust places Ordovician–Devonian dolomite on Pennyslvanian limestone, and was subsequently folded in the late Jurassic to Cretaceous(?). We will look at the style of deformation related to the younger event here and hopefully find folds and cleavage.

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Fig. 23. We will try to find Stop 11 on these maps (our Stop 3).

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Fig. 24. Google satellite images showing the Talc City thrust fault (our Stop 3). Get back on the highway, continue west on Hwy 190 to Hwy 136, and turn N. Stop 4 (to be determined by time). Overview of the Mesozoic structure of the southern Inyo Mountains. View of the Dolomite Canyon and green k-spar, beryl and fluorite. Thrust faults thought to be mid-Jurassic to Early Cretaceous in age. As we move closer to the coeval magmatic arc, the distinction between regional tectonic structures and structures related primarily to the emplacement of large intrusive masses becomes very fuzzy.

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Continue N on range-front road, 4 miles, turn right to Kern Knob. Stop 5. Assorted Mesozoic intrusions of the Sierra Nevada batholith. Late Cretaceous Kern Knob, a 2-mica granite intrudes Jurassic (174 Ma, U-Pb Zircon) Long John granodiorite and late Jurassic lamprophyre dikes of the Independence dike swarm. Look at the deformation of the older rocks, the protoclastic border on the younger intrusion and if you are lucky find some nice specimens of blue-green kspar, beryl, and fluorite!

Fig. 25. Geologic Map of the Kern Knob area (our Stop 5) (Griffin, 1986). See also Google Earth image to see if you can see the contacts that we will look at and point to.

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Fig. 26. Google Earth image of Kern Knob region. Compare to Figure 25. Note that N is to the left. Head west across Owens Valley and find a campsite in the Alabama Hills. We will wake up to hopefully stunning views of the Sierra! If we have time today, we will look at the East Sierra fault system (scarp, historical earthquakes and strike-slip offset). Day 6 (Tuesday, Sept. 20). Stop 1. East Sierra fault system (strike slip) and East Sierra Scarp (normal fault).

Fig. 27. Google Earth image of western Lone Pine, CA, with the Alabama Hills on the left (W).

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Drive N on Hwy 395. Stop 2. Bishop tuff in Owens Gorge.

Fig. 28. Google Earth image of Owens River Gorge. Stop 3. View of Long Valley Caldera.

Fig. 29. Google Earth image of the Long Valley Caldera.

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Stop 4. Mono Craters–Pahnum Crater–Obsidian Dome and a view of glacial moraines.

Fig. 30. Google Earth image of southern Mono Lake. Stop 5. Optional, if there is time: Mono Lake visitor center. Camp at Parker Creek. Dinner on you at the Mobil Station Day 7 (Wednesday, Sept. 21). Breakfast on you at the Mobil Station. Drive straight back and/or hike the Dana Plateau! Look over the faulted rim of the Sierra Nevada escarpment and the uplifted erosional surface that existed prior to Basin and Range faulting.

Fig. 31. View E to Dana Plateau and the road (Hwy 120) up Lee Vining Canyon.

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There’s good swimming at Lyell Creek off Hwy 120 on the drive back. Definitely stop at Olmsted Point to view the Sierra Nevada, Yosemite Valley, Half Dome, and Sierran granites. Drive back to Stanford.

Figure 32. Index map of part of Yosemite showing location of Mount Dana (Dana Plateau leads up to it) and the trail to Mono Pass. Lyell Creek and Olmsted Point also shown further west on Highway 120.

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Field Trip Driving and Stop Locations Day 1 (Sept. 15): Drive to campsite outside of Las Vegas in the Spring Mountains (Sites 1 and 2, Hilltop Campground, Spring Mountains National Recreation Area: 36.309345º, -115.607200º, Reservation numbers: 2-36397156 & 2-36397155, Contact: 888-448-1474). Directions from I-15 northbound, starting south of Vegas: Use the right 2 lanes to take exit 42A to merge onto US-95 N/Oran K. Gragson Fwy toward Reno 17.0 mi Turn left onto NV-157 W/State Rte 39/Kyle Canyon Rd 17.5 mi Turn right onto NV-158 N 4.6 mi Turn right onto Angel Peak Pl/Lucky Strike 476 ft Slight left onto Hilltop Campground Rd Day 2 (Sept. 16) Stop 1: Driving: From Hilltop Campground (1.25 hr / 51 mi without traffic): Head southwest on Hilltop Campground Rd toward Angel Peak Pl/Lucky Strike 135 ft Continue straight onto Angel Peak Pl/Lucky Strike 476 ft Turn left onto NV-158 S 4.6 mi Turn left onto NV-157 E/State Rte 39/Kyle Canyon Rd 17.4 mi Turn right onto US-95 S/Oran K. Gragson Fwy (signs for Las Vegas) 16.5 mi Take exit 76A for I-15 N/US-93 N toward Salt Lake City 0.5 mi Merge onto I-15 N 1.5 mi Use the right lane to take exit 45 for Lake Mead Boulevard 0.2 mi Use the right 2 lanes to turn right onto NV-147 E/E Lake Mead S Blvd East on Lake Mead Blvd to where the road passes over the northern part of Frenchman Mountain. Stop and hike to see basal unconformity and talk about the stratified units of the platform sequence and their thicknesses. Reference: Steve Rowland, Geology UNLV. http://geoscience.unlv.edu/pub/rowland/Virtual/virtualfm.html Stops 2 and 3: Red Rock Canyon Scenic area (>1 hr without traffic / ~37 mi from Frenchman Mountain) Driving Directions from the Las Vegas Strip south of Russell Road: Get on to the I-15 south Take exit 36 for Russell Road/ 215 west Keep left at the fork, follow signs for Interstate 15 south

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Keep right at the fork, follow signs for 215 west and merge onto 215 west for 13.5 miles Take exit 26 for Charleston Boulevard and turn left Continue onto State Route 159/ West Charleston Boulevard for 5.5 miles. Turn right into the entrance of Red Rock Canyon National Conservation Area Driving Directions from State Route 160 Get on I-15 Take exit 33 toward State Route 160 west / Blue Diamond Road Keep right at the fork and merge onto State Route 160 west / Blue Diamond Road for 10.5 miles. Turn right onto State Route 159 east/ Charleston Boulevard (opposite the gas station) drive for 10.5 miles. Turn left into the entrance of Red Rock Canyon Stop 2: Climb around and photo ops of giant cross-beds in the Aztec Sandstone along the N side of the Scenic Loop Drive. Stop 3: (From Axen, 1987, his Site 3, Fig. 3: Here we will look at a part of the Red Springs thrust and see evidence that it rode over the ground surface, burying debris derived from the erosion of the moving thrust plate beneath it in its footwall.

