WorldCat Identities

Babcock, R. Scott (Randall Scott)

Overview
Works: 84 works in 169 publications in 1 language and 1,316 library holdings
Genres: Guidebooks  Academic theses 
Roles: Author, Other
Classifications: QE86.G73, 557.9132
Publication Timeline
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Most widely held works by R. Scott Babcock
Hiking Washington's geology by R. Scott Babcock( )

4 editions published between 1999 and 2000 in English and held by 659 WorldCat member libraries worldwide

"Hiking Washington's Geology" explores the dynamic geologic history of Washington's dramatic landscape and highlights places that demonstrate why the region looks the way it does. 85 photos. 7 maps
Geology of the Grand Canyon( Book )

10 editions published between 1974 and 1978 in English and held by 400 WorldCat member libraries worldwide

Covers the geologic history of the Grand Canyon
Hiking Guide to Washington Geology by R. Scott Babcock( Book )

1 edition published in 2009 in English and held by 14 WorldCat member libraries worldwide

The stratigraphy and geochemistry of the Crescent Formation basalts and the bedrock geology of associated igneous rocks near Bremerton, Washington by Kenneth P Clark( )

2 editions published in 1989 in English and held by 5 WorldCat member libraries worldwide

A stratigraphic section developed for the Bremerton rocks in the Kitsap Peninsula suggests formation by rifting in a marine environment. Basal gabbro, dated by 40Ar/39Ar at 49.8 Ma plus or minus 0.8 Ma, and associated mafic to felsic plutonics, appear to be the source of a mafic dike complex that composes 100% of the stratigraphic level above the plutonics. These dikes are the apparent feeders to overlying submarine and subaerial volcanics. The previously unrecognized submarine sequence consists of interbedded basaltic breccia, tuffs, basalt flows, and basaltic sandstone, siltstone, and conglomerate. Approximately 1 km of columnar basalt flows cap the sequence. Structures in the Bremerton rocks suggest that as many as four deformations may have affected these rocks. In the middle Eocene, extension to the north or northwest caused rifting and emplacement of the mafic dikes and lavas; several faults show that this extension was joined or followed by northeast-directed compression. Small faults and shears may have formed later by compression to the northwest. Reactivation of one of these faults and emplacement of northwest-striking Cascade arc dikes suggest the latest deformation was extension to the northeast. The gabbro and basalts have chemistry transitional between N-type MORB and enriched ocean island basalt. Large-ion-lithophile to high-field-strength trace element ratios are similar to those of back-arc basin basalt. Felsic plutonics are enriched in elements (especially Zr) indicative of an arc influence. Several dikes intruding the gabbro are chemically indistinguishable from P-type (plume) ocean island basalt. Stratigraphic sections were developed in the basalts of the Crescent Formation and for basalts near Port Townsend in the Olympic Peninsula. Comparison to the subaerial basalts near Bremerton shows that the latter are quite similar to the upper subaerial Crescent Formation basalts and Port Townsend basalts. New chemical data for 16 flows of the Olympic Peninsula basalts are also similar to that of the Bremerton rocks. Stratigraphic and chemical similarities imply that rocks of all three areas are coeval. Deposition of the Crescent Formation basalts on a continentally-derived fan, stratigraphic and structural characteristics of the Bremerton rocks, and geochemical data on rocks of ail three areas suggest that these rocks formed by rifting of the western margin of the North America continent. Following rifting and basalt generation, the rocks may have moved north due to oblique convergence of the oceanic and continental plates, where they were thrust under Vancouver Island along the Leech River Fault. Thrusting moved outboard of the basalts and underlying fan; continued convergence thrust marine sediments that make up the Olympic core rocks beneath the basalts and underlying fan
The origin of serpentinites associated with the Shuksan metamorphic suite near Gee Point, Washington by Daniel L Wilson( )

2 editions published in 1978 in English and held by 5 WorldCat member libraries worldwide

