I think that a) is chemical, and b) would be chemical
Hi there!
The lowest point on earth is the Dead Sea, which is 420 meters BELOW sea level!
Some unknown fish and animals and creatures live here, but we unfortunately are unable to discover them because if you were to dive down this deep point you'd be squished, like a bug, because of the number of gallons of water resting on top of you.
Anyway, hope this helps!
They are can be except for wind weathering i believe. That is caused by the wind.
Ocean trenches are created by the moving apart of tectonic plates, volcanoes are pushed to erupt by the movement of tectonic plates and earthquakes are cause by the movement also.