Take Loop Drive to intersection with W hite Rock Spring Road and turn right (northwest). 23.9 38.4 End of W hite Rock Spring Road; park her. Cross the wash to the right (northeast) and walk cross-country toward the black hill for about 660 ft (200 m) until you meet an abandoned Jeep trail. W alk north on the Jeep trail, around the northwest end of the black hill to the Aztec Sandstone outcrop on the northeast side, to Site 3. A llow 15-20 minutes for the walk, 1.5 hours from the time you leave the parking area until you return. Driving to the parking spot from Stop 2 should take ~10 minutes (~1.7 mi). Stop 4. Optional and geologically unnecessary. Drive to Goodsprings to check out historic bar. south on I-15 to the west side of the Clark Mountains (CM) on the figure below. >1 hr (57 mi) from Stop 3:

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Head south on White Rock Mountain Rd 0.5 mi Turn right onto Scenic Loop Dr Toll road 6.6 mi Turn left onto NV-159 E 7.4 mi Turn right onto Hughes Park Dr W (signs for Clark County 215 S) 0.1 mi Use the left lane to merge onto Co Rd 215 S/Clark County 215 S via the ramp to Henderson Merge onto Co Rd 215 S/Clark County 215 S 12.9 mi Use the right 2 lanes to take exit 12A for I-15 S toward Los Angeles 1.4 mi Keep left and merge onto I-15 S 20.9 mi Take exit 12 for NV-161 0.3miTurn right onto NV-161 W/Goodsprings Rd (signs for Sandy Valley) 6.3 mi Continue straight onto NV-161 0.5 mi Stop 5. Pachalka Thrust (equivalent to the Winters Pass thrust). Spectacular exposure of knife-sharp contact between Precambrian gneisses in hanging wall and Cambrian clastic rocks in the footwall. Short hike up wash (Burchfiel and Davis stop 2.8) or along road (see their description below). This is a good example of higher thrust sheets carrying hotter metamorphic rocks in their hanging walls. See index map and google images. How to get there: Cima Road intersects 15 at exit 272. Take it to the north (called Excelsior Mine or Kingston Road in that direction). At a very slight bend, there is a small road to the east, to Pachalka Springs. Take that. Drive north to a poorly graded dirt road that leads eastward toward Pachalka Spring on the west flank of the Clark Mountains. The turnoff lies not far to the north of a round metal water tank on the east side of the road. Stop 2-8 Pachalka Spring road: the Pachalka thrust (Figure below). Google directions to Pachalka Spring from Goodsprings (~1.25 hr without traffic / 53 mi from Goodsprings; 2 hr without traffic / 96 mi from Stop 3 at Red Rocks): Head east on NV-161 toward Vegas St 6.8 mi Turn right to merge onto I-15 S Entering California 36.0 mi Take exit 272 for Cima Rd 0.3 mi Turn right onto Cima Rd 0.4 mi

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Continue straight onto Excelsior Mine Rd 5.5 mi Turn right onto County Rd 20913 3.7 mi

Optional Stop 6. …~45 min / 16 mi from Stop 5 Winters Pass thrust at Winters Pass

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To campsite on Day 2 Drive: 1.75 hr / 51 mi from Tecopa Pass, Kingston Range, campground to Bradbury Wash. Google directions to Bradbury Wash: Head west toward Excelsior Mine Rd 0.3 mi Slight right onto Excelsior Mine Rd 3.9 mi Slight left to stay on Excelsior Mine Rd 4.7 mi Continue onto Smith Talc Rd 4.0 mi Merge onto Mesquite Valley Rd

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1.3 mi Continue onto Furnace Creek Rd 7.5 mi TurnleftontoOldSpanishTrailHwy1min(0.3mi)Slight right 2.6 mi Continue onto Furnace Creek Rd 0.2 mi Turn right onto Tecopa Hot Springs Rd 2.0 mi Slight right onto CA-127 N 6.9 mi Turn left onto CA-178/Jubilee Pass Rd Continue to follow Jubilee Pass Rd 17.5 mi Stop 1. Amargosa chaos at Bradbury Wash. Stop 2. Badwater. Lowest point in the USA! High angle faults bound the Black Mountains. Wineglass canyons, alluvial fan size and shape etc. 1 hr / 37 mi from Stop 1. Directions from Stop 1 to Badwater: Continue west on Jubilee Pass Rd / Hwy 178 for 7.5 mi. Turn right (north) onto Badwater Rd and drive for 29.3 miles to Badwater. Stop 3. Natural Bridge Arch (on range front). Tertiary fanglomerates deposited along major normal fault. Discuss interpretations. 9 min / 5 mi from Badwater. Directions from Badwater: Drive north on Badwater Rd for 3.5 mi. Turn right (east) onto Natural Bridge Road. Stop at Furnace Creek for anything? Continue N on Hwy 190 toward Beatty Junction. Stop 5. Lake Manly shorelines Continue to Beatty Junction; turn right on dirt jeep track road toward Chloride Cliffs (before Daylight Pass). Take dirt road to a Y, take right down Monarch Canyon to camp. If time permits, we will take a look at the Boundary Canyon detachment before camping. Otherwise next morning. We will camp (wilderness) at the place in the canyon beyond which you cannot drive (a huge waterfall/cliff-No sleepwalking allowed…)

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Monarch Canyon campsite: Take a hard-to-see right off Daylight Pass Road before the summit. The dirt road says 4x4 to Chloride City or Chloride Cliff. Watch for dips and boulders, but it isn’t really 4x4 to the campsite. At the first possibility of turning right again, at a Y in the road to Chloride Cliff, hang a right and drive down the sandy wash road of Monarch Canyon. The end of the road is a turn-around at a huge cliff. (36° 43.775, 116° 55.021).

