scholarly journals Digital aeromagnetic data of Juan de Fuca to Queen Charlotte Island area, British Columbia

1987 ◽  
Author(s):  
Keyword(s):  
British Columbia ◽  
Aeromagnetic Data ◽  
Island Area ◽  
Queen Charlotte Island ◽  
Juan De Fuca

Summary of Coastal Geologic Evidence for past Great Earthquakes at the Cascadia Subduction Zone

1995 ◽  
Vol 11 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Brian F. Atwater ◽  
Alan R. Nelson ◽  
John J. Clague ◽  
Gary A. Carver ◽  
David K. Yamaguchi ◽  
...  
Keyword(s):  
British Columbia ◽  
North America ◽  
Subduction Zone ◽  
Forest Soils ◽  
Pacific Coast ◽  
Cascadia Subduction Zone ◽  
Level Change ◽  
The Past ◽  
The Pacific ◽  
Juan De Fuca

Earthquakes in the past few thousand years have left signs of land-level change, tsunamis, and shaking along the Pacific coast at the Cascadia subduction zone. Sudden lowering of land accounts for many of the buried marsh and forest soils at estuaries between southern British Columbia and northern California. Sand layers on some of these soils imply that tsunamis were triggered by some of the events that lowered the land. Liquefaction features show that inland shaking accompanied sudden coastal subsidence at the Washington-Oregon border about 300 years ago. The combined evidence for subsidence, tsunamis, and shaking shows that earthquakes of magnitude 8 or larger have occurred on the boundary between the overriding North America plate and the downgoing Juan de Fuca and Gorda plates. Intervals between the earthquakes are poorly known because of uncertainties about the number and ages of the earthquakes. Current estimates for individual intervals at specific coastal sites range from a few centuries to about one thousand years.

STUDIES IN FOREST PATHOLOGY: VII. DECAY IN WESTERN HEMLOCK AND FIR IN THE FRANKLIN RIVER AREA, BRITISH COLUMBIA

1949 ◽  
Vol 27c (6) ◽  
pp. 312-331 ◽  
Author(s):  
D. C. Buckland ◽  
R. E. Foster ◽  
V. J. Nordin
Keyword(s):  
British Columbia ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Forest Pathology ◽  
Abies Amabilis ◽  
Armillaria Mellea ◽  
Forest Region ◽  
Volume Increment ◽  
Juan De Fuca

An investigation of decay in western hemlock (Tsuga heterophylla (Raf.) Sarg.) and fir (mainly Abies amabilis (Loud.) Forb.) in the Juan de Fuca forest region of British Columbia has shown that the major organisms causing root and butt rots are the same in both species. These are Poria subacida (Peck) Sacc., Fomes annosus (Fr.) Cke., Armillaria mellea Vahl ex Fr., Polyporus sulphureus Bull. ex Fr., and P. circinatus Fr. Those organisms causing trunk rots of western hemlock, in decreasing order of importance, are Fomes pinicola (Sw.) Cke., F. Pini (Thore) Lloyd, Stereum abietinum Pers., Fomes Hartigii (Allesch.) Sacc. and Trav., and Hydnum sp. (H. abietis). These same organisms causing trunk rots of fir, in decreasing order of importance, are Fomes pinicola, Stereum abietinum, Hydnum sp. (H. abietis), Fomes Pini, and Fomes Hartigii. The logs of 963 western hemlock were analyzed in detail. Maximum periodic volume increment was reached between 225 and 275 years of age. Maximum periodic volume increment was reached between 275 and 325 years of age in the 719 fir that were analyzed. Scars were the most frequent avenue of entrance for infection. In 59% of the cases of infection studied the fungus had entered through wounds.

