The Grand Canyon landscape is geologically young, being carved within just the last 6 m.y.There are younger geologic deposits in Grand Canyon too, such as the Ice Age fossils found in caves, a 1000-year-old lava flow in the western canyon, and even the debris flow deposits that continue form each year.By the end of the 19th century, geologists had used these principles to put together an outline of the geological history of the world, and had defined and named the eons, eras, periods, and epochs of the geologic time scale.They did not know how many thousands, millions, or billions of years ago the Cambrian period began, but they knew that it came after the Proterozoic Eon and before the Ordovician Period, and that the fossils unique to Cambrian rocks were younger than Proterozoic fossils and older than Ordovician ones.The age of the fossil must be determined so it can be compared to other fossil species from the same time period.Understanding the ages of related fossil species helps scientists piece together the evolutionary history of a group of organisms.
He published the results of his work and established a basic set of principles for interpreting sedimentary strata.What would the geologist be able to deduce about the world we live in, based on what was left in the strata?Stratigraphy started to become a formal science due to the work of a man who published under the name Nicolaus Steno in the 17th century.Nonetheless, how geologists determine the age of rocks is a mystery to many members of the public, and even to many park rangers [see Photo 2], guides, and others who share the canyon’s geologic story with others. ” when geologists say a Grand Canyon rock formed 270 million years ago.Further confusion arises when one publication or geologist says, for example, that the Kaibab Formation is 270 m.y. The same questions arise for the other rock units at Grand Canyon. This article will answer these questions by providing a short primer on geologic dating methods and how they were applied to Grand Canyon rocks.