Explain why liquid water is not stable on mars today, but why we nonetheless think it flowed there in the distant past.

Liquid water is not stable on Mars but was stable in the past because Mars' atmosphere was thicker, trapping carbon-dioxide easily, warming the planet, making water stable. But the atmosphere dissolved, making Mars colder, so now liquid water is not stable.

Sequoia national park  /  inyo national forest, california, u.s. mount whitney is the tallest mountain in california, as well as the highest summit in the contiguous united states and thesierra nevada—with an elevation of 14,505 feet (4,421 m).

Answer decreased soil salinity;