Physicists think that the shape doesn't indicate that it was caused by an asteroid collision but from a tectonic plate rupture during Mars' early formation.Valles Marineris, or Mariner Valley, is a vast canyon system that runs along the Martian equator just east of the Tharsis region. Valles Marineris is 4000 km (2500 mi) long and reaches depths of up to 7 km (4 mi)! For comparison, the Grand Canyon in Arizona is about 800 km (500 mi) long and 1.6 km (1 mi) deep.
https://mars.nasa.gov/gallery/atlas/val ... mi)%20deep.
Are they correct?