The Bruce Peninsula, a carbonate bedrock escarpment, lies "downflow" from a sculpted bedrock terrain at the French River. The sculpted forms are attributed to a hypothesis of erosion by regional-scale, subglacial meltwater flooding. This paper presents new data from the Bruce Peninsula that tests the meltwater outburst hypothesis in a downflow direction of the predicted flood path. The bedrock surface of the Bruce Peninsula shows extensive development of sculpted features that bear a striking resemblance to s-forms at the mouth of the French River. They are self-similar and hierarchical in scale, ranging in dimensions from a few centimetres to several kilometres. Remarkable concentrations of potholes are located near the brow of the escarpment. The Bruce Peninsula lacks a pervasive cover of unconsolidated sediment. What little sediment exists has been modified into long, narrow drumlins. The Niagara Escarpment on the peninsula has been back wasted into the edge of the Paleozoic Michigan Basin. Along its east-facing slope, the escarpment is marked by more overdeepened reentrant valleys and intervening promontories than is normal for the rest of the escarpment. Clusters of rounded, percussion-marked boulders of exotic origin are concentrated at the heads of the reentrant valleys. Taken together, these features are inferred to support the hypothesis that subglacial outburst floods beneath the Laurentide ice sheet crossed Georgian Bay and strongly sculpted the Bruce Peninsula. The consistent orientation of the reentrant valleys, aligned with the French River sculpting across the basin to the northeast, and the backwasting of its caprock attest to the power and directional stability of the sheetfloods.

On the basis of vegetational physiognomy, 47 sites within 1 to 43 km of the southern James Bay coast were classified in the field into four fen types: graminoid, low shrub, graminoid-rich treed, and sphagnum-rich treed. The four types are directly related to differences in vegetational cover and in soil and water parameters, specifically depth to water level, peat thickness, selected groundwater nutrients, and distance from the coast. Detrended correspondence analysis was used to ordinate the vegetational cover of the fen sites. No one or two of the 16 soil and water parameters obtained in this study could be used to discriminate conclusively among fen types. Linear discriminant function (LDF) analysis, however, indicated that the better discriminators were pH, peat thickness, SO4−, K+, and depth to water level. When all water and soil parameters were used, regrouping by LDF analysis into the four a priori groups was achieved with 78% accuracy. Canonical analysis also showed separations when soil and water parameters for sites were plotted in two dimensions. Because of isostatic rebound, distance from the coast represents a temporal as well as a spatial gradient. Peat depth in the fens increases with distance from the coast, at a mean rate of 4.7 cm for each kilometre inland. Na+ plus Cl− in the groundwater of the fens decreases asymptotically with increasing distance from the coast.

Surface and subsurface waters on the Bruce Peninsula, Ontario, were sampled and analysed for Ca2+, Mg2+, pH, HCO3−; partial pressure of CO2(PCO2), and saturation states with respect to calcite (SIc) and dolomite (SId) were calculated. A total of 250 samples representing six hydrochemical environments were collected. These environments are (1) Georgian Bay and Lake Huron, (2) inland lakes, (3) rivers and streams, (4) wetlands, (5) conduit-flow springs, and (6) diffuse-flow springs. The seasonal behaviour and chemical separation of these waters are examined.Except for Georgian Bay and Lake Huron the waters of the peninsula are very hard, ranging from 180–320 ppm Ca2+ plus Mg2+ (as CaCO3), and display increasing hardness as the summer season progresses. Surface recharge and conduit-flow springs are generally saturated with respect to calcite and dolomite. Only diffuse-flow springs, which are among the hardest of waters, are commonly undersaturated. These waters are also the easiest to distinguish chemically and results of a linear discriminant function analysis suggest other waters of the peninsula to be of one class.

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The occurrence of abandoned shoreline bedrock erosional features at the edge of the Niagara Escarpment at Cabot Head indicates the existence of a group of islands in glacial Lake Algonquin during early postglacial time, referred to herein as the Cabot Head Archipelago. The abandoned shoreline features are situated as much as 80 m above the level of contemporary Georgian Bay. The range of abandoned shoreline bedrock erosional features, including shoreline cliffs, adjacent wave-cut platforms, wave-cut notches, shore stacks, shore caves, and other features, are described. The occurrence of these features is thought to be the result of the interaction between wave action in glacial Lake Algonquin and two distinct lithological facies representing the Wiarton -Colpoy Bay and Lions Head members of the Amabel Formation. The exceptional development of the abandoned shoreline bedrock erosional features in massive reefal dolostone between elevations of ∼250 and 255 m above sea level (asl) is interpreted as representing the relatively long-lived and stable Main stage of glacial Lake Algonquin (∼11 000-10 200 years BP). Shoreline erosional forms at elevations between ∼240 and 250 m asl may be indicative of declining lake levels partially controlled by bedrock structural factors. The final abandonment of the glacial Lake Algonquin shoreline in this area occurred when the eastern outlets of the lake became ice-free and its level dropped rapidly some 10 200 years BP. The Cabot Head Archipelago and the associated suite of raised and abandoned shoreline bedrock erosional features represent a rare assemblage of landforms within the Great Lakes basin, and possibly within Canada.Résumé : La présence de lignes de plages abandonnées et les caractéristiques d'érosion du socle à la bordure de l'Escarpement du Niagara à Cabot Head indiquent l'existence, au début de l'ère postglaciaire, d'un groupe d'îles dans le lac glaciaire Algonquin; ce groupe sera appelé ici l'archipel de Cabot Head. Les caractéristiques des lignes de plages abandonnées sont situées à des élévations pouvant atteindre 80 m au-dessus du niveau contemporain de la baie Georgienne. L'étendue de lignes de plages abandonnées, les caractéristiques d'érosion du socle, incluant les falaises littorales, les plateformes adjacentes érodées par les vagues, les encoches, les piliers sur les plages, les grottes et d'autres caractéristiques sont décrites. La pré-sence de ces caractéristiques serait le résultat de l'interaction entre l'activité des vagues dans le lac glaciaire Algonquin et deux faciès lithologiques distincts représentant les membres Wiarton -Colpoy Bay et Lions Head de la Formation d'Amabel. Le développement exceptionnel des caractéristiques d'érosion des plages abandonnées dans la dolomie récifale entre les élévations d'environ 250 et 255 m au-dessus du niveau de la mer suggère qu'elles aient été formées durant l'étage Main, stable et de longue durée, du lac glaciaire Algonquin (environ 11 000 à 10 200 ans avant le présent). Les formes d'érosion littorale à des élévat...

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