DOCSLIB.ORG

A Tale of Two Walker Lane Pull-Apart Basins in the Ancestral Cascades Arc, Central Sierra Nevada, California GEOSPHERE; V

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Tale of Two Walker Lane Pull-Apart Basins in the Ancestral Cascades Arc, Central Sierra Nevada, California GEOSPHERE; V Research Paper THEMED ISSUE: Origin and Evolution of the Sierra Nevada and Walker Lane GEOSPHERE A tale of two Walker Lane pull-apart basins in the ancestral Cascades arc, central Sierra Nevada, California GEOSPHERE; v. 14, no. 5 Cathy J. Busby1, K. Putirka2, Benjamin Melosh3, Paul R. Renne4,5, Jeanette C. Hagan6, Megan Gambs7, and Catherine Wesoloski1 1Department of Earth and Planetary Science, University of California, Davis, California 95616, USA https://doi.org/10.1130/GES01398.1 2Department of Earth and Environmental Sciences, California State University, Fresno, California 93720, USA 3U.S. Geological Survey, Menlo Park, California 94025, USA 15 figures; 1 table; 1 set of supplemental files; 4Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA 2 oversized figures 5Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA 6Exxon Mobil, Houston, Texas 77389, USA 7School of Oceanography, University of Washington, Seattle, Washington 98105, USA CORRESPONDENCE: cjbusby@ ucdavis .edu CITATION: Busby, C.J., Putirka, K., Melosh, B., Renne, P.R., Hagan, J.C., Gambs, M., and Wesoloski, ABSTRACT ter is dominated by Stanislaus Group basalt, trachybasaltic andesite, trachy- C., 2018, A tale of two Walker Lane pull-apart basins andesite, and andesite. Climactic eruptions at its southern end produced the in the ancestral Cascades arc, central Sierra Nevada, We integrate new geochronological, petrographic, and geochemical data Little Walker caldera and its Stanislaus Group trachydacite ignimbrites. In California: Geosphere, v. 14, no. 5, p. 1–50, https://doi.org/10.1130/GES01398.1. with previously published (Sierra Crest–Little Walker volcanic center) and new contrast, the Ebbetts Pass volcanic center erupted much less basalt, and an (Ebbetts Pass volcanic center) structural and stratigraphic data to describe two approximately equal mixture of basaltic andesite, andesite, dacite, and rhyo- Science Editor: Shanaka de Silva deeply dissected, spectacularly well-exposed Walker Lane pull-apart basins in lite. By virtue of its higher SiO2, on average, it shows geochemical evidence for Guest Associate Editor: David A. John the ancestral Cascades arc. The Miocene (ca. 12–5 Ma) Sierra Crest–Little Walker higher extents of crustal contamination. All of the volcanic rocks except the arc volcanic center and the Miocene–Pliocene (ca. 6–4.6 Ma) Ebbetts Pass arc Stanislaus Group are compositionally identical to Mesozoic plutonic rocks of Received 20 July 2016 volcanic center formed in pull-apart basins in the Walker Lane, a NNW-trending the Sierra Nevada Batholith, indicating a similar petrogenesis by shallow-level Revision received 25 January 2018 zone of dextral strike-slip and oblique normal faults at the western edge of the fractional crystallization with no evidence for deep-seated pyroxenite cumu- Accepted 15 May 2018 Basin and Range Province. The Sierra Crest–Little Walker arc volcanic center is a lates. Only the high-K2O Stanislaus Group requires a significant degree of transtensional arc volcanic field that is as areally extensive (~4000 km2) and as fractionation of clinopyroxene and Fe-Ti oxides. The major-oxide trends and long-lived (~3 m.y.) as the Pliocene to Holocene Long Valley transtensional rift clinopyroxene-rich modes of the Stanislaus Group may be the volcanic expres- volcanic field, which is also in the Walker Lane. The Ebbetts Pass volcanic center sion of processes that produced pyroxenite cumulates. The basal and most is the next major volcanic center to the north within the ancestral Cascades voluminous unit of the Stanislaus Group, the Table Mountain Latite, is a likely arc. It formed within a smaller pull-apart basin. Its estimated original volume parent to succeeding units of