Cariboo Region Research Articles

CHROMIAN SPINEL FROM PGE-BEARING PLACER DEPOSITS, BRITISH COLUMBIA, CANADA: MINERALOGICAL ASSOCIATIONS AND PROVENANCE

We report results of electron-microprobe analyses for detrital grains of chromian spinel ( n ≈ 800) and associated minerals recovered from modern fluvial and buried paleochannel (Pt–)Au placer deposits ( n = 30) of mostly Holocene age distributed throughout British Columbia. The majority of analyzed spinel-group minerals are members of the chromite–magnesiochromite solid-solution series, and extend to Fe 3+ -rich compositions of chromian spinel. The values of mg# [100Mg/(Mg + Fe 2+ )] and cr# [100Cr/(Cr + Al)] in grains from all 30 placer samples occupy a relatively narrow range, 58–82 and 68–92, respectively, consistent with a mafic to ultramafic source. Four types of core-to-rim patterns of zoning have been identified: 1) a weak decrease in Cr coupled with a strong decrease in mg# at typically constant cr# and fe 3+ #, as a result of limited chromian spinel – liquid fractionation and subsolidus Fe 2+ –Mg exchange with ferromagnesian silicates; 2) a sharp decrease in Cr and cr# and increase in fe 3+ # [100Fe 3+ /(Al + Cr + Fe 3+ )] with limited decrease in mg#, reflecting magmatic fractionation; 3) a significant increase in Cr and cr# with weak to strong decrease in mg#, reflecting late-stage interaction with a Cr-rich magma followed by variable enrichment in Fe 2+ during cooling; and 4) a strong decrease in Cr and cr# with a small increase in mg# and fe 3+ #, likely due to interaction with a more oxidized melt and subsolidus re-equilibration with an aluminous phase (Al-rich residual liquid or amphibole). Values of mg# in placer silicate grains (olivine, clinopyroxene, either Na–Al-poor or Na–Al–Ti-rich, rare aluminous orthopyroxene, edenitic amphibole, among others) and in micro-inclusions in chromian spinel attain 90–95. We evaluated the provenance of chromian spinel grains in the placers using the global spinel database and a new one focusing on Alaskan-type intrusions. Chromian spinel in the Atlin area and a majority of Dease Lake placers exhibits a pronounced Cr–Al trend indicative of an ophiolitic affinity (Slide Mountain and Cache Creek oceanic terranes). In certain placers in the Tulameen area, the chromian spinel defines a Cr–Fe 3+ trend indicating derivation from the Tulameen Alaskan-type intrusion in the Quesnellia island-arc terrane. Placer deposits in central British Columbia (Manson Creek – Cariboo region) display a mixed heritage involving both ophiolitic and Alaskan-type sources. The recognition of an Alaskan-type mafic to ultramafic source for some of the Cr–PGE-bearing placers in central British Columbia underscores the potential for bedrock mineralization in an area where such intrusions are presently poorly represented.

Use of Airborne Gamma Radiometrics to Infer Soil Properties for a Forested Area in British Columbia, Canada

We obtained radiometric data from a public-domain archive maintained by Natural Resources Canada and processed them to produce a ternary image for a portion of the Cariboo region. A field program was used to evaluate what information could be reliably inferred from the available data. This initial investigation confirmed that the radiometrics for this area exhibited consistent and useful patterns to interpret the lithology, mineralogy, depth, and moisture status of the surficial materials. Different colour patterns in the ternary image correlated well with different compositions of the various tills. We noted a clear association between higher values of radioactive emission and more recently deposited aeolian, alluvial, and glaciofluvial sediments that contained higher concentrations of relatively unweathered minerals. We observed a clear pattern of lower emission from wetlands and areas of wet soil. Airborne radiometrics, even at 500-m line spacing, provided invaluable and precise information—not otherwise obtainable—for mapping or modelling spatial variation in properties of the surficial material within the forested study area in British Columbia. We recommend further investigations to develop operational procedures for the use of such data in mapping surficial materials.

There's more to landscape than meets the eye: towards inclusive landscape assessment in resource and environmental management

Consideration of aesthetic values in resource and environmental management in North America emerged in the 1960s. It soon became enshrined as ‘visual resource management’, which emphasized a singular visual notion of aesthetics and an expert‐based approach to assessment. This paper challenges this dominant view. An empirical research study is presented in which a broader conceptualization of the landscape aesthetic and a participatory methodology for assessment were developed and used to explore the landscape experiences of inhabitants of the Cariboo region of British Columbia. Themes, categories and ideas of landscape experience grounded in participant perspectives revealed a richness of landscape and can be seen as an opportunity to supplement and enrich current landscape assessment and ‘visual’ management. More importantly, this conceptual and methodological reorientation in understanding landscape aesthetic sensibilities both reflects and supports the shift in current thinking within resource and environmental management more generally, from technocratic, state‐centred, expert‐based approaches to locally responsive (place‐based), participatory and inclusive approaches for dealing with environmental concerns and resource‐development issues.

