The correlation of ELSA cores from different maar sites is done with pollen and the specific marker tephra. The detailed correlation of cores within one and the same maar is done by distinct lithological markers. In nearby cores we always observe thick dust layers, flood layers, turbidites and slumps, which can be used to correlate events. A high resolution correlation can be best made by a continuous curve of organic carbon, which we determine with 1 mm resolution with the ISRS670 method. As an example, the two cores from Auel show an identical Corg curve even in minute details. This allows to correlate the cores precisely, and switch for a continuous sampling from AU3 to AU4 to finally arrive at a continuous sample record, the ELSA-20-Stack, see above.