Global cooling inferred from dropstones in the Cretaceous: fact or wishful thinking?

Traditionally, the Cretaceous has been considered as a long period of global warmth, a ‘greenhouse’ world. This view has been challenged in recent years by several lines of evidence; palaeobotany, stable isotopes, and palaeoclimatic modelling in particular. However, although these data demonstrate that cooling is likely, the only first‐hand evidence which demonstrates the presence of substantial ice build‐up in Cretaceous high palaeolatititudes are dropstones. These outsized or exotic clasts set in a fine‐grained sediment are often interpreted as a direct result of ice rafting. The reliability of this dropstone evidence and particularly its validity is questioned in demonstrating ice age interludes within the Cretaceous greenhouse.