Influence of feeding damage by small mammals on tree growth and wood quality in young lodgepole pine

This study assessed the impact of feeding injuries by snowshoe hare (Lepusamericanus Erxleben) and red squirrel (Tamiasciurushudsonicus Erxleben) on diameter growth, height growth, and wood quality of juvenile lodgepole pine (Pinuscontorta Dougl. var latifolia Engelm.) at Prince George and in the Cariboo Region, British Columbia. In the Prince George control stand, severe girdling damage (50–99% stem circumference) suppressed diameter and height growth of small-diameter (4.1–6.0 cm) trees, but had no effect on larger stems (6.1–8.0 cm). In the spaced stand, diameter and height increments also declined significantly with degree of partial girdling, particularly in small-diameter (3.1–5.0 cm) trees. Paradoxically, diameter increment increased significantly with degree of partial girdling in both stands at the Cariboo study area. Presumably squirrels prefer to feed on vigorous stems, and the lost growth of these trees may be substantial. There was no significant difference in amount of compression wood nor total solvent and water extractives between undamaged and damaged trees. Fiber lengths in wound-associated wood were consistently 19–21% lower than in controls. Damaged trees had greater average ring width and density than undamaged trees. The average increase in relative density of damaged over undamaged trees was 0.0343. These results suggest that a severe degree of partial girdling (which likely occurs more often in small-diameter trees) may significantly affect growth of lodgepole pine, particularly small (<5.0 cm DBH) trees.

Impact of red squirrel feeding damage on spaced stands of lodgepole pine in the Cariboo Region of British Columbia

This study measured the impact of red squirrel (Tamiasciurushudsonicus Erxleben) feeding damage on spaced stands of lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) in the Cariboo Forest Region of British Columbia. A limited regional assessment of animal damage in spaced stands indicated that squirrels were the most important small mammal damage agents and that lodgepole pine was the only tree species susceptible to squirrel feeding (bark and vascular tissues) injuries. Intensive assessment of damage in two stands showed that squirrel attack was significantly greater among large- (>60 mm dbh) than small-diameter stems. Significantly more spaced than control (unspaced) crop trees were attacked. There was a general decline in the proportion of trees wounded from 1980 to 1985. Some damaged trees grew faster in diameter than undamaged trees of the same size. However, at one study area, damaged trees showed faster radial growth than undamaged trees before and after squirrel attack. Squirrels appear to prefer feeding on vigorous stems and the lost growth of these trees may be substantial. Height growth of damaged trees was significantly reduced in one stand in the years following squirrel damage. Some limit to a tree's capacity to sustain damage, beyond which mortality is inevitable, seems likely. Impact of damage to spaced stands may be minimized by delaying spacing in susceptible areas or by increasing the prescribed number of stems remaining after spacing to compensate for expected mortality and severe damage.

Relationship between spacing and nitrogen fertilization of seedlings in the nursery, seedling size, and outplanting performance

Nursery sowings of coastal and interior varieties of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), Sitka spruce (Piceasitchensis (Bong) Carr), and lodgepole pine (Pinuscontorta Dougl.) were thinned to different spacings 5 weeks after germination. Spacings in the drills, which were 15 cm apart, were 1, 2, 4, 8, and 12 cm, with the nursery sowing rate (about 0.6-cm spacing) as control. Spacings were applied factorially with three levels of N fertilizer: 60, 140, and 235 kg N ha−1. Two-year-old seedlings were planted out at Campbell River (coastal Douglas-fir) and Port Alice (Sitka spruce), both on Vancouver Island, and at Lyne Creek (interior Douglas-fir) in the Cariboo region and at Fulton Lake (lodgepole pine) in the Prince Rupert region of British Columbia. Wider spacing and greater N supply increased 2-0 seedling dry weight, root-collar diameter, and shoot height and also affected distribution of dry matter between needles, stems, and roots. Wider spacing increased survival of outplanted interior Douglas-fir by 12%. Survival of coastal Douglas-fir and Sitka spruce species was high and only increased 4 to 7% due to wide spacing after one season, but after three seasons wide spacing increased survival 17 – 19%. Compared with control, 12-cm spacing increased first-season shoot growth 53% for coastal Douglas-fir, 82% for interior Douglas-fir, and 71% for Sitka spruce. Second-season shoot growth of lodgepole pine was increased 92% by the widest spacing. Much of the improved growth was explained in terms of increased seedling size. At the highest level of N supply, increasing spacing to 4 cm did not greatly reduce yield of seedlings with root-collar diameters greater than 3 mm, except for interior Douglas-fir. Thus moderate increase in spacing improved quality without materially reducing yield of seedlings per unit area of nursery. Nursery fertilization at 235 kg N ha−1 increased new-shoot growth one season after planting by 36–58% compared with the 60 kg N ha−1 level. After three seasons the effect of higher N supply was reduced to 0–42%. High N level increased survival of coastal Douglas-fir and Sitka spruce slightly, but decreased survival of interior Douglas-fir.

