Please forgive the busy people's backsides! The rocks we used are slightly metamorphosed weathered pieces of columnar basaltic andesite. Those of you who visited some of the hiking sites in the Western Oregon Cascades during the 1998 NARGS Annual meeting have seen this type of rock in natural outcrop. Long jointed columns are produced by a unique set of thermal and geochemical circumstances. The dominant set of joints is very elongate and a secondary set promotes natural breakage into large prismatic pieces of rock. Loren located the quarry and one of the nicest characteristic of these rocks is that the all of those that Loren obtained are naturally shed pieces. This means that breakage is old and all surfaces have a nice soft alteration to them that causes them to look especially mellow. Sometimes in quarry rock, the excess of freshly broken surfaces can be ugly and jarring.
Josef Halda has built and/or supervised the building of hundreds of rock gardens around the world
Rock Garden Construction Techniques: Using the Small Utility Cat and a Very Handy Tool
Placing Dwarf Conifers for Planting