Rob Roy runs the Earthwood Building School at www.cordwoodmasonry.com. Here is an explanation on Cordwood from his website. "Cordwood masonry is an old building technique whereby walls are constructed of short logs (called "log-ends") laid up widthwise in the wall within a special mortar matrix. The wall derives excellent insulation and thermal mass characteristics from insulation sandwiched between the inner and outer mortar joints. Cordwood houses are low in cost, use indigenous materials, and are easy and fun to build."
David Nash Owner of the Shepherd School and author of Understanding the Use of Handguns and the upcoming 52 Projects for a Self Reliant Life