The NSS Bulletin - ISSN 1090-6924
Volume 39 Number 4: 104-105 - October 1977

A publication of the National Speleological Society

A Growth Rate for Cave Gypsum Needles
Stewart B. Peck


Gypsun (selenite) needles in an Iowa cave grew to an average mass of 0.0056 g and a maximum mass of 0.0160 g in 90 years or less. This represents a mean and a maximum growth rate of 0.062 and 0.18 g/1000 years, respectively. If this maximum growth rate is applicable to needles in other caves, then, one of a frequently encountered large size (15 cm long and 5 mm wide, weighing 5 g) would required about 28,000 years for its formation. Such long development times argue strongly for the preservation of these fragile cave deposits.

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