The first is "escarpment margin" sedimentation, found along the major border faults bounding the half graben, where the deepest part of the basin meets the highest rift-shoulder mountains.[6] Comparatively little sediment enters the half-graben across the major bounding fault, since uplift of the footwall causes the land on the footwall side to slope away from the fault. Rivers on that side therefore carry sediment away from the rift valley.[7] But as the lowest part of the basin with the greatest rate of subsidence, the escarpment margin experiences the highest rates of sedimentation, which may accumulate to several kilometers in depth.[8] This sedimentation often includes very coarse debris such as huge blocks from rock falls, as well as fans of sediment from the basin wall. Other material is transported across or along the basin to the deep water parts of a rift lake along the escarpment margin.[6]