Sunday, October 30, 2016

My favorite limestone deposit in the USA is Bryce Canyon. It is a national park and it is breathtaking.

Grand Canyon (A), Chocolate Cliffs (B), Vermilion Cliffs (C), White Cliffs (D), Zion Canyon (E), Gray Cliffs (F), Pink Cliffs (G), Bryce Canyon (H)

It is called stratigraphy and is the most fascinating way to study the time scale of Earth. Statigraphy is the branch of geology concerned with the order and relative position of strata and their relationship to the geological time scale.

Yes, a geological times scale. What this cross section of USA's statigraphy shows is the rise and fall of Earth's oceans. For every layer of rock in this cross section there is a time period when Earth's ocean rose above the land and deposited rock that would become this vast and beautiful vista of color and composition. 

Sea Level Variations over Geologic Time 
By M. A. Kominz

...Long-term Sea Level Change Estimates (click here) are also made from sedimentary strata deposited on the continents. This is actually an excellent place to obtain observations of sea level change not only because past sea level has been much higher than it is now, but also because in many places the continents have subsequently uplifted. That is, in the past they were below sea level, but now they are well above it. For example, studies of 500}400 million year old sedimentary rocks which are now uplifted in the Rocky Mountains and the Appalachian Mountains indicate that there was a rise and fall of sea level with an estimated magnitude of 200}400m. This example also exempliRes the main problem with using the continental sedimentary record to estimate sea level change. The continents are not Rxed and move vertically in response to tectonic driving forces. Thus, any indicator of sea level change on the continents is an indicator of relative sea level change. Obtaining a global signature from these observations remains extremely problematic. Additionally, the continental sedimentary record contains long periods of nondeposition, which results in a spotty record of Earth history. Nonetheless a great deal of information about sea level change has been obtained and is summarized here....

The Grand Canyon has the oldest EXPOSED rock in the USA.

The Grand Age of Rocks: The Numeric Ages for Rocks Exposed within Grand Canyon (click here)

Grand Canyon National Park [see Photo 1] is one of the best places in the world to gain a sense of geologic, or “deep,” time because the canyon exposes a great swath of geologic history. Rocks exposed in Grand Canyon are truly ancient, ranging from 1840 million years old (m.y.), or 1.84 billion years old (b.y.), to 270 m.y. 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....

Bryce Canyon National Park (click here)