What is the best evidence that the ancient valley networks and lakes on Mars wer
ID: 117735 • Letter: W
Question
What is the best evidence that the ancient valley networks and lakes on Mars were carved by water and not another fluid (for example, CO2 or lava)?
The large volume of water ice currently trapped underground on Mars must have been liquid once
The clay minerals and salts we observe from this same time period can only form in the presence of liquid water
No other fluid can carve channels like water
Radar observations of frozen but dust-covered lakes of ice inside of impact craters
The large volume of water ice currently trapped underground on Mars must have been liquid once
The clay minerals and salts we observe from this same time period can only form in the presence of liquid water
No other fluid can carve channels like water
Radar observations of frozen but dust-covered lakes of ice inside of impact craters
Explanation / Answer
The best evidence that the ancient valley networks and lakes on Mars were carved by water and not another fluid (for example, CO2 or lava) is the clay minerals and salts we observe from this same time period can only form in the presence of liquid water.
Because geologic evidence shows that the past outflow channels are carved by floods, ancient river valley networks, deltas and lakebeds. The origin of those carved channels are liquid water, identified by the presence of rocks and minerals on the surface that could only have formed in liquid water. So, it is widely accepted that Mars had abundant water in the very early history which is retained on modern Mars as both ice and locked into the structure of abundant water rich materials. Such as clay minerals (phyllosilicates) which require liquid water for formation and sulfates.
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