Metavolcanic and metasedimentary rocks of the Shuksan Metamorphic Suite near Gee Point have been contact metamorphosed by high-temperature emplacement of ultramafic rock. This intrusion occurred at great depth (>25 km) and caused contact temperatures of about 500°C, resulting in epidote-amphibolite facies metamorphism. Minerals of the contact metamorphism are overprinted by mineral assemblages of the regional Shuksan blueschist facies metamorphism. The K/Ar age of the epidote-amphibolites is Jurassic (145-160 m.y.), and thus the age of Shuksan metamorphism is probably younger than Middle Jurassic. Ultramafic rocks found near Gee Point have been metamorphosed to serpentinites during Shuksan metamorphism and should be considered part of the Shuksan Metamorphic Suite. Shuksan blueschist facies metamorphism and the Gee Point epidote-amphibolite facies metamorphism probably occurred within a subduction zone. A tectonic model is proposed in which high-temperature ultramafic rock fills fractures and faults in a subducted plate, causing local contact metamorphism. Comparison of metamorphic relations at Gee Point with rocks of the Franciscan Complex suggests that Franciscan eclogites may also result from contact metamorphism caused by ultramafic intrusions
The petrology, petrography, and geochemistry of the Black Jack breccia pipe, Silver Star Plutonic Complex, Skamania County, Washington by Robert H Birk( )

2 editions published in 1980 in English and held by 4 WorldCat member libraries worldwide

Tourmaline-bearing breccia pipes are associated with late stage Tertiary porphyritic intrusive rocks in the Silver Star Plutonic Complex. Whole-rock geochemical analysis of rocks from the complex show a silica vs. alumina/(K2O + Na2O + CaO) trend (Feiss, 1978) toward geochemical conditions favorable for porphyry copper-type mineralization. Copper present in diorite, quartz diorite, and quartz diorite porphyry rocks probably entered silicates, whereas copper formed porphyry copper-type mineralization in the more felsic granodiorite and granodiorite porphyry intrusions. Optical, x-ray, and chemical analyses indicate two distinct populations of tourmaline present in the breccia pipes; an early "Hemlock Ridge-type" which preceded pyrite, and a later "Black Jack-type" which followed pyrite and preceded chalcopyrite. The Hemlock Ridge-type have refractive indices of [lower case epsilon] = 1.625 to 1.636 and [lower case omega] = 1.652 to 1.663, whereas the Black Jack-type have refractive indices of [lower case episilon] = 1.643 to 1.652 and [lower case omega] = 1.671 to 1.675. The ao unit cell dimension of the Hemlock Ridge-type are all less than 15.90 Å, and the Black Jack-type are all greater than 15.90 Å. Chemically, the earlier Hemlock Ridge-type tourmaline contains 28.5 to 32.3% AI2O3, 4.43 to 8.57% Fe2O3, and 10 to 20 ppm copper, whereas Black Jack tourmalines contain 22.7 to 26.4% A12O3, 11.7 to 16.4% Fe2O3, and 16-76 ppm copper. Although the Black Jack tourmalines are related in time and space to extensive chalcopyrite mineralization, crystal-field effects (Curtis, 1963) restrict copper's entry into the tourmaline structure more than iron. Therefore, copper is reflected indirectly by the high iron content of tourmaline. Tourmaline analysis is a viable exploration tool for copper in the Silver Star area, and the concepts and methods applied herein are valid, and probably can be applied regionally
Geology of the older precambrian rocks in the vicinity of Clear Creek and Zoroaster Canyon, Grand Canyon, Arizona by William S Lingley( )

2 editions published in 1973 in English and held by 4 WorldCat member libraries worldwide

The Clear Creek-Zoroaster Canyon area is located in the east- central section of the Bright Angel Quadrangle (Maxson, 1968) roughly seven miles east northeast of Grand Canyon Village, Arizona. The boundaries of the present study area are shown in Figure 1. The study area extends from Mile 83.7 to Mile 86 on the Colorado River below Lee's Ferry, Arizona. Older Precambrian rocks are exposed along the Inner Gorge of the Colorado River. They also crop out at Zoroaster Canyon, Clear Creek, and Cremation Creek. There are over 450 m of vertical exposure. Many outcrops are inaccessible due to steepness of the canyon walls. The clarity of these exposures is extremely good. The Older Precambrian rocks exposed within the study area are (1) the Vishnu Schist and associated amphibolites, (2) the Zoroaster Granite, and (3) the late, granitic pegmatites and aplites. All of these rocks show complex inter-relationships, and they are intensely deformed. In upper Clear Creek the Older Precambrian rocks are unconfor- mably overlain by the younger Precambrian, Grand Canyon Series. The Grand Canyon Series is composed of limestones, shales, and quartzites (Maxson, 1967). Throughout the rest of the study area the older Precambrian rocks show an angular unconformity with the overlying Paleozoic sediments. A summary of Grand Canyon stratigraphy is given by Maxson (1968)
Geology, petrology, and paleomagnetism of eocene basalts from the Black Hills, Washington coast range by Brian R Globerman( )

2 editions published in 1980 in English and held by 4 WorldCat member libraries worldwide

