What is a moon rill?
a line on the moon
perhaps the moon is splitted from this line.
for more information see: Quran the Muslims book, Qamar section, line 1
>> the splitting of moon is made by Muhammad the Last prophet.
Rill erosion begins when a small stream forms during heavy rain. Gully erosion , a rill channel becomes broader and deeper. Rill erosion is the removal of soil by concentrated water running through little streamlets, or headcuts. Gully erosion is a highly visible form of soil erosion that affects soil productivity.