【彭立穎】評論
exploration探索eruption(火山)爆發
【r70218】評論
Volcanic eruptions over the last 10 million years covered the area in ashes, which became compacted to form a soft, porous rock called tuff.過去千萬年的火山爆發,用灰燼覆蓋了這個地區,且經過擠壓形成了一種柔軟多孔洞的岩石,稱作凝灰岩(tuff)。