Approximately one to two and a half billion years ago (in the Amazonian era), the climatic conditions of Mars began to change at a catastrophic rate. As a result of the strongest volcanic and tectonic processes, the Northern Ocean arose and disappeared again, the greatest Martian volcanoes in our solar system were formed, and also several times the parameters of the atmosphere and hydrosphere of the planet changed significantly from time to time.
Scientists cannot say with certainty when the Amosonian era began on the red planet and the Hesperian era ended. According to some forecasts, this happened about 3.2 billion years ago, according to others, more optimistic, one and a half to two billion years ago and this is the longest period in the history of Mars until now. One way or another, but the Amazonian era on the red planet was a period of gradual transformation of Mars into a dead and inhospitable planet. This process was initiated by the gradual weakening of the magnetic field.
The planetary magnetic field appears due to the rotation of the planet's core, which is actually a huge "dynamo" generating powerful currents in the mantle and core of the planet.
According to one version, due to the fact that the mass of Mars is less than that of the Earth, it cooled down faster inside, a gradual decrease in the internal temperature led to a stop in the rotation of the core and, accordingly, the disappearance of the magnetic field. Of course, this did not happen instantly, but over thousands of years or even millions of years, however, it almost completely disappeared. Due to the cessation of processes in the core of the planet, the dying Mars began to be shaken by the strongest earthquakes and volcanic eruptions. Soon, tectonic movements decreased to the very minimum. Now, only colossal frozen volcanoes remind us that in the distant past Mars was probably similar to the Earth.
A strong weakening of the magnetic field of Mars, marked the beginning of a catastrophic chain reaction. Since Mars has less mass than Venus, a planet with a weak magnetic field was not able to withstand the solar wind and hold a dense, Earth-like atmosphere. Also, at the same time as the atmosphere, Mars was losing a large amount of water contained in it. Due to the decrease in the atmosphere layer, the greenhouse effect began to disappear, as a result of which the temperature on the planet's surface began to decrease. Water in a liquid state could now only be in the equator. At the poles of the planet, the oceans simply froze and began to look like ice caps, which over time were covered with frozen carbon dioxide. And to this day we can observe these very polar caps. If life existed on Mars,now there were fewer and fewer suitable places to maintain it. In the conditions of the disappearing atmosphere, the water cycle practically stopped, the water from the seas began to evaporate intensively in those reservoirs that remained, which began to represent a corrosive salt liquid practically unsuitable for life.
With the appearance of huge deserts, Martian dust storms began to arise, and Mars itself began to acquire a reddish hue. As a result, by the middle of the Amazonian era, atmospheric pressure on the planet's surface became so low that water on Mars could no longer be in liquid form, it simply evaporated into space, the last bodies of water disappeared.
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However, in some corners of Mars, water still remained for a long time after its disappearance from the main part of the surface. For example, at a depth of up to eleven kilometers in the valleys of the Mariner, atmospheric pressure was sufficient to find water there in liquid form. Perhaps such places have become the last refuge for the remaining, but already doomed life forms on a dead planet. When approaching our time, water disappeared from these places, and the atmosphere began to be less than 1/100 of the volume that once existed before. In the remaining atmosphere, the proportion of the content of heavy isotopes became extremely high (due to the "evaporation" of lighter atoms). Now, due to radiation from the Sun, the surface of Mars has become lethal even for bacteria, if they survived somewhere, then only deep under it.
In the future, under the influence of the solar wind, the evaporation of the atmosphere on Mars will continue, and no geological processes are expected on the lost planet.
Mr. Dan