What Martian valley was the landing area for the Sojourner rover?

The Martian valley that was the landing area for the Sojourner rover was Ares Vallis.

Sojourner arrived on Mars on July 4, 1997, as part of NASA’s Mars Pathfinder mission. The spacecraft landed in Ares Vallis, an ancient outflow channel in the Chryse Planitia region. The site was selected because its relatively safe terrain also offered rocks and landforms that could reveal evidence of past flowing water.

Ares Vallis is not simply a narrow valley in the Earthlike sense. It is a vast Martian channel, about 1,700 kilometers long, that appears to have been shaped by powerful fluid flows. Pathfinder’s landing site lay near the channel’s border with Chryse Planitia, in Mars’s Oxia Palus quadrangle.

A common mix-up is Valles Marineris, the enormous canyon system elsewhere on Mars. Nirgal Vallis and Mawrth Vallis are also Martian valleys, but neither was Sojourner’s landing area. Sojourner operated for 83 sols and traveled a little over 100 meters around the Pathfinder lander.