Data on 75 species from 124 quadrats collected from the intertidal and subtidal regions in the Flat Top Islands area of Georgia Strait in late spring to early autumn, 1972, were subjected to a number of community analysis techniques including a Williams and Lambert association analysis, a species constellation diagram, a cluster analysis of quadrats, an inverse analysis of species, a Zurich-Montpellier analysis, and a Bray and Curtis ordination. Association analysis and cluster analysis classification of quadrats delimited four communities: an intertidal, an upper subtidal, a lower subtidal, and a sandy bottom community. Species constellation diagram and inverse analysis classification of species delimited six communities: an intertidal, a shallow red algal, a laminarian, a turf, a deep water, and a sandy-bottom community. The Zurich-Montpellier analysis and the Bray and Curtis ordination did not produce clearly definable groups of quadrats. The results of all the analyses indicate that marine benthic algae form broadly overlapping distributions from which communities of varying affinities can be extracted. / Science, Faculty of / Botany, Department of / Graduate

Approximately 790 kilometers of continuous seismic reflection data were obtained with a 5000 joule Sparker in the Strait of Georgia, southwestern British Columbia. The Strait is a geological boundary between Upper Cretaceous Nanaimo Group rocks of the Vancouver Island area and Late Cretaceous-Early Tertiary continental rocks found in scattered outcrops on the southern mainland. Coast Intrusives form mountains on the mainland northeast of the Strait. The Fraser River has built a large submarine delta across the Strait and is the main source of Recent sediments. Deposition is occurring mainly on the delta front and in deep basins to the northwest. In the basin adjacent to the delta, flat-lying bottomset beds average about 200 meters in thickness. An older layer of bottomset beds in this basin overlies bedrock and extends under the present foreset beds. Thinner sedimentary layers of possible hemipelagic origin overlie Pleistocene banks and ridges along the mainland north of the delta. No significant amounts of Recent sediment are presently accumulating in the Strait south of the delta. Erosion of possible Late Pleistocene deltaic sediments has deepened the Strait in that area. Pleistocene deposits of probable drift, till and interglacial sediments occur mainly along the northeast side of the Strait. One extensive stratified deposit, possibly correlated with exposed Pleistocene deposits on nearby shorelines, may reach 550 meters in thickness. Below the Pleistocene, stratified reflectors, suspected to be Late Cretaceous-Early Tertiary bedrock, unconformably overlie Coast Intrusive bedrock along the mainland shore. The reflectors dip seaward at 8 degrees or more. Along the southwest Island coast Upper Cretaceous bedrock dips into the Strait. Deformation, most severe in the south, decreases northward. Dips of bedrock reflectors become less in mid-Strait before disappearing under delta deposits toward the mainland. Some synclinal and anticlinal folding occurs near mid-Strait. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

A mixing budget for the Strait of Georgia was prepared summarizing mixing processes and effects upon the physical oceanography of the strait. A mixing budget was defined as an itemized estimate of mixing mechanisms and the total state of mixing in the strait. Mixing effects in the Strait of Georgia were estimated from hydrographic data and from monthly summaries of meteorological data for four months: February, May, August and November of 1968. Mixing was estimated qualitatively by depth-averaging temperature, salinity, density and oxygen concentrations for four representative layers, each 25 metres thick and by producing contour plots for each variable for the layers (two upper layers, an intermediate layer and a deep layer). Quantitative estimates of mixing were made by computing the potential energy density and the energy density needed for total mixing for the representative layers plus the potential energy density of total stratification (a fresh water layer over a layer with oceanic salinity). Changes in potential energy were due to mixing plus advection. Estimates of the energy available for mixing were made for the different mixing mechanisms acting upon the strait: wind mixing, buoyancy flux (convection) mixing, tidal mixing, mixing by internal waves and entrainment mixing. The Strait of Georgia has three different domains which are influenced by different mixing mechanisms: the southern passages, the upper layers of the northern strait and the deep waters. The southern passages (including the San Juan Archipelago and Haro and Rosario Straits) are the site of intensive tidal mixing which keeps the entire water column well mixed} convection and wind mixing are also important during the winter. The upper layers of the northern strait (north of Boundary Pas sage) are well mixed by the wind in the winter and by the wind and convection in the autumn. The uppermost brackish layer is highly stratified in the spring and summer from the effects of surface heating and fresh water runoff; intermediate layers are mixed by entrainment upwelling. The deep waters of the strait are influenced chiefly by advection processes: estuarine flow and seasonal intrusions of new water masses. In the winter, cold low-salinity water intrudes and displaces the warm water left from the previous summer while in the summer, warm saline water replaces the cold winter water. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

No description available.