the Stanislaus Group (Eureka Valley Tuff and (~270 km3) is comparable to the estimated volume for the Lassen volcanic cen- Dardanelles Formation), but this particular liquid line of descent is otherwise ter in the last 825 k.y. (200 km3), a major magmatic focus in the northernmost rare in the Mesozoic and Cenozoic history of the Sierra Nevada. Walker Lane pull-apart basin. Postvolcanic faulting and erosion provide spectac- Volcano-tectonic activity continued for a longer period (ca. 12–6 Ma) in the ular three-dimensional time-integrated views of the structure and stratigraphy northern half of the Sierra Crest–Little Walker volcanic center than it did in of the Miocene to Pliocene volcanic centers described herein. The volcanic stra- the southern half (ca. 12–9 Ma), overlapping for ~1 m.y. with the onset of vol- OLD G tigraphy of this region is divided into four unconformity-bounded sequences: cano-tectonic activity at the Ebbetts Pass volcanic center to the north. This (1) Oligocene silicic ignimbrites erupted in central Nevada (Valley Springs provides local-scale confirmation of the regional-scale interpretation that a Formation), (2) Miocene arc volcanic and volcaniclastic rocks (Relief Peak For- transtensional rift tip propagated northward with time within the arc axis, in mation), (3) ca. 11.5–9 Ma high-K arc volcanic rocks (Stanislaus Group), and concert with northward migration of the Mendocino triple junction. Transten- OPEN ACCESS (4) Miocene–Pliocene arc volcanic rocks (Disaster Peak Formation). We present sional rift magmatism followed in its wake and continues today at various 19 new 40Ar/39Ar ages and integrate them with previous 40Ar/39Ar ages to erect points along the length of the Walker Lane. “Tectono-stratigraphic recycling” a detailed stratigraphic and intrusive chronology. For the first time, we present was a key geologic process throughout the development of these ancestral a systematic description of all of the volcanic and intrusive map units, using Cascades arc pull-apart basins, and it consisted of the transfer of megaslide outcrop photos, photomicrographs, modal analyses, and geochemical data. slabs, up to 2 km long and tens to hundreds of meters thick, from footwall to Geochemistry and modal analyses show that volcanism at the younger, hanging-wall blocks in the transtensional rift. A time-slice series of block dia- This paper is published under the terms of the smaller Ebbetts Pass volcanic center is more evolved than that of the Sierra grams is used to illustrate the structural controls on arc volcanism in the early CC-BY-NC license. Crest–Little Walker volcanic center. The Sierra Crest–Little Walker volcanic cen- stages of Walker Lane transtensional faulting (ca. 12–4.6 Ma). © 2018 The Authors GEOSPHERE | Volume 14 | Number 5 Busby et al. | Two Walker Lane pull-apart basins in the ancestral Cascades arc 1 Research Paper INTRODUCTION tionally, the importance of vertical-axis rotations along the western boundary of the central Walker Lane has been severely underevaluated (Carlson, 2017); The Sierra Nevada (California) forms an asymmetrical block-faulted moun- the stratigraphic and structural results described herein are ideal for future tain range with a gentle western slope and a steep fault-bounded range front studies on this. on the east. The steep eastern range front was previously interpreted to be the The Carson domain and Mina deflection represent very large right steps result of Basin and Range extension (Bateman and Wahraftig, 1966; Slemmons, in the central Walker Lane, ~60 km and 90 km, respectively, with vertical-axis 1953, 1966). However, it is now known to form the western boundary of the rotations described above. In this paper, we describe smaller right steps along Walker Lane, an ~100-km-wide, NNW-trending zone of dextral strike-slip and the western edge of the central Walker Lane (Fig. 1 and 2A): an ~15 km right oblique normal faults that lies along the western edge of the Basin and Range step, referred to herein as the Sierra Crest–Little