basalt

But under the water, volcanoes continued to erupt, sending up magma and forming mountains of basalt.

但是在水下，火山依旧喷发，滚滚岩浆形成了玄武岩的山脉。

As they approached the shore, a lanky, suntanned, salt-encrusted 26-year-old stepped out with a splash and clambered up onto a jumble of broken basalt.

当他们到达海岸，一个瘦长的，黝黑的，身上沾著些许海盐的26岁青年溅踏着水面爬上一堆杂乱破碎的玄武岩。