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33mi53km

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29mi46km

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40mi64km

27mi43km

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45mi72km

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3mi5km5mi

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168

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374

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178178178

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Death

Valley

Wash

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Salt

Creek

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Wingate

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argosa

River

Wash

Deep SpringsLake

Wyman

Cottonwood

Creek

Creek

Willow

Palmetto

Creek

Wash

OWENS LAKE(dry)

SouthHaiweeReservoir

NorthHaiweeReservoir

Lost Lake

Owl Lake

SEARLES LAKE

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To ManzanarNational Historic Site

Road conditionsrequire experienced4-wheel drivers.

Road conditionsrequire experienced4-wheel drivers.

Road conditionsrequire experienced

4-wheel drivers.

Vehicles longer than 25 feet (7.7meters) not allowed.

Vehicles longerthan 25 feet(7.7meters)not allowed.

Vehicles longerthan 25 feet(7.7meters)not allowed.

Rough, narrow, windingroad. Vehicles longerthan 25 feet (7.7 meters)not allowed.

Watch forflooding

Deepsand

In winter carrychains. Roadmay be closed.

In winter carrychains. Roadmay be closed.

In winter carrychains. Roadmay be closed.

Deep sand

PanamintDunes

SalineValleyDunes

EurekaDunes

IbexDunes

BigDune

NEVADA

CALIFORNIA

INYO

NATIONAL

FOREST

NELLIS AIR FORCE BOMBING AND GUNNERY RANGE

CHINA LAKE NAVALWEAPONS CENTER

CHINA LAKE NAVALWEAPONS CENTER

FORT IRWIN MIL ITARY RESERVATION

Josh

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HarrisburgFlats

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Dry Mountain8674ft2644m

Ubehebe Peak5678ft1731m

Cerro Gordo Peak9184ft2799m

WaucobaMountain11123ft3390m

Mount Inyo11107ft3385m

HunterMountain

7454ft2272m

Towne Pass

Lake Hill2030ft619m

Emigrant Pass5318ft1621m

Wildrose Peak9064ft2763m

Rogers Peak

BennettPeak

Porter Peak

Mengel Pass

Needle PeakSugarloafPeak

Sentinel Peak9636ft2937m

TheGrandstand

PanamintButte

6732ft2052m

Pinto Peak

Tin Mountain8953ft2729m

White TopMountain

Grapevine Peak8738ft2663m

BustedButte

BlackCone

Stonewall Mountain8875ft2705m

Mount Palmer7979ft2432m

Daylight Pass4316ft1316m

Winters Peak5033ft1534m

Pyramid Peak6703ft2043m

Coffin Peak5503ft1677m

Smith Mountain5912ft1802m

Mormon Point

Manly Peak7196ft2193m

Brown Mountain5125ft1562m

Striped Butte

Brown Peak4947ft1508mDeadman

Pass3263ft994m

Salsberry Pass3315ft1010m

Jubilee Pass1290ft390m

JubileeMountain

Ibex

Wingate Pass

South Pass

Straw Peak

Shoreline Butte

Eagle Mou3806ft1160m

Funeral Peak6384ft1945m

3040ft927m

NevaresPeak

SchwaubPeak

IndianPass

Kit FoxHills

Death ValleyButtes

Hole inthe Wall

Wahguyhe Peak

Chloride Cliff

Corkscrew Peak

Red Pass

ThimblePeak

Last ChanceMountain

8456ft2577m

Steel Pass

Magruder Mountain9046ft2757m

Mount Dundee

Gold Mountain

Palmetto Mountain8960ft2731m

Mount Jackson6411ft1954m

ChocolateMountain7703ft2348m

Owens Peak

4956ft1511m

3000ft914m

Mesquite Spring

Grapevine

UbehebeCrater

Scottys Junction

Lida Junction

Information

Information

Salt CreekInterpretiveTrail

HistoricStovepipe Well

KeaneWonderMill

KeaneWonderMine

Rhyolite(ghost town)

Emigrant

Stovepipe WellsVillage

Information

Emigrant

West

Side

Road

Aguereberry PointDay use only6433ft1961m

Skidoo(townsite)Day use only

EurekaMine

Ballarat(ghost town)

Panamint City(ghost town)

Father Crowley PointDarwin

Falls

Wildrose

Harmony Borax WorksInterpretive Trail

SEEDETAILMAPABOVE

Golden CanyonInterpretive Trail

RefugeHeadquartersZabriskie Point

Twenty MuleTeam Canyon

ArtistsPalette

Badwater

AshfordMill

(ruins)

SaratogaSpring

Eagle Borax Works(ruins)

ThorndikeMahogany Flat

Charcoal Kilns

Teakettle Junction

CrankshaftJunction

TheRacetrack

Two-way trafficto mouth of TitusCanyon.

To Tonopah and Reno

DantesView5475ft1669m

TrailerparkingNatural

Bridge

DevilsGolf Course

Badwater BasinLowest elevation inthe U.S., 282ft (86m)

below sea level

Leadfield(ghost town)

DevilsCornfield

Hells Gate

Beatty

Panamint Springs

Darwin

S

Tan

Trona

Lone Pine

Death Valley JunctiAmargosa Opera Hou

Lathrop Wells

Amargosa Valley

Beatty

Panamint

Valley

Road

Road

Canyon

Cutoff

one way

one w

ay

one way

Artists Drive

Harry Wade Road

Gold Point

Mine

Mine

ToBig Pine

ToLakeIsabella

ToBig Pine

ToDyer

RIDGECREST

BigPine

Road

Race

trac

k R

oad

BigPine

Road

Keeler

Lida

Eastern SierraInteragencyVisitor Center

ToLos Angeles

ToSan

Bernardino

State Line Road

8133ft2479m

��

Telescope Peak11049ft3368m

Scotty’s Castle Road

Dayli

ght Pa

ss R

oad

Badwater

Road

Mesquite FlatSand Dunes

4-wheel-drive road

High clearancerecommended

Timbisha Shoshonetrust lands

Area below sealevel

Salt flat

Unpaved road

Hiking trailCampground

Ranger station

Airstrip

Store

Telephone

Sanitary disposal station Wheelchair accessible

Radiator water

Gas station

Food service

Lodging

0

0 10 Miles

10 KilometersNorth

For Your SafetyThis is a harsh environment—any emergency situation can become life-threatening, especially in summer. Heed safety warnings in the park newspaper, including extreme heat and dehydration, unsafe driving, flash floods, and mine hazards. Ask about unpaved road conditions before traveling in the backcountry. Do not use this map for hiking or backcountry road travel. Detailed maps are available at the visitor center and ranger stations.

