Covering the basics of building a drystack retaining wall. And there is a giant rock sloping the wrong way right where the drystack needs to go. You always want to start with a strong foundation, and then you begin adding your big rocks to the outside, medium rocks on the inside, and small gravel in the cracks and filling the back. Sharp gravel is KEY! Never use round pebbles, as it's like trying to build with marbles. Sharp gravel will give you good traction and support, as well as drainage, when building a dry stack wall. Be sure to orient your long rocks into the slope, instead of in line with the wall. As well as tilting them slightly up slope. In the video Paul and Jocelyn are making this retaining wall to fix a switchback trail. The trail base is rock and gravel, filled with sand, and then covered in dirt. This makes for excellent drainage as well as a strong base for years to come.