GSA Connects 2021 in Portland, Oregon

Paper No. 189-3
Presentation Time: 2:30 PM-6:30 PM


PYLE, Eric, BS, MS, PhD; FGS, FGSA, Department of Geology & Environmental Science, James Madison University, MSC 6903, Harrisonburg, VA 22807, FEELY, Martin, Earth and Ocean Sciences, Geofluids Research Group, School of Natural Sciences,, National University of Ireland - Galway, Quadrangle Building, Galway, Ireland and WHITMEYER, Steven, Department of Geology, 1915 Marigold Cir, Harrisonburg, VA 22801-2455; Geology & Environmental Science, James Madison University, 801 Carrier Drive, MSC 6903, Harrisonburg, VA 22807

Anyone who has traveled to Ireland as a tourist in the last several decades has had to run the gauntlet of an array of both quality and kitschy goods at nearly every souvenir store and airport shop. Among the less prominent yet attractive items in these shops are items made of “Connemara Marble,” typically presented with an array of mythologies and little geology. Yet within each piece of Connemara Marble that is purchased is a time capsule of the geologic history of Connemara, western Ireland. This history is on display in locations around the globe, including Dublin, London, Yale University, and Pittsburgh and Harrisburg in Pennsylvania.

Petrologically, the Connemara Marble is hardly a marble at all, but represents a class of metamorphic rocks called ophicalcites, reflecting both an initial dolomitic limestone composition as well as later serpentinization. Late Proterozoic deposition occurred on the flanks of Laurentia and was followed by multiple Paleozoic metamorphic events in which the dolomites and interbedded siliciclastic materials transformed to foliated rocks containing silicate minerals including olivine, diopside and tremolite. Subsequent hydrothermal alteration of these minerals produced the visually appealing serpentine-rich rocks, albeit incompletely across Connemara, which restricts economic deposits to relatively few locations. The Connemara Marble records up to three deformation events, from microscopic folds to the kilometer-scale Connemara Antiform that formed during closure of the Iapetus Ocean. Later Mesozoic rifting left the Connemara Massif, complete with related intrusive rocks, attached to western Europe.

The significance of the Connemara Marble has less to do with any single geologist or outcrop, but rather its cultural impact of the region as a focus of geoheritage and a reflection of the Irish Diaspora of the 18th and 19th Centuries. It has been said that there are more people of Irish heritage living outside of Ireland than within it, yet many of them seek a connection to their homeland. Thus, each “worry-stone” or Claddagh ring bearing a green Connemara marble cabochon, incorporates a cultural record as important as its geologic history. This presentation will discuss the geologic and cultural importance of Píosa na hÉireann to both the history of Geology and to Irish heritage.