The tephra stratigraphy of two lakes in south-central British Columbia, Canada and its implications for mid-late Holocene volcanic activity at Glacier Peak and Mount St. Helens, Washington, USA

2004 ◽  
Vol 41 (12) ◽  
pp. 1401-1410 ◽  
Author(s):  
Franklin F Foit Jr. ◽  
Daniel G Gavin ◽  
Feng Sheng Hu
Keyword(s):  
British Columbia ◽  
Late Holocene ◽  
Glass Composition ◽  
Apparent Absence ◽  
The North ◽  
South Central ◽  
Tephra Layers ◽  
Tephra Stratigraphy ◽  
Eruptive Period ◽  
Mount St Helens

Several mid-late Holocene Glacier Peak tephras along with Mazama and Mount St. Helens Wn and P tephras were found in cores from Cooley and Rockslide lakes in southeastern British Columbia, ∼300 km northeast of Glacier Peak. The sediments in Cooley Lake host the late Holocene Glacier Peak A tephra (2010 calibrated (cal) years BP), four separate Glacier Peak Dusty Creek (GPDC) tephras (5780–5830 cal years BP), and a Glacier Peak set D tephra (6060 cal years BP). This is the first report of Glacier Peak A and D tephras in British Columbia. The A tephra has been correlated on the basis of glass composition and age to a late Holocene Glacier Peak tephra in the sediments of Big Twin Lake, 75 km northeast of Glacier Peak. The glasses in the four GPDC tephra layers from Cooley Lake are compositionally indistinguishable from those in Mount Barr Cirque and Frozen lakes in southwestern British Columbia. The layers likely represent four eruptions taking place over 50 years. Although set D tephra has not been correlated to a known proximal or distal deposit, its glass bears the Glacier Peak glass compositional signature and its interpolated age corresponds to the initiation of the set D eruptive period. The presence of GPDC tephra in lake sediments across southern British Columbia suggests a broad plume trajectory to the north and northeast, whereas the apparent absence of the A and D tephras in all but Cooley Lake suggest plumes with a northeasterly direction.

Mid-Holocene Glacier Peak and Mount St. Helens We Tephra Layers Detected in Lake Sediments from Southern British Columbia Using High-Resolution Techniques

2001 ◽  
Vol 55 (3) ◽  
pp. 284-292 ◽  
Author(s):  
Douglas J. Hallett ◽  
Rolf W. Mathewes ◽  
Franklin F. Foit
Keyword(s):  
British Columbia ◽  
High Resolution ◽  
Lake Sediments ◽  
Tephra Layer ◽  
Coast Mountains ◽  
The North ◽  
Subalpine Lakes ◽  
Tephra Layers ◽  
Depth Relationship ◽  
Mount St Helens

AbstractA Glacier Peak tephra has been found in the mid-Holocene sediment records of two subalpine lakes, Frozen Lake in the southern Coast Mountains and Mount Barr Cirque Lake in the North Cascade Mountains of British Columbia, Canada. The age–depth relationship for each lake suggests an age of 5000–5080 14C yr B.P. (5500–5900 cal yr B.P.) for the eruption which closely approximates the estimated age (5100–5500 14C yr B.P.) of the Dusty Creek tephra assemblage found near Glacier Peak. The tephra layer, which has not been reported previously from distal sites and was not readily visible in the sediments, was located using contiguous sampling, magnetic susceptibility measurements, wet sieving, and light microscopy. The composition of the glass in pumice fragments was determined by electron microprobe analysis and used to confirm the probable source of this mid-Holocene tephra layer. Using the same methods, the A.D. 1481–1482 Mount St. Helens We tephra layer was identified in sediments from Dog Lake in southeastern British Columbia, suggesting the plume drifted further north than previously thought. This high-resolution method for identifying tephra layers in lake sediments, which has worldwide application in tephrachronologic/paleoenvironmental studies, has furthered our knowledge of the timing and airfall distribution of Holocene tephras from two important Cascade volcanoes.

