retaining wall questions

[mooman]

I need to build a retaining wall in the back yard to control errosion and well....make it nicer. I was going to use railroad ties, but was also thinking about a old fashion rock wall. Best guess on how many tons of rock it will take to build a rock wall 3ft high and 30ft long. What is the best kind of rock to use. I'm just talking about staking them, not mortor or anything.

[cchapman84]

It's tough to make a rock wall without mortar that will actually last as a retaining wall. There's a lot of forces acting on a retaining wall, between water and gravity, and no mortar means you're going to have to have a much thicker wall. Also, make sure that you angle it back toward the fill so that it's less likely to just tip over (there are quite a few around here that have already done this).