例文
- The Tongan Volcanic Arc has been important in supplying the islands on the Tonga ridge with an andesite tephra soil that has resulted in " an extremely rich soil capable of supporting a high-yield, short-fallow agricultural system . " Also, the andesite / basalt from the volcanoes were initially used as " hammerstones, weaving weights, cooking stones, and decorative pebbles for grave decoration . " Tafahi island in the far north provided volcanic glass to initial human settlers.
