sentence: Some hydrothermal activity remains along the lake floor.
sentences_before: Fumaroles and hot springs remained common and active during this period. Also after some time, the slopes of the lake's caldera rim more or less stabilized. Streams restored a radial drainage pattern on the mountain, and forests began to cover the landscape. It is estimated that it took about 720 years to fill the lake to its present depth of 594 m. Much of this happened during a period when the climate was drier than it is now.
sentences_after: Mazama may erupt once again.
concept_name: hydrothermal activity
headings: Crater Lake Geology
categories: Geography of Oregon Lakes in the United States Volcanoes in the United States Calderas