| Peck used locally quarried andesite, a brittle stone that fractures into sharp, angular shapes and has a sparkly surface. |
| Both the sandstone and andesite show strong quartz and chert veining and carry disseminated pyrite. |
| The volcanic strata consist of sheet-like flows of andesite, dacite, basalts, and trachybasalts that are interbedded with agglomerates and tuffs. |
| Made from a single slab of andesite weighing at least 10 tons, this monolith is carved in the form of a doorway with niches on either side. |
| They are marked by eruptions of cooler, stickier lavas such as andesite, dacite and rhyolite. |
| Nevado del Ruiz volcano is an andesite stratovolcano located in the northern Andes of Colombia. |
