bluuebunny/crossref_metadata_2025 huggingface dataset:
Portuguese Bend landslide complex, southern California
Authors: Ehlig Perry L.
Published: November 2007

The Portuguese Bend landslide complex occupies a 2.5 mi2 (6 km2) amphitheater-shaped topographic embayment on the south flank of the palos verdes peninsula,22 mi(35km) south of the los angeles civic center in southern california.One-third of the complex consists of the active portuguese bend and flying Triangle landslides and the recently active Abalone Cove and Klondike Canyon landslides (Fig.1). The complex is in the northwest corner of the San Pedro, California, 7 1/2-minute Topo-graphic Quadrangle and adjoining partsof the Torrance and Redondo Beach 7 1/2-minute quadrangles.

As part of the greater Los Angeles metropolitanarea, the Portuguese Bend area is easily reached by automobile or by rapid transit District (RTD)buses. The most direct route from the los angeles civic center is south on the Harbor Freeway (1–110) to its terminous at gaffey street in san pendro.Continue south on Gaffey Street for 1.7 mi (2.8 km), turn right on 25th Street and go 2.8 mi (4.5 km) west to where 25th Street merges with Pales Verdes Drive South (PVDS). The east edge of the Portuguese Bend landslide is 1.5 mi (2.4 km) farther west on PVDS. The area can also be approached from the north by way of Crenshaw and Hawthorne Boulevards (Fig.1).An excellent overview of thearea is obtained from the ridge crest on the south side of Del Cerro Park, located near the southern terminous of Crenshaw Boulevard (Fig.1).

Hiking and riding trails and unpaved roads are present within undeveloped parts of the complex, but most of this area is private land and much of the area is within gated communities where entry requiresspecial permission. The only public land is the beacharea seaward of PVDS and west of Inspiration Point (Fig.1). Public parking along PVDS is restricted to a lot on the south side of PVDS, 0.1 mi (0.2 km) west of Wayfarers Chapel (Fig.1) and costs $3.00 per day.

Geologists wishing current information on the landslides or assistance in gaining access to the area should contact Tom Bandy, Community Services Director, City of Rancho Pales Verdes, 30940 Hawthorne Boulevard, Rancho Pales Verdes, CA 90274; telephone (213) 377–0360. Mr. Bandy is also the Executive Director of the Abalone Cove Landslide Abatement District and the Klondike Canyon Geologic Hazard Abatement District.
Banning fault, Cottonwood Canyon, San Gorgonio Pass, southern California
Authors: Morton D. M. , Matti J. C. , Tinsley J. C.
Published: November 2007

The Banning fault site is located at the mouth of Cottonwood Canyon, at the eastern end of San Gorgonio Pass. San Gorgonio Pass is the low divide separating the high steep terrain of the Peninsular Ranges Province to the south, from the higher but less steep Transverse Ranges Province to the north. The San Gorgonio Pass area is reached by taking 1–10 east from the Los Angeles-San Bernardino-Riverside region toward Indio.

Most places with spectacular exposures of the Banning fault are, unfortunately, on property with restricted access, but one location is readily accessible to the public in Cottonwood Canyon near the eastern end of the Banning fault. Cottonwood Canyon is reached by taking the Verbenia exit from 1–10 about 45 mi (72 km) east of Riverside and San Bernardino. Cross north over 1–10 and turn left on the first road, Tamarack. Proceed west 0.3 mi (0.5 km) on Tamarack to Cottonwood Canyon Road. Go north 1.8 mi (2.9 km) on Cottonwood Canyon Road to a sharp right turn. Park in a parking area to the north of the turn, which is at the mouth of Cottonwood Canyon. Part of Cottonwood Canyon Road is paved; the remainder is an improved dirt road easily passable by passenger cars and buses.
Cucamonga fault zone scarps, Day Canyon alluvial fan, eastern San Gabriel Mountains, southern California
Authors: Morton D.M. , Matti J.C. , Tinsley. L.C.
Published: November 2007

the cukamonga fault zone divides the high eastern SanMenlo Park, California 94025 site is located on the day Canyon alluvialfan where stands of the Cucamonga fault zone have produced impressive scarps crossing the fan surface (Fig. 1). This site is readily accessible by taking the base line.Roadexit from 1–10mi(16)km)east of the city of Ontario. Drive 0.25 mi (0.4 km) west onBaseline Road to Etiwanda Avenue; turn north and go 3 mi(5 km) to the end ofEtiwanda Avenue. At the end of EtiwandaAvenue, an east-west oriented dirt power-line service road is parelled and just south of the southernfault south of the Cuca-monga fault zone, Proceeding 0.5 mi (0.8 km) west from Eti wands even of the power-lineserviceroad, adort road leansnorth up the Day Canyon alluvial fan crossing the southern scarpof the Cucamonga fault zone. This road ends at a locked gate about 0.5m (0.8km) from the power line road, this point issituated on top of one of the northern scarps of the Cucamongafault zone. The U.S. Forest Service buildings, referred to as theDay Canyon Station, are located south of the locked gate at thetop of a 130 ft (40 m) high scarp. The dirt roads can be rough, but are generally easily passable for passenger cars.
Supergene enriched fluidized breccia ore, Lavender open pit copper mine, Warren (Bisbee) Mining District, Cochise County, Arizona
Authors: Bryant Donald G.
Published: November 2007

The Lavender open pit is approximately 80 mi (130 km) southeast of Tucson, Arizona, and can easily be reached by car from either Tombstone or Douglas on paved roads (Fig. 1). The overlook or observation site for the Lavender open pit copper mine is on U.S. 80 between Bisbee and Lowell. The topography and a few of the more famous landmarks—such as the Copper Queen mine, which was the first discovery, the Irish Mag mine, and Sacramento Hill (Ransome, 1904)—are shown on Figure 2.

