Thundereggs specifically form in rhyolitic lava. Rhyolitic lava ... the surrounding volcanic rock, the denser thundereggs are gradually exposed. In some cases, erosion can wear away the outer ...

Kilauea, one of the world's most active volcanoes, has been erupting on and off for nearly two months since it burst to life ...

Basalt is usually formed when lava solidifies on the earth’s surface ... The sediment comes from eroded rocks carried there by rivers or ice, and from the skeletons of sea creatures.

Now, an investigation of ancient lava formations by ... among those who thought the rocks were volcanic, which has since proved to be the case. That means wind erosion likely scoured sedimentary ...