i want to put down some 4x6 green treated landscape timbers to form a barrier between by gravel driveway and lawn to help keep the lawn gravel free and to make a nice clean line . i was planning on burying the 4x6 about 2 inches but dont think it will stay in place very well. anyone have a system to anchor the 4x6 that will keep it inplace better such as maybe a small footer every 8 feet or so where the timbers butt together . not sure about frost heave either ..