Cryolander

The Cryolander technique (Wiltshire et al., 1997) freezes the sediment surface using liquid nitrogen, producing a frozen "plate" of sediment over 10 mm in depth and 50 mm diameter. The freezing begins gently so as the sediment matrix is kept intact. In the laboratory a 10 mm block was cut from the frozen sediment in the (if necessary in the exact location of a Fluorescence measurement). The blocks were then sectioned at 0.2 mm intervals generally to a depth of 2 mm. Some studies only show 0.4 mm, 1 mm and 2 mm depth sections and are calculated by summing the respective sections.

The surface of the sediment collected with the Cryolander is often not completely flat. Thus Ôzero depthÕ is determined at the point at which 90-95% of the area is visibly level. Any undulations above this point are included in the 0-0.2 mm slice. Once each section has been sliced and transferred to an eppendorf they were re-frozen and lyophilised in preparation for pigment analysis.