Criterion I

Of the three major lands of rock, igneous, metamorphic, and sedimentary, only sedimentary rocks have the potential to preserve fossils to any reasonable degree. This is because igneous rocks are derived from molten material; obviously not a suitable habitat for dinosaurs or the preservation of their bones. Metamorphic rocks are formed by the intense folding and recrystallization of sedimentary rocks; these rocks

Figure 1.4. Typical scene at a dinosaur-producing outcrop somewhere in the badlands of the upper Great Plains, USA. In the foreground, paleontologists are excavating the fossils from the side of a butte, and treating them with liquid hardeners. In the swale behind the paleontologists, a grid is laid out, allowing the scientists to record the exact position of each of the fossil bones. Bags of plaster and burlap strips are scattered around, to be used in jacketing the specimens.

Figure 1.4. Typical scene at a dinosaur-producing outcrop somewhere in the badlands of the upper Great Plains, USA. In the foreground, paleontologists are excavating the fossils from the side of a butte, and treating them with liquid hardeners. In the swale behind the paleontologists, a grid is laid out, allowing the scientists to record the exact position of each of the fossil bones. Bags of plaster and burlap strips are scattered around, to be used in jacketing the specimens.

generally are no better. But, of course sedimentary rocks form in, and represent, sedimentary environments, many of them places where dinosaurs lived and died.

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