Land Formations and Bodies of Water: What am I?

I am a large area of flat land that is higher than the land around me.

I am a large area of flat land.

I am low land between hills or mountains.

I am a mound of raised land with a rounded top and am smaller than a mountain.

I am an opening in the earth's crust from which lava flows.

I am a large, tall mass of rock with steep sides and am higher than a hill.

I am a large crack in the ground formed by a river or earthquakes.

I am an area of land that is completely surrounded by water.

I am a thin waterway that allows water to flow into a lake or ocean.

I am a place where water falls over a cliff.