Research on the earth's glaciers found that when the volcano below the glacier begins to erupt, it will quickly generate a steam flow, explosively penetrate the ice layer, release ash into the high altitude, and produce zeolites, sulfides, and clay. These minerals have also been detected on some circular flat-topped hills on the surface of Mars, and they are widespread and abundant. Therefore, it is speculated that Mars was covered by ice sheets in the early days, and there had been more volcanic activity there. In order to reach the above conclusions, what premise needs to be added? ['Recently, the Mars Reconnaissance Image Spectrum Analyzer found that a volcano exists in the South Pole of Mars.', 'Mars geological activity is not active, most of the landforms were formed during ancient times.', 'Zeolites, sulfides, and clays are unique substances that are produced only after volcanic activity under the glacier.', 'Some ancient bacteria were found in the rocks of the flat-topped hills of Mars, indicating that there may have been a source of water here.']