The Petrology of Late Tertiary Dolerite Plugs in the South Cariboo Region, British Columbia

The petrology of four plugs of fresh, coarse-grained olivine dolerite, of Pliocene age, is described in this paper. Two plugs, which exhibit textural and mineralogical variations, are described in detail. Major element analyses and selected trace element analyses for fifteen samples illustrate the chemical nature of the dolerite as well as fractionation in small marginal portions of the plugs. Strontium isotope values indicate that the plugs represent basaltic magma that was not contaminated by crastal matter. Both the mineralogy and the chemistry of the plugs indicate that the magma was mildly alkaline, and suggest that it was a differentiate of a primary olivine basalt magma, perhaps derived through crystal fractionation in a high-level magma chamber.

Beef Production on Lodgepole Pine-Pinegrass Range in the Cariboo Region of British Columbia

Results from the Cariboo grazing trail confirm those from previous ones on lodgepole pine-pinegrass summer range near Kamloops. They also suggest that similar results could be expected in other regions with ecologically similar sites. Yearling steers in the Cariboo district had a 3-year average daily gain of 1.74 lb. for 97 days starting in early June. The average gain per acre was 17.8 lb. The average carrying capacity was 4.6 acres/animal unit month.

Potassium–argon ages of dolerite plugs in the South Cariboo region, British Columbia

Potassium–argon dates for late Tertiary dolerite plugs in south-central British Columbia indicate that a period of volcanism occurred in mid-Pliocene time.

Paleomagnetism of four late Miocene gabbroic plugs in south-central British Columbia

A paleomagnetic study was made of 101 cores from 20 sites representing about equally 4 small olivine gabbro plugs which intrude tectonically undisturbed olivine-rich plateau basalts of late Miocene age in the southern Cariboo region of south-central British Columbia. After alternating-field cleaning, statistical analysis of the stable remanence indicates that the site mean directions are significantly distinct within each plug so that even such small intrusive bodies (250–800 ft (78–248 m) in diameter) must be thoroughly sampled to derive a representative mean remanence direction. Both Tin Cup Mountain and Lone Butte plugs have normally polarized remanence, whereas Mount Begbie and Forestry Hill plugs have reversely polarized remanence. Statistical analysis indicates that these plugs were emplaced over a short span of geologic time of possibly less than 1 × 106 years and that at least three polarity intervals are represented. The geomagnetic pole position computed from the normalized site mean directions is 146.7 °W, 84.9 °N (δp = 4.8°, δm = 5.5°). This pole position is almost coincident with the pole position determined for the surrounding plateau basalts, and it is consistent with those obtained from other Miocene formations. These results support the hypothesis that the plugs represent the original volcanic vents from which the plateau basalts were extruded.

DERMEA PSEUDOTSUGAE N. SP., A CAUSAL AGENT OF PHLOEM NECROSIS IN DOUGLAS FIR

A new species of Dermea is described. The fungus was associated with extensive damage to young Douglas fir (P seudotsuga menziesii) following severe early frosts in the Cariboo Region of British Columbia. Inoculation tests proved the fungus was capable of invading bark wounds and causing necrosis. Life history and cultural characteristics of the fungus are presented. The development of the disease is described and discussed.

Rules of A Chinese secret society in British Columbia

The body of rules translated below was first discovered by a Park Ranger employed to restore the erstwhile gold-mining town of Barkerville, British Columbia, as an historical monument. Searching for authentic artefacts in an abandoned ‘Chinese Frėemason’ hall in the neighbouring town of Quesnel Forks, he came upon some tattered ceremonial robes, a Chinese book of codes and signs, and a board approximately 10 feet in length inscribed with Chinese characters. These (with some other items) were stored by the ranger at Barkerville, in a box marked ‘unidentified materials’, which was found by the authors in the summer of 1961, while carrying out field research on Chinese social organization in the Cariboo region of British Columbia. Mr. Ho identified the calligraphy on the board as a set of rules of the Chih-kung T'ang.