Walker pull-apart, and an Province (e.g., Faulds and Henry, 2008; Jayko and Bursik, 2012; Busby, 2013). ~5 km zone of right-stepping faults, referred to herein as the Ebbetts Pass pull- The Walker Lane accommodates ~20%–30% of the right-lateral motion between apart. This paper describes Oligocene through Pliocene volcanic sections that the Pacific and North American plates (Argus and Gordon, 1991; Dixon et al., will be appropriate for much-needed paleomagnetic assessment of the impor- 2000; Oldow, 2003; Unruh et al., 2003; John et al., 2012). This region has been tance of vertical-axis rotations. In this paper, we demonstrate the controls of described as the northernmost extension of the Gulf of California transtensional these faults on two large volcanic centers that formed in the pull-apart basins. rift, where the process of continental rupture has not yet been completed, and The central Walker Lane (Fig. 1) has more abundant Cenozoic volcanic rift initiation can be studied on land (Faulds and Henry, 2008; Jayko and Bursik, rocks than the northern and southern Walker Lane, probably because it lies 2012; Busby, 2013). The northern and southern segments of the Walker Lane at a higher rift angle relative to the overall plate margin (Busby, 2013). The are dominated by translation along long NNW-trending dextral strike-slip faults abundant volcanic rocks make the central Walker Lane ideal for detailed re- (Faulds and Henry, 2008; Jayko and Bursik, 2012; Busby, 2013). In contrast, constructions of transtensional rifting and magmatism in a continental setting, the central Walker Lane (Fig. 1) shows evidence of distributed dextral shear because the volcanic strata are dateable by the 40Ar/39Ar method (e.g., Busby accommodated by oblique-normal faults, block rotations, and partitioning of et al., 2008a, 2008b, 2013a, 2013b, 2016; Hagan et al., 2009; Nagorsen-Rinke oblique deformation between subparallel normal and strike-slip faults (e.g., et al., 2013; Fleck et al., 2015). Our studies have focused on the western margin Wesnousky, 2005; Dong et al., 2014; Bormann et al., 2016). of the central Walker Lane along the central Sierra Nevada range front and Faults of the central Walker Lane strike approximately NE, as well as ap- range crest (Fig.
Load more

Recommended publications
  • William J. Keith1, Maurice A. Chaffee*, Donald Plouffl, and Michael S
    DEPARTMENT OF THE INTERIOR TO ACCOMPANY MAP MF-1416-B UNITED STATES GEOLOGICAL SURVEY MINERAL RESOURCE POTENTIAL OF THE CARSON-ICEBERG ROADLESS AREAS, CENTRAL SIERRA NEVADA, CALIFORNIA SUMMARY REPORT By William J. Keith1, Maurice A. Chaffee*, Donald Plouffl, and Michael S. Miller2 STUDIES RELATED TO WILDERNESS Under the provisions of the Wilderness Act (Public Law 88-577, September 3, 1964) and the Joint Conference Report on Senate Bill 4, 88th Congress, the U.S. Geological Survey and the U.S. Bureau of Mines have been conducting mineral surveys of wilderness and primitive areas. Areas officially designated as "wilderness," "wild," or "canoe" when the act was passed were incorporated into the National Wilderness Preservation System, and some of them are presently being studied. The act provided that areas under consideration for wilderness designation should be studied for suitability for incorporation into the Wilderness System. The mineral surveys constitute one aspect of the suitability studies. The act directs that the results of such surveys are to be made available to the public and be submitted to the President and the Congress. This report discusses the results of a mineral survey of the Carson-Iceberg Roadless Areas, Stanislaus and Toiyabe National Forests, Alpine and Tuolumne Counties, California. The Carson-Iceberg was established as a wilderness study area under the Joint Conference Report on Senate Bill 4, 88th Congress. It was later classified as recommended wilderness (C4-986 and C5-986) and further planning (B5-986) during the Second Roadless Area Review and Evaluation (RARE n) by the U.S. Forest Service, January 1979.
