Athro, Limited Gubik Field Trip Section 20 Cretaceous Beach

On the beaches near skull cliff can be found small slabs of Cretaceous sandstone.

It has been speculated that these were used as hearth stones in the Point Barrow area. Though for them to have been used by a fire they would have had to be carefully dried. If any moisture is present, steam forming between the layers in the sandstone causes them to delaminate explosively. This sends shards of rock flying.