 However, repeated 40Ar/39Ar dating of impact melt rocks from both impact craters suggests that Clearwater East has an age of approximately 460–470 million years, corresponding to the Ordovician time period, whereas Clearwater West was formed 286.2 ± 2.6 million years ago, in the Early Permian.Both Clearwater impact structures also carry different geophysical (natural remanent magnetization) signatures and different geochemical fingerprints of the impacting meteorite in the impact melt of each crater.Clearwater East and Clearwater West are both complex craters with distinct central peaks.