1·Around the same time, a massive volcanic eruption in the Wrangell Mountains in Alaska occurred, blanketing the area in a layer of ash, up to a foot deep, called the White River tephra.
大致在同一时期，阿拉斯加州的弗兰格尔山脉出现了大规模的火山爆发，这个地区遂被深达一英尺的怀特河火山灰所覆盖。
2·Tephra is any fragmented material produced by a volcanic eruption, be it ash or rock.
无论是灰烬还是岩石，所有因火山爆发而形成的碎片状物质都称作火山灰。
3·New information on the response of vegetation to air-fall volcanic ash is provided by analysis of phytoliths from sediments containing major tephra beds.
含火山灰层沉积的植硅体分析为了解植被对从空中下降的火山灰的反应提供新的信息。