Geologic mapping in the Black Hills area strongly suggests that the middle Eocene basalts of the Crescent Formation and over- lying upper Eocene and Oligocene sedimentary rocks constitute a structurally coherent terrane that is bounded by northeast- and northwest-trending faults. I interpret the Black Hills as a homocline which dips about 10° to 15° to the west. Units within the block are commonly cut by normal and reverse faults, but are not appreciably folded. Major- and trace-element geochemical analyses indicate that the Black Hills suite is co-magmatic, and is composed of hyper- sthene-normative tholeiites which were apparently derived by plagioclase -- clinopyroxene -- olivine ± magnetite fractionation. The suite is petrochemically similar to basalts from the upper part of the Crescent Formation of the Olympic Peninsula, and the upper flows of the lower member of the Siletz River Volcanics of coastal Oregon. An island arc origin for the Black Hills rocks, and by analogy the Crescent basalts, is not supported by field and petrochemical evidence. Discriminant plots of incompatible element data for the Black Hills rocks indicate that the suite is nearly identical to tholeiites from an oceanic island (Hawaiian-type) setting, although the lavas approach mid-ocean ridge basalt compositions as well. These intermediate incompatible-element compositions of the Black Hills rocks, along with Sr isotopic ratios. resemble those of tholeiites from Iceland and Galapagos, both of which are oceanic islands that were erupted at, or close to, the ridge crest of an active oceanic spreading center. I suggest that the Black Hills lavas, and possibly the tholeiitic and overlying alkalic flows of Eocene age in the Oregon-Washington Coast Range, may reflect generation of the seamount chain on the crest or flanks of an active or fossil spreading center. The composition of the erupting lavas probably evolved toward progressive enrichment in certain incompatible elements (i.e. Ti, Zr, Y, Nb) as the chain moved away from the spreading center axis. The Coast Range oceanic island chain was subsequently sutured to the leading edge of North America by late Eocene to early Oligocene time. Paleomagnetic study of 35 sites in the Black Hills and adjacent areas indicates that most of the lava flows have declinations of remanent magnetizations that are significantly more easterly-directed than expected for cratonic North America, both before and after application of tectonic corrections. Using the preferred procedure for tilt-correction, the mean Black Hills paleomagnetic direction is: Dec.= 16.3°, Inc.= 67.3°, ∝(95= 4.9°. A rotation of 25.9° ±15° clockwise since middle Eocene time is inferred from these data; there is no evidence of north-south translation. The Black Hills show significantly less clockwise rotation than coeval rocks in the Oregon Coast Range, such as the Siletz River Volcanics, Tyee-Flournoy sediments, and Tillamook Volcanic Series. Data from the Willapa Hills south of the study area confirm the differential rotations the Oregon and Washington coastal blocks. The paleomagnetic results suggest that the entire Coast Range terrane, extending from the Olympic Peninsula to north of the Klamath Mountains, has not been a coherent terrane since middle Eocene time. A tectonic model more consistent with available paleomagnetic data involves accretion, and independent clockwise rotation of two or more Coast Range blocks, or "microplates", in response to oblique subduction of the Farallon plate beneath western North America during Paleogene time
The hydrogeology of north Lummi Island, Washington by William M Sullivan( )

2 editions published in 2005 in English and held by 4 WorldCat member libraries worldwide

