During the end of the Mesozoic and the beginning of the Cenozoic, the tectonic movement of the earth's crust moved Arizona and the rest of the North American continent away from the equator and the other continents. This is also a period of mountain building, called the Laramide Orogeny (which ended about 40 million years ago), causing stress to the fossils contained within the Chinle Formation. This is the origin of the fractures dividing the segments of petrified logs, which snapped beneath the weight of thousands of feet of rock.
Although the Colorado Plateau began to isolate and uplift during the Laramide Orogeny |
