In this video of Mount Kilimanjaro, you can get a good idea of how big the scree descent is, and how you can literally jog down it. It looks like they are assisting a disabled climber coming down the mountain, but I am not quite sure. At the end of the video, look at how steep the slope is. This route is used to descend from the Machame Route. This area is just below Stella Point in an area called the South East valley.