A 2005 photo of Elysium Planitia by the Mars Express spacecraft shows what may be ash-covered water ice. The volume of ice is estimated to be 800 by 900 kilometers in size and 45 meters deep, similar in size and depth to the North Sea. The ice is thought to be the remains of water floods and lava flows in the Cerberus Fossae fissures about 2 to 10 million years ago. The surface of the area is broken into 'plates' like broken ice floating on a lake. Impact crater counts show that the plates are up to 1 million years older than the gap material, showing that the area solidified much too slowly for the material to be basaltic lava.