Journal of Cave and Karst Studies - ISSN 1090-6924
Volume 62 Number 1: 20-26 - April 2000

A publication of the National Speleological Society

Results of a Speleothem U/Th Dating Reconnaissance from the Helderberg Plateau, New York
Stein-Erik Lauritzen and John E. Mylroie

Abstract

The Helderberg Plateau consists of Silurian-Devonian carbonates that crop out across central New York State, supporting a well-developed, multiply glaciated karst. Stalagmites and flowstone were collected from five caves spread across a 60 km long traverse of the Plateau from Albany west-northwest to Schoharie County. Subsamples from these spleothems yielded 36 U/Th alpha count dates ranging from 3 ka to >350 ka. While the data reported here are only a reconnaissance study, they represent the most comprehensive geochronologic data base for any karst area in the northeastern United States.

Hollyhock Hollow, southern Albany County: two cave-fill samples yielded three dates of 70-56 ka and four dates of 41-35 ka; the mid-Wisconsin dates may reflect the cave’s southerly position. Onesquethaw Cave, central Albany County: two stalagmites yielded 5 dates, all Holocene (<9 ka); the dates suggest that Onesquethaw Cave may be post-glacial in origin. Caboose Cave, eastern Schoharie County: five stalagmite and flowstone samples provided 13 dates, ranging from 207-56 ka, with distinct clusters at 100-56 ka and 207-172 ka; the dates support the cave being older than the last glaciation. Schoharie Caverns, 2 km west of Caboose Cave: six samples from one flowstone all dated to >350 ka; the dates indicate that the cave has survived more than one glaciation. Barrack Zourie Cave, western Schoharie County: two stalagmites yielded four dates, which cluster at 161-158 ka, with a younger overgrowth at 61 ka (two previously reported dates were 165 ka and 277 ka); the dates support the cave being older than the last glaciation.

The U/Th dates indicate that both pre- and post-glacial caves exist in New York. The dates cluster in the 100-56 ka and 207-158 ka range, and there are a surprising lack of dates from the last interglacial (130-120 ka), possibly an artifact of the sampling regime.

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