A rift flank is the elevated region that forms on either side of a rift valley due to the extensional forces that create the rift. Rift flanks are significant for understanding the tectonic processes that lead to continental breakup, the development of rift basins, and the uplift and erosion of the Earth’s crust.
Reference: Ebinger, C. J. (2005). “Continental Breakup: The East African Perspective.” Geophysical Monograph Series, 148, 305-324.