One of the most dominant features on the eastern edge of the moon is Mare Crisium, a large circular formation with a very flat floor measuring approximately 620 by 570 km and covering an area of approximately 176,000 sq meters. Mare Crisium is estimated to have been formed between 3.85 and 3.92 billion years ago and is characterized with a flat surface with evidence of wrinkling on the eastern and western edges. Some features of interest include two craters near the western edge, Picard with a diameter of 23 km and Peirce with a diameter of 18.5 km, and Promontorium Agarum to the southeast. Also visible in the image below are four dorsa - dorsum Termier (3 km wide, 90 km long) is the ridge formation running above and below the Luna 15 crash site; similarly, dorsum Harker (11 km wide, 200 km long) is the ridge immediately below the landing site for Luna 24; dorsum Oppel (7 km wide, 300 km long) is the ridge formation immediately above crater Peirce; and, finally, dorsum Tetyaev (11 km wide, 150 km long) is visible in the northeast periphery of Mare Crisium running immediately due south.