Geo Lab - The Monterey Formation Traditional Cache

Recently, I took an introductory geology class and learned much about the geologic history of the Monterey Peninsula. This cache is part of a nice and short series that I hope will help educate those who enjoy our beautiful local environment.

This cache is located along a nice road cut in which one can have an up close and personal view of the Monterey Formation. This sedimentary rock can be classified as a shale composed primarily of silt, clay, and diatoms. Since these materials are small, layered and easily disturbed, we can infer that the depositional environment must have been somewhere deep, marine, and far from the continental shelf. Scientists believe these sediments were originally laid down 5 to 20 million years ago!

The Monterey Formation has been surveyed extensively and is the source for a majority of the oil found in California. Many of the more silica rich (and thus stronger) pieces of shale are used for construction and are called Carmel Stone. Keep an eye out for more examples of this rock. If you look around the Monterey Peninsula, you will undoubtedly see these rocks in a variety of places.