Uzboi Vallis is believed to have been formed by running water. It is believed that layers were formed on the floor of Uzboi Vallis (as shown in the HiRISE image below) when drainage was blocked by the impact that formed Holden Crater to the north. Eventually the lake in the area of Uzboi Vallis went high enough to overtop the rim of Holden. The water then eroded the deposits to expose the layers as they are today. 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. 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. If real, the full length of this drainage system would be over 8000 km, the longest known drainage path in the solar system.
- Parker, T.J., Clifford, S.m., and Banerdt, W.B. (2000). Argyre Planitia and the Mars global hydrologic cycle. LPSC XXXI, Abstract 2033.