What can I do with a few tons of round river rock?

I might only have 2 months (God willing) before living offgrid. So I gotta ask way in advance of needing the info, but you know the Lao Tzu saying, "Dig the well before you are thirsty." The house I fuly intend to buy has this huge slope behind it where I intend to put a geothermal greenhouse. This slope is stabilized by a few tons of 3-4 inch rounded river rocks which mostly appear to be granite and marble. When I get around to building the greenhouse, I will have to do something with the vast majority of these rocks. Any ideas?

They sound perfect for an underground heat storage battery.  Check out the Deep Winter Greenhouse from the University of Minnesota.  Fans blow air through a basement filled with gravel.

Don't do like my neighbor and use them for your driveway.  They don't pack down so he's regrading it about once a month.  And I can hear a car pull in from 300 yards away.

Mike Jay wrote:They sound perfect for an underground heat storage battery.  Check out the Deep Winter Greenhouse from the University of Minnesota.  Fans blow air through a basement filled with gravel.

That actually sounds genius. Is the battery insulated and how deep does it need to be? My existing design includes a terrace cut into the hill.

I believe it's insulated and I think they go down 6-8'.  All the info is in that website with downloadable plans and details.  You might need to get an additional 20 tons of rock to fill out the basement.  They are assuming you're starting with bare ground but I bet you could get creative.

I look at materials laterally.
Round rocks dont pack well, unless in a drum or similar container.
I live in a forest where a cold breeze comes through.
I have built a wall with drums full of rocks or water.
The rocks or water ensure the drums dont blow away.
Now in your environments, you may also have a need to prevent drafts, but there is no need to mortar the rocks,
any small gaps allow the draft to filter through a bit and its not as bad as a gale blowing across the ground.

They would be beautiful as the footing for a barn or house, or used for a wall, fireplace or retaining wall.

A lazy man's way of using them in a wall is to build forms like you would if you were pouring concrete, and then mortar the rocks into place as you carefully stack them inside the form one at a time.  By doing this, you don't have to worry about keeping your wall true/plumb --- you just set the flattest side of the stone against the plywood form, and then plop a dollop of mortar behind it.  Once you remove the forms, you can go back with a piping bag and point the mortar joints if they aren't perfect.  Easy peazy.  Use course sand or small gravel and a bit more portland cement than normal, as round river stones can pop loose if you don't use a strong mix to really hold them.

Make sure you wet the stones before you add them to a wall, as that'll help the portland cement to stick to them better.

Adding rebar every couple of feet adds a great deal more strength to any wall.  Mortar the rebar into place solidly, as you don't want water to find it's way into the wall and cause the rebar to rust.

If you use this method, you can't build really tall forms, as you'll not be able to reach down into the cavity to carefully place the stones.  Generally, I'll make the forms no taller than 18 inches.  Once the wall reaches the top of the form, you need to unscrew them and move them up so you can continue the process to the full height of the wall you desire.

Some ideas:

1. Perhaps an obvious use is as a gabion wall to protect plants from wind, create a microclimate, habitat for small creatures, etc.

2. As part of a ‘keyhole garden’ (in-situ compost bin) e.g. make a gabion-like structure in the middle of a garden bed, with the rocks in the bottom layer. Feed it with vegetable scraps and water in. The nutrients and moisture disperses to feed the surrounding vegetables.

3. Talus garland around trees to keep them moist and regulate temperature

4. Thermal mass in a wall surrounding a heat source

Rocket stove thermal mass, is another idea of what you could do with that.

F Agricola wrote:3. Talus garland around trees to keep them moist and regulate temperature

Hi F, could you elaborate on this a bit more?  I'm not sure what a talus garland is...

Or make walls with them on the south of the greenhouse.
You'll have a draft problem so you'll need to close the back with something like lime sand mix.

Mike Jay wrote:

F Agricola wrote:3. Talus garland around trees to keep them moist and regulate temperature

Hi F, could you elaborate on this a bit more?  I'm not sure what a talus garland is...

A picture says a thousand words - the one below was borrowed from 'The Net' and best describes the idea for those in the Northern Hemisphere:

Hugo Morvan wrote:Or make walls with them on the south of the greenhouse.
You'll have a draft problem so you'll need to close the back with something like lime sand mix.

Rocket stove thermal mass, is another idea of what you could do with that。

Why not both? I think I saw a rmh somewhere with gabion mass.