The extent of lineative control such as jointing, as expressed in the alignment of the drainage network, can be judged only in comparison with the angularity of a channel system developed in a homogeneous, non-jointed lithology. This “background” value of random deflection of local stream direction from the general direction of the drainage exceeds 30° to either side in about 50% of a given channel length, and may exceed 60° to either side in 10% or more of channel length.