The Pierre Shale, which is divided into identifiable sedimentary beds called members, also contains abundant fossils of numerous species of ammonites, ancestors of the chambered nautilus.
The fossils, when combined with geologic mapping, allow the various exposed sections of the Pierre Shale to be pieced together in their proper relative positions to form a complete composite section (Figure 1).
The creationist approach of focusing on examples where radiometric dating yields incorrect results is a curious one for two reasons.The impact also created shocked quartz crystals that were blasted into the air and subsequently fell to the west into the inland sea that occupied much of central North America at that time.Today this shocked quartz is found in South Dakota, Colorado, and Nebraska in a thin layer (the Crow Creek Member) within a thick rock formation known as the Pierre Shale.The results of the Manson Impact/Pierre Shale dating study (Izett and others 1998) are shown in Figure 1.There are three important things to note about these results.
We often test them under controlled conditions to learn when and why they fail so we will not use them incorrectly. For example, after extensive testing over many years, it was concluded that uranium-helium dating is highly unreliable because the small helium atom diffuses easily out of minerals over geologic time.