Basalt stone can be found in many parts of the world. It is used as a building block, a paving stone, and as a functional cladding.
This particular wall, like many historic stone masonry walls, was built with a stone plinth at the base of the wall. The bottom four courses of the wall constitue the wall plinth. The plinth at the bottom of the wall is a patt of the building foundation. This wider and stronger area of stone masonry at the lower section of the wall adds strenth and helps better distribute the heavy load of the building onto the subsurface earth.
This is a beautiful historic wall, built with ashlar stone masonry. A pitching chisel was historically used to create the ornate ashlar edge at the top and bottom of each stone course of the wall.