Tuffaceous rock contains greater than 50% tuff, i.e. consolidated volcanic ash. Image: Tuffaceous rhyolitic pyroclastic deposit, with weakened areas (probably from initially hot gases) eroded out over the millenia to form the pits and holes of the wall rock. Banshee Canyon, near Hole in the Wall Campground, Mojave National Preserve, CA. (© Mike Malaska, via Flickr)
This is an image for Basaltic…? Felsic…? Porphyritic…? Confusion!.