The clay in the (Mix 2) gravel is put there to bind the large particles together on the road. This is exactly what you don't want in true rock garden soils. I would use very little of that, in favor of peat and sand. What do they use to spread over icy roads in the winter where you are? Here it is always a coarse sand, or sand/salt mix, although the sand is 1-2mm size.

Fortunately, the plants you've mentioned are pretty forgiving, but here are three recipes for true rock garden soil:
1 part loam
1 part washed gravel
1 part coarse sand (5mm)
1 part composted peat or fine bark chips

1 part loam
1 part peat or compost
1 part grit (mixed sizes)

2 parts coarse sand (5mm)
1 part loam
1 part bark or peat

I know a man who grow cactus here in Minnesota very successfully. His mix is 1 to 1.5 inch trap rock(very angular is the important thing) and enough good garden soil to fill in the cracks. The long, continuous edges of the large rocks provide better drainage than a bunch of smaller sized rocks used at the same ratio.

Rick

Thanks Rick. A few more of my own tests and your advice and now it all makes more sense to me and I will use the sand instead of the gravel/clay mix. The sand is fine (majority 1-2 mm with some 4-5 mm in there as well) but I mixed up a bucket of 2/3 potting soil and 1/3 sand to pot up my semps and I can see now how wonderful such a mix is. I'll add sand and peat and leave the gravel mix for the roads.

I took my cupful of gravel/clay mix outside to toss it and as I was pouring it out I noticed how the dry clay particles were just dust that just blew away.

We just got back from rock picking - as soon as the weather turns I want to start on this project (next week, so 'they' say).

Now, this is something that puzzles me...
The sand that Pudge describes is actually "very coarse" sand, on the Wentworth scale used both in geology and in geotechnical (i.e. construction) work (1mm to 2mm is "very coarse", and above that size is "pebbles").
Do the grain sizes called for alpine gardening soil recipes use any recognized size classification? I suppose only roughly....

Lori, I don't have a clue. But the "coarse sand (5mm)" I just copied, and seems really big to me too. Prior to seeing this, I thought of coarse sand as 1-2mm also. Not that I should have, but I've never seen any kind of alpine categorizing of size, except for number size of grit already labeled on the bag (0,1,2,3,4).

Rick

I didn't even know there was a scale for measuring sand, pebbles, rocks. It is so great to learn something new every day.

Nestor the gravel guy just dumped off a large pile of sand. The rocks I'm going to use are piled on the other side of the driveway. Tomorrow I'll pick up the peat. I can't wait to get started!

Lori, I wonder if you could answer a kind of off-topic question for me - the large rocks we picked are varied and I was trying to figure out what kind of rock is probably located in east-central Sask. Some look like granite, some like quartz, some like basalt... ***some sparkly like gold*** LOL. It is likely that there are all these kinds of rocks located in the same area that likely came from the same field? Do you know of a good website where I could identify a little better? I'm really just curious about them - they're all so beautiful.

Pudge,
Actually, it's kind of a funny but it's unlikely that most of the rocks you're seeing are really "from" your area. Most of the rocks we see at surface on the prairies were actually transported from large distances away by the movements of the glaciers... (Same where I grew up in central Sask... strange that one would become a geologist in the relative absence of rocks! Or of outcrops, at least!) I believe the nearest outcrops of in-situ bedrock (i.e. older than glacial age; exposed at the surface) would be up along the Hanson Lake Road area, approaching The Pas, and in the Shield area to the east and southeast, and in the Cypress Hills to the west...(I'll have to check this, against a map of Saskatchewan geology, though, to be sure that there isn't some pre-glacial strata outcropping in the river valleys in the area.)

So, anyway, the rocks you see in the fields, and in the young glacial deposits that are dug up as gravel pits (after being eroded/transported and weathered down into gravel), were generally transported by glacial action, generally from the Shield area.
So, the rocks you see are likely to be a mix of sedimentary, volcanic and metamorphic, since they were picked up across the vast terrain along which the glaciers moved. Yes, it's very likely that some of your rocks are granite or other volcanics, others are metamorphic (schist, gneiss), some are sedimentary (limestone, sandstone); the quartz cobbles or boulders could have had a variety of origins (may have been weathered out of very-coarsely crystalline volcanic rock, or from fracture-filling; or sedimentary from fillings of cavities, or metamorphic from recrystallization of sandstone). The sparkly ones may be schist, a metamorphic rock containing abundant flat, shiny crystals (biotite and muscovite) that are all aligned by heat and pressure and folding. Anyway, that may be a little more than you wanted to know, LOL!

Sorry, I can't think of a good website offhand for rock ID but I'll think about it and ask at work...

Hey there,
Check out the site below. It's a neat key to identify rock type.

: ) Always ready to encourage people in their love of rox!

~Onion

Here is a link that might be useful: Rock Identification Key

A very interesting read, Lori. And applicable to so many of us in the north too.

Thanks very much Lori - you answered my question completely and not at all too much information - a very clear explanation. With some of the names you've given I've found quite alot of pics and info on the web. Definitely have gneiss and schist in the pile.

One of my favourite pastimes as a kid on the farm was at a rock pile (and you must know how many of those there are - at least one on every field). Anyway, we'd stand at the top of the pile, lift up the biggest rock we could and then throw it down on another rock, hoping to break it open to see the colours inside the rock. How many times we took home 'gold' for mom, no doubt hoping that we'd turn into the Beverly Hillbillies and get a cee-ment pond LOL. Funny thing is, I still want to do that when I see a nice rock pile.

Thanks Onion - that site is very helpful for identifying.