bluuebunny/crossref_metadata_2025 huggingface dataset:
Salt-water intrusion in Prince Edward Island
Authors: Carr P. A.
Published: April 2011

The numerous saline estuaries situated throughout Prince Edward Island permit high tides to carry salt water a long way inland and to penetrate the bedrock aquifer. Very little groundwater consumption occurs around the banks of the Eliot River estuary, yet salt water has moved into the bedrock and created a large zone of diffusion. This salty water extends as far as 1200 ft inland and has penetrated to a depth of 185 ft. Beneath this salty water is fresh groundwater, which extends down to about 600 ft where it is underlain by salty water.The salty water in the upper 185 ft of the aquifer is not separated from the fresh groundwater by a confining stratum, but is kept in this position by the higher head of the fresh groundwater. This head maintains a dynamic equilibrium with the heavier salty water. The effect of density in maintaining the position of a fresh and salt water front is not as important as has been previously thought.
A laboratory study of suspension-effect density currents
Authors: Riddell John F.
Published: April 2011

Suspension-effect density currents formed by both natural and non-natural materials have been investigated in three series of laboratory tests. The lock exchange method of current formation has been shown to be unsuitable for suspensions of high settling velocity and a more effective, dropping method of release has been devised. The adoption of a new linear proportionality equation for correctly correlating the variables acting on the system has demonstrated the significance of the densimetric Froude-Reynolds number for suspension-effect current studies.Quantitative plots of extension against time and non-dimensional time have been prepared for a wide range of concentrations of different materials and the expected increase in both velocity and total extension with increasing concentration verified. For suspensions of constant initial concentration, increase in material particle size has been shown to result in underflows of increased velocity but reduced extension. Mixtures of coarse and fine material in the one suspension have also been investigated.Viscous scale effects have been examined by using two sizes of geometically similar flumes and a short range congruency type of diagram prepared for suspensions of a natural river sediment.Suspension effect currents are compared with the simpler solution effect currents and the greater influence of viscosity on the former discussed together with the suitability of using solution current congruency diagrams for model/prototype studies of suspension-effect currents.
Diaspore in Early Proterozoic quartzites (Lorrain Formation) of Ontario
Authors: Chandler F. W. , Young G. M. , Wood J.
Published: April 2011

Diaspore and kaolinite occur in quartzites of the Huronian Lorrain Formation in both the Bruce Mines and Flack Lake areas north of Lake Huron, Ontario. Regional metamorphism has in part converted these aluminous minerals to pyrophyllite. A later redistribution of silica and water resulted in partial conversion of diaspore and, to a lesser extent pyrophyllite, to a second generation of kaolinite.
Comparative Precambrian geochronology of the North American, European, and Siberian Shields
Authors: Burwash R. A.
Published: April 2011

A comparison of average values of U–Pb, Rb–Sr, and K–Ar isotopic dates from Precambrian shields in North America, Europe, and northern Asia suggests three major orogenies common to all areas. U–Pb and Rb–Sr age determinations, qualified by the more numerous K–Ar data, suggest mean values of 2600 ± 100 m.y., 1800 ± 100 m.y. and 1000 ± 100 m.y. An earlier event at 3300 to 3500 m.y. is locally recognizable in the Baltic Shield, the Ukrainian Shield, and the north-central United States. Anorogenic igneous events intermediate between the major orogenies are indicated in the Canadian, Ukrainian, and Aldan Shields, but these are as yet unmatched outside their own restricted settings.Isotopic dates are divided into two categores: anorogenic and orogenic. Within a specified orogeny, dates are further divided into precrystalline, syncrystalline, and postcrystalline. Regional correlations ideally should be based only on syncrystalline dates, recording times of final crystallization, unmodified by subsequent processes except initial cooling. Depth of crystallization and rate of uplift determine the difference between true and apparent time of crystallization. Precrystalline dates (survival values) and postcrystalline (rejuvenated or overprinted) dates should be excluded from the designated span of major orogenies.Rigorous statistical treatment of isotopic dates seems unwarranted on the basis of uncertainties in the geologic history of most rock bodies. Histograms may aid in the identification of anorogenic and precrystalline dates.
Radiocarbon dates, Mya arenaria phase of the Champlain Sea
Authors: Elson John A.
Published: April 2011

The history of the Champlain Sea is divided into an early cold period of subarctic water termed the Hiatella phase that lasted from its inception, about 11 800 years ago (Two Creeks time), until a low water phase about 10 800 years ago (Younger Dryas or Valders time). This was followed by an interval of warmer boreal water, here called the Mya arenaria phase, that lasted from about 10 800 years ago until 10 200 years ago or the end of the Champlain Sea.General descriptions, previously unpublished, of Groningen dates GrN 2031 (10 870 ± 100 B.P.), GrN 2032(10 450 ± 80 B.P.), GrN 2034 (10 590 ± 100 B.P.), and GrN 2035 (10 330 ± 100 B.P.) are presented. These dates record the Mya arenaria phase of the Champlain Sea, which may have had an initial rising (transgressive) phase, though the stratigraphic evidence, supported by three sets of radiocarbon dates, is not wholly conclusive.
The Ink Pots—a group of karst springs in the Rocky Mountains near Banff, Alberta
Authors: Everdingen R. O. van
Published: April 2011

