Photographic evidence has shown that a stalagmite shawl developed in a mining tunnel in less than 150 years. Other long stalactites and fair-sized stalagmites in a disused mining shaft have also been observed. There are also a host of stalactites growing under the Australian War Memorial; or perhaps even the Western Australian waterwheel which was frozen in limestone after only 65 years. The fact remains differing flows of materials can impact growth rates. It is only logical that when most are observed under current rates they can be backward calculated as very old but different natural conditions could have been much different in the past—such as a global flood cutting many of the underground caves where these structures are found in the first place.
Fast-growing stalagmites and stalactites are created by minerals running through the rock layers above and dripping or running into the cave. Because the rate of flow of these waters may have varied over thousands of years the rate observed today has nothing to do with the rates of the flow when forming.
Using a rapid growth rate, these cave formations could easily fit the biblical time line after the worldwide Flood 4,400 years ago. Unfortunately, evolutionary scientists struggle to keep the biblical time line out of science; although science, time after time, falls right into step with it.”https://creationtoday.org/rapid-cave-formation/