GEOARCHAEOLOGICAL STUDY OF BALLAST FROM THE 16th-CENTURY EMANUEL POINT NO. 2 SHIPWRECK, PENSACOLA BAY, FLORIDA

The presently named Emanuel Point No. 2 shipwreck was originally one of 11 ships comprising the Tristan de Luna expedition and among seven ships from that expedition that sank in Pensacola Bay during a hurricane in 1559. Although historical records verify that the expedition originated from the Iberian Peninsula and stopped at Veracruz, Mexico prior to sailing into Pensacola Bay, its exact route is uncertain. Recent and ongoing archeological excavations of the still-submerged and semi-preserved shipwreck have yielded numerous artifacts, including ballast composed of both rock and coral.

In this study we examine ballast samples from the Emanuel Point No. 2 shipwreck to A. Petrographically identify rock types used as ballast, B. Compare ballast types with those previously excavated from another shipwreck (Emanuel Point No. 1) that was part of the same 16th- century expedition, and C. Elucidate the original cross-Atlantic route traveled by the expedition through petrological and geochemical comparisons of ballast samples recovered from the Emanuel Point No. 2 shipwreck to rock types from Spain, Portugal, and various islands throughout the Atlantic.

Forty-three samples (62.3 kg) of rock and coral ballast were collected in situ from the shipwreck site during May-August 2008 and identified via transmitted light microscopy. Individual ballast samples vary in shape (angular to sub-rounded), size (5.5 to 63 cm in length) and weight (0.06 to 6.0 kg) and represent seven different types: vesicular basalt, n=4; limestone (fossiliferous and micritic), n=10; coral, n=5; tuff/rhyolite, n=5; vein quartz, n=1; sandstone, n=12; undifferentiated altered igneous rock, n=6. Except for the presence of coral and lack of granite, ballast from this shipwreck generally match ballast from the Emanuel Point No. 1 site.

Whole rock major- and trace element analyses identified three unaltered vesicular basalt ballast samples as alkaline, intra-plate types similar to basalts from the Azores and the Cape Verde and Canary Islands, therefore suggesting one of these islands may have been a stopping point for the ship on its voyage to the New World. Ongoing whole rock Ar/Ar age determination of one basalt sample may geochronologically help identify from which specific locality the basalt was collected for use as ballast.