I am again jumping back to the trench tunnels that Danni, Jeff, Dale, Carol-Anne and I explored this past weekend. Here is a cool picture down one of the crawls that lead into the shelves to either side of the main trench. The formations crowd the spaces so profusely that we dared not leave the trench for fear of damaging the cave.
As you can see the soda straws are everywhere. The soda straw grows by the calcium laden water that moves down its central tube and leaves a precipitate around its bottom edge. When this central tube is blocked the deposition moves to the outside of the growth and the tube becomes more carrot-like than straw-like. This is how stalactites form.
Most Ontario caves have formed after the last ice age, thus only about 14 000 years of cave forming potential. People who study caves see the process in a number of ways. I remember reading a book by somebody Davis who proposed distinct periods of cave development. Initially there was the scouring or solution that formed the cavities and then, the deposition, once the solution stopped. It was at this time that he proposed that the formations began to grow.
I suppose there is not really such a strict division in nature, the processes happen simultaneously in many places, deposition occuring up high and solution and abrasion happening at the tunnel floor.