Identification and significance of late Holocene tephra from Otter Creek, southern British Columbia, and localities in west-central Alberta

1977 ◽  
Vol 14 (11) ◽  
pp. 2593-2600 ◽  
Author(s):  
J. A. Westgate
Keyword(s):  
British Columbia ◽  
Late Holocene ◽  
Far North ◽  
West Central ◽  
Tephra Beds ◽  
Middle Unit ◽  
Mount St Helens

Three thin, light-coloured, ash-grade tephra beds occur within the uppermost metre of peat at Otter Creek bog in southern British Columbia. The youngest tephra is related to the ~2600 year old Bridge River tephra but is probably the product of a younger and weaker eruption that directed tephra to the southeast of the vent, believed to be located in the Meager Mountain district of southwestern British Columbia. The middle unit is ~2100 years old and is tentatively correlated with one of the upper beds of set P tephra of Mount St. Helens in Washington. The lowermost tephra is equivalent to the Yn bed of set Y, derived from an eruption of Mount St. Helens about 3400 years ago.The Yn tephra has been located as far north as Entwistle in west-central Alberta but mineralogically and chemically similar tephra elsewhere in this region is ~4300 years old and thus represents an older part of the Y set. Significant compositional differences between these two extensive members of the Y set have not yet been recognized.

Regional stratigraphy and age of Chilcotin Group basalts, south-central British Columbia

1983 ◽  
Vol 20 (4) ◽  
pp. 515-524 ◽  
Author(s):  
Mary Lou Bevier
Keyword(s):  
British Columbia ◽  
Pillow Lava ◽  
Snake River Plain ◽  
Eruptive Activity ◽  
South Central ◽  
Shield Volcanoes ◽  
Low Profile ◽  
Tephra Layers ◽  
River Plain ◽  
Age Determinations

Mio-Pliocene Chilcotin Group basalt flows form a 50 000 km2 lava plateau in south-central British Columbia. Two periods of eruptive activity at 2–3 and 6–10 Ma are indicated by a compilation of available age data, including 10 new K–Ar age determinations, and basalts from these two periods are chemically indistinguishable. The Chilcotin Group consists of thin, crudely columnar-jointed pahoehoe flows, some thick, tiered flows, pillow lava and pillow breccia, and rare silicic tephra layers. The presence of many vesicle sheets and cylinders and collapsed pahoehoe toes suggests that the basalts were volatile-rich. Known vents (gabbro and basalt plugs) for the basalt flows form a northwest trend along the axis of the lava plateau. The plateau appears to have formed from the overlap of many low-profile shield volcanoes and is similar in morphology to other plains basalts such as the Snake River Plain and parts of Iceland. Glaciation has stripped off an unknown volume of the flat-lying basalt flows.

scholarly journals Characterization of western spruce budworm outbreak regions in the British Columbia Interior

2018 ◽  
Vol 48 (7) ◽  
pp. 783-802 ◽  
Author(s):  
Lorraine E. Maclauchlan ◽  
Lori D. Daniels ◽  
Janice C. Hodge ◽  
Julie E. Brooks
Keyword(s):  
British Columbia ◽  
Spruce Budworm ◽  
Growth Suppression ◽  
Douglas Fir ◽  
Western North America ◽  
Western Spruce Budworm ◽  
The North ◽  
South Central ◽  
Ecosystem Classification

The western spruce budworm (WSB; Choristoneura freemani Razowski) shapes Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests throughout western North America with periodic, severe landscape-level defoliation events. The largest and most continuous recorded defoliation occurred in the 2000s, largely centered in the Williams Lake and 100 Mile House WSB outbreak regions, peaking in 2007 at 847 000 ha defoliated in British Columbia (B.C.). Unique WSB outbreak regions in south-central B.C. are described using biogeoclimatic ecosystem classification, geography, 106 years of documented defoliation, and 46 stand-level Douglas-fir host tree-ring chronologies. Since the 1980s, recorded defoliation in B.C. has shifted from coastal ecosystems and become a dominant disturbance in drier, colder, interior Douglas-fir ecosystems. Defoliation records demarcate four outbreaks from 1950–2012 and up to three growth suppression events from 1937–2012. Outbreak duration was shorter in the north and far south of B.C., with recovery periods (no trees showing growth suppression) shorter over all WSB outbreak regions in the 2000s, suggesting that trees may be increasingly susceptible to each successive defoliation event. Knowing the regional outbreak periodicity may facilitate early detection of incipient WSB populations, which is critical for management as many of our low-elevation Douglas-fir forests become more stressed with changing and unpredictable climate regimes.

