Here we present original Natural Gamma Ray (NGR) logging-data from borehole GLAD6 BOS04 5C against depth that have been used for core-log integration and for controlling the signal consistency relatively to the 4.30 m distant GLAD6 BOS04 5B core. The latter core has been used as basis in the framework of the REFINE project aiming to establish an age-depth model that bases on a combination of cyclostratigraphy and correlation analyses. The NGR in the downhole log (GLAD6 BOS04 5C) was measured with 20 cm vertical resolution, run with a logging speed of 2–3 m/min and 2 m depth spacing. Measurement errors (e.g., 2 sigma of a standard) range between 5 and 10%.