Lummi Island is a 10.8 square mile island in the northern Puget Sound Region, west of Bellingham, Washington. The population of Lummi Island has grown steadily for decades to approximately 900 permanent and 1,500 seasonal residents. The increasing demand for groundwater resources on the island has caused some wells to experience seasonal shortages and seawater intrusion, prompting an assessment of the hydrogeology for growth-management purposes. My study focused on characterizing the hydrogeology of the north half of the island (3.9 square miles) where most residents live and where groundwater is the sole source of potable water. I examined data collected from up to 130 wells including well logs, seasonal water level measurements, water chemistry, and precise GPS well-head elevations and positions. From these data, I created a three-dimensional bedrock and unconsolidated stratigraphic model using Department of Defense Groundwater Modeling Software. A dramatically undulating bedrock surface is concealed nearly everywhere by mostly fine-grained unconsolidated Pleistocene deposits up to 300 feet thick. Bedrock in the study area is dominated by tightly-folded sandstone, shale, and conglomerate of the Tertiary Chuckanut Formation (sandstone) in the north. This is separated by a deep southeastnorthwest trending trough from metamorphosed volcanics of the pre-Tertiary Fidalgo opiolite sequence (greenstone) in the south. The stratigraphic model and potentiometric data were used to identify and define the extent, volume, and thickness of at least 12 distinct aquifers. The major aquifer is the Sandstone Aquifer, one of two separate bedrock aquifers that occupy the majority of the study area. Half of 130 wells examined are in sandstone and greenstone. Hydraulic properties including horizontal hydraulic conductivity, estimated from well log data, indicate the Sandstone Aquifer is in the upper range of textbook values for fractured sandstone. The Greenstone Aquifer is much smaller and has the lowest hydraulic properties of any in the study area. Seasonal water level fluctuations are greatest in the bedrock aquifers. Ten Pleistocene aquifers were identified as thin, largely discontinuous coarse-grained (mostly sand) lenses within less permeable, fine-grained silt-clay diamicton. These aquifers fill depressions in the bedrock surface. Seven Pleistocene aquifers lie below sea level and three are perched well above sea level. The Legoe Bay and Nugent aquifers are the largest and most utilized Pleistocene groundwater source, occupying most of the southern half of the study area. These aquifers have the highest hydraulic properties and mostly negligible seasonal water level fluctuations. Recharge areas identified through the stratigraphic model, potentiometric surfaces, and water chemistry occupy the inland and upper regions of the study area. Infiltration of water through overlying glacial drift into bedrock aquifers is the most important recharge mechanism because of their large areal extent and because many Pleistocene aquifers receive recharge, in part, from where they are in contact with saturated bedrock. The average recharge magnitude, estimated from a site-specific water-mass balance, is 8 inches/year or 24% of average annual precipitation. A chloride-mass balance, performed as a semi-independent estimate, establishes a lower bound for recharge of 4 inches/year or 11% of average annual precipitation. Water-chemistry data vary among aquifer media. Water chemistry in the Sandstone Aquifer is dominated by sodium ions while most Pleistocene aquifers are dominated by calcium ions. Despite that nearly 80% of all wells that are completed below sea level, wide-spread seawater intrusion is not evident. Only 5 wells were determined to be intruded and, 14 additional wells may be experiencing some degree of intrusion. Occurrences of seawater intrusion are localized and are most common in the Sandstone Aquifer where low storage and fracture flow combine to increase contamination susceptibility
Geology of the Park Butte-Loomis Mountain area, Washington (eastern margin of the Twin Sisters dunite) by David L Blackwell( )

2 editions published in 1983 in English and held by 4 WorldCat member libraries worldwide

Mappable units in the Park Butte-Loomis Mountain area of northwestern Washington are distinguished on the basis of age, lithologic association, structural position, and metamorphic recrystallization. There are four volcanic/volcaniclastic units: the Chilliwack Group, the Cultus Formation, the Elbow Lake-Haystack Mountain unit, and the Nooksack Group: and at least three allocthonous crystalline units: ultramafic rock (including the Twin Sisters and Goat Mountain dunite bodies), the Yellow Aster Complex, and the Vedder Complex. All units occur as tectonic fragments (fault bounded blocks) which are juxtaposed along anastomosing, horizontal to low angle, west dipping faults. The upper Paleozoic Chilliwack Group is represented by the lower clastic sequence, Red Mountain limestone, and part of the upper clastic sequence. Stratigraphy, chemical composition, point count data on sandstones, and compositions of magmatic clinopyroxenes suggest a volcanic arc environment of deposition. The Loomis Mountain dacite center is tentatively considered partly correlative with the 'Permian volcanic sequence exposed in the Chilliwack Valley, British Columbia. In the study area, this dacite center is interbedded with the Triassic Cultus Formation. The Elbow Lake-Haystack Mountain unit is recognized by the presence of ribbon chert and titanaugite-bearing basalt in a sequence of siltstone and minor sandstone-graywacke. This unit is the most highly deformed of all the volcaniclastic units. The age is questionably Jurassic based on work in the Haystack Mountain area of Cruver (thesis in progress). In this thesis and that of Cruver, it is a newly proposed lithologic-tectonic element in the North Cascade foothills. The Yellow Aster Complex in the study area is subdivided into the Yellow Aster Complex sensu stricto and the mafic/ultramafic Yellow Aster Complex on the basis of differing lithologies. The Yellow Aster Complex sensu stricto consists of pyroxene gneiss and related intrusives and is correlative with the Yellow Aster Complex at Yellow Aster Meadows. Geochemical data for the non-gneissic greenschist facies intrusives suggest a volcanic arc environment of intrusion. The mafic/ultramafic Yellow Aster Complex occurs as tectonic fragments separate from the Yellow Aster Complex sensu stricto, and consists of pyroxenite, cumulate gabbro, and gabbro. The mafic/ultramafic Yellow Aster Complex may represent the structurally lower portion of the Yellow Aster Complex at Yellow Aster Meadows or possibly even a separate unit. Amphibole schist and pelitic schist of the Vedder Complex crop out as tectonic fragments imbricated with Yellow Aster Complex and ultramafic rocks within the Bell Pass fault zone. The Twin Sisters Dunite is interpreted from map relations to be imbricated with other rock units of the study area along low angle faults. Numerous smaller fragments of dunite and serpentinized dunite-harzburgite are imbricated throughout the area. The distribution of allochthonous crystalline rocks delineates the major low angle, west dipping fault zones within the area. The direction of thrusting is interpreted to be northwest-southeast or east-west based on the orientation of a large recumbent fold within the area. This low angle fault zone corresponds to the imbricate zone of Misch (1966). The low angle structures are slightly modified by Tertiary folds and Tertiary high angle faults in the study area
Geology and mineralization of the Great Excelsior Mine, Whatcom County, Washington by Russell J Franklin( )

