Real a'a lava flows are complicated. They are characterized by a prominent lava channel confined between levees. Shear zones, places where one portion of the flow is moving faster than an adjacent portion, usually occur. Small flows of pahoehoe lava also become channelized, but on a much smaller scale than a'a flows. As cake batter is poured onto an inclined surface, the first and foremost thing to do is to observe the formation of distinct features in the flow.
Levees form on the outer part of the flow.
These are not quite the same as levees on lava flows because the latter build up levees by overflowing the banks. Inside the levees the batter moves downhill. Ridges might develop in the flowing portions, analogous to large ridges in lava flows. The thickness of the flow varies with slope, time, position in the flow, and amount of batter poured. These variables can be tested by measuring width and thickness as functions of time, as described in the procedure.