Drainage patterns Drainage patterns A figure from a 1967 paper on using drainage patterns to interpret subsurface geology. Three of these patterns have been observed on Titan. Dendritic are the classical shape and form where there's little structural control of the direction that rivers travel. There may be flat-lying sediments underground, or there may be very resistant, unfractured and massive (non-layered) crystalline rocks, and the regional slope is very gentle. Such networks can be seen in the T3 radar swath on Titan. Parallel drainage networks indicate moderate to steep slopes, but may also occur where there are parallel, elongate landforms, like layered rocks that have been tilted. These have been observed on the T7 and T41 radar swaths. Rectangular drainage networks indicate that the subsurface rocks are jointed and/or faulted, with sets of joints or faults intersecting at near-right angles. These have been observed on the T13 and T44 radar swaths.