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L’un des grands paradoxes de l’histoire de la terre est la presqu’absence d’anciens littoraux rocheux. Les anciennes surfaces d’érosion, appelées discordances, nous intriguent par leur planéité. En bref ces horizons sont dépourvus de paysages ou de littoraux rocheux. Certains géologues ont proposé que tout continent stable s’aplanie en pénéplaine sous l’effet prolongé de l’érosion. Après des décennies d’explorations les géomorphologues admettent les limites du modèle de "pénéplanation" proposé par William Morris Davis. La méthode de l'uniformitarisme ou de l'actualisme à certainement ses limites. Geodoxa contribue à stimuler les consensus tout en faisant connaitre les controverses. Certains serons choqués par ce qui suit, souvent des jeunes géologues professionnels ou amateurs. D’autres connaissent la controverse depuis déjà trois décennies. Cette vidéo n’est que la première d’une série qui sera en anglais et en allemand. Nous remercions tous ceux qui se sont déjà impliqués et ceux qui s’ajouterons. Vous pouvez nous contacter via le site www.geodoxa.com.

The drumlins field

See: https://www.geodoxa.com/orogeny In his structural geology course at MIT (Massachusetts Institute of Technology), Burrell Clark Burchfiel says: “The backstop in the sandbox experiment is probably the most unsatisfying part of the whole setup. What, in nature, corresponds to a vertical, unyielding wall? Early papers on critically tapered wedges had cartoons showing bulldozers pushing wedges in front of them, but this is surely just trading one suspect metaphor for another. One thing to realize is that the critical taper models and sandbox experiments are meant to simulate or describe fold and thrust belts or accretionary prisms. That is, they are models of a small part of the anatomy of an entire mountain range, in particular, the exterior parts. The backstop then, is just the interior (hinterland) of the mountain range, and all the model requires is that this part of the mountain range consists of thicker crust and higher elevations. How that part of the range became thickened and whether sandbox experiments shed any light into this is beside the point.”

This series of 7 videos is joined to our publication: Georgian Bay bedrock erosion: evidence for regional floods, 2023; in the Geological Survey of Canada Open file (8909) as a field report and survey in the area of French River, Ontario. The intro is followed by 6 videos that illustrate 7 sites among the 16 surveyed sites between 2017 and 2022.

This series of 7 videos is joined to our publication: Georgian Bay bedrock erosion: evidence for regional floods, 2023; in the Geological Survey of Canada Open file (8909) as a field report and survey in the area of French River, Ontario. The intro is followed by 6 videos that illustrate 7 sites among the 16 surveyed sites between 2017 and 2022.

45 deg 54' 24.54" N, 80 deg 50' 43.73" W

Our team surveyed this Hincks Island on the 5th of August 2022. You can explore photogrammetry 3D at https://skfb.ly/owS76. Hincks Island is situated in the Killarney-French River area of Georgian Bay in Ontario (Lat 45.948884374757725, Long -81.2172538377334). We did the 3D survey and filmed the East part of the island with Mavic Mini 2.

Notice the crescentic furrows adorning the bedrock. They are named sichelwannen (from German "sickle bassin"). Check our other videos to see how these grooves are sculpted by vortices in turbulent subglacial floods.

This small island north of One Tree Island is situated in the French River area of Georgian Bay in Ontario ( Lat 45°51'4.75"N, 80°47'11.41"W). We did the survey with Mavic Mini 2 on a sunny day (4th of August, 2022). We see countless sculpted forms (s-forms) mainly sichelwannen and long furrows sculpted at the end of the last Ice Age.

This series of 7 videos is joined to our publication; Georgian Bay bedrock erosion: evidence for regional floods, 2023; in the Geological Survey of Canada Open file (8909) as a field report and survey in the area of French River, Ontario. The intro is followed by 6 videos that illustrate 7 sites among the 16 surveyed sites between 2017 and 2019.

This series of 7 videos is joined to our publication: Georgian Bay bedrock erosion: evidence for regional floods, 2023; in the Geological Survey of Canada Open file (8909) as a field report and survey in the area of French River, Ontario. The intro is followed by 6 videos that illustrate 7 sites among the 16 surveyed sites between 2017 and 2022.

This series of 7 videos is joined to our publication; Georgian Bay bedrock erosion: evidence for regional floods, 2023; in the Geological Survey of Canada Open file (8909) as a field report and survey in the area of French River, Ontario. The intro is followed by 6 videos that illustrate 7 sites among the 16 surveyed sites between 2017 and 2022.

This series of 7 videos is joined to our publication; Georgian Bay bedrock erosion: evidence for regional floods, 2023; in the Geological Survey of Canada Open file (8909) as a field report and survey in the area of French River, Ontario. The intro is followed by 6 videos that illustrate 7 sites among the 16 surveyed sites between 2017 and 2022.

This series of 7 videos is joined to our publication; Georgian Bay bedrock erosion: evidence for regional floods, 2023; in the Geological Survey of Canada Open file (8909) as a field report and survey in the area of French River, Ontario. The intro is followed by 6 videos that illustrate 7 sites among the 16 surveyed sites between 2017 and 2022.

This series of 7 videos is joined to our publication; Georgian Bay bedrock erosion: evidence for regional floods, 2023; in the Geological Survey of Canada Open file (8909) as a field report and survey in the area of French River, Ontario. The intro is followed by 6 videos that illustrate 7 sites among the 16 surveyed sites between 2017 and 2022.

Towards the end of the ice age melt water from glaciers played a major role in shaping our land. During the last decades, glaciologists were able to recognize the traces of these subglacial water floods. This video will help to appreciate how vortex are carving the sculpted forms (s-forms) on the bedrock under the continental ice sheet.

Cette vidéo a été présentée à la conférence CANQUA / AMQUA 2018 à Ottawa afin de préparer les téléspectateurs à une visite sur le site exceptionnel de Cantley, au Québec. La visite sur le terrain a été dirigée par David R. Sharpe de la Commission géologique du Canada. Vers la fin de l'époque glacière l'eau de fonte des glaciers a joué un rôle plus important que l'on ne croyait. Ces eaux auraient été la cause de plusieurs catastrophes à l'échelle régionale sur plusieurs continents. Le site de Cantley au Québec est un des sites le plus emblématique de l’une de ces catastrophes. Les roches sculptées sont d’âge précambrienne du Grenville. Ce marbre contient un grand nombre de morceaux granitiques que nous appelons inclusions. Ces inclusions résistèrent mieux que le marbre aux eaux catastrophiques ce qui engendra une multitude de s-forms appelées ‘obstacle marks’, marques d’obstacle. En regardant les animations qui se superposent aux affleurements, le spectateur saisira facilement, par intuition, l’action des puissants vortex. L’évènement s’est sans doute produit dans une brève lapse de temps que les islandais appellent un Jökulhlaup.