Late Pleistocene Glacial Erosion Along the Niagara Escarpment of Southern Ontario

Straw, Allan

doi:10.1130/0016-7606(1968)79[889:lpgeat]2.0.co;2

Cited by 31 publications

(15 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2) who describe 'escarpment noses' along the north shore of eastern Lake Ontario and also submerged in the same region. Otherwise no very large scale forms have yet been recognized in the literature, with exception of the large re-entrant valleys, such as the Short Hills re-entrant west of St. Catharines and the Dundas Valley re-entrant, which are attributed primarily to ice-gouging by through flowing high velocity ice streams (Straw, 1968). Straw payed little attention to the headlands, which he termed 'promontories', separating the re-entrants, although on his Figure 8 they are highlighted to display a rounded appearance facing up-flow, and he identified Coffin Hill on the south side of Owen Sound, amongst others, as a 'huge rock drumlin'.…”

Section: Bedrock and Glacial Geologymentioning

confidence: 99%

“…We are not aware of any distinct break in the spectrum of forms and it is our belief that the forms are essentially selfsimilar from the size of centimetre wide obstacle marks at least up to the size of the 'promontories' described by Straw (1968) north of Hamilton which can be kilometres wide, and tens of metres high. Essentially the same point was made by Shaw and Sharpe (1987b) in discussing an erosional origin for drumlins, some of which were rock cored.…”

Section: Scale Of Formsmentioning

confidence: 99%

“…However, if the extension of the scale range to include large kilometre scale promontories, and their concomitant reentrants, along the Niagara Escarpment is accepted then some difficulties are posed. Straw (1968) maps the re-entrants and the implied ice-flow direction as far north as Cabot Head. Only in the Beaver Valley and Blue Mountain area is there any sign of a discontinuity in the regional flow direction (towards a more northerly flow).…”

Section: The Algonquin and Ontarian Eventsmentioning

confidence: 99%

See 2 more Smart Citations

Sculpted Bedrock Forms along the Niagara Escarpment, Niagara Peninsula, Ontario

Tinkler¹,

Stenson²

2007

gpq

View full text Add to dashboard Cite

Assemblages of subglacial sculpted bedrock forms (p-forms; Dahl, 1965) are identified on resistant units of the Niagara Escarpment in the Niagara Peninsula, and on the Onondaga Escarpment. The scale of the features is much larger than previously recorded for bedrock glacial features in the Peninsula (Feenstra, 1981) and we suggest that there is a continuous spectrum of forms from small obstacle marks with dimensions of a few centimetres, through ridges and furrows measured in tens of metres, to promontories on the order of kilometres. Such assemblages comprise fluted surfaces with a consistent orientation between N40E and N45E, and which show very little variation within a site. Mapping the features has increased our awareness of their extent, and of the problems they pose for mechanisms proposed to explain them. The morphometry of the forms is similar to that described elsewhere, and the irregular edge of the Niagara Escarpment to oncoming flows is thought to be responsible for the prominent features described. The apparent removal of substantial bedrock blocks implies flow velocity well in excess of 3 m/s. Therefore the sculpting of the forms is attributed to fast flowing subglacial meltwater which may have had a discharge of the magnitude of 2.1 x 106 cumecs.On a identifié des ensembles de formes sous-glaciaires sculptées dans la roche en place (p-forms) dans des unités de roches résistantes de l'escarpement du Niagara et de l'escarpement d'Onondaga. L'échelle de ces formes est beaucoup plus grande que ce qu'on a déjà rapporté sur les formes glaciaires dans la roche en place de l'escarpement (Feenstra, 1981); nous croyons que ces formes existent dans toutes les tailles, à partir des simples marques de quelques centimètres en passant par des crêtes et des entailles décamétriques, jusqu'aux promontoires de l'ordre du kilomètre. De tels ensembles comprennent des surfaces cannelées dont l'orientation préférentielle se situe entre N40E et N45E et qui montre très peu de variation à l'intérieur d'un même site. La cartographie de ces formes a permis de se rendre compte de leur grande étendue et des difficultés de comprendre les mécanismes qui en sont à l'origine. La morphométrie des formes est semblable à ce que l'on a déjà décrit; on croit que la forme irrégulière du rebord qu'oppose l'escarpement du Niagara aux écoulements est responsable pour les formes remarquables décrites. L'enlèvement apparent de gros blocs de roche en place suppose des vitesses d'écoulement de plus de 3 m/s. Conséquemment, la sculpture des formes est attribuée à une eau de fusion sousglaciaire très rapide qui a pu avoir un débit de l'ordre de 2,1 x 10em3/s

show abstract

Section: Bedrock and Glacial Geologymentioning

confidence: 99%

Section: Scale Of Formsmentioning

confidence: 99%

Section: The Algonquin and Ontarian Eventsmentioning

confidence: 99%

See 1 more Smart Citation

Sculpted Bedrock Forms along the Niagara Escarpment, Niagara Peninsula, Ontario

Tinkler¹,

Stenson²

2007

gpq

View full text Add to dashboard Cite

show abstract

“…Gao (2011) alternatively favoured varying degrees of glacial and subglacial meltwater modification of a preglacial landscape for the development of the bedrock valley system in southern Ontario with some of the deep, gorge-like features in the interlake zone being interpreted as tunnel valleys and the re-entrant valleys along the Niagara Escarpment and broad, trough-like depressions such as the Laurentian Valley being formed by multiple cycles of glacial erosion possibly enhanced by subglacial meltwater activity. Many workers, including us, however, favour a polygenetic origin for the valley network invoking numerous cycles of glacial modification of a preglacial drainage system that may, in part, be controlled by structurally controlled joint sets and deep-seated terrane boundaries in the underlying Precambrian basement (Straw 1968;White and Karrow 1971;Karrow 1973;Eyles et al 1997;Edgecombe 1999;Sharpe et al 2013). Mechanical erosion by glacial ice may have served to modify the preexisting valley system, in places deepening and widening the bedrock valley.…”