Unlike many of the porphyry copper deposits of the Lavender open pit mineralization is in a fluidized [intrusive] breccia pipe, not porphyry, and is Nevadan (130 Ma), Laramide, in age. The fluidized breccia is composed of exotic ments and boulders that have been transported from below in fine-grained or rock flour matrix of pulverized rock and ported sulfides. The transporting media was a circulating water slurry flowing along preexisting fractures. The ore actually mined in the Lavender pit were not in the porphyry rocks but were transported fragmental sulfides in the matrix mineralized fragments and boulders with later supergene chalcocite enrichment. The mineralization in the porphyrins limited to pyrite with a thin coat of chalcocite, and was very grade.
Roadcut exposure of the San Andreas fault zone along the Antelope Valley Freeway near Palmdale, California
Authors: Barrows Allan G.
Published: November 2007

The spectacular, trench-like roadcut where the Antelope Valley Freeway (California 14) crosses the San Andreas fault zone not only excellently exposes the geology within the zone but is also the most readily accessible point on the San Andreas fault for residents of the Los Angeles region. The locality is 60 mi (100 km) from the Los Angeles Civic Center via I-5 ad California 14, and is about 1 mi (1.6 km) southwest of the city of Palmdale between the offramps for Palmdale Boulevard and Avenue S (Fig. 1).

The Antelope Valley Freeway is a limited-access, divided highway; stopping along the shoulder to view the geology is not permitted. Slowing down while traveling through the cut is also very dangerous because of high-speed freeway traffic. The best way to view the roadcut is to exit the freeway at Avenue S and climb the hill outside the fence along the freeway.
Potrero Canyon fault, landslides and oil drilling site, Pacific Palisades, Los Angeles, California
Authors: McGill J. T. , Lamar D. L. , Hill R. L. , Michael E. D.
Published: November 2007

This stop is located in the Pacific Palisades areaof the City of Los Angeles, directly west of the Sunspot Restaurant and Motel, 15145 Pacific Coast Highway, between traffic signals at Chautauqua Boulevard, 0.5 mi, (0.8 km) to the southeast, and Temescal Canyon Road, 0.6 mi (1.0 km) to the northwest (Fig. 1). The mouth of Potrero Canyon is situated behind the motel. The site can be reached from central Los Angeles to the east via the Santa Monica Freeway (I-10), which continues west of the McClure Tunnel in the City of SantaMonica as the Pacific Coast Highway (California 1), or from the Ventura-Oxnard area to the west via the Pacific Coast ing is Highway through Malibu. Parking is available directly west of the restaurant-motel, or, for afee, directly across the highway; during periods of beach use on summer weekends, parking may be difficultand heavy traffic may be a problem. Extreme care should be taken if it is necessary to cross Pacific Coast Highway.
Turbidite features in the Pico Formation (Pliocene) at Santa Paula Creek, California
Authors: Baldwin E. J.
Published: November 2007

Exposures of turbidite features in the Pico Formation arelocated in Santa Paula Creek along the east side of CaliforniaState Highway 150, 3.1 mi (5 km) north of Main Street, SantaPaula (Fig. 1). Santa Paula is 14 mi (22.4 km) east of the city ofVentura, Ventura County, southern California.

At the roadside entrance to the site, there is a chain and a not respassing sign. Permission to enter may be obtained from the Santa Paula Water Department (805-525-5591). The best exposures of the strata start at a silted dam and gauging station andcontinue south for about 600 ft (180 m). Santa Paula Creek crosses the steeply dipping strata at a right angle, thus providing an excellent cross section for study (Fig. 2).
Sedimentology of Cretaceus strata in Wheeler Gorge, Ventura County, California
Authors: Dibblee T.W.
Published: November 2007

Wheeler Gorge is the narrow part of the North Fork of Matilija Canyon that cuts through the Santa Ynez-Topatopa Range of the western Transverse Ranges, in Ventura County. This canyon is within the Los Padres National Forest.Wheeler Gorge is accessible from California 33 which passes through it and Wheeler Springs, a small resort in this canyon 1 mi (1.6 km) west of Wheeler Gorge. Wheeler Springs is about 19 mi (30 km) north of Ventura on the coast and about 7 mi(11 km) northwest of Ojai in Ojai Valley (Fig.1). At Wheeler Gorge the canyon is so narrow and steep-walled that three short tunnels had to be cut and three bridges built for California 33.The North Fork of Matilija Creek and Wheeler Springs are shown on the Wheeler Springs 7 1/2-minute Topographic Quadrangle of the U.S. Geological Survey.
Jadeitized Franciscan metamorphic rocks of the Pacheco Pass-San Luis Reservoir area, central California Coast Ranges
Authors: Ernst W. G.
Published: November 2007

The Pacheco Pass-San Luis Reservoir area is located in the central Diablo Range along the crest and eastern flank of the uplift. The site is transected by California State Highway 152, a four-lane, divided roadway near and east of the summit (elevation 1,368 ft; 410 m). The area is situated about 120 mi (200 km) southeast of San Francisco and 285 mi (450 km) northwest of Los Angeles. The location is illustrated in Figure 1. Access is provided by Highway 152, and a portion of the former road; four of the six outcrops referred to in this report are roadcuts. Because of heavy automobile and truck traffic on Highway 152, special care must be exercised when examining the rocks, and vehicles should be parked in turnouts or on the shoulder well off the pavement.
Marin Headlands, California
Authors: Wahrhaftig Clyde , Murchey Benita
Published: November 2007

The Marin Headlands are the hills on the north shore of the Golden Gate opposite San Francisco (Figs. 1,2; see Point Bonita and San Francisco North 7DDD÷-minute Quadrangles). They are entirely within the Golden Gate National Recreation Area(GGNRA), a unit of the National Park System. Collecting of rock specimens is by permit only, obtainable on adequate scientific or educationaljustification from the GGNRA headquarters at Fort Mason, San Francisco 94123 (415-556-0560). Application for permit should be made at least two weeks in advance of the visit.