The Ink Pots are a group of springs in Banff National Park. The one feature that makes these springs of more than passing interest is the greenish milky appearance of two of the ponds in the group. This difference in appearance of the water cannot be explained by dissolved or suspended chemicals, or by algae growth. It can be explained by differences in flow velocity, which cause differential suspension of fine sand and silt. Temperature and chemical character of spring water from the Ink Pots indicate, respectively, shallow circulation and a relatively short 'contact' time.
Compressional wave velocities of Keweenawan rock specimens from the Lake Superior region
Authors: Halls H. C.
Published: April 2011

Compressional wave velocities, measured in 114 samples of Keweenawan volcanics and clastics at hydrostatic pressures of up to 2 kb, are used to compute Keweenawan formation velocities. In certain instances, formation velocities are sufficiently distinct from one another to permit a reliable geological identification of seismic refractors in the Lake Superior basin. It is further concluded that slightly metamorphosed volcanics, such as the Portage Lake Series of the Michigan Copper district, cannot be responsible for 'Upper Refractor' velocities of 6.6–6.9 km/s observed at depths of about 10 km beneath Lake Superior. Amphibole-bearing volcanics, hitherto unreported, were sampled in the basal parts of the Keweenawan extrusive sequence, and represent a higher grade of regional metamorphism than commonly found in the Portage Lake Series. Since metamorphic grade appears to increase with depth, amphibole-bearing volcanics with sample velocities as high as 6.7 km/s at 2 kb, must seriously be considered as the cause of the Upper Refractor.
St. Dominique fault: A new interpretation
Authors: Kumarapeli P. S.
Published: April 2011

The St. Dominique fault has been customarily regarded as a thrust fault because of its close spatial association with the thrust faults of Logan's Line. It also is, however, closely associated in space with the normal faults in the St. Lawrence Valley. Moreover, evidence from the shape of the fault-trace in plan and from possible cognate structures favor the interpretation that the St. Dominique fault is a normal fault. This fault, as well as other normal faults in the St. Lawrence Valley, seems to have formed during the Mesozoic Era.
Evidence for an ancient glacier surge in the Swiss Alps
Authors: Röthlisberger H.
Published: April 2011

The climatic and glacial history of two locations in the central Alps has been discussed by Zoller et al. (1966). A brief outline of one aspect of this work is given here. In order to explain some peculiar lateral moraines which are only 30–50 m above the valley floor, and a thick layer of presumably glacial deposit down valley, a surge has been postulated, which was triggered by a rock avalanche onto the glacier.
Recent observations on the surging Otto Glacier, Ellesmere Island
Authors: Hattersley-Smith G.
Published: April 2011

Air photographs show that the Otto Glacier in northwestern Ellesmere Island started to surge sometime between 1950 and 1959, with the result that the terminus advanced about 3 km as a floating ice tongue. Maps prepared from the 1959 photographs and from additional photographs taken in 1964 show a further advance of 2-3 km. Information from a subglacial relief map of the terminal part of the glacier, constructed from the results of radio-depth sounding over the glacier in 1966, may have a bearing on the mechanism of glacier surges. Other glaciers in northern Ellesmere Island show features indicative of past surges.
Ice-sheet surges and the geological record
Authors: Hollin John T.
Published: April 2011

If they had occurred, ice-sheet surges would have caused sea-level rises of up to 50 m from Gondwanaland and say 20 m from Antarctica. The rises would have taken 100 years or much less, and the sub sequent falls would have taken 50 000 years or so, as the ice built up again. Such rises may explain the extensive (hundreds of miles ?) and sharp (submergence time 4 years ?) coal – marine shale contacts in the Carboniferous cyclothems. The chief rival explanation for these contacts is sudden subsidence. Tests should show (1) if such contacts are better correlated with periods of glaciation or with areas of tectonic activity, (2) how extensive the contacts really are, (3) if there is any evidence of erosion during sea-level falls, (4) if the amplitudes and periods of the cycles fit surges or subsidence, (5) how fast the submergences were, and (6) if any coolings began at the contacts. Wilson suggests that in the Pleistocene the surge coolings were sufficient to trigger the northern ice ages. If so, interglacial pollen profiles should show rapid but temporary marine transgressions beginning at the break of climate. Evidence suggesting such transgressions occurs in England and the United States, but is still insufficient to disprove explanations such as local downwarping. There is no evidence yet for surges in Wisconsin or Post-glacial time. There is some evidence that the Antarctic Ice Sheet is currently building up, but this could be a response to a Post-glacial accumulation increase rather than the prelude to a surge.
Initiation of glacier surges
Authors: Robin G. de Q.
Published: April 2011

Three types of instability leading to glacier surges have been suggested, namely stress instabilities, temperature instabilities, and water-film instabilities. Evidence of approximately equal volumes of ice being involved in repeated surges of the same glacier favors stress instabilities as the most likely cause. Since for a steady rate of discharge a section of a glacier undergoing extending flow tends to be of the order of thirty meters thicker than for compressive flow under otherwise similar conditions, it is suggested that surges originate when the glacier flow switches between these two modes of flow. In the accumulation zone of a glacier, a surge would be triggered off by a change from extending to compressive flow over a length of the glacier. If the volume of ice and movement velocities involved are sufficiently large this could lead to repeated surging, although a tendency to stability appears to exist. In the ablation zone, the tendency to change modes of flow would be preceded by a period during which the lower part of the glacier acts as a rigid, sliding dam and increases ice thickness upstream. In this zone, if the volume discharge of the glacier increases beyond a critical limit that depends on bedrock topography, it would initiate a surge.
Water lubrication mechanism of glacier surges
Authors: Weertman J.
Published: April 2011

