21. North of this was the Columbia Embayment, where the continental margin was east of the surrounding areas. 22. The passive continental margin became active when the Farallon Plate started to dive below the North American Plate. 23. At times some of the metamorphosed downgoing slab may be thrust up or obducted onto the continental margin . 24. The Stephen Formation formed at a low-latitude miogeoclinic continental margin , at the western limit of a continental craton. 25. Due to its increased density, it flows down the Antarctic continental margin and continues north along the bottom. 26. Until recently, technological limitations had prevented extensive and detailed mapping of the U . S . continental margin , 27. Unlike most subduction zones worldwide, there is no deep oceanic trench present along the continental margin in Cascadia. 28. In plate tectonic terms, the Atlantic Plain is known as a classic example of a passive continental margin . 29. Another major point of discussion regards the presence of erosional deep canyons along the continental margins of the Basins. 30. As plants took hold on the continental margins , oxygen levels increased and carbon dioxide dropped, although much less dramatically.
