Various clues determine reliable coral samples

This piece of a core sample taken from offshore of the Fort Lauderdale region of Florida is from an elkhorn coral that lived 6,200 years ago. Coral type, orientation of corallites, and evidence of other fauna and characteristics within the core sample are used to determine how reliable the coral sample is to use for past sea-level reconstruction. Here, USGS Oceanographer Anastasios Stathakopoulos points to an assemblage of intergrown organisms that includes vermetid worms (small brown circles), crustose coralline algae (white layers) and encrusting foraminifera (thin pink/purple layers) which encrust the surface of the coral skeleton (off-white color). The presence of these intergrown encrusting organisms helps scientists estimate the depth at which this coral lived. This core is stored in the USGS core archive in St. Petersburg, Florida.