    [Show full text]
  • Highway Conditions Introduction
    Chapter 4 Highway Conditions Introduction The Ebbetts Pass National Scenic Byway (NBS) began as a trail that American Indians most likely used for trade and a hunting access route, and was later utilized by fur trappers. By the early to mid 1800’s pioneers and miners crossed over the pass. With the discovery of silver and the demand for more supplies to be delivered to the region, so came improvements to the road. Today, the highway itself is managed and maintained by the California Department of Transportation (CalTrans). The road twists you further into the mountains narrowing with no centerline near Lake Alpine as it separates both the Carson-Iceberg and Mokelumne Wildernesses, luring the traveler farther away from society. The journey takes one both physically and psychologically closer to wildness. Beyond the crest of Ebbetts Pass, the descent winds through a rugged volcanic landscape overlooking the canyons below. This asphalt ribbon transitions back to a distinct, 2-lane highway with a centerline when you reach the floor of Silver Creek, just east of Silver Creek Campground. This portion of the byway is steep, narrow, and windy, and is not suitable for semi trucks, buses, and most Recreational Vehicles (RV’s). It is best left for smaller vehicle travel. Average Daily Traffic CalTrans collects data annually that reflects the number of vehicles that travel along Highway 4 in a given month. This data is compiled into average annual daily traffic counts (AADT). AADT numbers are calculated using electronic highway counters, determining the yearly figure and dividing by 365 days/year.
    [Show full text]
  • Birth of a Plate Boundary at Ca. 12 Ma in the Ancestral Cascades Arc, Walker Lane Belt of California and Nevada
    Origin and Evolution of the Sierra Nevada and Walker Lane themed issue Birth of a plate boundary at ca. 12 Ma in the Ancestral Cascades arc, Walker Lane belt of California and Nevada Cathy J. Busby Department of Earth Science, University of California–Santa Barbara, Santa Barbara, California 93106, USA ABSTRACT Sierra Nevada range front (from Long Valley The Sierra Nevada frontal fault system was to the Tahoe Basin) lies squarely within the previously interpreted to accommodate Basin The Walker Lane belt of eastern Califor- Walker Lane belt, not to the west of it as pre- and Range extension (Bateman and Wahrhaftig, nia and western Nevada is the northernmost vious workers have inferred. 1966; Surpless et al., 2002), but recent GPS extension of the Gulf of California transten- The leading tip of Walker Lane transten- and earthquake focal mechanism studies have sional rift, where the process of continental sion is marked by large arc volcanic cen- shown that the faults currently accommodate rupture has not yet been completed, and rift ters sited in transtensional stepovers; these NW-SE–directed movement between the Sierra initiation can be studied on land. GPS and include the ca. 11.5–9 Ma Sierra Crest–Little Nevada microplate and the North American earthquake focal mechanism studies dem- Walker volcanic center; north of that, the ca. plate (shown on Fig. 3; Sonder and Jones, 1999; onstrate that the Walker Lane belt currently 6.3–4.8 Ma Ebbetts Pass volcanic center; and Unruh et al., 2003). The question is, when did accommodates NW-SE–directed movement north of that, the active Lassen volcanic cen- NW-SE Walker Lane transtension replace E-W between the Sierra Nevada microplate and ter.
    [Show full text]
  • Planning Commission County of Alpine, State of California
    PLANNING COMMISSION COUNTY OF ALPINE, STATE OF CALIFORNIA CORRECTED AGENDA Thursday, January 28, 2021 5:00 P.M. Nick Hartzell, Chair Meeting Location: Jim Holdridge, Vice-Chair VIRTUAL MEETING ONLY Tom Sweeney Bob Broyer VIRTUAL MEETING NOTICE The Planning Commission meeting will be conducted virtually and not available for in person public participation (pursuant to State Executive Order N-29-20). The meeting will be an internet based video and phone conference. Public participation is available at the following: Website link: https://zoom.us/j/97965207316 Phone number: 669-900-9128 Zoom meeting ID: 979 6520 7316 IMPORTANT NOTICE REGARDING COVID-19 AND PARTICIPATION IN THE PLANNING COMMISSION MEETING To participate in this Alpine County Planning Commission meeting, the public are invited to observe and address the Commission telephonically or electronically. Instructions for public participation are below: Public Participation Instructions: The meeting will be conducted via teleconference using the Microsoft Zoom program, and Commissioners will attend electronically or telephonically. The meeting will have no physical location to physically attend. The public may observe the Zoom meeting via computer by clicking on the following link: https://zoom.us/j/97965207316 or the public may listen via phone by dialing 1-669-900-9128 and then when prompted, entering the Meeting ID Access Code 979 6520 7316 You will be asked for a “Participant ID”. You do not need a Participant ID to join the meeting, press the pound key (#) again and you will be automatically connected. 1. If a member of the public wishes to comment on a particular agenda item, the public is strongly encouraged to submit their comments in writing via email to the Community Development Department at [email protected] by 2:00 p.m.