Park RegulationsIt is your responsibility to know and abide by park regulations. If in doubt about an activity, ask at a ranger station or see the park newspaper for details. To protect park features the following are prohibited: • Campfires outside developed campgrounds • Wood gathering • Driving off roads (includes bicycles) • Collecting, removing, or disturbing rocks, plants, animals or historic artifacts • Pets off leash, off roads, or on trails • All weapons • Littering.

Entrance FeePlease stop at Furnace Creek Visitor Center, Stovepipe Wells Ranger Station, Beatty Ranger Station, or the entrance station at Grapevine to pay the park entrance fee.

Vehicles, including bicycles, must stay on roads.

Furnace CreekVisitor Center

Scotty’s CastleVisitor Center and Museum

Death Valleypark boundary

Timbisha ShoshoneNatural and Cultural

Preservation Area

The Timbisha Shoshone Home-land Act of 2000 provides for the tribe’s living permanently on lands held in trust within their ancestral homeland. Trust lands, located by dots at left, are also shown on the large map. The Act also pro-vides special use areas, includ-ing the Timbisha Shoshone Natural and Cultural Preserva-tion Area, for sustaining the tribe’s traditional cultural and religious activities.

To Preserve a Way of Life

190

Furnace CreekVisitor Center

Furnace Creek RanchBorax Museum

FurnaceCreek Inn

TexasSpring

Picnic area

Sunset

Airport

Timbisha ShoshoneVillage (private; novisitor services)

ToArtists Drive

and Badwater

ToDeathValley

Junction

ToStovepipe Wells

FurnaceCreek

0.5 Kilometer0

0 0.5 Mile

Furnace Creek Visitor Center Area

39

Campsites for night 4 in Death Valley National Park: All are first come, first serve. Coming down from Augueberry Point, we can go to Wildrose (36°15.964, 117° 11.372; elevation 4100’) but we need to backtrack next day as the road out to Panamint Valley from Wildrose is still closed. We could be intrepid and go up the mountain to Mohogany Flats Campground (the road begins at Wildrose) which is at 8200’. We can go back to Emigrant Springs campsite on the main highway (36°29.796 117°13.653; 2100’ elevation). Campsite in the Alabama Hills (Night 5). Take a left off 395 on the Whitney Portal road. When you get to the bouldery Alabama Hills we will look around for a nice spot to camp (see the dirt roads in the image below)

40

Last night campsite: Parker Creek 37°51.376, 119°8.304. Take northern end of June Lake Loop road to south from 395 south of its intersection with Hwy 120. Take the dirt road to the right that goes up the ridge/hill and down into Parker Creek.

41

Appendix: Additional information from previous field trip guides for our stops. Frenchman Mountain: In 1990, Brian Wernicke edited a Geological Society of America book titled Basin and Range extensional tectonics near the latitude of Las Vegas, Nevada. This book, along with an earlier GSA Bulletin paper by Wernicke et al. (1988), captures the status of geologic research in Southern Nevada in 1990 concerning extensional tectonics. One chapter in this book (Rowland et al., 1990) is devoted to the tectonic history of the Frenchman Mountain Block; the authors concluded that Frenchman Mountain moved about 80 km (or about 50 miles) to the west between about 10 million and 6 million years ago, in the Miocene. The detachment fault that is inferred to exist somewhere beneath Frenchman Mountain in this model was not detected by Langenheim et al., (2001). from Steve Rowland, Geology UNLV, http://geoscience.unlv.edu/pub/rowland/Virtual/virtualfm.html Red Springs Thrust: At the site, the tan-weathering "silty unit" at the base of the Banded Mountain Member of the Bonanza King Formation lies in thrust contact above the Jurassic Aztec Sandstone and the conglomerate of Brownstone Basin (Fig. 3). Throughout most of the Spring, Muddy, and Mormon Mountains, the frontal thrusts detached at or near the "silty unit," in the middle of a sequence of strong dolostone, rather than forming a decollement zone in the weaker shales below the Bonanza King Formation-a mechanically puzzling situation (Burchfiel and others, 1982). At this site, the conglomerate of Brownstone Basin is composed of: (1) cobbles and reworked pebbles of jasper-rich Triassic Shinarump Conglomerate, (2) clasts of late Precambrian or early Cambrian quartzites and (3) matrix and clasts of Aztec Sandstone (Davis, (973). Paleocurrent analysis indicates transport to the east-northeast (Jones and others, 1984). The quartzites must have been derived from the Wheeler Pass allochthon to the west, the nearest thrust plate that carried those rocks, indicating tbat the Wheeler Pass thrust is older than the Red Spring thrust (Axen, 1984; Jones and others, 1984). The Triassic detritus is believed to have originated in the overturned fold in parautochthonous rocks to the west (Fig. 2, site 4), and the reworked Aztec Sandstone is probably locally derived and/or from the same fold. In its thickest section, exposed in Brownstone Basin (Fig. 2), the conglomerate has a stratigraphically higher lithofacies composed of Paleozoic carbonate clasts (Davis, 1973; Axen, 1984; Jones and others, 1984). The abrupt change in clast type is interpreted to be due to the approach of the Red Spring thrust sheet as it overrode the land surface and its own detritus (Davis, 1973). Due to its structural and stratigraphic setting, the conglomerate of Brownstone Basin is correlated with the Lavinia Wash sequence found by Carr (19S0) below the correlative Contact thrust to the south. He obtained a K-Ar date of I50 ± 10 Ma on a tuff in the Lavinia Wash sequence. Thus the conglomerate of Brownstone Basin is thought to be Late Jurassic or Early Cretaceous(?) in age. This suggests that the Wheeler Pass thrust is pre-Late Jurassic in age, and that the Red Spring thrust is Late Jurassic in age. From Axen (1987). Pachalka Springs/ Winters Pass Thrust: Drive north to a poorly graded dirt road that leads eastward toward Pachalka Spring on the west flank of the Clark Mountains. Stop 2-8 Pachalka Spring road: the Pachalka thrust. Short hike up wash (Burchfiel and Davis stop 2.8) or along road (see their description below). Note: I think walking up the wash is the ticket here, not the road. Our stop will be in the first narrow valley containing bedrock exposures of Precambrian(?) granite and granitic gneiss. The thrust contact between these crystalline rocks and underlying Wood Canyon Formation quartzites of the miogeoclinal section (Mesquite Pass plate) is extremely well exposed on the north side of the valley at the level of the road. Although we refer to this thrust fault as the Pachalka thrust, we believe that it is correlative with the Winters Pass thrust. The thrust contact is knife-edge sharp and separates upper-plate mylonitic gneisses from lower-plate mylonitic quartzites [NOTE: please do not collect samples from the thrust contact exposed along the road; it is an exceptional locality and should be preserved]. Directly below the contact is a layer, one to four cm thick, of black "ultramylonite". This "ultramylonite" is seen in thin section to be a very fine-grained aggregate of white mica, biotite, and an opaque ore mineral (probably magnetite). Rocks more than 100 m above and as much as 5 m below the shallow west-dipping thrust are characterized by a penetrative mylonitic foliation and a stretching lineation that plunges S 80º W at low angle. S-C fabrics in the mylonitic gneisses are well-developed and consistently indicate top to the east motion. Hornblende dioritic dike rocks were apparently intruded along the thrust fault at the base of the Pachalka thrust plate during its emplacement. Highly sheared and foliated dike rocks underlie the crystalline plate along much of its exposed base north of the valley containing stop 2-8. Locally, these dike rocks cross into the upper plate where they are generally less deformed than in exposures directly beneath the plate. Samples of the diorite have been collected for possible dating. From the thrust contact exposed along the road, walk eastward through an overturned section of Wood Canyon quartzites and Carrara Formation to observe the deformational style of the lower plate. The Zabriskie Quartzite that normally lies between these two units is missing along the road, presumably because of tectonic thinning, disruption or both. It reappears in typical development not far north of the road and along it to the east. The first gray limestone ledge encountered above the Carrara phyllites is in the overturned limb of a major syncline below the thrust plate. The syncline can be seen in cross-section along the skyline to the north. This Carrara limestone is separated from the Wood Canyon quartzites by green phyllites of the lowermost Carrara Formation. Foliation development, small similar folds, and boudinage within the limestone indicate that it was extremely ductile during deformation. The next limestone ledge to the east is the same limestone bed repeated on the normal limb of the overturned syncline. Farther east along the road, below Carrara phyllites, are several exposures of the Zabriskie Quartzite in anticlinal hinges. The folds contain a well-developed, southwest-dipping axial plane cleavage. From Burchfiel and Davis (1988). Winters Pass and Winters Pass Thrust (optional): Winters Pass thrust and clastic-carbonate transition (stratigraphy).(Stop 3-7,8 of Burchfiel and Davis (1988). The Winters Pass road follows the trace, mostly concealed, of the Winters Pass thrust fault. The Winters Pass plate NW of the road consists of a well-exposed, northeast-dipping, shelf succession about 3200 m thick. This section extends from crystalline basement into the Cambrian Bonanza King Formation. The basal unit of the section, the Noonday Dolomite, rests unconformably on Precambrian gneiss and granitic rocks. Locally, a thin (several m) basal conglomerate is present along the irregular erosion

