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As you drive through the Rocky Mountains, you can't help but notice the geology.  Rocks are everywhere.  Cliffs, knobs, and road cuts reveal layer upon layer of rocks.  Our property is located at the northern section of the Pikes Peak batholith, an up welling of pink granite through metamorphic rocks of gneiss and schist.

We have rocks of all sizes from the 2-5 inch rocks that I call rubble to massive rock outcroppings.  As I worked my vegetable garden area, I removed the rocks (mostly rubble size) from the garden soil.  However, it seemed each year a new crop of rocks was appearing.  I had a theory that the rocks were growing in my garden better then my plants (of course, it only seemed this way).  In a few years, I had a rock pile about 3 feet high and 5 feet across.

So what to do with all these rocks piling up?  My solution is to use these and other rocks in landscape features such as:   erosion control,   a rock walk, and   a rock wall .  Working with rocks is not as easy as one might think.  In Lessons Learned, I share some of my experiences working with rocks.

My flower gardening activities are also rock usage intensive. Click here for my flower gardening page.

click on an image for a larger view in another window

Erosion Control

We have decomposed granite instead of soil.  Basically, decomposed granite is pink Pikes Peak granite that has eroded into small, irregular shaped particles about 1/4 inch in diameter.  Decomposed granite washes much like sand and, in El Niño years when when we may have a major rain storm of 3 inches or more, our driveway will wash.

1989 Ditch
This is a view of a ditch along a portion of our driveway, showing erosion damage in 1989.
          1997 Ditch
This photograph shows erosion damage to the same ditch that occurred in a 1997 rain storm.

First, we put rubble in the ditch but, on the rare occasions when we had a major rainstorm, the water flowed so fast and forcefully that the rubble washed out of the ditch  Rocks as big as 8 inches across would wash as the above photograph taken in 1997 shows.  We, therefore, went around our property and, using our tractor, moved much larger rocks to line the side of the ditch.
2001 Ditch
Here is the same ditch in 2001 showing the large rocks lining the wall next to the driveway.
2001 Ditch
This photograph also shows the ditch in 2001.  Notice how the driveway has been graded to slope toward the ditch.  We did this so water drains towards the ditch and not down the grade of the driveway.
2001 Pipe
We still use rubble as erosion control in places such as this entrance to the drainage pipe that goes under our driveway.  Grass grows around the rubble and holds it in place during a major wash event.
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Rock Walk

Although our decomposed granite is much like sand and is rarely muddy, I put a rock wall around our hot tub for two reasons: to keep debris from getting into the hot tub and to give us a place to drain off after getting out of the hot tub.

Hot Tub This 1991 picture shows my initial attempt at a walk.  I used some 8 x 16 inch pavers we happen to have around and some larger flat rocks.  The pink flowers are fire weed which have since died out.

This initial walk had some problems.  It wasn't pretty.  Grass and flowers still got into the hot tub. The biggest problem, however, was critters.  First, a chipmunk (and then her descendants) moved in under the tub.  Next, a rabbit thought the hot tub would make a fine cover for her home.  I felt that the burrowing was undermining the hot tub base and needed to convince the critters that this was not a good place for a home.

As I roamed our property, I noticed many flat rocks ranging from 8 inches to 30 inches in diameter.  Over the years, I collected these flat rocks and in 1999, rebuilt the rock walk.

This 2000 picture taken from the balcony above the hot tub shows the rock walk.  The rocks are placed right next to the tub wall and prevent burrowing animals from getting under the tub.  In the lower right corner, the existing board walk from our back door just shows. Hot Tub

The rock walk has two additional features.  In the winter, snow is easier to remove from around the hot tub.  Also, the sun heats the rocks and melts the snow quicker then the surrounding grass and dirt areas.
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Rock Wall

My attempts at building a rock wall have been modest so far.  When we put our hot tub in behind our house, we didn't have enough flat area along the tub for walking.  I put in a line of rocks and filled in a flat area about 2 feet from the tub.  This certainly was not wide enough for walking around the tub.