    [Show full text]
  • The Cultural History Of
    THE KIRKWOOD INN THE CULTURAL HISTORY OF HELP PRESERVE THE PAST Kirkwood Station, as it was originally called, soon became a hostelry, post office and stagecoach Remember, as you explore the Kirkwood region you depot, which served many travelers through the are entering a historic area. You may find relics of KIRKWOOD Sierra in the late 1800's. In 2019, the Kirkwood the past and wonder how they got here. Inn celebrated its 155th year of friendly western hospitality. By leaving these items as you found them, you will CALIFORNIA leave in place clues that could help us answer these very questions. If you take artifacts home with you, or move them to other spots, you may destroy clues to the past. Every artifact is not merely something to be held and examined, it is also a piece of a puzzle which, when put together with other pieces, allows us to unravel the mysteries of the past. Please treat all historic and archaeological sites with care and respect when you visit them. The remains of prehistoric and historic cultures are a part of our Reno heritage. When artifacts are stolen and archaeological 80 Truckee 395 sites are destroyed, we lose important clues about the 80 89 Today the Inn is a popular restaurant and bar 50 Tahoe City past, forever. Strict laws protect artifacts and sites on Carson City located at Kirkwood’s entrance on Scenic California 50 Gardnerville state and Federal and Native American lands. Report 99 Auburn So. Lake Tahoe State Route 88. The Inn sits on the point where 49 88 395 80 89 violations to your local law enforcement or land 5 50 Alpine, Amador and El Dorado counties’ boundaries Placerville Sacramento 50 management agency.
    [Show full text]
  • 5.1 Historic Period Human Interaction with the Watershed
    Upper Carson River Watershed Stream Corridor Assessment 5. Human Interaction With the Watershed 5.1 Historic Period Human Interaction With the Watershed The purpose of this section is to summarize human activities that have had some effect on the Carson River watershed in Alpine County, California. Regional prehistory and ethnography are summarized by Nevers (1976), Elston (1982), d’Azevedo (1986), and Lindstrom et al. (2000). Details of regional history can be found in Maule (1938), Jackson (1964), Dangberg (1972), Clark (1977), Murphy (1982), Marvin (1997), and other sources. A book published by the Centennial Book Committee (1987) contains an excellent selection of historic photographs. Particularly useful is a study on the historical geography of Alpine County by Howatt (1968). 5.1.1 Prehistoric Land Use Human habitation of the Upper Carson River Watershed extends thousands of years back into antiquity. Archaeological evidence suggests use of the area over at least the last 8,000 to 9,000 years. For most of that time, the land was home to small bands of Native Americans. Their number varied over time, depending on regional environmental conditions. For at least the last 2,000 years, the Washoe occupied the Upper Carson River Watershed. Ethnographic data provides clues as to past land use and land management practices (see extended discussions in Downs 1966; Blackburn and Anderson 1993; Lindstrom et al. 2000; Rucks 2002). A broad range of aboriginal harvesting and hunting practices, fishing, and camp tending would have affected the landscape and ecology of the study area. Shrubs such as service berry and willow were pruned to enhance growth.