42

surface developed beneath the Noonday. The clastic rocks overly the Noonday Dolomite, including the Johnnie, Stirling, wood canyon, Zabriskie and lower Carrara formations. The thin Zabriskie Quartzite is folded at a small scale. Several ledges of thick grey limestone, some containing numerous algal structures (Gervinella sp.) are interbedded in the lower Carrara Formation with greenish phyllitic shales. This is the famous clastic-carbonate transition in the Cordilleran passive margin sequence, representing the “rift to drift” transition for the evolution of the margin. It is a sequence that is similar along strike in the Cordillera from Alaska to Mexico!!! I think this should be a good place to look at the stratigraphy. Southeast of the road in Winters Pass is a small exposure of the Precambrian and Cambrian clastic sequence that lies ABOVE the Winters Pass thrust. This is the only segment of the thrust in Winters Pass that is not buried beneath alluvium. If time permits, we will walk to an exposure of the foliated thrust contact. The footwall of the thrust here is a section of overturned Bonanza King Formation. The hinge of the overturned syncline trends NE-SW parallel to the trace of the thrust fault here. Several thin tectonic slices of orange-weathering silty carbonates of the upper Carrara Formation lie exposed below the Winters Pass thrust, the clearly are not in stratigraphic continuity with the overturned Bonanza King carbonate rocks.] Kingston Range detachment and Shadow Valley Miocene Basin: (Discussion only, no stops). This is an aside on the geology of the Kingston Range, the Kingston Peak detachment fault and the Shadow Valley Miocene basin deposits: I could not find any good field guides for this region and, given my unfamiliarity, seems not a good idea to venture into the unknown with a bunch of people in tow, despite wanting to include it. Work in the 80’s and 90’s by first Davis and Burchfield and then several papers by Friedman et al. have shown that an extensive normal fault system bounds the Clark Mountains and is exposed in the Kingston Range. The fault system is currently very shallowly dipping and Cenozoic sediments are reported as dipping up to ~ 40° with calculated bedding to fault angles of about 40°. The map below shows the trace of the fault. Volcanic rocks at the base of the section are as old as Ma and the Miocene Kingston Range pluton intrudes the fault and is dated at Ma. Faults then cut the sediments and the older faults and stopped moving before volcanic rocks were unconformably deposited atop these units. One of the characteristics of the succession is a grand amount of avalanche or landslide deposits into the basin. These are generally associated with the early period of slip on normal faults when they are steep (60-70°) while alluvial fan and fluvial deposits are associated with ending slip on normal faults. The attached map shows some of these avalanche deposits. The key to their interpretation is that the breccias are encased within Miocene sediments as mega sedimentary lenses. So they are sedimentary in origin, despite possibly triggered by earthquakes on high angle faults… ]

