The Geology series are made from crank clays mixed with various substances to give extra texture (grits, feldspars, sand and wood-wool) and to leave the clay still throwable. After bisque firing, various techniques are used to apply oxides and the glazes which react with the oxides during firing to give a broad spectrum of colours including greys, pinks, browns and greens. The final firing melts the grits and feldspars so that they expand and erupt from the surface of the clay.