The author reviews and amplifies his theory of glacier surges. This theory is based on the premise that a glacier surge occurs when a water layer at the base of a glacier attains a thickness sufficient to drown the obstacles in the bed that offer the greatest hindrance to sliding. The following new result is presented: in the case of a glacier bed which is very smooth, the stress concentrations in the vicinity of obstacles in the bed are so high that the power-law creep equation is no longer valid. As a consequence, the size of the controlling obstacles is reduced and thus a surge is more likely to occur.
Propagation of glacier surges
Authors: Robin G. de Q. , Barnes P.
Published: April 2011

Propagation of glacier surges has been discussed in terms of stresses acting in the three major zones of the surge. The steeply sloping front of a surge appears sufficient to explain the thickening of a glacier and the rise in velocity of ice motion which takes place across this zone in terms of accepted stress–strain rate data for ice. Explanation of the high velocities which occur in the next zone in spite of little change in the available shear stress is more difficult, but the experimental results of Barnes and Tabor on ice close to the melting point appear to offer an explanation of the unusually high rates of flow. In the tensile zone, where velocities slow down, the net lowering of the glacier surface after the surge has passed is explained in terms of the depth of crevassing and easier flow of ice at melting point when under tensile and shear stresses.
Carbonate–sulphate–redbed facies and cyclic sedimentation of the Windsorian Stage (Middle Carboniferous), Maritime Provinces
Authors: Schenk Paul E.
Published: April 2011

After the late Devonian orogeny, thick Carboniferous, mainly continental redbeds, derived from intrabasinal horsts, accumulated in a complex rift-valley system called the Fundy basin. During the mid-Carboniferous Windsorian Stage, generally hypersaline seas flooded repeatedly into the tortuously interconnected, intrabasinal grabens. The resulting carbonate–sulfate blankets intertongue laterally with increasingly coarser redbeds and even basalt adjacent to the horst. Macrofaunal, microfaunal, insoluble residue, heavy-mineral, and trace-element analyses and Irwin-logs have limited success in identifying remnants of each particular blanket. Nevertheless, a Windsorian facies model is constructed from detail microscopy and Recent analogues, including field work in Bermuda.Windsorian carbonates are mainly shallow marine to supratidal; calcium sulfate is mainly diagenetic and supratidal, precipitated within, not on, subaerial salt flats; and redbeds are mainly subaerial and diagenetic, pigmented by post-depositional alteration of iron-rich detrital minerals. Dolomitization was both penecontemporaneous within the salt flat by influxing lagoonal water, and also secondary within buried, permeable, basinward lithosomes by refluxing brine. Gypsum–anhydrite nodules metamorphose on stress from mosaic, through penemosaic structures, and finally to massive, porphyroblastic plutons.Floodings in the Antigonish–Mabou basin were from the north–the present Gulf of St. Lawrence. Cyclic sedimentation was probably due to fluctuating supply of terrigenous detritus into a continually subsiding basin.
Deep resistivity measurements in the Fraser Valley, British Columbia
Authors: Samson J. C.
Published: April 2011

Deep resistivity soundings were made in the Fraser Valley, British Columbia, using signals induced by a large, direct-current, dipole source. Interpretation of apparent resistivity data indicates that 500 m of conducting ocean sediments overlie a resistive second layer and conducting third layer. A comparison of resistivity data with well data indicates that the resistive layer is composed of 4–5 km of sedimentary rocks covering 2–4 km of granitic rocks. The extremely low resistivity in the third layer is probably due to water saturation of the granitic to intermediate rocks at this depth.
Precambrian (Aphebian) microfossils from Belcher Islands, Hudson Bay
Authors: Hofmann H. J. , Jackson G. D.
Published: April 2011

A small assemblage of primitive microscopic fossils is here reported for the first time from the lower part of the Belcher Group in Hudson Bay. The microbiota includes chains and clumps of bacteria, and filamentous and spheroidal structures of probable algal or fungal affinities. In addition, a variety of isolated and clustered spheroids and other structures of probable biologic origin is present. The structures are more than 1600 m.y. old, and occur in a black chert associated with thick dolomite beds considered to be of Aphebian (Early Proterozoic) age. Morphologically comparable Precambrian microfossils occur in the Gunflint Formation (Early Proterozoic, Ontario) and the Bitter Springs Formation (Late Proterozoic, central Australia).
Pennsylvanian correlation using blattoid insects
Authors: Durden Christopher J.
Published: April 2011

The stratigraphic distribution of blattoid (cockroach-like) insect genera in the type Pennsylvanian permits the zoning of lacustrine members in this sequence. When taken with the associated floras and the intercalated marine faunas, blattoid fossils permit fine correlation between the name-type Pennsylvanian of Pennsylvania, the goniatite-bearing Upper Carboniferous of Europe, the fusuline-bearing Pennsylvanian of Kansas, and other contemporaneous sequences, especially those of exclusively limnic facies such as the Morien, Pictou, and Narragansett Basins. Application of epochal ages, developed in Europe, to the type and other regions of the Pennsylvanian is now possible. The time distribution of the major genera is presented with a time-stratigraphic plot of data control points in the type region, and a documentation of the relevant systematics is appended.
A large-scale magnetotelluric survey in Western Canada
Authors: Caner B. , Camfield P. A. , Andersen F. , Niblett E. R.
Published: April 2011