San Francisco MUNI bus No. 76 runs on Sundays and holidays only, between San Francisco and Fort Cronkhite Visitor Center (FCVC, Fig. 1). For schedule and stops in San Francisco call the MUNI system (415-673-MUNI). The Golden Gate Transit District bus No. 10 makes daily stops at the Alexander Avenue off-ramp (Locality 1, Fig. 1); buses Nos. 20,50, and 80 make daily stops at Spencer Avenue (Locality 2, Fig. 1); and bus No. 10 also stops at Tamalpais Valley Junction, from which a road and trail go to the Tennessee Valley trailhead (Locality 3, Fig. 1). Call 415-332-6600 for the Golden Gate Transit schedule and stops in San Francisco.

Automobile access from San Francisco is via U.S. 101 north across the Golden Gate Bridge and the secondoff-ramp (Alexander Avenue) on the north side of the bridge; turn left at first opportunity (about 100 m), go back underneath the freeway, and keep to right up the hill into the Golden Gate National Recreation Area (GGNRA) and Marin Headlands. Approaching from the north on U.S. 101, take the third Sausalito off-ramp (the only off-ramp between the Waldo Tunnel and the Golden Gate Bridge), turn left immediately at the stop sign, and then turn right immediately up the hill at the sign to the GGNRA. The Tennessee Valley Trailhead(Locality 3, Fig. 1) is accessible from California 1 between U.S. 101 and Tamalpais Valley Junction. All travel away from roads must be made on foot, horseback, or bicycle; motorized vehicles are prohibited off designated roads.
Table Mountain of Calaveras and Tuolumne Counties, California
Authors: Rhodes Dallas D.
Published: November 2007

Table Mountain is located in the western foothills of the central Sierra Nevada Range east of Stockton, California (Figs. 1 and 2). California 108 generally follows the ridge from Knight’sFerry to Sonora. Although Table Mountain is not now the obstacleit was for the early gold seekers, only four paved roads cross it:O’Byrnes Ferry Road through Peoria Pass, Rawhide Road nearJamestown, California 49 north from Sonora, and Parrot’s FerryRoad west from Columbia. From Vallecito northward, California4 provides some views of the upstream and more discontinuousparts of the flow, as does California 108 north to Sonora Pass.Most of the lower part of Table Mountain is privately owned andpermission should be sought from local land holders. The higherareas are in national forests. Poison oak grows in abundancealong the flanks of Table Mountain and caution is advisable.
Multiple deformation in the Bennettville area of the Saddlebag Lake pendant, Central Sierra Nevada, California
Authors: Trent D. D.
Published: November 2007

The Bennettville area of the Saddlebag Lake pendant(Fig. 1) straddles the boundary of the Tuolumne Meadows andMono Craters quadrangles. Bennettville is located in the SE 1/4, NW 1/4, Sec.19, T.lN., R.25E. Park vehicles on California 120 atthe road junction to Saddlebag Lake, 9.6 mi (19 km) west of LeeVining and 2.4 mi (4 km) east of Tioga Pass. Bennettville isreached by walking west through the campground to a welldefined fisherman´s trail that begins at the far western edge of thecampground on the north side of Mine Creek. The trail roughlyparallels Mine Creek to Bennettville, an abandoned gold miningcamp, where two buildings remain in arrested decay.
The ultramafic rocks at Eunice Bluff, Trinity Peridotite, Klamath Mountains, California
Authors: Carter Bruce A. , Quick James E.
Published: November 2007

Eunice Bluff is located in the Klamath Mountains of northern California, approximately 30 mi (48 km) south of the Oregon border and 10 mi (16 km) west of I-5 (Fig.1A). It is easily reached by conventional automobile on paved and graded roads, followed by a short walk through open forest. From Gazelle, take the Gazelle-Callahan road west 15.5 mi (24.8 km) and turn left (south) on the road to Kangaroo Lake. Drive 3.7 mi (5.9 km) and turn left (east) on a U.S. Forest Service road with a large steel gate. Drive 2.5 mi (4 km) to Cabin Meadow Creek, turn right (south) and drive 1 mi (1.6 km) up the creek. At this point the road forks; cross the creek and continue an additional 1.2 mi (1.9 km) upthe east side of the creek to the dead end of the road, avoiding the minor logging roads that turn off to the left. From the dead end, walk up the logging skid-road 0.25 mi (0.4 km) east past a small meadow, and then walk 0.25 mi (0.4 km) southsoutheast up the creek to Cabin Meadow Lakes. Eunice Bluff is the prominent light-colored outcrop above the south end of the upper lake. The beginning of the trip, survey point A, is on the large ledge that is about 400 ft (122 m) south of and 100 vertical ft (30.5 m) above the upper lake. The outcrop is usually accessible from May through November but may be covered with snow at times during the rest of the year.
Paleozoic stratigraphic section in Dry Canyon, Whetstone Mountains, Cochise County, Arizona
Authors: Wrucke Chester T. , Armstrong Augustus K.
Published: November 2007

The Whetstone Mountains are in southeastern Arizona along the boundary between Cochise and Pima Counties, about 42 mi (70 km) southeast of Tucson (Fig. 1), Benson, 15 mi (25 km) to the northeast, and Sierra Vista, about the same distance to the south, are the nearest towns. Most of the Whetstone Mountains, including the Dry Canyon area, are in Coronado National Forest. Dry Canyon, on the lower southeast flank of the mountains, is in the Benson15-minute Quadrangle and the Apache Peak and McGrew Spring 7½-minute Quadrangles. Along the canyon, and particularly on the ridge on its south side, a thick sequence of paleozoic rocks is exposed, which is the focus of this report.