Rock Wall Prior to building the rock walk above, I rebuilt the rock wall about five feet from the hot tub.  Here is the current rock wall.  I filled in the intervening space with rubble and then top soil to create a level area.
This photograph shows the hot tub drain I put in.  A hose section runs under the grassy area to the hot tub drain.  The other end of the hose is hidden in the rock wall by a small rock.  The rock is on the right of the hose end.  When draining the hot tub, I attach a long hose to the buried hose and drain the water into the meadow. Rock Wall                                             

I am not satisfied with the rock wall yet.  The angle is too sharp in relation to the board walk and the rocks not attractively placed.  So, the project continues...

Rock Wall, 2002

I decided to change (once again...) the rock wall in April, 2002. First I removed the original rock wall, setting the rocks aside for use in the new version. I decided where I wanted the rock wall to meet with the existing deck and where I wanted the rock wall to terminate. Then, I planned the curve in the wall.

Rock Wall This photograph shows the rock wall in progress. I placed a wide, heavy rock next to the deck to use as a step. Then I created the rock wall much as I would build a puzzle. As I balanced each rock, I put rubble and dirt behind the rock to keep it in place. I was filling in behind the wall with rubble when I took this photograph.

If you look closely, you can see where I extended the hot tub drain through the new wall. I also stood the rocks on end rather then laying them flat as in the prior wall. This looked better to me and used less rocks but was more difficult to build.

not avail Here is how the rock wall looked during the autumn. I placed rubble and decomposed granite behind the rocks and then filled in the rest of the area with dirt from my vegetable garden. Right behind the rocks, I put in a 6 inch band of precious compost.

I planted grass in the larger area. In the compost, I planted gypsophila repens, a prostrate baby's breath. This grew fairly well until the local rabbit tried it out for lunch and decided it was quite tasty, thank you.

Now that I have a rock wall that I am satisfied with (finally), I can continue work on the terrace below the wall in 2003.
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Lessons Learned

While working with rocks, I learned the following:

  1. Rocks are heavy.  A surprisingly small rock weights a lot.  Our rocks are gneiss, schist, granite, and quartz.  I can lift a rock about 1 cubic foot in volume.  I can move a rock about 8 cubic feet in volume.  Our tractor can lift a rock about 27 cubic feet in volume.  These are not large rocks.
  2. Rocks are abrasive.  I wore through both leather and cloth gloves while working with rocks.  I finally just kept the old gloves and wound duct tape around the fingers and palms as needed.
  3. Rocks have odd shapes.  A rock that looks like it will fit into the space you made for it will usually be just a little bit too long or too wide or have a small bump that keeps the rock from fitting properly.
  4. Rocks are not flat.  Although I thought the rocks I planned to use in the rock walk were flat, in reality they were just a little warped or a bit rough.  Your bare feet can feel every wave and weave in a rock walk.  As a corollary, flat rocks all have a different depths which preclude you from having a level bed on which to place the rocks.  I understood why people purchase rocks for walks as I tried to produce a level surface with rocks of varying depths.  One rock was 3 inches into the ground, its neighboring rock was 6 inches down.  This disparity in depth resulted in my having to do a lot of custom digging for each rock.
  5. Rocks do not have tensile strength.  A large flat rock dropped 2 feet will invariably and randomly break into 2 or more rocks of unequal sizes.
  6. Rocks are hard.  In what seems like a contradiction to the above bullet, a very small but intrusive bump on a rock will be nearly impossible to remove, even with a concrete chisel and a sledge hammer.
  7. Rocks change their volume.  (at least they seem to...)  Rocks take up less space when placed in your project then when they were lying about in the woods.  I found I needed at least twice as many rocks for each project then I estimated.  For my next project, I will have many more rocks then I think I need.  This will also allow me to overcome some other rock properties such as odd shapes and lack of flatness.  I will have more possibilities for fitting the rocks together as they want to fit not as I think they should fit.
  8. Rocks are forever.  After all the effort to work with rocks, your project will be there forever or at least until you decide to modify the project just a little.  Rocks don't need to be watered, they won't die from too much sun, they won't freeze in winter, and they will eventually be host to mosses and lichens.
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