岩漿經火山爆發碎裂成顆粒小於2mm的碎屑所膠結組成的岩層。碎屑組成的成分包括有玻璃質顆粒、岩石破片和晶體等三種，依不同比例所組成。在澎湖主要出露的地點有青螺、赤嶼、馬鞍山嶼和七美龍埕等地。凝灰岩這類細小的火山碎屑物都是快速冷凝的熔岩，澎湖所見的凝灰岩大都是棕紅色或灰色。赤嶼底部之凝灰岩，厚約1〜2公尺，，質地疏鬆，淘選度良好，主要由灰白及棕紅色之粗粒礦物所組成，除呈現水平層理外，並有粒級層之構造，上層顆粒較細，下層顆粒較粗，灰白色礦物愈向上也愈少。內含玻璃質碎片和晶體或晶體破片，幾乎皆由石英所組成，玻璃質碎片大多經過蝕變作用，而形成綠泥石或其它黏土礦物，岩層中具有正斷層與逆斷層的構造。本標本採集自湖西鄉赤嶼。
岩漿經火山爆發碎裂成顆粒小於2mm的碎屑所膠結組成的岩層。碎屑組成的成分包括有玻璃質顆粒、岩石破片和晶體等三種，依不同比例所組成。在澎湖主要出露的地點有青螺、赤嶼、馬鞍山嶼和七美龍埕等地。凝灰岩這類細小的火山碎屑物都是快速冷凝的熔岩，澎湖所見的凝灰岩大都是棕紅色或灰色。赤嶼底部之凝灰岩，厚約1〜2公尺，，質地疏鬆，淘選度良好，主要由灰白及棕紅色之粗粒礦物所組成，除呈現水平層理外，並有粒級層之構造，上層顆粒較細，下層顆粒較粗，灰白色礦物愈向上也愈少。內含玻璃質碎片和晶體或晶體破片，幾乎皆由石英所組成，玻璃質碎片大多經過蝕變作用，而形成綠泥石或其它黏土礦物，岩層中具有正斷層與逆斷層的構造。本標本採集自湖西鄉赤嶼。
The magma is fragmented by volcanic eruption into a rock layer cemented by debris with grains less than 2mm. The composition of debris includes glass particles, rock fragmentscrystals, which are composed under different proportions. The main locationswhere tuffs are exposed includeCingluo Village, Chiyu, MaanshanIsletDragon Sea-eroded Platform in Qimei Township. Small volcanic debris such as tuffs is fast-condensing lava,most of the tuffs seen in Penghu are brown-redgray. The tuff at the bottom of Chiyu is about 1 to 2 meters thick. Its texture is loosethe panning degree is good. It is mainly composed of gray-whitebrown-red coarse-grained minerals. In addition to the horizontal bedding, there is also a structure of granular layers, whose upper layer is finerlower layer is coarser.And theless the gray-white minerals are, the higher they go up.Tuff contains vitreous fragmentscrystalscrystal fragments, which are almost all composed of quartz. Most of the vitreous fragments undergo alteration to form chloriteother clay minerals. Its rock layers have normalreverse fault structures. This specimen was collected from Chiyu, HuxiTownship.