The Dry Canyon area (Fig. 2) is reached via Arizona 90, which trends south toward Fort Huachuca and Sierra Vista from its junction with I-10, about 2.7 mi (4.5 km) west of Benson. At a point 13 mi (21.5 km) south of 1–10, a dirt road, marked by a simple ranch gate, leads westward a few mi (km) across public land into Dry Canyon. This road is best traveled using a four-wheel-drive vehicle, but it was passable with difficulty for passenger cars in 1982.
Shelf and deep-marine deposits of Late Cretaceus age, Cape Sebastian area, southwest Oregon
Authors: Hunter Ralph E. , Clifton H. Edward
Published: November 2007

The outcrops described in this report are in the vicinity of Cape Sebastian, Curry County, Oregon (Fig. 1). The principal outcrop (Point A, Fig. 2) is in the Cape Sebastian Sandstone as restricted by Bourgeois (1980), at the south tip of the Cape Sebastian headland. Visitors can most easily reach the outcrop by a 1.2-mi-long (2 km) foot trail that leads down to the south tip of the headland from the parking area at the south end of the road through Cape Sebastian State Park (Point B, Fig. ). The entrance to the state park is on U.S. 101, 6 mi (10 km) south of Gold Beach, Oregon. The outcrops of the Hunters Cove Formation of Dott (1971) are located along the shore of Hunters Cove and can most easily be reached by walking northward along the beach from the parking area alongside U.S. 101 just south of the cove (Point C, Fig. ).
Depoe Bay, Oregon
Authors: Snavely Parke D.
Published: November 2007

The Depoe Bay field site is located on the central Oregon coast, adjacent to U.S. Highway 101, opposite the fishing village of Depoe Bay, Lincoln County, Oregon (Fig. 1). The pillow lavas of the Depoe Bay Basalt are well exposed in sea cliffs just beyond the low seawall along the west side of the highway. The Sandstone of Whale Cove and breccias of the Cape Foulweather Basalt can be reached by steep trails that lead down to the base of the sea cliffs along the north sideof the outer bay. Here, and elsewhere along the Oregon coast, extreme caution should be exercised not to work too close to sea level, as unexpectedly large waves can sweep a person off the rocks. A one-hour excursion aboard a fishing boat that leaves from the innerbay is highly recommended, as this trip provides an opportunity to view the geology along this scenic coastline.
Record of early High Cascade volcanism at Cove Palisades, Oregon
Authors: Taylor Edward M. , Smith Gary A.
Published: November 2007

This site is a series of scenic viewpoints on the east rim of Crooked River canyon above Cove PalisadesState Park, near the boundary between sections 2 and 11, T.12S., R.12E., U.S. Geological Survey 7.5-minutequadrangle Round Butte Dam, Oregon. From downtown Madras, Oregon, follow signs marked “Cove”or “Cove State Park” on paved highways westward to the park entrance. From Redmond, Oregon, travel north on U.S. 97, turn northwestward at the exit to Culver, then follow signs marked “Cove” on paved highways to the park entrance (Fig. 1). Highways to the overlook and park are open all year. Just east of the park entrance, take the paved road north (“To Viewpoints”)along the east edge of the canyon rim to any of three viewpoint parking areas.
Columbia River Gorge
Authors: Beeson Marvin H. , Tolan Terry L.
Published: November 2007

The Columbia River Gorge is located astride the Cascade Range along a 72 mi (120 km)stretch of the Oregon/Washington border 1). The western half of the gorge is covered by the Camas and Bridal Veil 15-minute quadrangles. Primary access to the gorge is by two major highways which traverse its length-the two-lane State Highway 14 along the Washington side and the four-lane Interstate 84 freeway along the Oregon side. Also along the Oregon side are segments of the old Columbia River Scenic Highway, which when completed in 1917 was the first paved highway to extend the length of the gorge. All sites to be visited on the Oregon side are along the old Columbia River Scenic Highway (Fig).
Geology of the Vantage area, south-central Washington
Authors: Carson Robert J. , Tolan Terry L. , Reidel Stephen P.
Published: November 2007

The Vantage area is located along the Columbia River in the central portion of Washington State at the boundary between Grant and Kittitas counties (Fig.1). The area lies entirely within the eastern portion of the Yakima Fold Belt of the Columbia Plateau. The area is covered by the Beverly, Evergreen Ridge, Ginkgo, and Vantage 7.5-minute quadrangles. The Vantage area can be reached via Interstate 90 from the east or west or State Route 243 from the south (Fig.1). All sites within the Vantage area are along paved roads.
Dry Falls of the Channeled Scabland, Washington
Authors: Baker Victor R.
Published: November 2007

Dry Falls is located on the Coulee City 7%-minute Quadrangle(Fig. 1) at Lat. 47°36'N, Long. 119°21'W; sec.6, T.24N., R28E, in Grant County, Washington. It can be reached by passenger car or bus on Washington 17, 18.5 mi (29.6 km) north of Soap Lake or 1 1/2 mi (2.4 km) south of the junction of U.S. 2 and Washington 17 near Coulee City, Washington. The falls are easily viewed from a public overlook atDry Falls State Park.
A Tertiary accreted terrane
Authors: Tabor R. W.
Published: November 2007

The rocks of the Olympic Peninsula and their counterparts to the south in the Coast Ranges of southern Washington and Oregon comprise one or more Tertiary accreted terranes which are part of the collage of terranes that make up most of northwestern Washington (Coney and others, 1980).

The Olympic Mountains in Olympic National Park are one of the best examples of an accreted subduction complex of Tertiary age found in the conterminous United States. The Hurricane Ridge Road, south of Port Angeles, crosses parts of the complex where the observercan see spectacular outcrops of pillow basalt, pelagic interbeds, and submarine fan deposits, as well as the complex structures engendered during accretion of these rocks to the continental margin of North America.

