106 37th Annual Undergraduate Research Exhibition Sponsored by Sigma Gamma Epsilon (Posters)

All students are encouraged to submit research to this poster session. Investigations from ANY geological subdiscipline are welcome. Presenters who are SGE members are eligible to compete for monetary awards distributed at the meeting.

Monday, 20 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Limestone as Building Material at the Forts of Crown Point State Historic Site (USA, NY)

Paper number: 106-48
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Crown Point State Historic Site (USA, NY) occupies a strategic peninsula on the southwestern shore of Lake Champlain that was contested by the French and British forces before American independence in 1776. French forces built Fort St. Frederic starting in 1734; English soldiers began construction of His Majesty’s Fort of Crown Point in 1759. Both forts are composed of Ordovician shallow-water limestones quarried on site from three formations: Crown Point, Valcour, and Orwell. In this study, we set out to determine the bedrock composition of building stones of each fort to aid in their preservation. To accomplish this, we characterized outcrops of all three formations. Crown Point is recognized by its coarser (sand-sized) grains, Valcour by high dolomitization in a ribbon pattern, and Orwell by the presence of nodular chert. We next identified building stones to formation for both forts. Every 4m, we identified 2 building stones to formation: one 70cm above ground and one 20cm above ground.  At Fort St. Federic, we sampled the entirety of two of its five sides, while at His Majesty’s Fort, we sampled two of four sides of its officer’s barracks and three of four sides of its barracks for soldiers. This gave us a total of 168 building stones sampled, 78 from the French fort and 90 from the British fort. A Chi-Squared test revealed significant differences in composition between the forts. While Valcour rocks were the preferred building stones for both forts, they were twice as likely to be used at the British fort. Valcour made up 41% (37 of 90 stones) of the sampled French fort, but 82% (64 of 78 stones) of the sampled British fort. Both forts are constructed on Valcour bedrock, so its dominance reflects ease of quarrying and reduced transport distance. However, its overrepresentation in the British fort may reflect a preference for a harder building material. Valcour’s high degree of dolomitization, finer grain size, and lack of nodular chert makes it less prone to weathering than stones from Crown Point or Orwell formations. The higher susceptibility to erosion for the non-Valcour building stone walls of Fort St. Frederic requires greater preservation effort to maintain than His Majesty’s Fort of Crown Point.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414157

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