2 editions published in 1985 in English and held by 4 WorldCat member libraries worldwide

The Great Excelsior Mine is located in the North Cascades of northwest Washington, approximately 6 miles (10 km) east of the town of Glacier. The deposit consists of Ag with subordinate Au and is hosted within felsic volcanic breccias, tuffaceous siltstones and graywackes, and felsic tuffs belonging to the Middle Jurassic Wells Creek Volcanics. The deposit is located approximately 1000 feet (305 m) below the contact between the Wells Creek Volcanics and the overlying Nooksack Group metasediments. Both units comprise the lowermost structural-metamorphic unit of the western North Cascades System. The Wells Creek Volcanics have been informally subdivided into four mappable units. From oldest to youngest they are; 1) the Lower Volcanic Unit, 2) the Sedimentary Unit, 3) the Siliceous Tuff Unit, and 4) the Upper Volcanic Unit. Combined, these units represent a minimum of 4000 feet (1220 m) of intermediate volcanics along with intercalations of marine shales, siltstones, volcanic graywackes, and shaley tuffs. The contact between the Wells Creek Volcanics and the overlying Nooksack Group appears to be gradational. The base of the Wells Creek Volcanics is not exposed in the study area. The Wells Creek Volcanics and Nooksack Group have been subjected to regional low-grade metamorphism which produced mineral assemblages common to the prehnite-pumpellyite metamorphic facies. The Wells Creek Volcanics are structurally dominated by a large, open, upright, north trending anticline. At least three vertically separated mineralized zones (based on a 1.5 oz/ton Ag cutoff) have been identified on the property. These occur in gently to steeply dipping tabular zon es which are commonly subparallel to the stratigraphy. The mineralization is characterized by microscopic argentite, tetrahedrite, polybasite?, and electrum replacing pyrite and locally calcite. The three zones combined represent 2.5 million tons of mineralization which average 4.67 oz/ton Ag and 0.047 oz/ton Au. The Great Excelsior deposit shares several features common to typical Kuroko-type deposits. These features include: 1) the mineralization is associated with felsic volcanics, 2) it was deposited in a submarine environment, 3) fluid temperature and composition are similar to those of Kuroko fluids, and 4) it was deposited in an island arc tectonic setting. The major differences between them are the Excelsior deposit lacks massive stratiform mineralization and commercial base metal concentrations. The absence of massive stratiform mineralization can be explained by either: 1) extensive boiling of the hydrothermal solution resulting in subsurface deposition of metals, or 2) by dispersal of a low density hydrothermal plume by current action above the sea floor. The absence of commercial base metal concentrations can be explained by one or more of the following: 1) the base metals have been removed by erosion, 2) the hydrothermal solution was devoid of base metals, or 3) the base metals were flushed through the system and were dispersed. Thermochemical calculations suggest that the metals were transported primarily as chloride complexes and petrographic and field observations indicate precipitation took place in response to boiling and/or reaction with host rocks
Paleomagnetism of the Snoqualmie batholith, Central Cascades, Washington by Suzanne J Beske( )

2 editions published in 1972 in English and held by 4 WorldCat member libraries worldwide