Paleomagnetism of the Triassic Guichon Batholith and Rotation in the Interior Plateau, British Columbia

1971 ◽  
Vol 8 (11) ◽  
pp. 1388-1396 ◽  
Author(s):  
D. T. A. Symons
Keyword(s):  
British Columbia ◽  
Pole Position ◽  
Upper Triassic ◽  
Late Triassic ◽  
Ratio Analysis ◽  
Tectonic Block ◽  
Clockwise Rotation ◽  
The North ◽  
South Central ◽  
Intrusive Rocks

The Guichon Batholith, located near the south end of the Interior Plateau in south–central British Columbia, is composed of unmetamorphosed massive felsic intrusive rocks in several distinct phases (Northcote 1969). Stratigraphic and radiometric evidence indicate that the batholith was emplaced during the Late Triassic (198 ± 8 m.y.) and unroofed by Early Jurassic. Analysis of the remanence of 92 cores (184 specimens) from 19 representative sites led to the isolation of a stable primary remanent magnetism at 15 sites after alternating-field demagnetization. Variance ratio analysis of the remanence directions indicates that the phases cannot be distinguished by the paleomagnetic method. This supports the evidence from contact relationships and K–Ar isotopic dating of biotites that the phases cooled nearly contemporaneously. The pole position determined for the Guichon Batholith (12.9° E, 65.6° N) is discordant with other Upper Triassic pole positions determined for North American formations. The discordance may be explained by a clockwise rotation 40° ± 10° of the batholith and surrounding rocks in the southern end of the Interior Plateau, with most of the Plateau to the north acting as a stable non-rotated tectonic block. Other evidence is cited which is consistent with this hypothesis.

scholarly journals Sea level change: late Holocene sea level change, south-central British Columbia

1996 ◽  
Author(s):  
J J Clague ◽  
P T Bobrowsky ◽  
J -P Builbault ◽  
R W Mathewes
Keyword(s):  
British Columbia ◽  
Sea Level ◽  
Late Holocene ◽  
Sea Level Change ◽  
Level Change ◽  
South Central ◽  
Holocene Sea Level

Depositional systems and seismic stratigraphy of a Quaternary basin: north Okanagan Valley, British Columbia

1996 ◽  
Vol 33 (6) ◽  
pp. 917-927 ◽  
Author(s):  
S. Vanderburgh ◽  
M. C. Roberts
Keyword(s):  
British Columbia ◽  
Systems Approach ◽  
Alluvial Fan ◽  
Seismic Profiles ◽  
The North ◽  
South Central ◽  
Depositional Systems ◽  
Late Wisconsinan ◽  
Okanagan Valley ◽  
Basin Fill

Seismic and core data from north Okanagan Valley, a deep (~700 m of fill), elongate (~3 km wide by 45 km long) basin located in the Cordillera of south-central British Columbia, reveal a thick sequence of fine and coarse elastics. The architecture of the basin fill was delineated using 16 km of high-resolution, reflection seismic profiles, and 30 lithologic logs. Using a depositional systems approach, four systems were identified: subglacial fluvial, glaciolacustrine, alluvial fan, and channel. The subglacial fluvial system consists of a basal suite of compact, stratified to poorly stratified coarse clastics deposited beneath glacial ice under high hydrostatic pressure. Older sediments were almost completely excavated from the basin fill during periods of maximum subglacial flow during Late Wisconsinan glaciation. One of the outcomes of this study is that it lends support to the notion that Late Wisconsinan glaciers were capable of almost totally eroding older Pleistocene basin deposits while depositing thick sequences of subglacial fluvial sediments. During deglaciation, the basin was occupied by a lake in which laminated silt and clay were deposited (glaciolacustrine system). The wedge-shaped alluvial fan system interfingers with the finer clastics of the basin fill. Incised into the upper part of the basin fill are channel sediments forming the channel depositional system. Two stages in the evolution of the north Okanagan basin were identified: in the first stage (~10 ka), lake sediments were rapidly accumulating coeval with the formation of alluvial fans and fan deltas; the second stage shows the present-day architecture of the basin fill.