43

44

Armagosa Chaos: Upon entering Death Valley Monument, and for the next 4 mi (about 6.5 km) westward, the road is close to exposures of the Virgin Spring phase of the chaos and its contact with the underlying complex. Here, as elsewhere, the contact is marked by an abrupt change'from the gray of the complex to the brighter and more varied colors of the chaos. In this area, only isolated erosional remnants of the chaos remain, but they show features much like those that characterize larger bodies of the Virgin Spring phase. Of the chaos-forming units at this locality, the Noonday Dolomite is the easiest to identify. It is the yellowish gray, resistant unit that supports most of the knobs within 0.5 mi (0.8 km) of the highway. At numerous places, one can observe details of the faulted lower surfaces and the intensely fractured nature of the various overlying rock units. The best exposure of the Virgin Spring chaos along California 178 lies adjacent to and south of the highway and west of the Monument boundary (point a, Fig. 2). There the chaos underlies the steep north face of a hill about 300 ft (90 m) high and displays most of the features that are commonly ascribed to the lower part of the chaos in general. The lower part of this face is underlain by the gray weathering, locally red-stained crystalline complex. Within it are sheared masses of dark green diabase dikes and nearly white granitic pegmatite dikes. All are thoroughly sheared and become progressively more so upward to the nearly horizontal contact with the overlying chaos. The strong evidence of dislocation along this contact, together with the deformation recorded in the chaos, impressed Noble to the extent that he identified it as an occurrence of his Amargosa thrust. The pale gray to dark lavender, thin fault-bounded lenses at the base of the overlying chaos consist of arkosic sandstone and siltstone of the dominantly clastic lower part of the Crystal Spring. The dark green lenses higher on the face are slices of the diabase sill that, region-wide, separates the lower clastic members from the carbonate member. The latter, in turn, is represented by the still higher, dark reddish brown lenses. This hill, like other hills in the vicinity, is upheld by yellowish gray dolomite of the Noonday Dolomite. Strata of the Johnnie Formation are exposed on the south side of the hill crest. Both the Noonday and Johnnie, like the Crystal Spring, occur as fault-bounded lenses and thus also qualify as chaotic. The full thickness of the Crystal Spring ordinarily ranges between 2,500 and 4,000 ft (750 and 1,200 m; Fig. 3). The fault-bounded slices of Crystal Spring exposed on the nearby vertical north face of the hill in the lower Bradbury Wash are limited to about a 2oo-ft-segment (60 m) of the face. The Beck Spring Dolomite and Kingston Peak Formation may have been eroded away from this location in Precambrian time before the Noonday Dolomite was deposited, but most of the Crystal Spring has been faulted out in the formation of the chaos. Each slice retains its proper stratigraphic position, younger over older. From Troxel and Wright (1988). Mosaic Canyon : STOP 6 of Wernicke et al. (19XX) -- Mosaic Canyon The striking structural discontinuity immediately east of the parking lot is the Mosaic Canyon Fault (Figure 4). Here, it places unmetamorphosed Late Precambrian-Cambrian clastic rocks (Stirling and WoodCanyon Formations) onto orange-brown marbles of the Noonday Dolomite. Walk up Mosaic Canyon into grottos with polished walls of lower plate Noonday Dolomite. Within lower Mosaic Canyon, it is possible to see many of the complex ductile structures described in Hodges et a1. (1986). These include: Fl-2 isoclinal folds, D3 symmetric and asymmetric boudins, and asymmetric folds and dome-and-basin structures formed by 06 and 07 interference. Aguereberry Point: Stop 5 of Wernicke et al. (19XX). Driving up Wildrose Canyon, we passed the fault contact between the Miocene Nova sediments and metamorphosed strata of the Kingston Peak Formation. This fault, the Emigrant Fault, cuts an earlier normal fault between the Noonday Dolomite and Johnnie Formations, the Harrisburg Fault. Both are down-to-the-west, but the older Harrisburg Fault now dips east. We are now standing on the Lower Cambrian Zabriskie Quartzite, in the hanging wall of the Harrisburg Fault, but the footwall of the Emigrant Fault. To the west, behind us, lies the Harrisburg Flats area (Figure 3). Discontinuous pods of pale orange-brown dolomite are brecciated horses of Noonday which mark the trace of the Harrisburg Fault. Here, the fault dips <20 0 E, placing phyllites of the upper Johnnie Formation (brown hills in the foreground) on more resistant units of the Kingston Peak Formation. Some of the hest exposures of the Harrisburg fault occur in the poorly accessible upper part of Tucki Wash, where the upper part of the Johnnie Formation is separated from the Noonday dolomite hy a hedding parallel fault marked by a few meters of gouge. The trace of the fault can he seen by looking due north of Augereberry Point. Tucki Mountain forms the near skyline, capped by gently east-dipping light orangish brown outcrops of the Noonday dolomite. Down and to the right of Tucki, at the break in slope between the rolling topography on top of the range and the steep slopes plunging valleyward, a contact between a very dark brown band (Kingston Peak Formation) and an overlying light orange-brown unit (Noonday Dolomite) can be seen. The Noonday forms a prominent dip slope, making a "turtleneck" on the topography. At its base lie the dark-brown fine clastics and carbonate of the Johnnie Formation, succeeded upward by desert-varnished exposures of the Sterling Quartzite. The strongly east-tilted, post-Noonday rocks are cut by a number of very low-angle, down-to-the- normal faults one of which underlies these rocks at shallow depth, repeating the Zabrlskle Quartzite. One of the most spectacular of these is the Tucki Wash Fault, whose low-angle trace exposed in natural cross section on the north face of Tucki Wash. Tucki Wash Fault is truncated by a structurally higher low-angle fault (the Trellis Canyon Fault) east of the summit of Tucki Mountain. The Trellis Canyon Fault (which appears to be continuous with the Mosaic Canyon Fault, Stop 6) also truncates the Harrisburg Fault. To the east, we can see the north-south striking segment of Death Valley, with the Black Mountains on the other side. The most prominent feature of the Blacks are its turtlebacks (exhumed normal fault surfaces), which occur as three in echelon, north-west striking topographic domes on the front of the range. The northernmost of these, the Badwater turtleback, can be seen as a horizontal scar about three-fourths of the way up to the range crest from the valley floor, From our vantage point, a foreground ridge obscures the valley floor. The best exposure of the scar occurs just to the left of a small butte at the south shoulder of the foreground ridge. Above the scar, on the distant skyline, we can see Nopah Peak, comprised of a sharp, craggy summit on the left and a rounded summit on the right. The fault that defines the Badwater turtleback places Miocene volcanics of the Artist Drive Formation onto Precambrian crystalline basement, a stratigraphic throw of at least 10 km. A similar fault at the east foot of the Panamints below Augereberry Point bears the same relationship. These faults are among those responsible for rotating the earlier Harrisburg Fault and imbricate splays to the east. Due East from Augereberry Point, the Black Mountains plunge eastward into the valley. Behind them lie the Funeral Mountains. The structure separating them is the Furnace Creek Fault Zone, which has on the order of 50 km of right-lateral offset across it. The combined Black Mountains-Funeral Mountains front forms a boundary between relative youthful tectonism and topography to the southwest and a presently more serene, eroding extensional terrane to the northeast. Emigrant Fault: Wernicke et al. (1986) STOP 3 –6.8 miles from Augueberry Point. Emigrant Fault in Emigrant Canyon. We have just passed through a series of tight turns in a narrow gorge, where a lens of orange-brown and grey marbles of the Noonday Dolomite is juxtaposed against the Skidoo pluton along a branch of the Emigrant Fault. The canyon opens up to a few hundred meters width with an alluviated bottom and recessive outcrops of Tertiary gravel on both sides. Park 'vehicles about a quarter mile north of the point where the

