With the pond complete, that means one of our two structures is out of the way. Now it's time to turn our attention to the more exciting structure: the cascade design itself. And that means taking another look at the rocks we'll be using.
The most important rocks are what might be termed the "spillway" rocks. By "spillway" I mean the rocks directly over which the water will cascade. In my sample cascade design, I use two such rocks, one above the other. This gives my cascade design two levels (separate waterfalls, if you will), for greater visual impact.
The spillway rocks should be relatively flat (as opposed to rocks that are more rounded in shape). They should also have sharp, squarish edges. Water will cascade more cleanly over such edges. When rocks have blunt, gently-curving edges, some of the water tends to follow that curve and trickle back under the rocks. Not only is the cascading effect in the latter case less spectacular, but you'll also lose a lot of your water (because it won't fall cleanly into the pond).
In sum, the idea behind the selection of spillway rocks for a cascade design is to choose rocks that are most likely to channel the falling water in the precise direction in which you want it to go. How you lay the spillway rocks is also important to this end, as we'll see later. In addition to seeking out relatively flat rocks with sharp edges, see if you can't find rocks that are slightly cupped. That is, occasionally you'll come across rocks that curl up ever so slightly at the edges, leaving a depression in the middle. The natural channel in such rocks will be greatly advantageous for the creation of the spillways in your cascade design. Their raised edges will help keep the water from deviating where you don't want it (namely, behind the rocks).
You may have been intrigued by one of the supplies I listed on Page 1: "Large plastic flower pot." Here's what that's all about. I used an empty flower pot, 11" high, that had a 1/2"-diameter drainage hole in the bottom (to match the diameter of my tubing). The pot simply functions as housing for the tubing (within the cascading structure for the waterfall). You could easily substitute something else that might work better; I selected a plastic flower pot simply because this is an item gardeners always have in abundance (and usually are dying to find a use for!). For instance, a terra cotta pot would be even better, since it provides more stability. A crate made of rigid plastic would also work. The idea is to have some sort of housing to hold the tubing in place, while you lay up the rocks all around it. This housing won't show when you're finished: it will lie hidden at the center of your rock work.
You'll essentially be building four mini-rock walls around the pot, to box it in. Make a small trench for the tubing to sit in under the rocks, so that the rocks don't weigh it down. This will keep the tubing free, so that you can slide it through the pot up or down, at will. This gives you the leeway that you need, since you won't know at exactly what height you'll want the water spouting out until you've finished laying the rocks.
After laying my first course of rocks in the front, I covered them with a sheet of black plastic, 4' long x 3' wide. I extended one end of the plastic up to the top of the plastic pot, while tucking the other over the lip of the preformed pond liner and down into the water. I then disguised this plastic with rocks, so that it wouldn't be visible in the pond (the end of the plastic near the pot will be hidden by rocks later, as I build up the wall). Using this cheap plastic (I simply sliced up a trash bag) is a frugal substitute for the more expensive flexible pond liner that one would use for a larger cascade design (and that you could use in this project, too, if it fits into your budget). The plastic serves the same purpose: namely, to catch more water than the rocks alone could and funnel it into the pond. Much of the water that would otherwise be lost to splashing strikes against this plastic and falls back into the pond, instead.
Also after laying the first course of rocks in front (and just after laying the black plastic), I laid one long, flat rock spanning them all and sitting right on top of that plastic. In the waterfall photo showing the cascade design in progress (above right), the black plastic and the spillway rocks are absent in order to give you a clearer shot of this rock and of the first course of rocks upon which it sits. My long, flat rock juts out in the direction of the pond, forming an overhang. It will serve as a shelf for my first spillway rock, so I'll refer to it subsequently as my "shelf rock." If you wish to reproduce this cascade design, seek out a long, flat rock of ample mass for such a shelf rock.
On Page 4 we'll discuss the laying of the rocks for the cascade design in more detail, which includes strategies of minimizing water-loss....
