posted a pic on the landscape design gallery.

you can use ' stepped' sections of rock or you can build a gradual arcing rise and or a combination of both to go from 12" to 3 feet in height change. ..... but you will have a very hard time doing it with roundish rocks and hope to get a stable dry lay.

It's not impossible but you will be 'working' the rock, not merely choosing one and setting it.

Get the chisel, saw and hammer out.
and or the concrete and mortar.

This is not a good application for rounded rock. If you dig a foundation (can be packed gravel) and use mortar, you can get a stable wall, but you really want stone that will hold together. If you like the look of precast retaining wall blocks, they will be stable and can retain a 3' elevation change. Lay them level and step down towards the lower heights.

I've started building the wall and have posted photos on the Landscape Design forum gallery. (Also, there is an interesting series of posts there in response to my question.)

-- wd

Look into slip formed construction
otherwise you migt as well stak bowling balls

We're going to be building a large patio out of stone. A friend of mine said that we need to build it on a foundation dug below the frost line(we're in New England), but the mason claims that since it's a dry wall, we don't need to do a foundation because the water will percolate through. The patio will be raised about 24 in. in most areas and 30 in. in one area. What is the right way to do this??

Your mason is correct. Your stone retaining walls should be constructed on a foundation of compacted native gravel (meaning you need to remove all the loam and clayey soils beneath the walls to good gravel, or excavate down sufficiently such that at least 6 inches of gravel can be placed under the bottom layer of stones, and that bottom layer of stones is totally below grade).