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canyon widens. East of the road, one can see dark olive-green metabasaltic rocks (prohably belonging to the Surprise Member of the Kingston Peak Formation) intruded by white-weathering dikes of the Skidoo pluton. Both are tectonically overlain hy brown fanglomerates of the upper Nova Formation. Tertiary basalt flows within the upper Nova gravels are exposed west of the road, where locally they dip as ruch as 45° E. Proceed on foot up the small side canyon east of the road that contains the exposures of the metabasalts and Skidoo dikes. On the north side of the small side canyon, just to the left of the first outcrop of metabasalt, is an exposure of the Emigrant Fault, which is expressed by a yellowish-orange band within gouge made at the expense of both hanging wall and foot wall rocks. The badlands topography formed by the gouge is common throughout the Tucki area. Here, the Emigrant Fault dips only about 10° to the west, and we believe that this fault is responsible for the smoothly-contoured topography developed atop the Skidoo pluton, which we refer to as the Skidoo turtleback. Return to vehicles and Continue N to 190 head west onto the Darwin Plateau. Talc City Thrust: Dunne (1988) 17.3 Pavement temporarily ends as we enter southeast portion of Talc City Hills. Road coincides with a complex fault zone—perhaps an interplay of the Darwin tear fault and an East Sierran thrust fault--that juxtaposes the upper plate of the Talc City thrust fault to the left against late Paleozoic strata of plate 2(?) to the right. Assignment of this plate to the east Sierran assemblage is equally reasonable. 18.0 18.3 Buildings and dump piles of Talc City mine at 3:00 o'clock. At 9:00 o'clock is vertical contact between Hidden Valley DoIomite (to left) and banded, siIver-blue strata of Lost Burro Formation. Pavement ends and road branches just past mine. Bear left and then take those road branches that leads to and then swing close around the end of the spur of Lost Burro Formation about 0.2 mi ahead. 18.7 T-junction marked by metal drum on left. Turn left and proceed past various cross tracks. 18.9 Road crosses inconspicuous trace of Talc City thrust and we enter exposures of footwall (plate 3). Road swings broadIy left, then climbs uphill and becomes bulldozed and bumpy. Turning now to our vantage point, note at 7:30o'clock the cluster of buildings at the end of the ridge. These sit atop a southwest-dipping East Sierran thrust fault that has elevated middle Paleozoic strata, provisionally assigned to plate 2, against Late Cambrian and younger strata of plate 4 (to right of buildings). that near the fault are overturned toward the northeast. Letting our eyes wander rightward up the ridge within plate 4, we note: a) strata progressively change dip to vertical, then to steep but upright—northeast dips; b) a fault with its trace parallel to beds repeats much of the Paleozoic section causing us to see two bands of pale-gray Eureka Quartzite and overlying dark-gray Ely Springs Dolomite. 19.1 miles: STOP 11. FOLDED TALC CITY THRUST FAULT Park on saddle where road turns 120 degrees left to proceed farther uphill. Consult Figure 7. At this stop we will examine the Talc City thrust fault where it has been overprinted by East Sierran folds. Follow the road uphill, examining exposures of footwall (KeeIer Canyon) strata along the right roadcut until you encounter the Talc City thrust fault, above which is massive-looking dolomite. Follow fault trace across slope to right until you have ascertained its dip direction and amount (85º SW). Intense foliation in thin interval of Keeler Canyon strata closest to fault is approximately parallel to fault. In this foliated interval, note rare, small, isoclinal, commonly rootless folds, axes of which trend southwest; these are statistically parallel to the inferred northeast transport direction of the Talc City thrust plate. SIip on this thrust fault is at least 15 km. Turn around and follow fault trace back to the road and beyond (Hint: don't go below road). Fault bends right to follow road, and lens of foliated, dark gray Rest Spring Shale appears along fauIt. Note that foliation in Rest Spring Shale dips northwest. As fault trace approaches bulldozed area surrounding mine headframe on top of hill, Rest Spring Shale pinches out and fault trace bends abruptly to left. Follow trace downhill about 20 m until you get a feeling for amount and direction of its dip here (80º SW) From the first exposure of the fault to this point, we have walked through a northwest-plunging synform-antiform fold pair defined by the folded thrust fault surface. Through this area the fault occupies a footwall decollement with in the weak Resting Spring Shale, which became unevenly smeared out during thrusting and then was further re-distributed into fold cores during superposition of East Sierran folds. As we walk back toward the vehicles, examination of Keeler Canyon (footwall) strata a few meters below the road reveals in them small, dark-brown, spherical chert nodules ("golf balls") that are characteristic features of the stratigraphically lowest beds of the Keeler Canyon Formation. Their occurrence here next to the Rest Spring Shale is evidence that footwall strata of the Talc City thrust fault are inverted. Walk back to vehicles and then continue eastward up to the top of the hill approximately 150 m beyond them. Examine attitudes of bedding and cleavage on the hill top to determine all that you can regarding the fold structure there. Because bedding and southwest-dipping cleavage locally are perpendicular there, and because the line of intersection between them plunges northwest, 'you immediately suspect that you are on the hinge of a northwest-plunging, northeast-vergent fold. Now look northwest across the drainage to the slope that faces us. Voila! There in all its glory is the antiform upon whose crest we are standing. Note the parasitic (drag) fold, of appropriate asymmetry, on the left limb of the fold. This large antiform is typical of East Sierran folds, being northwest plunging, northeast vergent (locally overturned), slightly chevron-like in profile, and slightly asymmetric. A composite stereogram of bedding, cleavage and lineation data measured around this fold and others like it in immediately adjacent areas is presented in Figure 9. The Talc City thrust fault is folded by this antiform, being southwest dipping where we first examined it and northeast dipping on the slope that is N45ºW from us (thrus fault is the line, dropping toward the right that separates less massive-looking rock above from well bedded, ribby looking Keeler Canyon Formation below). Now, look southeast in the up-p1unge direction of this antiform to the slope facing us. There, at deeper levels within this fold, shortening has been accommodated by numerous folds of relatively short wavelength and amplitude rather than by one large antiform. At first it is tempting to think that these smaller folds might signify the proximity of a detachment surface bounding a concentrically folded panel of rock, toward the center of which lies the hill upon which we stand. However, mapping suggests near coincidence of overturned limb and axial plane cleavage compared with 1arge angle between upright limb and cleavage demonstrates that folds are asymmetric. that hinge surface traces of numerous folds, commonly in en echelon sets, continue across the ridge and for some distance beyond, with some folds increasing in wavelength and amplitude in that direction. Such variability of wavelength and amplitude seems to be a primary geometric characteristic of East Sierran folds in this region. Walk about 30 m south-southeast downhill and search for depositional top features in these southwest-dipping, structurally upright Keeler Canyon strata. Several such features demonstrate that depositional tops are to the northeast. Thus, as at the locality with the "golf balls", these beds are structurally upright but stratigraphically overturned. For this reason I have consistently used the term "antiform" for this fold, which exposes relatively younger rock in its core. Technically, this fold is an antiformal syncline. Yes, Virginia, there really are such things! Guiliver (1976) was the first to recognize that much of the Keeler Canyon Formation exposed below the Talc City thrust fault was inverted, probably during emplacement of the thrust plate. Recumbent, isoclinal folds of moderate size locally re-invert narrow panels of rock within this generally overturned footwall sequence. I envi ion the exposed footwall block of the Talc City thrust fault to have evolved as the inverted limb of a large, recumbent fault-propagation fold (Suppe, 1985) that was severed along its hinge surface so as to become a "horse"

