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Desert Diary
Fossils/Big Numbers


Large numbers have little meaning to many people until put into a familiar context. Many rocks of the northern Chihuahuan Desert, for example, are Cretaceous in age, and we blithely talk of that age ending some 65 million years ago. Yet, how many of us have a real inkling of how long that actually is?

To most of us, the beginning of the Christian Era was a long, long time ago—but 32,500 such eras could have occurred since the end of the Cretaceous. If you traveled around the world once a year, it would take you almost 2,600 years to accumulate 65 million miles. And if we consider an average human life span to be 70 years, then the end of the Cretaceous was some 928,000 life spans ago, itself a number too big for most of us to encompass.

More mind-boggling, however, is the fact that you would have to multiply the Cretaceous-to-present time span more than 70 times to get back to the beginning of earth and the solar system.
pen and ink


Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.

Big Numbers Design


Dalrymple, G. B. 1991. The Age of the Earth. Stanford University Press, Stanford, CA, 474 pp.

Web Resources

Age of Earth

End of the Cretaceous