GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 102-3
Presentation Time: 9:00 AM-6:30 PM


FEHR, Jeannie Lyndsey1, EVANS, Kevin Ray1, PAVLOWSKY, Robert T.2 and DOGWILER, Toby3, (1)Department of Geography, Geology, and Planning, Missouri State University, 901 S. National Ave, Springfield, MO 65897, (2)Department of Geography, Geology, an Planning, and Ozarks Environmental and Water Resource Institute, Missouri State University, 901 S. National Ave., Springfield, MO 65897, (3)Department of Geography, Geology and Planning, Missouri State University, 901 S. National Ave., Springfield, MO 65897; Department of Geography, Geology ,and Planning, Missouri State University, 901 S. National Ave., Springfield, MO 65897

The Ostionan Ostionoid culture, associated with the earliest ceramics found in Jamaica, spanned 650 – 850 CE. The later date overlaps with a calibrated carbon-14 age-date of 956 ± 122 CE for raised serpulid reefs between Black Spring Point and Billy's Bay. A newly discovered ceramic potsherd 10.3 by 10.5 cm and irregular in shape is cemented to a weathered outcrop of the White Limestone Group, exposed in the surf zone approximately 45 cm in front and 50 cm below the crest of a raised, serpulid-encrusted, shore platform. The ceramic material provisionally is identified as Ostiones-style redware, based on the two-sided orange-brown slip and orange-red paint on the exterior of the sand-tempered fragment. The location at Harvey's Bay, 17° 54' 2.90" N latitude, 77° 47' 37.64" W longitude, is approximately 1.0 km southwest of Black Spring Point and 1.2 km northwest of the community of Fort Charles along the St. Elizabeth parish coast in southwestern Jamaica. This site is 6.8 km northwest of the Blue Marlin site at Treasure Beach.

Serpulid worms secrete calcareous, curvilinear tube-like exoskeletons. They are sessile benthic organisms found at intertidal and greater depths. Tidal range in southwestern Jamaica is minimal, around 15 cm. The serpulid reefs between northern Billy's Bay and Black Spring Point, a distance of 2.5 km, are displaced vertically up to 1.1 m above sea level. A wave-cut notch and heavily weathered lower portions of the reefs suggest significant duration at elevation, which would indicate neotectonic uplift of the reefs on the upthrown side of the Pondside Fault, which parallels the coastline.

The location of the ceramic potsherd below a raised reef may be coincidental, but the unusual circumstances of preservation by cementation is informative. Carbonate cement of equant sub-millimeter crystals bind the fragment to bedrock. Such cementation generally occurs in meteoric settings, which indicates post-uplift cementation. Beachrock and presence of marine cements have not been reported along this coastline. Rather, exposed rock and the lower part of the serpulid reef commonly show salt weathering and formation of tafoni. The present-day rocky shoreline is an artifact of post-Hurricane Ivan beach loss in 2004, so presumably, the potsherd came to rest and was buried in sand prior to relatively recent re-exhumation.