Five magnetotelluric stations were operated in two clusters in southern British Columbia and Alberta, in order to determine the conductivity structures in each of the two main regions delineated by geomagnetic depth-sounding. A wide period range was covered (20 to 7500 seconds), to permit resolution of structure at lower crustal and upper mantle depths.At the eastern cluster (Pincher, Fernie), a moderately conducting zone (30–50 ohm-meters) is defined starting at depth 30–35 km and extending to a depth of at least 100 km. At the western cluster (Penticton, Osoyoos, Grand Forks) a conducting layer (10 ± 5 ohm-meters) starts at depth 15 ± 5 km; below this layer (of thickness 20–40 km) the resistivity increases to a value of the same order (30–50 ohm-meters) as at the eastern cluster.
Upper Devonian miospores from the Escuminac Formation, eastern Québec, Canada
Authors: Brideaux Wayne W. , Radforth Norman W.
Published: April 2011

Miospores of early Frasnian age are described from the third unit of the Escuminac Formation in eastern Québec, Canada. The assemblage comprises 34 species, including 8 species proposed as new, 2 new combinations, and 12 sparsely represented forms not considered synonymous with previously described species.The assemblage is most closely comparable to a Middle Devonian assemblage from the Orcadian Basin, Scotland. Similarities are also noted with European and Russian assemblages, particularly from the Eifelian–Givetian of the Russian Platform. Except for five long-ranging species, elements of Lower Carboniferous assemblages are lacking. Evidence suggests a transitional nature for this Escuminac assemblage. Miospores of relatively large size, a feature of Middle Devonian assemblages, are present. Marked differentiation of large and small spore types, found in several other Upper Devonian assem blages is absent. Apiculate and anchor-spined species dominate the Escuminac assemblage.
U–Th–Pb and Rb–Sr ages in granite reference sample from southwestern Saskatchewan
Authors: Rosholt J. N. , Peterman Z. E. , Bartel A. J.
Published: April 2011

Concordant total rock 206Pb–238U, 207Pb–235U, 207Pb–206Pb, 208Pb–232Th and 87Sr–87Rb ages of 1805 ± 40, 1815 ± 55, 1820 ± 110, 1790 ± 60, and 1810 ± 50, in millions of years, respectively, were obtained on the reference sample of biotite granite. The sample is a piece of drill core from a depth of 7300 ft (~2225 m), about 80 ft (~24.4 m) below the top of the Precambrian basement complex, in southwestern Saskatchewan.
The Mid-Atlantic Ridge near 45° N. X. Sediment distribution and thickness from seismic reflection profiling
Authors: Keen M. J. , Manchester K. S.
Published: April 2011

The distribution of sediment on the crest mountains and high fractured plateau of the Mid-Atlantic Ridge at 45° N has been studied by seismic profiling. Sediment is ponded in intermontane valleys within the crest mountains and the plateau. It is also draped over the highlands of the plateau. Mean sediment thickness increases with distance from the valley out to 160 km, the limit of the study. The sediment data is not conclusive with regard to a break or change in the rate of the ocean-floor spreading between 8 and 10 m.y. ago in this area. Rates of sedimentation have been a few cm/1000 y during the past few m.y. It may have been more rapid in the past 100 000 y.
Strain variation in shear belts
Authors: Ramsay J. G. , Graham R. H.
Published: April 2011

In rocks deformed by natural orogenic processes it is usual to find that the finite strain state varies from locality to locality. In some deformed rocks high strain states are localized within approximately planar zones commonly known as "shear belts".The general relationships that exist between variable displacement and variable strain state are established, and these general equations are solved for particular types of strain within shear zones. Only a limited number of types of solution are possible. Using these solutions the geometric forms of the structures found in shear zones in several regions are analyzed. Methods for computing the finite strain through these zones are described, and these finite strains are integrated to determine the total displacements across these zones. Schistosity is developed in some of the shear zones described. It is not parallel to the walls of the shear zone and is therefore not parallel to the dominant displacement (shear) directions. The schistosity appears to be formed perpendicular to the principal finite shortening (i.e. perpendicular to the shortest axis of the finite strain ellipsoid). Variations of the schistosity planes represent variations in the finite strain trajectories of XY planes in the strain states ([Formula: see text] ellipsoid axes). The intensity of development of the schistosity is correlated with the values of the principal finite strains.
Relation between electric analogue patterns of groundwater flow and accumulation of hydrocarbons
Authors: Tóth J.
Published: April 2011

