Are these 'humps' not natural features? When water flows down a slope, over time, it erodes it. It doesn't however, erode it in a uniform way, it forms channels. Geologically, Darland Banks form one side of a river valley through chalk bedrock. Chalk is a soft, porous rock and erodes quickly. Given that our climate has been much wetter in the past, could it not have been the case that during the geological past, water has fallen on the banks in such a quantity that it has overwhelmed the natural tendency to soak into the chalk and instead has flowed over it down into the valley, eroding the channels over time. Those channels themselves would in time, weather away and become less pronounced?