This area–known as the Deuteronilus contact of the Isidis Basin–has been interpreted as a possible ancient shoreline. There are also suggestions that this contact is of volcanic origin.
One direct benefit of a high resolution image is the ability to monitor the detailed morphology of the contact to help to determine whether this formation is the result of an ocean or of a volcanic filling of the Isidis Basin.
Written by: HiRISE Science Team (6 November 2013)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_033242_1845
Image: NASA/JPL/University of Arizona