STUDIES OF WATERFOWL IN BRITISH COLUMBIA: PINTAIL

Dafila acuta is an abundant transient through British Columbia following routes along the outer coast, the inner coast, and the main north and south river systems of the interior. The spring migration takes place during March and April and is not protracted but the autumn migration is one of successive movements from mid-August to early December. The largest flight sometimes appears on the mainland coast in late October. Both northbound and southbound flocks concentrate on the Coastal Plain. The chief wintering grounds are in western Oregon and in California, the most densely populated nesting grounds in Alaska. Recoveries of banded birds have verified observational migration data and have shown also that many individuals use the same route in successive years, some arriving at a given point on approximately the same date. In British Columbia the principal nesting ground is the parklands of the Cariboo region and the peak of the spring migration is in late March or early April. Following its conclusion the residual population is scattered over a wide area characterized by grassland and many types of ponds and sloughs. Courtship is at its height in April and laying commences in May. Nest sites usually are dry and may be several hundred yards from the nearest water. The majority of young appear in June and are led by the females to meadows and marshes provided with adequate cover. The females remain with the brood and actively defend them during adolescence. Males leave the females when incubation begins and gather in small bands on water adjacent to the nesting grounds. Many migrate in advance of the flightless period. Downy young feed largely on the larvae of aquatic insects. The most important item in the diet of adults during autumn and winter is seeds of various meadow and aquatic plants. On the coast this element is characterized by Polygonaceae and Scirpus americanus, in the interior by Potamogetons and Scirpus acutus. Insects and animal matter generally constitute a less important food. The pintail is second to the mallard, Anas platyrhynchos, in economic importance and like it is a source of revenue to the Province. On the debit side the pintail causes some loss to agriculture by eating forage crops but this is not extensive and is amenable to control.

THE ARGYNNIDS OF THE CARIBOO REGION OF BRITISH COLUMBIA (LEPID.)

The Cariboo region comprises that section of Central British Columbia between the Fraser river and the mountains of the N. Thompson river, extending northward from Clinton to Quesnel; through it the old Cariboo trail (now a motor road) passes and railway communication with the south is afforded by the P. G. & E. Ry. Its altitude is around 2500 ft. and it consists largely of rolling, wooded country interspersed with numerous lakes; in the southwest in the vicinity of Jesmond, Mt. Bowman, a northern spur of the mountains back of Lillooet, rises to a height of about 7500 ft. The summer rainfall is slight, and the area belongs in the so-called “dry belt”.

Studies of Waterfowl in the Cariboo Region, British Columbia

Studies of Waterfowl in the Cariboo Region, British Columbia

Nesting of the Bonaparte Gull in British Columbia

The Bonaparte Gull (Larus philadelphia) has been definitely recorded as nesting at Atlin Lake in extreme northwestern British Columbia (Brooks and Swarth, Pac. Coast Avifauna No. 17, 1925, p. 28). These authors refer also to reported nesting colonies at Fort St. James and at Moorehead Lake in the Cariboo region, the latter reference being based on evidence submitted by local residents and observations, by the senior author, of small flocks of adult Bonaparte Gulls flying directly toward this lake after fishing in lakes some twelve miles to the southwest. This was in July, 1901. Apparently these are the only references in literature to the species nesting in British Columbia. Consequently the discovery on June 24, 1935, of a small nesting colony at Bridge Lake in the Cariboo region is considered of sufficient interest to place on record. The location and topography of Bridge Lake is set forth in an article describing a Herring Gull colony at .that place. (See Munro, Condor, 37, 1935, pp. 214-215.) It was following a visit to this Herring Gull colony, and while returning to shore, that the presence of Bonaparte Gulls was detected through seeing a single individual of this species fly toward a small wooded island situated about half way between the gull rock and the mainland. While I was proceeding toward this island and was distant from it about 150 yards, two adult Bonaparte Gulls flew toward the boat, and after circling over, and swooping down several times, alighted on the water alongside. These were photographed at a distance of twelve feet. The two birds followed the boat with short flights, descending on the water between times, and became increasingly excited as the wooded shores were neared. The reason became apparent when two downy young were discovered swimming in and out among the flooded brush along the shore. These were captured without difficulty and proved to be approximately a week old, with sheathed primaries showing about threequarters of an inch beyond the down. Meanwhile the two adults, sometimes accompanied by a third, either circled overhead or stood on a dead branch of a birch tree which extended over the water