Factors influencing the distribution of Egregia menziesii (Phaeophyta, Laminariales) in British Columbia, Canada

1978 ◽  
Vol 56 (9) ◽  
pp. 1198-1205 ◽  
Author(s):  
D. K. Gordon ◽  
R. E. DE Wreede
Keyword(s):  
British Columbia ◽  
High Temperature ◽  
Laboratory Experiments ◽  
Algal Flora ◽  
The West ◽  
Common Component ◽  
Strait Of Georgia ◽  
Low Salinity ◽  
Factors Influencing ◽  
Juan De Fuca

Egregia menziesii (Turner) Areschoug is a common component of the algal flora along the west coast of Vancouver Island, Queen Charlotte Strait, and the Strait of Juan de Fuca but is absent from the Strait of Georgia in British Columbia, Canada. This distribution pattern was found to be correlated with temperature and salinity in that E. menziesii is not present in areas where there are seasonal periods of low salinity and high temperature. To test this correlation, field transplants of sporophytes and laboratory experiments with sporophytes and culture work were carried out. The results suggest that the distribution of E. menziesii is limited by specific combinations of salinity and temperature; it requires high salinities and temperatures less than 15 °C for its survival.

Seiche Excitation in Port San Juan, British Columbia

1979 ◽  
Vol 36 (10) ◽  
pp. 1223-1227
Author(s):  
D. D. Lemon ◽  
P. H. LeBlond ◽  
T. R. Osborn
Keyword(s):  
British Columbia ◽  
Water Waves ◽  
Pressure Gauge ◽  
Low Frequency ◽  
San Juan ◽  
External Forcing ◽  
Edge Waves ◽  
Rectangular Basin ◽  
Juan De Fuca ◽  
Juan De Fuca Strait

Seiche motions observed in San Juan Harbour with a bottom-mounted pressure gauge have been Fourier-analyzed and interpreted in terms of a theoretical model of oscillations in a rectangular basin with an exponential depth profile. Two of the observed periods (at 14.6 and 38.5 min) are identified with resonances of the basin; two other significant low frequency peaks (at 21 and 55 min) do not coincide with resonant periods of the basin and must be due to strong external forcing. Higher frequency fluctuations (20–160 s) are attributed to swell and to its subharmonic interactions with edge waves. Key words: water waves, seiches, mathematical model, Juan de Fuca Strait, British Columbia

A New Gunnel, Pholis clemensi, from the Coast of Western North America

1964 ◽  
Vol 21 (5) ◽  
pp. 933-939 ◽  
Author(s):  
Richard H. Rosenblatt
Keyword(s):  
British Columbia ◽  
New Species ◽  
North America ◽  
North American ◽  
North American Species ◽  
Western North America ◽  
The North ◽  
The Family ◽  
Juan De Fuca ◽  
A New Species

A new species, Pholis clemensi, referred to the family Pholidae, is named and described from 12 specimens taken in southern British Columbia waters and the Strait of Juan de Fuca. Pholis clemensi is compared with other members of the genus, and a key is given to the North American species.

A Redescription of the Rare Cottid Fish, Artedius meanyi, New to the Fauna of British Columbia

1963 ◽  
Vol 20 (6) ◽  
pp. 1505-1511
Author(s):  
Richard H. Rosenblatt ◽  
Donald Wilkie
Keyword(s):  
British Columbia ◽  
The Other ◽  
Juan De Fuca ◽  
Subjective Synonym

Nine specimens of Artedius meanyi (= Ruscarius meanyi), previously known only from the types, have been taken in Howe Sound and the Strait of Juan de Fuca. The genus Ruscarius, of which meanyi is the type, though retained as a subgenus, is placed in the synonymy of Artedius. The subgenus Ruscariops Hubbs is considered a junior subjective synonym of the subgenus Ruscarius Jordan and Starks. A. meanyi is redescribed and compared with the other members of the genus.