Tephrostratigraphy of Olympia Interglacial Sediments in South-central British Columbia, Canada

1975 ◽  
Vol 12 (3) ◽  
pp. 489-502 ◽  
Author(s):  
J. A. Westgate ◽  
R. J. Fulton
Keyword(s):  
British Columbia ◽  
Washington State ◽  
Plateau Region ◽  
Distinctive Character ◽  
Correlation Studies ◽  
Fine Grained ◽  
South Central ◽  
The Pacific ◽  
Definitive Statement ◽  
Mount St Helens

The Olympia interglacial sediments in the Interior Plateau region of British Columbia contain several thin, fine-grained rhyolitic and dacitic tephras, which undoubtedly represent the distal portions of widespread air-fall eruptive units. Successful discrimination of these tephras can be made by their mineral assemblage and composition of glass, magnetite and ilmenite, as determined by use of an electron microprobe; positive identification is not possible solely on the basis of field criteria such as coloration, degree of weathering, granulometry, thickness and stratigraphic position.Each tephra layer serves as a valuable time-parallel stratigraphic marker because of its regional extent and distinctive character. Those documented in this study include, in order of increasing age: Rialto Creek tephra, about 20 000 years old; Cherryville tephra, about 25 000 years old; Riggins Road tephra, about 30 000 years old; Duncan Lake tephra, about 34 000 years old; Dufferin Hill and Sweetsbridge tephras are probably close in age to Duncan Lake tephra; Kamloops Lake tephra is slightly older than 34 000 years; Mission Flats tephra is probably older than 35 000 years; Coutlee tephra is more than 37 000 years old; and the exact age of Okanagan Centre tephra is unknown. Such a detailed tephrochronological record should greatly facilitate geochronological and correlation studies of Olympia interglacial sediments in south-central British Columbia and adjacent areas of the Pacific Northwest.No definitive statement can be made at present on the identity of source volcanoes, but it is very likely that the commungtonite-rich tephras are derived from Mount St. Helens in Washington State.

OREL SECURITY OFFICER BORIS GORDON AND THE «RED CHAPEL»

2020 ◽  
Vol 9 (3) ◽  
pp. 164-175
Author(s):  
A.Yu. SARAN ◽  
◽  
M.V. SOKOLOV ◽  
Keyword(s):  
Central Asia ◽  
Nazi Germany ◽  
Career Ladder ◽  
Security Officer ◽  
State Security ◽  
Successful Career ◽  
The North ◽  
South Central ◽  
Foreign Countries ◽  
Party Work

The purpose of the article is to study the biography of B.M. Gordon as a successful security officer in the 1920-s and 1930-s. He worked his way up the career ladder from a junior investigator to the head of regional divisions – territorial bodies of the VChK/GPU/OGPU/NKVD and the legal residency of the INO GUGB of NKVD in Germany. Having started his chekist service in the Orel province, he served in the South – Central Asia, in the North – in Arkhangelsk province,in the capital of the USSR, and in the capital of Nazi Germany – Berlin. Gordon fought with the white guards and evicted the dispossessed peasants, controlled the Soviet military and gathered information about the armies of foreign countries; he managed to work at both Soviet and party work. Finally, the energetic work and successful career led Boris Moiseyevich Gordon to his death, when in 1937, J.V. Stalin decided to destroy completely all the former operational leadership of the state security agencies, replacing it with new personnel.

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