Alien Base Entrance Discovered On Mercury? 2012 HD

The image is a portion of the MDIS global mosaic basemap that was acquired during Messengers's first year in orbit. To the right (Victoria Rupes Cliffs) we can cleary see an un-natural anomaly, as nature never creates straight lines, ever! The scale is 5.6km long or 3.4 miles, that is gigantic. Could this be an entrance/exit for Extraterrestrial spaceships or something else?

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