Site 16 is quite typical of the stream valleys that are found further to the south in the radar image. All of this area was covered by meters of ash during the 1790 eruption, but this deposit has now undergone considerable fluvial erosion. Radar-bright linear features in this area are radar-facing walls of the valleys. Small dark patches within this area are most likely to be reworked (by fluvial activity) ash that has collected in topographic lows.
From here you may continue on to Site 17 or you can pick another point from the Radar Tourpage.