A mortarless, or dry-set, stone wall imparts an old-style character to the landscape. A well-built dry-set wall will last for years. The first settlers in America built walls this way, and many of those walls are still standing today.
Besides not requiring mortar, a dry-set wall doesn't need a footing. It will flex as the earth moves due to freezing and thawing, but it won't fall down. For this kind of durability, however, you must select stones with as much surface contact between them as possible.
Where the contour of the stones form spaces that could cause the stone to move, fill in with small pieces of stone. You'll also need bondstones -- long, flat stones that are long enough to span the front and rear wythes of the wall, tying them together. Taper the sides of the wall inward from bottom to top about 1 inch for every 2 feet of height. You might have to cut the upper course of bondstones to length.
About 2 days to excavate and set a 3x10-foot wall
Round-nose shovel, mason's line, stakes, tamper, circular saw, hammer, mason's hammer, stone chisel, level, cordless drill
Designing layout, digging, lifting and setting stone
Gravel, stones, 1x2s (for batter gauge), 1-1/2-inch screws
Sort the stones into size groups. Use the largest, flattest stones for the base, smaller stones for the succeeding courses, and smaller chunks for filling in. For the wall footing, lay out and excavate a trench 8 inches deep and 6 inches wider than the wall on each side and at each end.
Shovel about 4 inches of gravel into the trench; level and tamp it. Set bondstones on both ends of the trench. Using stones of different lengths, lay the front wythe (face) of the first course. Place a bondstone every 4 to 6 feet. Set the thinner edge of the stones in the center of the trench.