Hot springs and geysers are heated geothermally using Earth's mantle as it's source.
Found at the lowest point of a large drainage area, these seasonal, marsh-like ponds collect and store water from rain and runoff. Unlike vernal pools, playas generally fill when temperatures are unsuitable for plant growth, and often the water is salty, alkali or both.
source- google
Answer:
<em>A. 6,000 years</em>
Explanation:
Original sample N = 60 g
The half life of N/2 is 3000yrs
"""""""""""""""""""N/4 is 6000yrs
N/4 ===> 15 gram
it takes 6000yrs to decrease to 15grams
