Sedimentary cores are widely used for studying Quaternary records. However, the
amount of sediment that is available is proportional to the diameter of the core, which is rarely
bigger than 15 cm. One way to obtain more sediment is to use two cores retrieved from almost
the same location and use them as if they represent a unique sedimentary record. In the present
work, an experimental design has been applied to verify if “twin cores” from an estuary can be
considered as representing the same sedimentary record with twice the amount of sediment to
study. Because sediment can be characterized based on its color, the variables used as
replicates in the experimental design are the three Lab CIE colors acquired with a X-Rite
Colortron spectrophotometer. Sediment cores were retrieved from the upper saltmarsh of Gilão
River’s estuary, southern Portugal. Twin cores, with in between distances of 50 cm, 100 cm
and 200 cm, from two different sites were analysed. Results from a nested ANOVA show that
even for the closest twin cores (50 cm apart) there is at least one color variable that shows
significant variations between the profiles of both cores. These results clearly show that “twin
cores” cannot be used as a unique sedimentary record without any previous testing, at least in
such transitional regions