Here you have a chance to take a close look at basalt rock. Basalt was a valuable source of tools for Indians living in the canyon. Manos (MAH-nose) and metates (muh-TAH-tays) for grinding corn, picks for carving out caves, and axes, hammers, and other tools that had to stand up to heavy use were often made from basalt.
Tuff forms from volatile volcanic eruptions that spew ash and cinder into the air. Solid particles can actually flow like liquids during these massive explosions. Basalt forms during quieter eruptions flowing from fractures or vents in the earth’s surface as molten lava and cooling relatively quickly.