ridges again :)
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by chrisbayes
if these are channels then why wouldn't the black stuff settle in the channels. what is special about the black stuff that it settles on the lip of the channel? the black stuff looks like it has settled in the corners of a ridge
Posted
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by Wounded_Knee
Theres an answer here
http://talk.planetfour.org/#/boards/BPF0000002/discussions/DPF00002i3
Posted