Paleomagnetic results have been obtained from eight sites in the Miocene (15-18 m.y.) Snoqualmie batholith, Central Cascades, Washington. After ac magnetic cleaning, four magnetically stable sites remained, yielding a pole at 221.0°E, 84.5°N, ([lower case delta]p = 7.9, [lower case delta]m = 9.3, k = 286.4). A stability test was formulated based on the ratio of the intensity of natural remanent magnetism, NRM, (after ac demagnetization) to the weak field susceptibility. This ratio, Qd proved effective in determining magnetically stable samples from samples showing a wide spectrum of stability from within the Snoqualmie batholith, and therefore, was strictly applied to all samples. Experiments with saturation isothermal remanent magnetism indicated that stable NRM is dominated by magnetic grains with single domain characteristics. Paleomagnetic results from the 25.0-26.5 m.y. Grotto batholith (Beske et al 1972) were combined with data from the Snoqualmie batholith to give a Miocene pole for the Central Cascades at 208.5°E, 85,5°N, ([lower case delta]p = 4.5, [lower case delta]m = 5.4, k = 360.4). These poles show no large scale tectonic rotation or translation of the Central Cascades since the Miocene when compared with other Miocene poles from North America, This suggests that the post-mid-Cretaceous movement postulated by Beck and Noson (1972) for the Central Cascades relative to the North American craton ceased by the Miocene. Furthermore, this data does not support the post-Miocene rotational movement of the Nevadan tectonic zone postulated by Watkins (1965b)
Petrology and structure of the Lookout Mountain--Little Devil Peak area, North Cascades, Washington by Jeffrey A Cary( )

2 editions published in 1990 in English and held by 4 WorldCat member libraries worldwide

The focus of this study is on the protolith types, metamorphism and deformation of the Cascade River Schist and related rocks in the Lookout Mountain - Little Devil Peak area of the North Cascades, Washington. Two distinctive protolith assemblages are recognized in the Cascade River Schist, a volcanic arc assemblage in the Lookout Mountain area and an oceanic/forearc assemblage in the Little Devil Peak area. The volcanic arc sequence consists from the bottom up of andesitic to rhyolitic tuffs and flows, coarse-grained volcaniclastics and fine grained pelites. The lower tuff/flow unit grades downward into and is transitional with the underlying Triassic Marblemount Meta-Quartz Diorite. Bulk rock chemistry and lithologic associations suggest an island arc tectonic setting. U/Pb zircon geochronology suggests a 220 Ma age for soda rhyolite tuff in the Cascade River Schist. U/Pb geochronology suggests that the Cascade River Schist and Marblemount Meta-Quartz Diorite are coeval, and contact relationships suggest that the two units are cogenetic. In the Little Devil Peak area, the Cascade River Schist is composed of an oceanic/forearc assemblage consisting of ultramafite, amphibolite, quartzite, quartzofeldspathic schists and marble. This facies of the Cascade River Schist has been mapped as the Napeequa unit (Tabor et al., 1988). Intruding the Cascade River Schist are the 75 Ma Marble Creek Pluton and the Haystack Creek Pluton. High Al hornblende and magmatic epidote indicative of high-pressure crystallization (>6-10 Kb) are present in the intrusives, suggesting emplacement at deep crustal levels. A low pressure - low temperature (400 ± 50° C; 3 i 1 Kb) greenschist facies metamorphism has affected the Marblemount Meta-Quartz Diorite and Cascade River Schist in the Lookout Mountain area. The Cascade River Schist, Marble Creek Pluton and Haystack Creek Pluton in the Little Devil Peak area underwent a high temperature - high pressure (600 ± 50° C; 9 ± 1 Kb) amphibolite facies metamorphism. The age of the amphibolite facies metamorphism is indicated by the 75 Ma age of the synmetamorphic Marble Creek Pluton. The age of the greenschist facies metamorphism is unknown, but is probably Late Cretaceous. Deformation of these rock units produced a northwesterly trending penetrative foliation with a subvertical dip. In the Lookout Mountain area, greenschist facies rocks contain a shallow, NW-plunging stretching and mineral lineation. Numerous rotational features associated with the deformation indicate that the kinematic regime during greenschist metamorphism was right-lateral, strike-slip. The Entiat - Le Conte fault, a post metamorphic structure, trends northwesterly through the study area. It juxtaposes different facies of the Cascade River Schist, which were metamorphosed under disparate P/T conditions. Geobarometry suggests 15 km of post metamorphic dip-slip displacement along this structure. This study has defined a mappable, stratigraphic sequence in the Late Triassic Cascade River Schist. It has also documented both high- and low-pressure regimes during Skagit metamorphism. Deformational fabric associated with the greenschist facies metamorphism suggests orogen-parallel, right-lateral, strike-slip shear
Net shore-drift of Thurston County, Washington by David M Hatfield( )

