The rocks are over 65 million years old formed by volcanic activity.

The bedrock of the park is basalt formed by volcanic activity 1.1 billion years ago.

The wilderness contains several U-shaped valleys formed by glacial activity.

But he knew enough to guess that this mountain, and the surrounding hills, had been formed at some time by volcanic activity.

Furthermore, coincidence detection can reduce the jitter formed by spontaneous activity.

The stones were originally formed by volcanic activity in the Miocene era.

Sakurajima was formed by later activity within the caldera, beginning about 13,000 years ago.

There are eight plains and 12 crater lakes on the mountain that were formed by volcanic activity.

A black sand beach was formed by volcanic activity.

In addition to the weathering process, some clay minerals are formed by hydrothermal activity.