Terrane (or tectonostratigraphic terrane) as used in this guide refers to a discrete structural block with stratigraphic and/or structural coherence; it is separated from its neighboring terranes by faults. Moreover, a large terrane that was coherent during its later geologic history, can be subdivided into smaller terranes whose earlier geologic histories differ.
Republic graben, Washington
Authors: Moye Falma J.
Published: November 2007

The Republic graben, located in northeastern Washington, extends from the Canadian border south approximately 48 mi (80 km) to the Columbia River. It can be reached on hard surface road from the east and west along Washington 20 from Kettle Falls or Tonasket, respectively, or from the south along Washington 21 from Wilbur (Fig. 1). The town of Republic, where lodging, food, and gasoline can be obtained, is located about 6 mi (10 km) north of the geographic center of the graben.

All of the stops shown in Figure 2 are accessible by two wheel drive vehicle. Most of the area describedin this report is on land owned by the Colville Indian Reservation, which has headquarters in Nespelem, Washington, 40 mi (64 km) south of Republic; Figure 2 shows the northern boundary at the reservation. North of Thirteenmile Creek, land is controlled by the National Forest Service or is privately owned. Permission should be obtained from private land owners and the Colville Tribal Headquarters before entering their land from the road right-of-way.
Structural relationships on the eastern margin of the Shuswap Metamorphic Complex near Revelstoke, British Columbia, Canada
Authors: Lane Larry S. , Brown Richard L.
Published: November 2007

Revelstoke (population 10,000) lies at the confluence of the Illecillewaet and Columbia Rivers in southern British Columbia (51°N, 118°12' W);and is 435 mi(700 km) east of Vancouver, British Columbia, and 250 mi (400 km) west of Calgary, Alberta (Fig.1). Principal access is by the Trans-Canada Highway and Canadian Pacific Railway. Provincial highways, secondary, and logging roads provide access to many geologically significant localities throughout the area (Brown and others,1981). The Big Bend Highway (British Columbia 23) runs northward from the Trans-CanadaHighway, past Revelstoke Dam 3 mi (5 km) north, to Mica Dam 96 mi (155 km) north.
Valley of Ten Thousand Smokes, Katmai National Park, Alaska
Authors: Hildreth Wes , Fierstein Judy
Published: November 2007

The pyroclastic deposits of the Valley of Ten Thousand Smokes (VTTS) lie within Katmai National Park, 450 km southwest of Anchorage and 170 km west of Kodiak (Fig. 1). The only convenient access is by boat or amphibious aircraft from King Salmon to Brooks Camp on Naknek Lake; scheduled commercial service is available during summer months. Brooks Lodge offers a daily commercial shuttle by bus or van to the Overlook Cabin, perched on a scenic knoll near the terminus of the VTTS ash-flow deposit, at the end of a 37-km dirt road from Brooks Camp. Cabins, meals, camping, and National Park Service programs are available at Brooks Camp, but the Overlook Cabin and the Baked Mountain Hut (a day’s walk up th VTTS) provide no amenities other than primitive shelter from the normally foul weather. The distal part of the ash-flow sheet can be reached in an hour’s walk by rough trail from the Overlook Cabin, but anything more than a brief visit demands a backpack, boots and sneakers, high-quality rain gear, a sturdy tent, warm clothing, maps and compass, water bottles, food, an ice axe or staff, goggles for ash storms, a rope for fording streams, and a plan (or philosophy) for dealing with brown bears-which are commonly encountered with little warning. High winds, rain, bears, icy streams, and remoteness make the VTTS a true wilderness, exhilarating but dangerous, occasionally glorious, usually uncomfortable, and never to be trifled with. Information can be obtained by writing to the Superintendent, P.O. Box 7, King Salmon, AK 96613. U.S. Geological Survey 1:62,500 topographic maps, Mt. Katmai A3, A4, B3, B4, and 135, cover the VTTS and several neighboring stratovolcanoes, and the Mt. Katmai 1:250,000 sheet provides a desirable regional perspective.
Virgin River Gorge; Boundary between the Colorado Plateau and the Great Basin in northwestern Arizona
Authors: Langenheim R. L. , Schulmeister M. K.
Published: November 2007

The Virgin River Gorge and one of its tributaries are traversed by I-15 between milepost 12, about 13 mi (21 km) east of Mesquite, Nevada, and Milepost 28, about 12 mi (19 km) west of St. George, Utah (Fig. 1). Geologic features are readily observable from the road and from a scenic viewpoint in the Virgin River Canyon Recreation Area, which is entered from an interchange between mileposts 18 and 19. The site is in the northern half of the Purgatory Canyon, Arizona, 7½-minute Quadrangle and in the northeastern quarter of the Littlefield, Arizona, 15-Minute Quadrangle.
Chulitna region, south-central Alaska
Authors: Hawley C. C. , Jones D. L. , Smith T. E.
Published: November 2007

The Upper Chulitna region of Alaska is on the south flank of the centralAlaska Range on the southeast side of Denali National Park (Fig. 1). It was first recognized as an unusual entity by S. R. Capps, who mapped a belt of Triassic rocks (1919) during a reconnaissance of mineral deposits; he called the area the Upper Chulitna region.

The Chulitna River forms a barrier to access, but once across the Chulitna the country is open and ranges from rolling, easily hikeable country to rugged and difficult. Some of the key sections of the Chulitna region are strikingly exposed in canyon walls, and flybys from either fixed- or rotary-wing aircraft provide excellent overviews of the geology (Figs. 2, 3).
The Alaska Tatonduk River section; An exceptional Proterozoic into Permian continental margin record
Authors: Allison Carol Wagner
Published: November 2007

The Tatonduk River section is located in the Nation Arch, a wedge-shaped area in eastern Alaska bounded by the Alas-ka-Yukon Territory border and the Dawson, Tintina, and Glenn Creek fault complexes (Fig. 1). The Yukon River flows north through the western portion of this wedge. The Tatonduk River flows west from the Yukon Territory, joining the Yukon River 13 mi (21 km) north of the village of Eagle.

