Travertine forms from hot spring water percolating up through underground limestone. When the water evaporates, it leaves behind layers of dissolved limestone and other minerals, giving it its banded appearance. The characteristic holes in travertine are the result of trapped gas bubbles; as the gas escapes, crystals form in the cavities. The resultant stone is a smooth, porous, naturally decorative material which offers a soft cream hue, and overall old-world beauty, and a dense and durable surface.