The best answer to the question presented above would be the first statement. Stalactites are chemical sedimentary rocks that form when the minerals in the cave are left behind by the water. They saturate and form into these stalactites.
They have less-runny lava, meaning that it doesn't travel as far before cooling, meaning that the layers build up more steeply, but don't go out as far. You also get layers of ash on the composite volcano to help build it up too
GROUNDWATER is the largest source of freshwater on earth.