T. Rex and the Crater of Doom

Early geologists based their understanding of Earth’s past on the chronology outlined in the Bible and thus assumed that Earth was only a few thousand years old. In addition, early geologists were catastrophists: They assumed that massive geological formations like the Alps could only have been created by sudden, violent changes since they a few thousand year would not have allowed for such formations to develop slowly. Once geologists stopped relying on Biblical accounts, they began to theorize that Earth was much older. In the 19th century, geologists James Hutton and Charles Lyell introduced uniformitarian thinking in geology given that Earth was an ancient planet that likely formed through gradually changes over time.

In trying to understand geological processes, 19th century geologists began to carefully map the different types of rock surfaces in different locations of the world. This endeavor yielded many discoveries that advanced industrialization and technology, revealed minerals and oil, and helped geologists understand thrust faults. Their painstaking work provided a “rock record” that modern geologists use to build on this knowledge.

Alvarez recalls training in geology as a graduate student at Princeton. There, he was taught from a uniformitarianism