Scheduled commercial air service is available to Eagle from Fairbanks, and there is road access to Eagle from May through September. Access to the Tatonduk River section is via riverboat or helicopter. There are no established trails into or within the Taonduk River valley. The high gradient and boulder bed of the river require a very shallow-draft boat with sufficient power to maintain control in the strong current. Shoaling near the mouth and multiple channels upstream demand skill in identification of the main channel.

This region falls partly within the boundaries of Yukon-Charley National Rivers Preserve, supervised by National Park Service personnel based in Eagle, and by the Doyon Regional Corporation, based in Fairbanks. Current land management policies allow access to the Tatonduk River valley; however, written permission is advisable for fossil collection, and helicopter usage in specific areas and periods is restricted.
The Ambler sequence at Arctic Ridge, Ambler District, Alaska
Authors: Schmidt Jeanine M.
Published: November 2007

Arctic Ridge (67°09'18''N, 156°23'18''W to 67°12'42''N, 156°21'12''W) is located in the Ambler mineral district on the southern flank of the Brooks Range, northwest Alaska (Fig. 1), in the Ambler River A-1 Quadrangle. The ridgeline is 1.5 mi (2.5 km) due east of VABM Riley, between the Kogoluktuk and Shungnak rivers (Fig. 2).

Access to the area is easiest by helicopter. Arctic Ridge lies 270 mi (430 km) northwest of Fairbanks, 170 mi (270 km) east of Kotzebue, and 310 mi (500 km) northeast of Nome. Commercial helicopters are usually available for charter in Fairbanks and Nome. The traverse of the Ambler sequence begins on the highest peak (locally known as Arctic peak, elevation 3,560 ft; 1,085 m, Fig. 2) of the southern ridgeline, southeast of the buildings in Subarctic Creek valley (Fig. 3). Permission to cross private land and patented claims should be obtained prior to a visit from the NANA regional corporation (Northwest Alaska Native Association, based in Kotzebue) and Kennecott Mining Company (Salt Lake City, Utah), respectively. An alternative is to charter a small single-engine plane to Arctic airstrip (Fig. 2). This is a private airstrip, and permission for landing must be obtained from Kennecott Mining Company prior to any visit. From the airstrip, walk approximately 7.5 mi (12 km) northeast along a dirt road to Arctic camp, and from there up to Arctic peak.

The ridge is often covered by patchy snow into early July, but most outcrops are accessible by early June. The area usually remains free of snow cover until mid-September; however flurries can occur in any month. The ridgeline is steep, craggy, and locally difficult to traverse. Allow 5 to 10 hours in addition to the time required to arrive in the area. Interesting sidehill outcrops are 500 to 1,500 ft (150 to 450 m) in elevation below the ridgeline and often on steep slopes; allow extra time or use a helicopter to reach these.
The Doonerak fenster, central Brooks Range, Alaska
Authors: Mull C. G. , Dillon J. T. , Adams Karen E.
Published: November 2007

Dietrich River and hiking 5 mi (8 km) to ridges northwest of Kuyuktuvuk Creek and Trembley Creek (an elevation gain of 2,000 to 3,000 ft [600 to 900 m]), a visitor gains access to some of the major stratigraphic units exposed in the fenster and at the base of the allochthon. However, in this area, exposures are not as good, and the structure is much more complicated than in the area of Mount Doonerak and Amawk Creek to the west.

Only the base of the Endicott Mountains allochthon is present in the area of the Doonerak fenster. The upper part of the Upper Devonian elastic sequence and the Mississippian to Trias-sic rocks on the allochthon are best exposed from the Brooks Range crest at Atigun Pass north to the mountain front, and are most easily reached from the Dalton Highway in the northern Endicott Mountains.

The Doonerak fenster is located in the central Brooks Range about 35 mi (55 km) south of the Endicott Mountains front. It can be traced for at least 70 mi (110 km) southwest from the Dalton Highway (the Trans-Alaska Pipeline haul road) about 50 mi (80 km) north of the village of Coldfoot. The area is located on the Wiseman and Chandalar 1:250,000 quadrangle maps and the Wiseman D1 and D2 and Chandalar D6 1:63,360 quadrangle maps.

The most significant stratigraphic and structural relationships in the fenster and at the base of the overlying Endicott Mountains allochthon are best exposed near Mount Doonerak and in the canyon of Amawk Creek 15 to 22 mi (24 to 35 km) west of the Dalton Highway. These areas are most easily reached by helicopter, or by bush planes, which can be landed on a gravel bar near the junction of Bombardment Creek and the North Fork of the Koyukuk River. The area is within the Gates of the Arctic National Park, and permission for helicopter access must be obtained in advance from the Superintendent, Gates of the Arctic National Park, P.O. Box 74680, Fairbanks, Alaska 99707.

The eastern end of the fenster is accessible by foot from the Dalton Highway from between miles 225 and 226. By wading the Dietrich River and hiking 5 mi (8 km) to ridges northwest of Kuyuktuvuk Creek and Trembley Creek (an elevation gain of 2,000 to 3,000 ft [600 to 900 m]), a visitor gains access to some of the major stratigraphic units exposed in the fenster and at the base of the allochthon. However, in this area, exposures are not as good, and the structure is much more complicated than in the area of Mount Doonerak and Amawk Creek to the west.

Only the base of the Endicott Mountains allochthon is present in the area of the Doonerak fenster. The upper part of the Upper Devonian elastic sequence and the Mississippian to Trias-sic rocks on the allochthon are best exposed from the Brooks Range crest at Atigun Pass north to the mountain front, and are most easily reached from the Dalton Highway in the northern Endicott Mountains.
Geologic features of Ignek Valley and adjacent mountains, northeastern Alaska
Authors: Molenaar C. M. , Mull C. G. , Swauger D.A.
Published: November 2007

Ignek Valley lies along the northern most salient of the Brooks Range front in the Arctic National Wildlife Refuge in northeastern Alaska (Figs. 1 and 2). Lying between the Shublik Mountains on the south and the Sadlerochit Mountains on the north, Ignek Valley includes the entire drainage of Ignek Creek and the headwaters of the Katakturuk River, which drains northward through the Sadlerochit Mountains as an antecedent river. The entire area is in the Mt. Michelson 1:250,000-scale Quadrangle or on the Mt. Michelson C-3 and C-4 1:63,360-scale quadrangles.

Access to the area is easiest by helicopter, which can be chartered at Deadhorse (Prudhoe Bay), 85 mi (137 km) to the northwest. In addition, bush planes have landed on nearby gravel bars and terraces, or at Schrader Lake 15 mi (24 km) southeast of Ignek mesa (informal name). Charter air service is available at Deadhorse, or Kaktovik, 60 mi (96 km) to the northeast. Because Ignek Valley is within the Arctic National Wildlife Refuge, permission to use helicopters or to conduct geological investigations within the refuge must be obtained by writing to the Refuge Manager, Arctic National Wildlife Refuge, Box 20, 101 12th Avenue, Fairbanks, Alaska 99701.
Lower Paleozoic craton-margin section, northern Potosi Valley, southern Spring Mountains, Clark County, Nevada
Authors: Cooper John D.
Published: November 2007

Potosi Valley, located in the southern Spring Mountains approximately 30 mi (48 km) southwest of Las Vegas, Nevada (Fig. 1), exhibits a well-exposed section of the lower Paleozoic Goodsprings Dolomite of Hewett (1931). The best section is exposed on the west side of northern Potosi Valley in the east face of a 4-mi-(6.4-km-) long strike ridge (Fig. 2) containing a 3,300 ft (1,000 m +) thick succession of Middle Cambrian through Middle to Upper Devonian carbonate rocks (Fig. 3). These strata provide an instructive look at the Cordilleran craton-margin to miogeoclinal transition sequence comprising part of an alloch-thonous assemblage in the upper plate of the Keystone thrust. This accessible area has much to offer the student interested in Great Basin stratigraphy, sedimentology, and structure.
Steamboat Springs, Nevada
Authors: White Donald E. , Slemmons David B.
Published: November 2007

Steamboat Springs geothermal area, Nevada is at the boundary between the Sierra Nevada and the Great Basin, and 10 mi (16 km) south of downtown Reno (Fig. 1). Access to the thermal area is convenient by bus or passenger car, from Nevada 431 at the northern edge of the area and U.S. 395 at the eastern edge.
Complex fold and thrust relationships, Mac Canyon, northern Pilot Mountains, west-central Nevada
Authors: Oldow John S.
Published: November 2007

Mac Canyon is located on the northwestern flank of the Pilot Mountains, approximately 3.6 mi (6 km) east of Mina, in west-central Nevada. Mina is situated on U.S. Highway 95 approximately 33 mi (50 km) southeast of Hawthorne and about 76 mi (120 km) northwest of Tonopah. Mac Canyon is accessible by a good gravel road that leaves the southeastern quadrant of the Mina townsite (Fig. 1). The road ends at an old mine dump (suitable for parking) approximately 0.15 mi (0.25 km) south of the mouth of the canyon. A fair trail leads north along the range-front fault of the Pilot Mountains and is an easy walk to the canyon mouth. Some problem may be encountered in locating the appropriate road from Mina to the northwestern flank of the Pilot Mountains, because it is not marked. If local directions are sought, ask for the road to Water or Spearmint Canyon (site of the town water supply). Location of the town airstrip and use of the accompanying copy of parts of the Mina and Sodaville quadrangles should be sufficient direction. It is important to note that some of the roads indicated on the map have moved since publication of the quadrangle maps. Roads are good and passenger cars can be used. It is doubtful that buses could negotiate the road to the parking site, but they probably could approach to within about 2.4 mi (4 km) of the trail head.
1954 Fairview Peak earthquake area, Nevada
Authors: Slemmons David B. , Bell John W.
Published: November 2007

On December 16, 1954, two large-magnitude earthquakes occurred nearly simultaneously in the Fairview Peak-Dixie Valley area of western Nevada (Fig.1) (Slemmons, 1984). The first earthquake (Ms = 7.25) was centered near the middle of the Fairview Peak fault zone, where it crosses U.S. 50. It was followed four minutes later by a second shock(Ms=7-)centered on the east flank of the Stillwater Range in the northwest part of Dixie Valley, about 37 mi (60 km) to the north. Both earthquakes were accompanied by extensive and spectacular surface faulting (Slemmons, 1957). The combined rupture zone is about 62 mi (100 km) long and 18 mi (30 km) wide. The most spectacular scarps of this zone are at the main site (Figs.2 and 3) on the southeast side of Fairview Peak, an area that is about 5.5 mi (9 km) south of U.S. 50 and is accessible by passenger car on a new graded road.
The Snake Range décollement, eastern Nevada
Authors: Miller Elizabeth L. , Gans Phillip B. , Lee Jeffrey
Published: November 2007

The northern Snake Range is located in east-central Nevada, along the Utah-Nevada border. It can be reached by driving approximately 50 mi (80 km) east from Ely, Nevada, on U.S. 50 (Fig. 1). The closest town of Baker, Nevada has food, accommodations (The Silver State motel), and nearby camping. The field trip stops described below are some of the most easily accessible; for a more complete field trip guide and road log, the reader is referred to Gans and Miller (1983).
Mesozoic structural features in Sonoma Canyon, Sonoma Range, Humboldt and Pershing counties, Nevada
Authors: Stahl Stephen D.
Published: November 2007