The types of features of electric analogue patterns of groundwater movement found most frequently associated with hydrocarbon accumulation are: regional systems, ascending limbs, and stagnant zones. The reason for the preferential accumulation of hydrocarbons under these hydraulic conditions appears to be an increase in the effectiveness of the structural and lithologic traps. This may be explained by: 1) the large quantities of hydrocarbons transported by the regional flow systems; 2) effective segregation of hydrocarbons from the transporting water owing to a divergence between the flow directions of the migrating fluids; 3) effective mechanical (capillary) filtration by the large number of permeability changes along ascending, hence cross-formational flow paths; 4) effective segregation of gases from the water due to a rapid decrease in pressure along ascending flow paths; 5) slight inclination of oil- or gas–water interfaces causing even minor structures to become relatively effective traps.Examples of theoretical subsurface hydrodynamics as well as of practical observations of hydrocarbon occurrences found in literature implicitly or explicitly corroborate these findings. 1) According to Kortsenshteyn 1964, the amounts of economic hydrocarbon reserves are directly proportional to the volume of the transporting flow system; 2) the consistent association of hydrocarbon accumulations with artesian basins often reported by Soviet petroleum geologists and hydrogeologists clearly indicates conditions favorable for hydrocarbon associations in regions of ascending groundwater flow; 3) by application of Hubbert's equation given for the tilt of the oil– or gas–water interface a theoretical ratio of 8.4:1 is expected for preferential association of hydrocarbons with zones of stagnant and ascending groundwater as compared with the lateral limbs of flow systems along the Etzikom Coulee cross section, and by analysis of the analogue flow-pattern an empirical ratio of 6.8:1 is found, representing a good agreement between anticipation and facts; 4) in the Volga–Ural petroleum province a definite decrease in number and importance of major hydrocarbon fields with decreasing depth is reported, suggesting an effective filtration as a consequence of the ascending movement of groundwater.Thus the theoretical considerations, experimental results, and practical observations all indicate that certain hydrocarbon accumulations are identifiably related to the presently prevailing pattern of groundwater flow. This, in turn, can be realistically approximated from the configuration of the water table and consists of topographically controlled, hydraulically continuous, and regionally unconfined flow systems, modified in detail by the local heterogeneities of the geologic framework.
New evidence for an independent Wisconsin-age ice cap over Newfoundland
Authors: Brookes Ian A.
Published: April 2011

A reinterpretation of the relative ages of glacial striae in southwestern Newfoundland, and new evidence from erratic till-boulder provenances there, support an early view, since abandoned, that at the last glacial maximum the island supported its own ice cap and was not affected by ice from Labrador.
The Extension of the Alert Geomagnetic Anomaly through Northern Ellesmere Island, Canada
Authors: Praus Oldrich , DeLaurier Jon M. , Law L. K.
Published: April 2011

Earlier studies have shown that the anomaly in geomagnetic variations in the vicinity of Alert at the north end of Ellesmere Island is compatible with a narrow band of induced electric currents flowing in a northeast–southwest direction in the earth's crust or upper mantle. The present analysis of magnetic recordings obtained at 11 sites in Ellesmere Island during 1967 indicates that the Alert anomaly extends to the southwest as far as Eureka, a distance of 475 km. The anomaly has its greatest effect at Alert, and its "strength" diminishes by a factor of 2 or 3, 225 km to the southwest. Its half-width up to this point is about 50 km. The anomalous zone curves to the west near Greely Fjord 300 km southwest of Alert and appears to broaden near Eureka. The path of the anomaly closely follows the structural trends of the near vertical, tightly-folded strata of the Franklinian geosyncline underlying the whole Lake Hazen Plateau region of northern Ellesmere Island. Evidence for the extension of the anomaly through Ellesmere Island includes the near reversal of Wiese vectors on opposite sides of the zone, the confinement of the horizontal magnetic variation and its polarization transverse to the direction of strike, and the large contrast between apparent resistivities observed inside and outside the zone.
Shallow Water Heat Flow Measurements in Bras D'or Lake, Nova Scotia
Authors: Rankin Douglas S. , Hyndman Roy D.
Published: April 2011

A light-weight oceanic thermal gradient probe was used for heat flow studies in Bras d'Or Lake, Nova Scotia. The measurements were made in St. Andrew's Channel, an elongated trough 270 m deep and 540 m wide. The heat flux of 1.50 μcal/cm2 s (63 mW/m2) is corrected for sedimentation, conductivity contrast, topography, and surface temperature differences.
The Position of the Ocean Level during the Interstadial at about 30 000 B.P.—A Discussion from a Climatic–Glaciologic Point of View
Authors: Mörner Nils-Axel
Published: April 2011

Several 14C-dated marine shells (and exceptionally even estuarine peat) found at about the present sea level—just below to just above—in different regions of the world suggest a eustatic high stand at about 30 000 B.P.; however, this appears to be incorrect for two main reasons.1. From climatic–glaciologic point of view the interstadial at about 30 000 B.P. (Denekamp, Plum Point, etc.) must correspond to an ocean level far below the present (or roughly corresponding to the Late Glacial one at about 12 000 B.P.).2. Contamination of a sample containing dead or almost dead carbon by 1–5% modern carbon will give the sample an apparent age of 36 000–24 000 B.P.
A Pleistocene Lion-like Cat (Panthera atrox) from Alberta
Authors: Harington C. R.
Published: April 2011

A tooth-bearing facial fragment of the extinct cat Panthera atrox is described. The specimen, from Pleistocene gravels near Bindloss, Alberta, extends the known northward range of this species on the Great Plains. Although the exact geological age of the specimen is uncertain, occurrences of P. atrox elsewhere suggest its presence in southeastern Alberta during a relatively warm phase of the Late Pleistocene.
Environmental Influences on the Distribution and Abundance of Conodonts from the Dundee Limestone (Devonian), St. Mary's, Ontario
Authors: Ferrigno Kenneth F.
Published: April 2011

