Examination of photos of Mars received by American orbit flight vehicles Viking Orbiter 1 and Viking Orbiter 2 in 1976-1980 and Global Surveyor Orbiter in 1997-2003 allowed a number of explorers to put forward an assumption of existence in the northern half of Mars in the past an ocean or several connected seas. On large extent of the Martian surface - Amazonis -Arcadia planitias (plains) and Terra Sirenum-Likus sulci (lowlands) boundaries, Acidalia-Chryse planitias (plains) and Tempe-Arabia terras (lowlands) boundaries and in other places - outlines of an ancient sealine are good distinctive.
In "Mars before and after catastrophe. Thoughts about a life on the Red planet" by A. Koltypin analysis of blank, topographic and relief maps of Mars have carried out. On the basis of such analysis the ancient Martian ocean 6-8 km in depth, named by me the Great Northern ocean, was outlined in the northern part of Mars, and the ancient continent Tsarsis with plains and raises from 1 to 7 km in altitude with separate mountain chains up to 9 km in altitude and volcanoes up to 30 km in altitude - in the southern part of Mars. Inside of it Mariner-Eos-Aurora rift zone, flanking to the Great Northern ocean, analogous to the Red sea and the Great African lakes on Earth, and also Argyre planitia and Hellas planitia great inner seas up to 6-9 km in depth , located in the places of meteoritic craters, was outlined. The main elements of continental relief are channels of ancient Martian rivers fallen into the Great Northern ocean and the inner seas. At the ocean and continent boundary insular systems (Deuteronilus and Protonilus) and coastal lowlands are well visible.
According to the investigations spent in 2002-2004 by 2001 Mars Odissey, there is large quantity of resources of water under a surface of Mars which indicates that oceans on Mars have simply freezed.
The analysis of blank, topographic and relief maps of Mars testify to powerful bombing of its surface by asteroids during the catastrophe, happened hundred (ten) thousand - 5, maximum 16 million years ago. The main blows to Mars occured in the places where Hellas, Argyre and Isidis craters are now. Impacts have led to formation of numerous disruptions of Martian crust, orogenesis, volcanic eruptions and, in the long run, to loss of a larger part of oxygen and atmosphere by Mars (see "Great catastrophe on Mars").
In the conclusion of "Mars before and after catastrophe. Thoughts about a life on the Red planet" the possibility of existence of reasonable life on Mars is considered and the hypothesis about contacts between Mars and Earth some million - hundreds, perhaps, even ten thousand years ago is put forward (advanced).
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