Sediment core climate records rely on undisturbed layers of sediment to preserve chronology and preferably a large amount of sediment deposited annually to minimize the number of years spanned by a given sample. As a result, scientists survey geographically applicable regions to choose coring sites which are both located in stable areas and have high sedimentation rates.
Surveying
3.5 kHz Bathymetry
Our reconnaissance work, based on 3.5kHz records collected on earlier cruises (from as long ago as the 1960s) indicates the Demerara Rise is a good region to collect cores. The map to the right shows the penetration time of a 3.5kHz sound signal, with larger green circles indicating deeper penetration (softer sediment) and red circles indicating no penetration (a hard surface). There are areas of both the upper and deeper Rise that appear to have soft sediment indicated by deep penetration of the sound signal. The parallel, rather than intersecting, lines in the 3.5 kHz records (see subfigures) suggest that the sediment has not been disturbed since deposition. These lines represent reflectors that are caused by changes in the properties of the sediment. We will generate new 3.5kHz records along survey lines and target those areas with flat, parallel, reflectors and deep 3.5kHz penetration.