Samples collected from the Dundee Limestone at St. Mary's, Ontario yielded 3400 identifiable conodont specimens representing 16 genera and 33 species. Three "groups" of conodont species are recognized, based on their distribution in the section. Group I (Angulodus walrathi, Hindeodella austinensis, Neoprioniodus pronus, Ozarkodina congesta, Icriodus nodosus, Panderodus sp., and Acodina formosa) is distributed generally throughout the section. Group II (Plectospathodus sp., Polygnathus linguiformis linguiformis and Ozarkodina lata) occurs from near the base of the section to the 24-ft (7-m) level and from the 28- to 39-ft (8.5- to 12-m) levels. Group III (Ligonodina delicata, Lonchodina arcuata, Neoprioniodus alatus, Neoprioniodus n. sp., Polygnathus robusticostata and Prioniodina aversa) occurs only from the 24- to 3 3-ft (7- to 10-m) levels. The presence and absence of conodont "groups" can be related to changes in lithology of the limestone.The distribution of the "groups" of conodonts and their apparent relation to lithological changes suggest the following: 1. Group II may consist of shallow, quiet water conodonts; 2. Group III may consist of conodont species which existed in a shallow water environment with good water circulation; and 3. the conodont animal was probably nektonic during some stage in its life cycle rather than planktonic, and possibly benthonic during another stage.
Ambiguous "Glacial" Striae Formed Near Waterbodies
Authors: McLellan A. G.
Published: April 2011

Striations indistinguishable from glacial striations are formed by boulders pushed shore-wards by lake ice. Thus striations alone do not provide unequivocal evidence for the direction of movement of continental ice sheets.
A Study of Fenitization Around the Alkaline Carbonatite Complex at Callander Bay, Ontario, Canada
Authors: Currie K. L. , Ferguson John
Published: April 2011

Fenitization in granitoid rocks is first noticeable in the form of hematite veinlets, accompanied by increased ordering of potash feldspar. With increasing fenitization, plagioclase is converted to albite plus calcite, and K-feldspar progressively converted toward maximum microcline. Acmitic pyroxenes become increasingly abundant. The chemical changes producing these effects consist of the substitution of sodium plus another cafemic ion for silicon in such a way as to maintain charge balance. The fenitizing fluid was essentially an NaCl brine, roughly 1 molal in alkali chlorides, and 0.01 molal total acidity. The content of iron, calcium, and magnesium was high. The oxygen fugacity was near 10−17 bars (hematite–magnetite), and the sulfur fugacity near 10−12 bars. Fenitization may have occurred at temperatures as high as 700°, but the main fenitization took place at temperatures slightly above 500° and fenitization ceased at about 450°. Pressures were low, probably less than 500 bars. The source of the fenitizing solutions was carbonatite, which in turn was derived from nephelinitic magma.
The Recovery of Pennant Sandstone from Uniaxial Compressive Load
Authors: Cruden D. M.
Published: April 2011

A permanent deformation of about 10% of the elastic deformation takes place in creep experiments on Pennant sandstone. This permanent deformation is approximately equal to the total amount of time-dependent deformation of the rock. Time-dependent recovery from the compressive load is neither stress dependent nor as marked as previously considered.
Bowie Seamount. A Recently Active, Flat-topped Seamount in the Northeast Pacific Ocean
Authors: Herzer R. H.
Published: April 2011

Bowie Seamount, situated off the west coast of Canada at 53° 18′ N, 135° 39′ W, is a long northeast-trending, volcanic mountain comprising a series of intersecting ridges. These ridges may have grown from extrusions along intersecting fractures in the oceanic crust. Two terraces form the flattened summit of the volcano at approximate depths of 80 and 235 m. These are thought to be remnants of platforms produced by combined shallow-water vulcanism and wave erosion during Pleistocene and Recent times when sea level was lower than it is today. The last episode of volcanic activity on the summit occurred after the formation of the upper terrace which is probably no more than 18 000 years old. Samples dredged from the upper half of the volcano include: pillow fragments, fragments of non-pillowed flows, pillow breccias, bombs, tuffs, ash, and unsorted tephra. The rocks are mainly alkali olivine basalts, accompanied by a few intermediate rocks which are believed to have been derived by differentiation of the basaltic magma.
Slope Asymmetry of the Beaufort Plain, Northwest Banks Island, N.W.T., Canada
Authors: French H. M.
Published: April 2011

The Beaufort Plain of northwest Banks Island is currently being dissected by a series of valleys which portray a striking asymmetry of their slopes. In most valleys aligned in a direction northwest southeast, the steeper slope faces towards the southwest. The importance of both fluvial and degradational processes is stressed in the interpretation of these valleys. The asymmetry is the result of differing microclimates existing upon differently exposed slopes, which favors the development of solifluction processes on the northeast facing slopes. Consequently, the stream moves laterally towards the slope producing the least colluvium. The southwest facing slope is then undercut and steepened in angle through the operation of fluviothermal erosion processes. The microclimatic differences on the two slopes can be related to the dominant westerly winds in this part of the arctic which (a) deposit snow preferentially on the lee sides of valleys during the winter and (b) promote evaporation from exposed slopes during the summer.
The Hudsonian Orogeny Near Flin Flon, Manitoba: A Tentative Interpretation of Rb/Sr and K/Ar Ages
Authors: Mukherjee A. C. , Stauffer Mel R. , Baadsgaard H.
Published: April 2011

Whole rock Rb/Sr age dating near Flin Flon, Manitoba, yields isochrons of 1775 ± 89 m.y. for the Amisk Group (mainly volcanic rocks), and 1805 ± 14 m.y. for the granodioritic Annabel Lake Pluton which intrudes the Amisk. These are considered to be emplacement ages (within their error–limits).A tentative interpretation of the Hudsonian Orogeny in this area is derived by fitting the Rb/Sr ages and previously published K/Ar ages to the sequence of events as determined from detailed structural studies. According to this interpretation, Amisk volcanism began approximately 1865 m.y. ago, and the Hudsonian Orogeny ended approximately 1800 m.y. ago.
A Permian Hydrozoan Mound, Yukon Territory
Authors: Davies G. R.
Published: April 2011

