Ok, there’s a lot to think about here.
1. This rock outcrop is of the “Chatsworth Formation” and made of Sandstone. The age of this formation is the upper cretaceous, so that puts it between 66 million years ago to 100 million years ago. There’s a lot that can happen in that time!
2. The North American plate and Pacific plate run into each other in this general area. Also the Chatsworth fault is very close by. Between all these forces that interact with each other these mountains have changed positions over the years.
3. These mountains used to be located South of North American closer to Central America, and over the millions of years have moved North and inland some. Many millions of years ago they used to be by the ocean.
4. Rivers running along sandstones like this sometimes you see holes getting worn out by rocks caught up in curves in the path and harder rocks getting hung up in these curves and wearing away the rock.
5. Tafoni are ellipsoidal, pan to bowl shaped, natural rock cavities. These sometimes develop both on inclined or vertical surfaces and occur in groups. They include pits, hollows, niches, little or big recesses, and honeycombing.
a. Visors associated with large tafoni are overhanging shelves that look like awnings on your house. Tafoni’s are mostly formed by ocean spray onto the surface of these rocks, this ocean spray contains salt. These small particles work and wear themselves into small cavities and wear on the rock they’ve landed on by drying out and growing thus expanding and breaking the surrounding rock. This continues and continues till you see cavities or honeycombing within the rock surface.
6. Simi mean’s “Wind” in the Native Indian language, Chumash. Any of you that have been up here in bad winds, know what the small sandstone grains do to your hand and face. You can image what millions of years of this can do.
So, the questions are:
Used for reference:
- https://pubs.usgs.gov
- U.S. Department of the Interior, Professional papers and Geological surveys
- Wikipedia
- WWW.Tafoni.com
- History of Simi Valley
Logging Requirements: Please E-Mail me the answers, don't post any pictures of the site itself.
1. Type in GC700JF Tafoni in Simi Valley.
2. What process or processes came into play with this example of Sandstone?
3. Do you see Honeycombing? How many small cavities are together in one place?
4. Is this a Visor?
5. What is the smallest and largest size cavity do you see?