A giant sediment trap in the Florida keys

Aerial photography, high-resolution seismic profiling, coring and jet probing have revealed a large sediment-filled sinkhole in the Key Largo National Marine Sanctuary off Key Largo, Florida. The 600-m-diameter feature straddles coral reef and carbonate-sand facies and contains >55 m of marine lime sand and aragonite mud. Bulk 14C age determinations of mud from a 30- m sediment core indicate infilling rates exceeding 20 m/ka between 3 and 5.6 ka. The total thickness and nature of the sediment near the base of the sinkhole are not known.