1 edition published in 1983 in English and held by 4 WorldCat member libraries worldwide

Geochemistry of the main-stage migmatitic gneisses in the Skagit gneiss complex by Randall Scott Babcock( )

1 edition published in 1970 in English and held by 4 WorldCat member libraries worldwide

Vanishing night skies : the effects of light pollution on the National Park System : a survey by David J Simon( Book )

1 edition published in 1999 in English and held by 3 WorldCat member libraries worldwide

Coastal zone processes and geomorphology of Skagit County, Washington by Ralph Francis Keuler( )

2 editions published in 1979 in English and held by 3 WorldCat member libraries worldwide

Geomorphic mapping of 130 km of marine shoreline in Skagit County reveals repeated morphologic and sedimentologic trends along many segments of the coast. The shoreline segments within which the trends are repeated are the littoral drift cells or shore drift sectors that act as nearly closed systems with respect to longshore sediment transport. The longshore trends include changes in mean grain size of beaches, sediment sorting, foreshore morphology, back- shore width and morphology, bluff morphology, and mean beach slope. The last parameter, slope, can be used as an index or surrogate measure of simultaneous changes in the other longshore trends. The longshore trends, besides being a convenient method to describe the coastal geomorphology, are found to be equally useful as tools to map directions of littoral sediment transport on a net, long-term basis, and, to help define the boundaries of drift sectors. Transport direction and littoral cell boundaries are included on the accompanying maps. Wave erosion of shore bluffs, as opposed to fluvial delivery, is the primary source of beach sediment. Mean minimum long term erosion rates are 5 cm/yr for unconsolidated bluffs, 0.7 cm/yr for jointed rocks fronted by wave cut platforms, and less than 0.1 cm/year for massive, resistant rock types. Shoreline segments with large, hazardous mass movements are relatively few, but within those segments large slope failures appear to provide a high percentage of the sediment contribution to beaches
The paleomagnetism of a thick middle tertiary volcanic sequence in Northern California by Douglas Edward Craig( )

2 editions published in 1981 in English and held by 3 WorldCat member libraries worldwide

The mean direction of remanent magnetism for 44 sampling sites from Oligo-Miocene lava flows in northern California points about 12° east of the expected Oligo-Miocene geomagnetic field direction for the area. Our paleomagnetic data and other data indicate that the Cascade Range has rotated clockwise since the middle Tertiary. Similar, but larger, clockwise rotations have been documented in previous studies throughout the Coast Ranges. Two mechanisms are suggested to account for the differential rotation that has occurred within the Coast and Cascade Ranges. First, the Coast Ranges are rotated and then accreted to a curved continental margin during the Eocene, leaving the Washington Coast Range relatively unrotated at the end of the Eocene. Secondly, during post- Eocene rotation, the thick crystalline crust of the Klamath Mountains prohibited the southern end of the Cascade Range from rotating as rapidly as the northern end, producing an oroclinal bend in the range
The geology and structure of the Canyon Creek-Church Mountain area, North Cascades, Washington by Jeffrey T Jones( )

2 editions published in 1984 in English and held by 3 WorldCat member libraries worldwide

