Compost, Soil, Humus, Loam , Silt, Clay, Sand ?

I know the technical definition of each but what combination do I need to create a good planting medium for a raised bed?

I need to fill a large raised bed for planting without spending a lot of money and want to be able to plant in it next spring. It will take about 4-5 cubic yards to fill the now empty bed.

I can get river sand and silt, (composted) cow and horse manure, partially composted redwood needles, and a soil amendment made from mostly fir bark and sand all free in any quantity I need. What I can't get is top soil. So my question is, will a mixture of these things make a decent planting mix? If so what percentage of each should I use and what else if anything would I need to add to make it work?

I think a mix would be fine....it's all good stuff you mentioned there....I've made raised beds with old driveway gravel in a pinch and grown wonderful flowers. I wouldn't (myself) worry about the percentages, unless you want to grow prize roses or something similar, all the ingredients you listed are pretty much what topsoil consists of, and you can always amend every year with compost, or mulch, to improve...fertilize if you feel you have to....

Thanks. I just wonder mostly about the silt or sand. Without it it is pretty much basic compost. Does it need "dirt" for minerals or somethingor is it just for texture?

The sand would lighten it up---give it a bit of drainage----I don't know about minerals----I just use whatever is at hand, it always works. A bit of silt and sand, as long as it's not salty, couldn't hurt, I wouldn't think.

OK, thanks. I'll go ahead and add some to my mix. I get on the river and it shouldn't be salty.

clay would offer minerals and act as a soil binder and also retain some moisture. but that may be why you are using raised beds in the first place. lol.
I agree you can probably grow in any combination of those things, but if drainage is too quick it may flush out all the nutrients so you will probably have to fertilize often.
the silt and compost might be more prone to washing or blowing away.
do you have any clay you could add?

If you don't, I have extra... *sigh* ....

No clay :~(
But I am watching the freecycle and maybe I'll luck out and find some.

I know I could amend clay with the compost to get beautiful results. So send a couple yards of that clay my way please!

I can get all the silt or sand I want and composted manure is fortunately available from a friends farm so I can add more each season if needed. But I have never been in a situation where there was no base soil to work with like this.

The bed is 22" deep on the bottom tier and 32" deep on the upper tier. It sits on a 6"-8" bed of gravel and the ground behind it slopes down and away from it. So it should have good drainage (too good ?)

There is clay down there under all that rock but I can't dig it out since it is buried under the gravel and about 2 ft of rubble that they used as land fill when they built this place. (It is an apartment complex) We found that out when we dug down to put in a small pond and all we got for the first two ft. was rusty metal and chunks of concrete and then the clay.

WOW..........your freebies are a literal gold mine. I just do not see anything but a great soil about to be created. Give yourself three years. Add lots of compost at the end of your season till lightly and plant a cover crop. If you have leaf material you can add with the compost in the fall or use as mulch throughout the growing season.

Keep on educating yourself by reading organic gardening source sites like this.