Section: Discussionmentioning

confidence: 99%

“…1) (e.g., Spencer 1890;Straw 1968;White and Karrow 1971;Flint and Lolcama 1985;Eyles et al 1993Eyles et al , 1997Gao 2011). Early conceptualizations envisioned this valley as part of a large preglacial drainage system centred over the Great Lakes basins (Fig.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the groundwater resource potential of the Dundas buried bedrock valley, southwestern Ontario: an integrated geological and hydrogeological case study

et al. 2018

View full text Add to dashboard Cite

Population growth in the groundwater-dependent municipalities of southwestern Ontario has prompted interest in the exploration for new, previously untapped, groundwater resources. In this study, the groundwater resource potential of the sediments infilling a deeply buried bedrock valley network centred beneath the Region of Waterloo and the counties of Brant and Hamilton-Wentworth are explored. The objectives of this study are to further refine valley location and geometry, understand infilling sediments and their hydrogeological properties, and characterize waters contained within the aquifers to inform future water management decisions. Results of a regional ground gravity survey were instrumental in locating buried bedrock valleys and guided follow-up drilling. Continuous sediment coring and monitoring well installations were completed to target thick and coarse-grained sediment packages that, based on existing borehole data, showed aquifer potential. Hydraulic testing and groundwater sampling results provided valuable insights into groundwater quantity and quality. Highly transmissive aquifers, some worth investigating further, have been identified within portions of the valley network. The aquifers appear to occur at a number of stratigraphic positions and do not necessarily occur as the deepest unit overlying bedrock. Bedrock topography likely played a role, however, in their preferential preservation. They are commonly overlain by thick sequences of relatively impermeable sediments, providing excellent protection from anthropogenic contamination. Information from water chemistry, however, does suggest hydraulic connection to the surface at some locations. Groundwater quality and quantity information combined with a conceptual three-dimensional geologic model aids in the selection of groundwater resource exploration targets within the untapped resources of the deep, Dundas buried valley sediments.Résumé : La croissance démographique dans les municipalités qui dépendent de l'eau souterraine dans le sud-ouest de l'Ontario entraîne un intérêt croissant pour l'exploration de nouvelles ressources d'eau souterraine non exploitées. L'étude explore le potentiel de ressources d'eau souterraine de sédiments qui remplissent un réseau de vallées creusées dans le socle rocheux centré sous la région de Waterloo et les comtés de Brant et Hamilton-Wentworth. Les objectifs de l'étude consistent à mieux définir l'emplacement et la géométrie des vallées, comprendre les sédiments qui les remplissent et leurs propriétés hydrogéologiques et caractériser les eaux contenues dans les aquifères afin d'éclairer les décisions futures en matière de gestion de l'eau. Les résultats d'un levé gravimétrique régional au sol ont servi à situer des vallées ensevelies creusées dans le socle et ont guidé les forages de suivi. Le carottage continu des sédiments et l'installation de puits de surveillance ont été réalisés dans le but de cibler des séquences de sédiments grossiers épaisses qui, à la lumière de données de forage existante...

show abstract

Rock creep and the development of the Niagara cuesta

Barlow

2002

Earth Surf Processes Landf

View full text Add to dashboard Cite

This work addresses the post-glacial development of the Niagara Escarpment, specifically the east-facing scarp slopes between Hamilton and Collingwood. The escarpment is one of a series of scarps that shape the Great Lakes Basin. One interpretation suggests that the escarpment has evolved through homoclinal recession to the west. It is therefore viewed as an erosional feature brought about due to fluvial action on the weaker shale formations that underlie the cap rock. However, the deposition of large amounts of drift during the Pleistocene glaciation has resulted in the disruption of the preglacial drainage pattern within the Great Lakes Basin. Therefore, the current drainage is typically orthogonal to the scarp face with an absence of fluvial action along the base. Consequently, the cuesta is experiencing an extremely slow rate of retreat. Conventional thinking on the evolution of the present morphology suggests that it developed rapidly following deglaciation due to periglacial processes. The concept of the escarpment as a relict feature during the Holocene therefore pervades the modern literature.However, the cambering of the cap rock towards the scarp face and the apparent motion of individual joint-bounded blocks indicates that in the absence of exogenetic processes, a slow development due to endogenetic processes has dominated the modern development of the escarpment. It has been proposed that the present morphology of the cliffed sections may be due to deformation within the shale layers. In order to test this hypothesis, the rheology of the rocks that form the escarpment was tested and compared to the gravitational stresses that would be expected within the rock mass. The results indicate that the compressive strength of the shale layers of the Cabot Head Formation is lower than the expected effective stresses. It is therefore concluded that in the absence of high confining stresses, as would be expected near the cliff face, slow plastic deformation within this formation is occurring. The morphological expression of this deformation is seen in the cambering of the escarpment, the dilation of pre-existing joints, and the rotation of joint-bounded blocks.

show abstract

Late Pleistocene Glacial Erosion Along the Niagara Escarpment of Southern Ontario

Cited by 31 publications

References 0 publications

Sculpted Bedrock Forms along the Niagara Escarpment, Niagara Peninsula, Ontario

Sculpted Bedrock Forms along the Niagara Escarpment, Niagara Peninsula, Ontario

Evaluating the groundwater resource potential of the Dundas buried bedrock valley, southwestern Ontario: an integrated geological and hydrogeological case study

Rock creep and the development of the Niagara cuesta

Contact Info

Product

Resources

About