Niger Vallis (Mars)

Named after the River in Africa.

Niger Vallis is a valley on Mars that appears to have been carved by water. It merges with Dao Vallis which runs southwestward into Hellas Planitia from the volcanic Hadriacus Mons. Like Dao, it was formed around the Late Noachian and Early Hesperian Epochs. (wikipedia entry)

A vallis is a valley. On Mars large valles are named after words for Mars/star in various languages. Small valles are named after classical or modern names of rivers.