A carbonate mound built by the hydrozoan Palaeoaplysina has been found in a poorly-exposed sequence of Lower Permian rocks in the northern Richardson Mountains of the Yukon Territory. Similar hydrozoan mounds have been described from Russia and northwestern United States. The Yukon mound is 12 ft (3.7 m) thick and at least 70 ft (21 m) long. It is underlain by marine siltstones and sandstones, and probably shale. The main mound rock is composed of curved hydrozoan plates enclosed in a bioclastic wackestone matrix, and is overlain successively by tubular–foram packstone and oolitic grainstone. Palaeoaplysina is characterized by a plate-like, laterally-expanding growth form, an internal canal system, a cellular calcareous skeleton, and 'mamelons' on the upper surface of well-preserved plates; 'mamelons' are the principal criterion for placing Palaeoaplysina in the Class Hydrozoa of the coelenterates.The Yukon mound is part of a thick sequence of Lower Permian terrigenous clastic and carbonate rocks deposited on the northern shelf of the ancestral Aklavik Arch. The repetition of similar rock types in the sequence indicates cyclicity, a thesis supported by similarities between the Yukon mound sequence and the Virgilian mound cycles in New Mexico.Lower Permian hydrozoan mounds and associated facies in the Pre-urals of Russia are known oil producers. The possibility exists that hydrozoan mounds, perhaps in multiple cyclic build-ups, may occur in upper Paleozoic rocks in the subsurface of the Yukon Territory. With suitable porosity development and source rocks, these predicted subsurface mounds could become hydrocarbon reservoirs and thus targets for oil exploration.
Limnogeological Studies of the Eastern Part of the Lake Superior Basin
Authors: Mothersill John S.
Published: April 2011

The topography of the lake-bottom between St. Mary's River and Michipicoten Harbour (Lake Superior, Ontario), consists of a lake-shelf, 2 to 4 miles (3.2–6.4 km) wide, and a series of north–south aligned topographic deeps and highs, 3 to 4 miles (4.8–6.4 km) wide, lakeward. This topographical trend is in marked contrast to the east–northeast and east–southeast trends of the onshore Precambrian rocks.The Holocene sediments of the lake-bottom consist of sand, which covers the lake-shelf and topographical highs, and clay-silt which covers the topographical deeps. The sands of the lake-shelf area can be differentiated from the sands of the topographical highs on the basis of grain-size parameters and mineral composition. The clay-silt sediments of the topographical deeps form the following consistent stratigraphic sequence: an upper, thin veneer of dark yellowish brown silt; an intermediate unit of olive gray, fine-grained silt to coarse-grained clay; and a lower unit of dark yellowish brown silt. These Holocene sediments, which may range from 2 to greater than 180 cm in thickness, are underlain by varved sediments of Pleistocene age.
A Pleistocene Mountain Goat from British Columbia and Comments on the Dispersal History of Oreamnos
Authors: Harington C. R.
Published: April 2011

A mountain goat cranial fragment from gravels beneath two thick glacial tills near Quesnel Forks, British Columbia is referred to Oreamnos sp. It is considered to be of last (Sangamon) interglacial age, or older. Oreamnos seems to have entered North America from Eurasia across the Bering Isthmus during a Pleistocene glaciation prior to the last (Wisconsin) glaciation.
Geology of the Caribou Deposit, Bathurst, New Brunswick
Authors: Roscoe W. E.
Published: April 2011

The Caribou deposit occurs in a mixed volcanic–sedimentary zone which is transitional between graphitic argillite and silicic tuffaceous rocks. The silicic tuffaceous rocks form the core, and the graphitic argillite the outside, of the steeply plunging Caribou synform.The Ore Zone Unit consists of the volcanic–sedimentary transition zone and the sulfides. The Caribou deposit consists of three or more en echelon lenses of pyrite – sphalerite – galena – chalcopyrite and footwall disseminated sulfides. Sulfide zoning in the deposit indicates that the stratigraphic top is towards the silicic volcanic rocks. The deposit has a galena–sphalerite zone on the silicic volcanic side and the hangingwall contact is sharp. There is a chalcopyrite-rich zone on the sedimentary side and the contact is indistinct. Very fine spheres, cubes, and framboids of pyrite in both the deposit and the sedimentary wallrocks, as well as pyrite colloform structures in the deposit, appear to be relict primary or diagenetic structures.All the rocks, including the sulfides, have been regionally metamorphosed to lower greenschist facies and contain a pervasive slaty cleavage or schistosity, which is the earliest imprint of structural deformation. Pyrite, sphalerite, galena, chalcopyrite, arsenopyrite, quartz, stilpnomelane, and sericite are in a granoblastic intergrowth typical of metamorphosed sulfides. This early structural deformation has fractured and granulated pyrite and, to a limited extent, sphalerite; and chalcopyrite, galena, and sphalerite flowed plastically. The early slaty cleavage or schistosity has been deformed by minor structures and folded into the Caribou synform.Many features of the Caribou deposit and similarities to other volcanic-associated stratiform base metal deposits indicate a syngenetic origin involving submarine deposition of sulfides derived from volcanic, exhalative, hydrothermal solutions and possibly as pyroclastic debris.
Cretaceous Deposits in the Musquodoboit River Valley Nova Scotia
Authors: Lin Chang L.
Published: April 2011

