Uzboi Vallis is a valley lying situated within the Margaritifer Sinus quadrangle (MC-19) region on Mars.

Eventually the lake in the area of Uzboi Vallis went high enough to overtop the rim of Holden.

The sediments that make up the layers appear to be coarse in size, suggesting they were probably formed by a rapid flow.

It has been suggested that Uzboi, Ladon, Margaritifer and Ares Valles, although now separated by large craters, once comprised a single outflow channel flowing north into Chryse Planitia.

[7][8] The source of this outflow has been suggested as overflow from the Argyre crater, formerly filled to the brim as a lake by channels (Surius, Dzigai, and Palacopus Valles) draining down from the south pole.