Sonoma Canyon is on the west flank of the Sonoma Range, directly south of Winnemucca, Nevada (Fig. 1A, B). Coming from either the east or west on 1–80, take the second Winnemucca exit (“to U.S. 95 north”), turn west on Business 1–80 at the base of the ramp, and continue on Business 1–80 through the U.S. 95 junction. If entering Winnemucca via U.S. 95, turn right (west) at the junction with Business 1–80 (highlighted by“to 1–80” signs). Travelers from all directions are now on the same road and heading in the same direction and should get into the left lane of Business 1–80 west. Approximately 0.5 mi (0.8 km) west of the Business I-80/U.S. 95 junction, turn left (southeast) on Hanson Street (at sign for “Hanson Street Overpass”) and follow this road over the railroad tracks. At the base of the viaduct, turn right (southwest) on Grass Valley Road. Follow Grass Valley Road southwest and then south (at a “Y”in the road after passing the Grass Valley school and Star City deli/laundromat) for approximately 11.5 mi (18.5 km). The pavement ends at the Pershing County line. Turn left (east) onto the Sonoma Canyon access road (no sign; Fig. 1C). This turnoff is approximately 0.75 mi (1.3 km) north of Sonoma Ranch, which is well marked. The total distance from the center of Winnemucca is about 13 mi (21 km).
Post-Early Triassic, pre-middle Eocene folds and thrust faults, northern Adobe Range, Nevada
Authors: Ketner Keith B.
Published: November 2007

The Adobe Range is in northeastern Nevada near the city of Elko (Fig. 1). The northern end of the range can be reached in less than an hour from Elko via 1–80 and a gravel and dirt road that extends northward from the Ryndon Exit, 10 mi (16 km) east of Elko. (From the Ryndon Exit, proceed 7 mi (11.2 km) north to intersection; 2.7 mi (4.3 km) northwest to house; then right 3 mi (4.8 km) up Coal Mine Canyon to area shown on Fig. 2.) The areas indicated on Figures 2 through 4 are shown on the Coal Mine Basin 71/2-minute Quadrangle, and the geology of the northern Adobe Range is shown in Ketner and Ross (1983). In dry weather, these areas can be reached by two-wheel drive pickup truck or by vans, but four-wheel drive vehicles are recommended. These locations are inaccessible by bus.
The Athabasca Glacier, Alberta, Canada
Authors: Osborn Gerald
Published: November 2007

The Athabasca Glacier, a major tourist attraction in the Canadian Rockies, lies close to Alberta 93 (the Icefields Park-way) in Jasper National Park, 100 mi (160 km) northwest of Banff and 60 mi (95 km) southeast of Jasper. The Icefields Chalet and Parks Canada Information Center (Fig. 1) are accessible by bus from Banff and Jasper. Interpretive exhibits are on display at the center. From the highway a paved road leads to a parking lot within 0.3 mi (0.5 km) of the glacier terminus (Stop 1, Fig. 1). The preglacial area is easily explored on foot, and the ice-front sometimes can be traversed with ordinary boots. However, steep slopes, crevasses (sometimes hidden by snow), and meltwater pools occur in the terminal area; extended travel without partners, rope, crampons, and ice axe is not recommended. A less-steep, less-dissected part of the glacier surface is accessible via the snowmobile track that descends the lateral moraine on the southeast side of the glacier (Stop 2, Fig. 1); the head of this road can be reached by shuttle bus from the Information Center. Foot travel is generally safe on the track itself but may not be off the track.
Menan Buttes, southeastern Idaho
Authors: Creighton D. N.
Published: November 2007

The Menan Buttes are located at the Madison County-Jefferson County border in southeast Idaho, 56 mi (90 km) southwest of Yellowstone National Park and 9.8 mi (15.7 km) west-southwest of Rexburg, Idaho (Fig. 1). From Rexburg, take Idaho 33 west and turn south at an improved light-duty road that is 2.6 mi (4.3 km) past the bridge that crosses the Henry’s Fork (Fig. 1). North Menan Butte lies 1.9 mi (3 km) south of Idaho 33. From Idaho Falls, take U.S. 191/20 northeast to the town of Lorenzo; turn left at Idaho 80 and go past the town of Annis and a double bend in Idaho 80 where the road passes up and over two small volcanic cone remnants (Fig. 1). After passing the remnants, turn north at the second paved road that extends northward. North Menan Butte lies 3.9 mi (6.2 km) north of Idaho 80 on this road. As shown on Figure 1, paved light-duty and unimproved dirt roads encircle North Menan Butte and allow easy access for two-wheel drive vehicles. North Menan Butte is owned by the U.S. Bureau of Land Management and is open to the public, whereas South Menan Butte is privately owned, and permission is required from David South to gain entry. Since the two buttes are similar, it is advisable to study the one with public access rather than asking for access to the privately owned butte.
Geologic framework of the Boise Warm Springs geothermal area, Idaho
Authors: Wood Spencer H. , Burnham Willis L.
Published: November 2007

The Boise Warm Springs area is 2 mi (3.3 km) southeast of the Idaho State Capitol building (Fig. 1). Turn north from Warm Springs Avenue onto Old Penitentiary Road. Take the first left turn, about 200 ft (70 m), and proceed west about one block to Quarry View City Park. A major part of the area is a public park administered by the City of Boise and the Idaho Historical Society. A prominent outcrop of rhyolite, locally known as “Castle Rock” is on private land, but at the present time access is not restricted.
Thousand Springs area near Hagerman, Idaho
Authors: Whitehead R. L. , Covington H. R.
Published: November 2007

Numerous spectacular springs discharge from the Snake Plain aquifer along the north side of the Snake River canyon near Hagerman, Idaho (Fig. 1). This stretch of canyon, known as the Thousand Springs area, contains 11 of the 65 springs in the United States that discharge more than 72,400 acre-ft annually (Meinzer, 1927, p. 27). The springs can be reached by automobile or can be viewed from a distance. Most springs are on private land and permission is needed to enter the area, but some, such as Niagara Springs, are on public lands.