Rock work can be veneer style where a rock facing is applied to concrete or concrete block (cinder block) or stone that is stacked freely with mortar in between. A rock wall can weigh a thousand pounds per linear foot and a six foot high column can weigh three thousand pounds. It is very important that the foundation is the correct size for the walls or columns being contemplated. Soil conditions need to be taken into account as well. Many rock work projects fail due to poor footing and foundations and or poor soil conditions.