    [Show full text]
  • 2019 Frog Lake, Winnemucca Lake, Round Top Lake, and Fourth of July
    State of California California Department of Fish and Wildlife North Central Region Frog Lake, Winnemucca Lake, Round Top Lake, and Fourth of July Lake, Alpine County 2018 and 2019 Angler Survey Box Analysis Frog Lake Round Top Lake Winnemucca Lake Fourth of July Lake Ben Ewing District Fisheries Biologist: Alpine, Amador, Calaveras, and Lake Counties May 2020 1 Introduction Environmental Setting The Carson Pass Trail incorporates Frog, Winnemucca, Round Top, and Fourth of July Lakes in the Mokelumne Wilderness of the Sierra Nevada mountain range in Alpine County (Lockhart and Mussulman 2016). Three different watersheds are represented between the four lakes. Frog Lake is within the Carson River watershed. Winnemucca and Round Top Lakes are within the South Fork American River watershed, while Fourth of July Lake is within the Mokelumne River watershed. Much of the land surrounding the lakes on the Carson Pass trail is of montane and alpine habitat. Eldorado National Forest (ENF) manages the land in the Carson Pass trail area (Lockhart and Mussulman 2016; Chellman 2018). Due to the popularity of the Carson Pass Trail, ENF has placed restrictions on the Carson Pass Management Area to ensure opportunities for solitude, a primitive recreational experience, and to protect popular camping destinations from overcrowding and heavy impacts (ENF Website). The Carson Pass Trailhead is accessed off Highway 88 at the top of the Carson Pass. Frog Lake Frog Lake is a six-acre lake in Alpine County located at 38° 41’ 16.06 N 119° 59’ 10.03 W situated at 8,865 feet above mean sea level (Figure 1).
    [Show full text]
  • Chronology of Emplacement of Mesozoic Batholithic Complexes in California and Western Nevada by J
    Chronology of Emplacement of Mesozoic Batholithic Complexes In California and Western Nevada By J. F. EVERNDEN and R. W. KISTLER GEOLOGICAL SURVEY PROFESSIONAL PAPER 623 Prepared in cooperation with the University of California (Berkeley) Department of Geological Sciences UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1970 UNITED STATES DEPARTMENT OF THE INTERIOR WALTER J. HICKEL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director Library of Con;gress CSJtalog-card No. 7s-.60.38'60 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price $1.25 (paper cover) CONTENTS Page Abstract-------------------------------~---------------------------------------------------------------------- 1 Introduction--------------------------------------------------------------------------------~----------------- 1 Analyt:cal problems ____________________ -._______________________________________________________________________ 2 Analytical procedures______________________________________________________________________________________ 2 Precision and accuracy ___________________ -.- __ _ _ _ _ __ _ _ _ __ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 2 Potassium determinations_______________________________________________________________________________ · 2 Argon determinations--------~------------------~------------------------------------------------------ 5 Chemical and crystallographic effects on potassium-argon ages----------.-----------------------------------------
    [Show full text]
  • Oregon and California National Historic Trails
    National Park Service National Trails Intermountain Region News U.S. Department of the Interior Oregon and California National Historic Trails Horseshoe Spring Crossroads Chapter - California National Historic Trail Oregon-California Trails Association Hastings Cutoff National Trails System Bureau of Land Management National Park Service What’s New? Spring 2011 Department of the Interior The Great Emigrant Flood off 1849-1854 We are excited to provide this istorians often compare the 1848 discovery of gold in American Indians especiallyly susufferedffered ffromrom the streaminstreamingg HCalifornia to the effect high octane fuel has on a fire. onslaught of “forty-niners”” across the western landscape. For update on activities since OCTA’s Within the next few years more than 250,000 gold-seekers centuries, native peoples hadad lived in the West and farmers scrambled across the Sierra-Nevada in search of without outside competitionon fforor fortune or a new life. resources. However, the floodood ooff last meeting in August 2010 in pioneers and the additionalal The road to California was not a single route. It followed rivalry for food sources, the established Oregon Trail to Fort Bridger before splitting land, water, and Elko, Nevada. either toward Salt Lake City or to Fort Hall, and eventually space threatened to the Sierra-Nevada, where it further split into several interior destroy their way of life. valley destinations. One of the routes through Utah, known as the Hastings Cutoff, rejoined the main California Trail at the Wagon ruts and traces can Humboldt River in northeastern Nevada. still be found in the vast undeveloped West — Travel conditions on the cutoff during most years were reminders of the triumphs,, generally harsh.