Two carbonaceous samples recovered from pre-Pleistocene unconsolidated deposits in a borehole at Elmsvale, Musquodoboit River Valley, Nova Scotia, were dated as Early Cretaceous in age. The thickness of the deposit encountered was 551 ft (168 m). Available information suggests that the upper segment of the present Musquodoboit River was a tributary-stream of the Shubenacadie drainage system.
Some Aspects of the Morphometry of Paraglacial Alluvial Fans in South-central British Columbia
Authors: Ryder J. M.
Published: April 2011

The construction of paraglacial alluvial fans commenced during deglaciation and was dependent upon the temporary abundance of glacially formed debris. Correlation and regression analyses for five groups of fans located within the Interior valleys of south-central British Columbia, indicate that fan gradient is significantly related to the relative relief, area, height, and slope of associated basins. These factors exerted an influence upon fan geometry through processes of stream and mud-flow deposition.Paraglacial fans are distinguished from fans of arid regions by their steeper gradients and a weaker statistical relationship of fan gradient with basin parameters which is subject to greater variation between local regions. This is attributed to the plentiful supply of glacial drift and local changes in its character. Since the basins of most paraglacial fans were formed preglacially, whereas arid region fans and associated basins were formed concurrently, a weaker control of basin character upon fan geometry is to be expected for the former.
Preliminary Analysis of Geophysical Measurements North of Juan de Fuca Ridge
Authors: Srivastava S. P. , Barrett D. L. , Keen C. E. , Manchester K. S. , Shih K. G. , Tiffin D. L. , Chase R. L. , Thomlinson A. G. , Davis E. E. , Lister C. R. B.
Published: April 2011

Preliminary analyses of gravity, magnetic, seismic reflection and refraction, dredging, and heat flow measurements off Queen Charlotte Islands and Vancouver Island are presented. Seismic reflection and gravity measurements show the presence of a sedimentary basin at the foot of the continental slope in which the sediments are progressively more intensely deformed from north to south, indicating the interactions between the lithospheric plates. Heat flow values in the northern part of Explorer Ridge, and recovery of fresh basalts with little mineral coating in this region suggest that Explorer Ridge is a presently active spreading segment of East Pacific Rise. Seismic Refraction results in the deep ocean basin west of Queen Charlotte Islands show a marked anisotropic mantle P wave velocity, the direction of maximum velocity being 107° east of north and the maximum change in velocity being about 0.6 km/s.
27-Day Recurrence Phenomena in the Geomagnetic Field at Alert
Authors: Edwards R. N. , Kurtz R. D.
Published: April 2011

The temporal variations of the geomagnetic field at Alert are studied for a two-year period during a minimum of the 11-year sun-spot cycle. During this period (27 August 1962 to 21 September 1964), a recurrent geomagnetic storm is observed, persisting for 29 solar rotations. It produces lines in the geomagnetic power spectrum at frequencies corresponding to the harmonics of 27 days. A further 13 lines, equispaced in frequency by (1/27) cycles/day, are associated with sidebands of the daily line and are believed to result from amplitude modulation of the SqP/DS current system.
Sulfur Isotope Partitioning in Metallic Sulfide Systems
Authors: Kajiwara Y. , Krouse H. R.
Published: April 2011

Sulfur isotopic fractionation factors involving pairs of pyrite, pyrrhotite, sphalerite, chalcopyrite, and galena have been determined experimentally over the temperature range 250 °C to 600 °C.Since chalcopyrite and pyrrhotite are not stable at higher PS2 conditions, buffer assemblages were necessary to control PS2 in experiments with these minerals. Since low PS2 values and low temperatures are unfavorable to rapid isotope exchange, techniques were devised whereby equilibrium constants could be estimated indirectly in systems where direct measurements are not possible because of the time factor.Current data place the sulfide minerals in the following order of 34S enrichment under equilibrium exchange conditions: pyrite > (pyrrhotite [Formula: see text]sphalerite) > chalcopyrite > galena in agreement with theoretical predictions. In agreement with theory the equilibrium exchange constant K for a given mineral pair depends upon temperature as follows: 1000 ln [Formula: see text], where A denotes a constant. The A values for various mineral pairs have been determined with ± 10% uncertainties as follows: 11.0 × 105 (py–gn), 8.0 × 105 (sp–gn), 6.5 × 105 (cp–gn), 4.5 × 105 (py–cp), 3.0 × 105 (py–sp, py–po), 1.5 × 105 (sp–cp, po–cp), and [Formula: see text] 0 (sp–po).
Geology of the Crater Lake Collapse Structure in Southeastern Saskatchewan
Authors: Christiansen E. A.
Published: April 2011

The Crater Lake depression is the surface expression of the Crater Lake collapse structure. The structure comprises 2 main concentric fault zones forming an inner and outer cylinder of collapse beneath Crater Lake. The inner cylinder, which is about 300 ft (~100 m) in diameter, was down faulted about 140 ft (~43 m) in Late Cretaceous – Tertiary – Early Pleistocene time and the outer cylinder, which is about 700 ft (~213 m) in diameter, was downfaulted 50 to 100 ft (15 – 30 m) during the last deglaciation about 13 600 years ago. The Crater Lake structure was formed presumably by collapse as a result of the removal of salt from the Prairie Evaporite Formation by groundwater.