What does the rock formation 'flowstone' refer to?

Flowstone refers to a type of mineral deposit that occurs when water flows over a surface, usually within caves. More specifically, it is formed by mineral-rich water that deposits minerals as it flows, producing a smooth, sheet-like layer of minerals. This occurs in environments where water is continuously dripping or flowing over the rock surfaces, allowing dissolved minerals to accumulate and harden, ultimately resulting in a flowing appearance.

The correct answer highlights this process, distinguishing flowstone from other geological formations. Understanding flowstone helps in recognizing the unique characteristics of cave environments and the processes that shape them. The other options refer to different geological features and processes, such as freezing water or volcanic activity, which do not relate to the formation of flowstone.