Age
Geologists employ biostratigraphy, the use of index fossils, for dating sedimentary rock units like the Coon Creek. Index fossils are species of plants or animals that existed over a wide area for a geologically short period of time (Russell and Parks 1975). The cephalopod Jeletzkytes nodosus is a time-sensitive fossil found in rocks a little younger than 70.6 million years old in the western United States. Other index fossils from Coon Creek date a little older than 70.6 million years. The overlap indicates that Coon Creek sediments were probably deposited between 70 and 71 million years ago.
Read more about this topic: Coon Creek Formation
Famous quotes containing the word age:
“No such sermons have come to us here out of England, in late years, as those of this preacher,—sermons to kings, and sermons to peasants, and sermons to all intermediate classes. It is in vain that John Bull, or any of his cousins, turns a deaf ear, and pretends not to hear them: nature will not soon be weary of repeating them. There are words less obviously true, more for the ages to hear, perhaps, but none so impossible for this age not to hear.”
—Henry David Thoreau (1817–1862)
“Our age believed herself pregnant with auspicious progeny, but when her hour came, it turned out to be dropsy.”
—Franz Grillparzer (1791–1872)
“The higher the mountain on which you stand, the less change in the prospect from year to year, from age to age. Above a certain height there is no change.”
—Henry David Thoreau (1817–1862)