ly cover the globe at these times. There is rock and fossil evidence of Jurassic and Cretaceous interior seaways and continental margin flooding (Golonka and Kiessling 2002). The Sundance Seaway in western USA (Danise and Holland 2018) and the Sub-Boreal Seaway of the United Kingdom (Foffa et al. 2018) are examples of Jurassic seaways and basin subsidence. The Sundance Seaway was nearly 2000 kilometers long and was flanked on the west by a fold and thrust belt (Danise and Holland 2018). In the Cretaceous there were a number of seaways, including the Western Interior Seaway on the tectonically active margin of North America (Robinson Roberts and Kirschbaum 1995) (Figs. 15 and 16). I. Pleistocene Ice Age and submarine canyons Intense volcanic activity and increased ocean temperatures associated with seafloor spreading have been used to explain this Ice Age. The release of hot volcanic water warmed the ocean and strong evaporation from a much warmer ocean provided the water for the ice (Oard 1987, 2004). Water turning to ice caused sea level to drop around the globe. Submarine canyons are found on all the continental shelves of the world. At the peak of the Pleistocene Ice Age, most continental shelves were subaerially exposed and underwent erosion when global eustatic sea level was ~120 m below its present position. Rivers incised valleys across what is today the continental shelf. The delivery of sediments to the shelf break during sea level low-stands provided a sediment source for down-slope turbidity flows and canyon incision (Harris and Whiteway 2011). The Perth Canyon is an example of a submarine canyon located on the edge of the continental shelf, some 30 km offshore from Perth, Western Australia (Fig. 17). It is Australia’s largest submarine canyon. It is roughly the length of the Grand Canyon, but twice as deep (reaching depths of 4 km below sea level) (Trotter et al. 2019). Figure 16.Western Interior Seaway, North America A. Generalized map of the Western Interior Seaway during the maximum marine transgression of the Late Cretaceous (Pang 1995). Facies indicate the transition from nearshore to deeper water. B. Cross-section of the subsided Western Interior Basin between Utah and the mid-continent. Continental deposits were derived from runoff from the Cordillera in the west. Marine deposits are found further east (after Birgenheier et al. 2017). DICKENS Flood Waters Lead to Seafloor Spreading 2023 ICC 461
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