HiRISE 3D: A Source of Dunes
This image shows the head of an Abalos Undae dune field revealing possible sand source near base of Planum Boreum. This is in the north polar region of Mars.
https://www.uahirise.org/anaglyph/ESP_079495_2625_ESP_079455_2625_RED
NASA/JPL-Caltech/UArizona