Friday, January 19, 2007

Friday Field Foto #8: Cretaceous shoreline deposits

I've missed the last few Fridays...

The Book Cliffs are in central Utah and western Colorado and are famous for their spectacular outcrops of Cretaceous shoreline deposits. The seaway, which once stretched across the whole of North America from the Gulf of Mexico to the Arctic Ocean, left a fantastic record of relative sea level changes in these sedimentary rocks. The landward or basinward movement of the shoreline can be mapped along the Book Cliffs by identifying the various sedimentary environments (coastal plain, beach, shoreface, shelf, etc.) in the record.

The map above illustrates this paleogeography nicely. Note how much of Colorado is part of this seaway at this time. Eventually, the rivers and shorelines (as recorded by the stratigraphy) march across Colorado too. This image taken from a fantastic website by geologist Ron Blakey at the University of Northern Arizona. Check it out.


Thermochronic said...

I've gotta say, the combination of the field photo and the paleogeographic map is excellent, I wish more textbooks set it up like that.

Anonymous said...

This page is fantastic, what you show us is very interesting and important, do you want to see something more? Look: Great investment opportunity in Costa Rica: hotel in jaco beach, jaco beach review, apartment beach jaco rental. Visit us for more info at:

Anonymous said...

I recommend east site because I consider it very interesting. It offers specifications on real estate properties. It is very simple to know on the image and the culture Costa Rica and mainly to know the height important that it has east country with respect to the investments in real estate related to the tourism.
Definitively he will be very useful for you

Great investment opportunity in Costa Rica:

Great investment opportunity in Costa Rica: jcondos house, costa rica beach condos, condos rentals. Visit us for more info at: