From the lower plate which melts in the earths mantle.
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
It depends on the map. There should be a key indicated.
The answer to this question is More elastic
A product usually become inelastic if that product does not have any subtitute to fulfill the same function.
In the long run, advancement in technologies will create a way cheaper method in producing energy (such as electric, nuclear, or solar) which will make natural gas become more elastic.
