Smith & Bailey (2017a) have criticized the methods applied for time series analysis in our study of a late Campanian chalk core in the North Sea (Perdiou et al. 2016). These critics rely essentially on two points: (1) the resolution spacing that can be applied to our gamma-ray data; (2) the use of the autoregressive order 1 (‘AR1’) noise model, which allows calculation of significance thresholds.

With respect to point (1), in their comment and re-analysis of our gamma-ray signal, Smith & Bailey recall our methods section where we correctly report that gamma-ray probes used by Schlumberger have a cone of influence of c. 40 cm, and therefore that gamma-ray values must be smoothed over a complex running mean over an interval between 40 and 60 cm, which alters the record of potential high-frequency Milankovitch cycles. Smith & Bailey rely on our assertion to justify that our gamma-ray data series based on 457 data points with an average vertical spacing of c. 15 cm should actually be re-interpolated at 45 cm (thus with a significant lower resolution) without any loss of spectral information. Then they calculate a new multi-taper method (MTM) periodogram based on this re-interpolated time series and claim …