    [Show full text]
  • A Tale of Two Walker Lane Pull-Apart Basins in the Ancestral Cascades Arc, Central Sierra Nevada, California GEOSPHERE; V
    Research Paper THEMED ISSUE: Origin and Evolution of the Sierra Nevada and Walker Lane GEOSPHERE A tale of two Walker Lane pull-apart basins in the ancestral Cascades arc, central Sierra Nevada, California GEOSPHERE; v. 14, no. 5 Cathy J. Busby1, K. Putirka2, Benjamin Melosh3, Paul R. Renne4,5, Jeanette C. Hagan6, Megan Gambs7, and Catherine Wesoloski1 1Department of Earth and Planetary Science, University of California, Davis, California 95616, USA https://doi.org/10.1130/GES01398.1 2Department of Earth and Environmental Sciences, California State University, Fresno, California 93720, USA 3U.S. Geological Survey, Menlo Park, California 94025, USA 15 figures; 1 table; 1 set of supplemental files; 4Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA 2 oversized figures 5Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA 6Exxon Mobil, Houston, Texas 77389, USA 7School of Oceanography, University of Washington, Seattle, Washington 98105, USA CORRESPONDENCE: cjbusby@ ucdavis .edu CITATION: Busby, C.J., Putirka, K., Melosh, B., Renne, P.R., Hagan, J.C., Gambs, M., and Wesoloski, ABSTRACT ter is dominated by Stanislaus Group basalt, trachybasaltic andesite, trachy- C., 2018, A tale of two Walker Lane pull-apart basins andesite, and andesite. Climactic eruptions at its southern end produced the in the ancestral Cascades arc, central Sierra Nevada, We integrate new geochronological, petrographic, and geochemical data Little Walker caldera and its Stanislaus Group trachydacite
    [Show full text]
  • Eldorado National Forest Visitor Guide Where to Go - Campgrounds & Picnic Areas
    United States Department of Agriculture Eldorado National Forest South of Little Round Top (Photo by Mark Sandperl) Visitor Guide Thousands of visitors are drawn each year to the Eldorado National Forest’s rivers, Contents What To Do? 2 lakes, and streams alive with fish; mountains and meadows for alpine and nordic skiing; campsites and picnic areas in alpine backcountry and dense forests. Four Where To Go? - Campgrounds 3 hundred- Highway miles 50 and of hikingHighway trails 88 pass- run through through all the kinds Forest, of terrain,making fromit an easygentle drive oak from Where To Go? - Trails 4 foothills on the west to the 10,000-foot crest of the Sierra Nevada. Two major highways Traveling 5 SacramentoThe miners who and thecame San to FranciscoCalifornia Bay in the Area. gold rush of 1849 called the land “el dorado” Where To Go? - Highlights 6 Know Before You Go 7 fortoday! the fabled Spanish “land of gold.” We hope that after you have enjoyed Eldorado Map 8 National Forest’s natural riches you will think the name is even more appropriate The Forest Service is committed to nurturing and managing the National Forests in Quick Facts ♦ Acreage = 615,037 order to ensure the health of the land. As we respectfully use and play in these precious ♦ Elevation = ranges from 1,000 to 10,000 feet publicLocated lands, in the we Central are taking Sierra part Nevada in a shared region, vision the Eldorado for the future. National Forest is considered ♦ Climate = Warm, dry summers and cold wet winters. an urban forest.
    [Show full text]
  • A Historical Context and Methodology for Evaluating Trails, Roads, and Highways in California
    A HISTORICAL CONTEXT AND METHODOLOGY FOR EVALUATING TRAILS, ROADS, AND HIGHWAYS IN CALIFORNIA Appendices C-K Appendix C. Timeline for Development of Engineering for Highways in California 1895-2009 ..1 Appendix D. Historic Roads and Highways in California .............................................................17 Appendix E. Designated California Legislature Roads in California ............................................22 Appendix F. Scenic Highways in California .................................................................................23 Appendix G. Interstate Highways throughout California ..............................................................24 Appendix H. California Tolls Roads and Turnpikes .....................................................................25 Appendix I. Oregon-California Trail Guidelines and Classification System ................................29 Appendix J. Evaluated Roads and Highways in California ...........................................................31 Appendix K. Caltrans Evaluated Roads and Highways ................................................................42 Appendix L. Highway Route Numbers and Date of Construction ................................................48 Prepared for: Cultural Studies Office Division of Environmental Analysis California Department of Transportation Sacramento 2016 http://www.dot.ca.gov/ser/guidance.htm#highway Appendix C Timeline for Development of Engineering for Highways in California 1895-2009 1895 The Bureau of Highways is created with the
    [Show full text]