Naturaly Forming Clay Soils

A small group of Missoulians would like to begin a guerrilla garden this summer. We've found an opportunistic space that is in a severe state of disrepair. It's considered part of the Clark Fork river corridor, has no taxable owners, and is currently a repository for haplessly wandering hobo folk, knapweed, and run off. On the MT Cadastral website there is no indication it is zoned or owned by anyone. We've seen fit to take over this space in the spring, and control the invasive species/erosion that is taking root. Our goal is to repair the damage, while feeding nature and ourselves at the same time. To do this we'll need to build a few basic retaining walls to start a terracing system. After much consideration, a cob and stone wall seems to fit in nicely with a theme of non-permanent human structures, that can eventually degrade as the natural systems take over and roots begin to hold the hillside in place. I'm not native to Montana or knowledgeable in building cob structures. I'm at a loss as to where we can find a local naturally occurring source of clay rich soils. Most soils I see tend to be a very sandy loam that aren't well suited for cob construction. This project could be replicated up and down the hillsides as an example of trying to control and treat parking lot run off before it leads to erosion and pollution of our local water ways. As a grass roots sort of garden I would like to set the example of what a few rouge citizens can do with a bit of thought and a lot of careful planning. Any thoughts would be greatly appreciated.

Miller Creek! That's the magic word. If you drive out Lower Miller Creek and follow the road up around into upper Miller Creek you will be driving on the sediments of Glacial Lake Missoula (if you don't know about that, you should!) There is a massive development underway out there and no end of excavation. Several thousand homes are slated, I believe (in an area with questionable water supply imo) you will see the new homes in the Lower area and lots of activity in the upper area. The fiasco is called the Maloney Ranch Subdivision undertaken in part by the local WGM developers. The "ranch" manager is Artie Doris, who can be cantankerous. None of these folks are friendly to radicals like us, so it might be a long shot. But scope it out, look for an active excavation project and talk to the little guy contractor. Maybe he can give you some dirt. We live in the area and sit on a giant mound of the stuff. I have enough soils (and pottery) experience to know that this is serious clay. I made a pot of nothing but the sub soil and it was lovely. It is a small pot because there wasn't even enough sand or other fine grit to give it any structure as a pottery material. Google Earth the Lower/Upper Miller Creek Rd area and see what you can see, (the clay/soil is pale pink/brown), then take a field trip. Doris might still live in a big yellow house halfway to Upper, on the lower right side of the road. Approach with caution. Do not wear your earring. His health has been poor... The whole area, three thousand acres (?) is owned by an out-of -state family corp.

How much clay do you need? I will keep an eye out. FYI, westward toward the Fish Creek exit on the fwy, you can see huge road cuts that show the layers of sediments, same stuff. Check it out. It's quite beautiful.
Regards, Kathy J.

There is quite a bit of clay out toward frenchtown, take mullan rd to the old hwy. Or the best site I have found is out toward nine mile. Take the nine mile exit, and as you go down the hill toward the steak house, there is a good cut right off the road. Its further than Miller Cr, but it is nice red clay right off the road. There is a lot of clay around missoula, you can get soil maps to show you where the major deposits of clay are.