Stalactites can grow very rapidly (Talk.Origins)
- Stalactites can grow very quickly. Some have been observed to grow more than half an inch per year. The largest stalactites and flowstones could have formed in a few thousand years.
Source: Meyers, Stephen and Robert Doolan, 1987. Rapid stalactites? Creation Magazine 9(4) (Sep.-Nov.): 6-8.
CreationWiki response: (Talk.Origins quotes in blue)
1. The fast-growing stalactites form via processes very different from calcium carbonate stalactites found in limestone caves. Limestone is not soluble in water. When carbon dioxide (from decaying plants in the soil above the cave) mixes with water, it forms a very weak carbonic acid. This turns the calcium carbonate into calcium bicarbonate, which dissolves. When drips are exposed to air in the cave, a little carbon dioxide escapes from them into the atmosphere, which reverses the process and precipitates a small amount of calcium carbonate. The upper average rate for limestone stalactite growth is ten centimeters per thousand years, with lower growth rates outside of tropical areas.Fast-growing stalactites, on the other hand, either grow from gypsum through an evaporative process, or they form from concrete or mortar. When water is added to concrete, one product is calcium hydroxide, which is about 100 times more soluble than calcite. The calcium hydroxide absorbs carbon dioxide from the atmosphere to reconstitute calcium carbonate.
Not true at all. The calcium carbonate Crystal Spring Dome stalactite is a fast growing.
Also, lab experiments, by Emmett L. Williams and others, have shown that calcium carbonate can in fact spawn fast growing stalactites. The problem is that Talk.Origins model for calcium carbonate stalactite formation is completely unreasonable for a post-flood environment.
Williams et al "DEPOSITION OF CALCIUM CARBONATE IN A LABORATORY SETTING" CRSQ Volume 12, Number 4 March, 1976
Williams et al "Solution And Deposition Of Calcium Carbonate In A Laboratory Situation II" CRSQ Volume 13, Number 4 March, 1977
Willaims et al "Solution And Deposition Of Calcium Carbonate In A Laboratory Situation III" CRSQ Volume 15, Number 2 September, 1978
Williams et al "Solution And Deposition Of Calcium Carbonate In A Laboratory Situation IV" CRSQ Volume 17, Number 4 March, 1981
2. The time for stalactite growth also has to allow for time for the cave to dissolve in the first place, which is a very slow process, sometimes on the order of tens of millions of years. Then the geological conditions have to change so that the cave is no longer under water. Only then can stalactite growth begin.
This is true only if carbonic acid did the job, however there is evidence that both processes originally involved sulfuric acid not carbonic acid. Sulfuric acid would greatly speed up bot cave and stalactite formation because it readily devolves limestone. This is supported by none Creationists sources so it seems that Talk Origins data is out of date.
- Reference: Cavern Genesis
- Reference: Cave Geology
- Reference: Limestone
- Reference: Rapid cave formation by sulfuric acid dissolution
- Note: only the last reference is a Creationist source.
Furthermore, there is overwhelming evidence pointing towards the possibility of rapid stalactite formation.
- Stalactites in Cedarville, Ohio, grew in a mere 35 years. That calculated growth rate was a minimum 0.53 cm3 per year. 
- A mine in Pennsylvania reports a growth rate 40 times that found in Cedarville. 
- A massive stalactite called "Crystal Spring Dome" has been shown to grow at a rate of 2.5 in3 per year.
- E. B. Cannell has shown stalactites at Ottawa River ,Quebec, growing at a rate of 4.61 cm3 per year.
3. Direct measurement via radiometric dating gives stalactite ages over 190,000 years (Ford and Hill 1999). Other deposits in caves have been dated to several million years old. For example, argon-argon dating of alunite (an aluminum sulfate mineral) gives an age of 11.3 million years for a cave near Carlsbad Caverns.
Several things need to be noted here:
- Given the fact that stalactites form by precipitation and volcanic activity it is likely that these dates are at least partly a result of inheritance of isotopic ratios form their source material. This likely hood is increased if sulfuric acid was involved in the formation rather than carbonic acid, since sulfuric acid will dissolve substances that carbonic acid can't.
- Those feature that are dated more than once actually show a rapid formation. In each case the dates are from all along the growth pattern and all of them are within the margin of error of each other, this means that the growth times are statistically zero. They can be any were from 0 - 140 thousand years and 4.5-5.5 thousand years is within this range.
4. Oxygen isotope measurements in stalactites give an indication of outside temperatures. They are consistent with the coming and going of ice ages back at least 160,000 years.
Oxygen isotope measurements are not independent dating methods but they are totally dependent upon the climatic models used to interpret them. Talk Origins interpretation is based on Uniformitarian climatic models. However climatic models based on a recent Global flood would place them just after the Flood at 4.5-5.5 thousand years ago. This is a good example of "Your theory does not work under my theory, so your theory must be wrong."