Today's Image of Mars is of the boundary between Candor Chasma and Ophir Chasma, both of which are located in the Valles Marineris canyon system on Mars. The Valles Marineris is the largest canyon system in the solar system and would span almost the entire United States from East Coast to West.
Candor Chasma is one of the largest canyons in the Valles Marineris canyon system and it borders Ophir Chasma to the south. The photo below shows a small stretch of the border between Candor and Ophiir Chasma.
This image was taken by HiRISE, but they have not captioned it as of this posting, so clicking on the image will take you to all posts labeled with Valles Marineris.