Earthbag construction for livestock

I have a nice spot, near where my house will eventually be constructed, where I want to begin building my livestock shelter (barn). When it's time to build my home, I definitely want to go with earthbag construction, but having never done it before, I'm thinking that building a small livestock shelter, or barn, would be a great way to get started in gaining experience. This first structure will be a dome, or at least start out as one. I'm still up in the air if I want to fully dome the structure, or go up in more of a round structure with a roof on it. The size is planned as a small, 12 foot diameter circle. Besides the door, my thoughts include at least 2 windows, either with glass, or simple shutters, for seasonal light and ventilation.

Here's my first question (and I'm sure I'll have plenty more!).

Buying stone/gravel for foundation work is expensive. And I am on a fixed, minimal income.
Any thoughts on using the shale we have in abundance here for the foundation and lower courses of bags?

I know for a fact that what we have drains very well, and thought utilizing natural resources for a natural type building would be a good idea. I could buy the rock/gravel needed, but would rather use the money elsewhere!

Hopefully, I'll get some informational feedback, and hopefully some ideas from some of  you who have actually done some earthbag construction.

Grab a few bags and try it! Straight shale, then a couple with different amounts of clay heavy soil added, then maybe one or two with Portland added.  

See what compacts well and doesn't fall apart.  You may need to triple bag the base layers instead of the usual double if the shale is sharp.  But that should get you a good idea for your base bags and upper layers.  

I really want to know how it turns out.  If I have to guess, straight shale won't hold compaction well but with a touch of clay or Portland it will.  I hope I'm wrong, though.

Weather!

Just as I thought I had a good chance of starting to collect my materials and getting set up.. more rain.... and MORE.

That's okay, I guess, gives me more time (between rainy days of course) to go up and do more clearing so when I do get the materials gathered it will be wham bam phew!

Perhaps in the next few days (rain permitting) I'll get some good pics and share here where I'm going to be building, and then maybe some more as I go. Definitely appreciate any feedback and opinions.

Have a Blessed Day! (and stay dry....)

Well, the site I was planning to use is no longer an option. I'm moving!

Now I will need to find a site on the new property to build on, and may end up having to purchase all fill materials since the new place is pretty flat. Fortunately there are some good resources in the area, so I feel confident this idea will still come to fruition.