A Review of Geophysical Studies in the Canadian Cordillera

1971 ◽  
Vol 8 (7) ◽  
pp. 788-801 ◽  
Author(s):  
M. J. Berry ◽  
W. R. Jacoby ◽  
E. R. Niblett ◽  
R. A. Stacey
Keyword(s):  
British Columbia ◽  
Heat Flow ◽  
Rocky Mountain ◽  
The United States ◽  
Vancouver Island ◽  
Geophysical Data ◽  
Fault System ◽  
Canadian Cordillera ◽  
Crust And Upper Mantle ◽  
Juan De Fuca

Geophysical studies of the crust and upper mantle have been conducted in the Canadian Cordillera for over two decades, but only recently have sufficient data been collected to permit a synthesis and a correlation with the major geological units. The studies have included gravity, heat flow, and magnetotelluric observations, geomagnetic depth sounding, and high level aeromagnetics as well as both small and large scale refraction and reflection seismic surveys.It now appears that major crustal units may be recognized geophysically:(i) Seismic and gravity data suggest that the Plains and Rocky Mountains are underlain by two units of the North American craton with a crustal section 45–50 km thick. The northern unit appears to terminate at the Rocky Mountain Trench while the southern unit may extend to the Omineca Geanticline.(ii) The combined geological and geophysical data suggest that the Rocky Mountain Trench and possibly the Kootenay Arc near the 49th parallel mark the edge of the Precambrian continental margin and that the western Cordillera was formed by a complex succession of plate interactions with repeated reactivation of block boundaries.(iii) A combination of magnetic and heat flow data suggest that the region between the Rocky Mountain Trench and the Fraser Lineament is part of the Cordilleran Thermal Anomaly Zone recognized by Blackwell in the United States.(iv) Seismic data in Central British Columbia suggest that the Pinchi Fault system is a boundary between two crustal blocks.(v) The crustal thickness of the Coast Geanticline appears to increase gradually to the west to approximately 40 km and, at least in southern British Columbia, does not have a root zone below the mountains.(vi) The crustal section beneath Vancouver Island is abnormally thick and there is some paleomagnetic data which suggest that the Island may not have been formed in its present position, contiguous to the Cordillera. The crustal section for the northern part of the Insular Trough is significantly thinner.(vii) The active spreading of the Juan de Fuca Rise – Explorer Trench is now well documented. The geophysical data suggest active subduction of the Juan de Fuca plate beneath Oregon, Washing-ton, and southern Vancouver Island. However, further north there is no evidence for subduction.

Late Pleistocene history and geomorphology, southwestern Vancouver Island, British Columbia

1979 ◽  
Vol 16 (9) ◽  
pp. 1645-1657 ◽  
Author(s):  
Neville F. Alley ◽  
Steven C. Chatwin
Keyword(s):  
British Columbia ◽  
Continental Shelf ◽  
Late Pleistocene ◽  
Vancouver Island ◽  
Glacial Lakes ◽  
Small Lakes ◽  
Strait Of Georgia ◽  
Coast Mountains ◽  
Juan De Fuca ◽  
Juan De Fuca Strait

The major Pleistocene deposits and landforms on southwestern Vancouver Island are the result of the Late Wisconsin (Fraser) Glaciation. Cordilleran glaciers formed in the Vancouver Island Mountains and in the Coast Mountains had advanced down Strait of Georgia to southeastern Vancouver Island after 19 000 years BP. The ice split into the Puget and Juan de Fuca lobes, the latter damming small lakes along the southwestern coastal slope of the island. During the maximum of the glaciation (Vashon Stade), southern Vancouver Island lay completely under the cover of an ice-sheet which flowed in a south-southwesterly direction across Juan de Fuca Strait, eventually terminating on the edge of the continental shelf. Deglaciation was by downwasting during which ice thinned into major valleys and the strait. Most upland areas were free of ice down to an elevation of 400 m by before 13 000 years BP. A possible glacier standstill and (or) resurgence occurred along Juan de Fuca Strait and in some interior upland valleys before deglaciation was complete. Glacial lakes occupied major valleys during later stages of deglaciation.

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