Four major rock assemblages ranging from Precambrian to Lower Cretaceous occur in the Canyon Creek/Church Mountain area of northwestern Washington. Lithologic, structural, and fossil evidence were used to discriminate among the assemblages and to correlate them with the Chilliwack Group, the Nooksack Group, the Yellow Aster Complex, and a unit previously included in the Chilliwack Group, referred to here as the "chert/basalt unit." These assemblages were juxtaposed during middle Cretaceous tectonism along low angle and high angle faults. There is some evidence for additional structural deformation after the middle Cretaceous. The Chilliwack Group, consisting of volcanic rocks, volcaniclastic rocks, and limestones, were found to dominate the four assemblages. Limited stratigraphic control is provided by three limestone units in the Chilliwack Group that have been dated on fossil evidence as Devonian, Mississippian-Pennsylvanian, and Permian. On Mount Liumption, volcanic rocks are in flow contact with the Mississippian-Pennsylvanian limestone unit. Similar relationships are seen on the north side of Church Mountain between volcanic rocks and a limestone of uncertain age. The volcaniclastic rocks are laminated to thinly bedded siltstone and argillite, and thickly bedded volcanic arenite and cobble conglomerate. The Chilliwack Group may be interpreted as a volcanic-arc assemblage. The Upper Jurassic to Lower Cretaceous Nooksack Group is restricted to the southern portion of the study area. These stratified rocks consist of massive pebbly siltstone, volcanic arenite, cobble conglomerate, and minor andesitic volcanic rocks. Belemnite molds and Pleuromya and Buchia fossils are fairly abundant in most lithologies of this group. The Church Mountain fault, which is well exposed on the south face of Church Mountain, separates the Chilliwack Group from the underlying Nooksack Group. The northeast striking fault dips up to 75o to the northwest on Church Mountain, and flattens considerably a few kilometers to the northeast. The fault zone is manifested by mylonitized scaley argillite, sandstone boudins, and sporadic serpentinite. This fault has previously been mapped as a thrust (Misch, 1966), however its steep dip in the Church Mountain area raises some question as to this interpretation. More study is needed to determine the sense of motion along the fault. It could be a folded thrust fault, a strike-slip fault, or a normal fault. Rocks of the Yellow Aster Complex exist as tabular fault-bounded bodies within the Chilliwack Group. These rocks consist of felsic gneiss that has been intruded by gabbro, diorite, quartz diorite, trondhjemite, granite, and greenstone. Serpentinite is commonly associated with the Yellow Aster Complex, but it is restricted to fault zones within and surrounding it. Closely associated with the fault slabs of the Yellow Aster Complex, and occuring along the western margin of the area, is the chert/basalt unit. This is an assemblage consisting of alternating layers of basalt and ribbon chert. The basalt bears titaniferous augite and well developed quench textures, which are not recognized in the Chilliwack Group. The association of argillaceous chert with basalt may represent a deeper marine facies of the Chilliwack Group, or, alternatively, these rocks could be unrelated to the Chilliwack Group
Structure and petrology along a segment of the Shuksan thrust fault, Mount Shuksan area, Washington by Peter A Leiggi( )

2 editions published in 1986 in English and held by 3 WorldCat member libraries worldwide

The structural geology of the Mt. Shuksan area is dominated by the Shuksan thrust fault. This fault juxtaposes the mid to late Paleozoic Chilliwack Group with the structurally overlying, early Cretaceous Shuksan Metamorphic Suite. The Shuksan thrust fault is a complex imbricate zone, approximately 1.5 km wide in map view, in which rocks of the Shuksan Suite and Chilliwack Group are imbricated with lesser amounts of exotic tectonic slices. Mesoscopic structures are chaotic and mostly disordered although a dominant shear fabric is pervasive. The macroscopic structure of the fault zone is relatively simple: it forms a shallowly-dipping plane with a general attitude of N30°-35°W, 25°-35°NE. The low-angle structures are slightly modified by Tertiary high-angle faults and shear zones which exhibit small displacements. No evidence of a "root zone", as postulated by Misch (1966), was discovered in this study. The imbricate zone is composed of tectonic slices and fragments of exotic and autoclastic rocks, commonly in a sheared pelitic matrix or in other sheared rock of the Chilliwack Group. Exotic slices present include: serpentinite, ultramafic tectonite (forsterite-tremolite-talc rock), schist of the Vedder Complex, blueschist termed the Baker Lake blueschist in this study, and meta-hornblende gabbro of uncertain affinity. Forsterite-tremolite-talc rock contains a mineral assemblage indicative of the upper amphibolite facies of regional metamorphism. It, and the meta-hornblende gabbro, are the only rock units of the tectonic slices that occur north of Day Creek. The other tectonic slices occur in the south of the study area in association with a possible large tectonic fragment of titanaugite-bearing meta-basalt and meta-chert which may be correlative with the Haystack Mountain unit of Cruver (1983). Radiometric dating of albite-muscovite schist similar to that on Vedder Mountain yields a K/Ar date of 274 ± 9 Ma and a Rb/Sr date of 273 ± 6 Ma. These ages are within the range of dates for the Vedder Complex (Armstrong and others, 1983) and suggest correlation of this schist with the Vedder Complex. In addition, petrographic, chemical, and mineralogic data suggest that other barroisitic-amphibole-bearing coarse schists from the study area are also correlative with the Vedder Complex. A blueschist fragment, the Baker Lake blueschist, contains the distinctive mineral assemblage: crossite + lawsonite + chloromelanite. This key assemblage suggests metamorphism at ~250°C at ~6.5 kbars. Chemical, mineralogical, and petrographic characteristics of this blueschist suggest that it is not correlative with other known high pressure rock units of the western North Cascades
 
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