21. The required silica was provided by volcanic exhalations and / or by upwelling . 22. Bambach and his associates propose several possible explanations for a catastrophic carbon dioxide upwelling . 23. World War II, of course, unleashed a further upwelling of patriotic fervor. 24. Americans reacted to the attacks last fall with a tremendous upwelling of patriotic feeling. 25. Nonetheless, some diffusive upwelling does probably occur. 26. Major upwelling occurs between 25 degrees northern latitude ( Canary Current, 2002 ). 27. Upwelling occurs year-round at Cap Blanc ( Ras Nouadhibou ) and northward.28. The most common occurrence of phosphorites is related to strong marine upwelling of sediments. 29. This mechanism in best illustrated when comparing the Peru and northwest Africa upwelling systems. 30. The upwelling magnetic flux pushes through the photosphere, exposing the cooler plasma below.
