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prettygoodwordrille (RIL) - n., a long, narrow depression that resembles a channel found on the surface of the Moon and various lunar and planetary bodies.
They can be straight or sinuous like a river channel:
Thanks, WikiMedia!
Origin remains unknown, especially for Lunar rilles, though collapsed lava tubes are a leading theory for several. Martian rilles like Mamers Valles above certainly look like water erosion, though. From German Rille, groove, a cognate of rill, creek/stream, though that dates back to Old English rīth, rivulet.
---L.
They can be straight or sinuous like a river channel:
Thanks, WikiMedia!
Origin remains unknown, especially for Lunar rilles, though collapsed lava tubes are a leading theory for several. Martian rilles like Mamers Valles above certainly look like water erosion, though. From German Rille, groove, a cognate of rill, creek/stream, though that dates back to Old English rīth, rivulet.
---L.