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that was translated along with the main upper plate. Whether this horse was derived from the footwall or hanging wall of the original fault is unclear. A schematic evolution for this structure is shown in Figure 10. Return to vehicles, turn around, and retrace route to T-junction originally encountered at mile 18.7.

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Kern Knob Intrusive Rocks (Griffin, 1988; Dunne, 1988): Consult Figure 1 of Griffin. At this stop we have an opportunity to bang on some rocks and examine field relationships between three dated intrusions. East of us lie the lower slopes of Long John Ridge on which are dark, boulder exposures of the Long John pluton cut by several east-trending, dark-green dikes of the Independence swarm. Both the Long John pluton and Independence dikes are cut by scattered northwest-trending, southwest dipping shear zones. Both pluton and dikes are intruded by light-colored, northwest trending, northeast-dipping, protoclastically deformed marginal dikes of the Kern Knob pluton and, farther west, by the main body of the Kern Knob pluton, which does not contain any shear zones like those cutting the Long John pluton and Independence dikes. If time permits, make a traverse up the dark band of Long John granitoid trapped between the Kern Knob marginal dikes to examine intrusive relationships and the protoclastic fabric in the dikes. You may encounter pegmatitic veins containing amazonstone (blue-green K-spar) or beryl.

Axen, G.J., 1987, The Keystone and Red Spring thrust faults in the La Madre Mountain area, eastern Spring Mountains, Nevada, in Hill, M.L., ed., Cordilleran Section of the Geological Society of America: Centennial Field Guide Volume 1, p. 57-60.

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Burchfiel, B.C., and Davis, G.A., 1988, Mesozoic Thrust Faults and Cenozoic Low-angle Normal Faults, Eastern Spring Mountains, Nevada, and Clark Mountains Thrust Complex, California, in Weide, D.L., and Faber, M.L., eds., This Extended Land, Geological Journeys in the Southern Basin and Range: Geological Society of America Cordilleran Section Meeting Field Trip Guidebook, p. 86-106.

Dunne, G.C., 1986, Mesozoic evolution of the southern Inyo Range, Darwin Plateau and Argus and Slate Ranges, in Dunne, G.C., ed., Mesozoic

and Cenozoic structural evolution of selected areas, east-central California, GSA Cordilleran Section Field Guide to Field Trip no. 2, p. 3-43.

Drewes, H., 1963, Geology of the Funeral Peak quadrangle, on the east flank of Death Valley: U.S. Geological Survey Professional Paper 413, 78

p. Hodges, K.V., Walker, J.D., and Wernicke, B.P., 1987, Footwall structural evolution of the Tucki Mountain detachment system, Death Valley

region, southeastern California, in Coward, M.P., et al., eds., Continental extensional tectonics: London, Geological Society, p. 393-408.

Hunt, C.B., and Mabey, D.R., 1966, Stratigraphy and Structure, Death Valley, California, U.S. Geological Survey Professional Paper 494-A, p.

A130. Mattinson, C.G., Colgan, J.P., Metcalf, J.R., Miller, E.L., and Wooden, J.L., 2007, Late Cretaceous to Paleocene metamorphism and magmatism

in the Funeral Mountains metamorphic core complex, Death Valley, California: GSA Special Paper 419, p. 205-223, doi: 10.1130/2006.2419(11).

Troxel, B.W., and Wright, L.A., 1987, Tertiary extensional features, Death Valley region, eastern California, in Hill, M.L., ed., Cordilleran

Section of the Geological Society of America: Centennial Field Guide Volume 1, p. 121-132. Wernicke, B.P., Hodges, K.V., and Walker, J.D., 1986, Geological Setting of the Tucki Mountain Area, Death Valley National Monument,

California, in Dunne, G.C., ed., Mesozoic and Cenozoic structural evolution of selected areas, east-central California: Geological Society of America Cordilleran Section Guidebook, p. 67-80.

Wright, L.A., and Troxel, B.W., 1984, Geology of the north half Confidence Hills 15’ quadrangle, Inyo County, California: California Division

of Mines and Geology Map Sheet 34. Scale 1:24,000.