Experimental Blog #94

Comments on "Reading the Rocks - The Autobiography of the Earth" by Marcia Bjornerud

In the beginning they call it the Hadean Eon, from about 4.6 billion to about 4.4 billion years ago, but the oldest surviving rocks are about 4 billion years old. The first signs of life seem to appear in the Archean Eon about 3.5 billion years ago.

Predation emerges at the end of the Proterozoic Eon; around 570 million years ago to around 545 million years ago, at the beginning of the Paleozoic Era. Everything before the Paleozoic Era is called the Precambrian Era. Fish evolve during the Devonian Period, from around 420 million years ago, which is followed by the Carboniferous Period at about 355 million years ago.

In the Mesozoic Era reptiles evolve, and they are followed by the dinosaurs, in the Jurassic and Cretaceous Periods at around 200 and 140 millions of years ago. And so on to the Cenozoic Era at about 65 million years ago, which comes to the Pleistocene and Holocene Epochs from 3 million to 10 thousand years ago.

These are only some of the divisions, subjects, and events that are described in this book of modern geology, which now includes the ultra-modern new sciences of biogeochemistry and paleoclimatology. The "old" sciences of geology and biology seamlessly merge today and can hardly be separated. The currently accepted geologic timescale at the beginning of this book includes 5 "mass extinctions".