We salvage materials from the surrounding land and river bed: river rock to form gabion cages ... scrap metal) or retaining walls (tires, corrugated steel pieces, gravel). As many recycled ...

Basalt rock formations cradle the deep ... basalt formations to build the Historic Columbia River Highway, masons created stone retaining walls and viaducts that still stand today.

These are not retaining walls, however ... Tightly interlock the rock. Misshapen rocks work much better than rounded river rocks — friction between the faces of the rock allows the stones ...

Avoid rounded stones like pea gravel or river rock; they don't form strong interlocking ... Get the first course of landscape retaining wall blocks right Use a torpedo level to level each of ...