It is primarily formed because of hydrothermal activity, which involves water and high temperatures.

However, many hot springs can be found in the city, indicating hydrothermal activity.

The seafloor deposits appear to be connected with hydrothermal activity.

Some hydrothermal activity remains along the lake floor.

Consequently, hydrothermal activity would have provided sufficient energy for biological activity.

Mineral deposition from hydrothermal activity added additional chemicals to the mixture.

It was a focus for later felsic intrusions and hydrothermal activity.

Such hydrothermal activity is most common during the later stages of volcanism.

As of 2005, some hydrothermal activities and gas fumaroles were active among these volcanoes.

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