Tuff is mainly composed of pyroclastic materials less than 2 mm in diameter (i.e., volcanic ash) that are cemented by finer volcanic dust. Tuffs form from the deposition of fine pyroclastic materials from the volcanic plumes of eruptions that are transported by the eruption’s airflow, the atmospheric air streams and wind. Hence, tuffs are a product of the deposition of materials out of the air after an eruption. The landscape of the ancient quarry caves in the Zhangyu Cave Tianjing area in the Yandangshan Global Geopark are almost entirely composed of tuff. The materials of the third phase of eruptions in the main park of the Yandangshan Geopark are all tuffs.