My Turn: Geologically unique Franklin County armored mud balls 


Published: 3/17/2021 11:07:03 AM

As you may know Massachusetts has memorialized over 50 symbols that reflect our state history, science, and culture. We have a state bean, muffin, donut, cat, and horse as well as geological things such as a state building stone, fossil, dinosaur (submitted by Rep. Jack Lewis, January 2021), explorer rock, glacial rock, and history rock. Armored mud balls should be added to this list because they are rare and intriguing Mesozoic Era geologic features only found in Franklin County.

The “State Geologist recognizes this particular feature as one of the rarest structures in the world, represents a unique geologic environment to create such a feature and is only found here in Massachusetts. That alone makes this feature worthy of recognition.” (Dr. Steve Mabee, Feb. 24, 2021, email. Note: This email is for information only. The Office of the State Geologist does not take any political position.)

The amusingly named “armored mud balls” are indeed an official geological phenomenon. They are formed by streams or beach waves rolling sticky mud into ball shapes becoming coated by pebbles. That is the armor. To be preserved in the geological rock record they must be quickly buried before drying and disintegrating. The fragile armored mud balls can then be gradually lithified (compacted and cemented) along with the surrounding sedimentary rock. This special series of events makes lithified armored mud balls extremely rare. I have made a six-minute YouTube video explaining armored mud balls –

I was the discoverer of these features in Turners Falls in the early 1970s and wrote a paper published in the Journal of Geology about them (1982). The geological literature records only about 10 places in the world with lithified armored mud balls. All are in remote locations and probably none are visible today.

The dramatic Franklin County specimens are found in local quarried stone plus in accessible rock outcrops, such as at Greenfield’s Stop and Shop Supermarket parking lot and a Turners Falls park. A church in Greenfield center has an armored mud ball in the quarried stone above the entrance. The most impressive examples are preserved and displayed in the Greenfield Community College Geology Path. These excellent specimens show well-formed balls from golf ball to basketball size all with obvious pebble armor.

If the Franklin County specimens become designated as a Massachusetts symbol, this official recognition will give them the attention they deserve. People love them. They are an interesting, educational, and fun geoscience “dinosaur age” story and they are truly unique, being found only in Turners Falls, Greenfield, and Deerfield. This notoriety will help Franklin County tourism and perhaps lead to visitors and residents finding more locations with armored mud balls and perhaps dinosaur fossils as well. At least they will have fun exploring and observing the rocks and landscapes of beautiful western Massachusetts.

I would greatly appreciate your suggestions and comments. State Rep. Paul Mark is supportive of this effort and it appears that January 2023 will be the next time a bill could be filed.

The website has more information about armored mud balls and other local geological topics including my new book “Exploring Franklin County.”

Richard D. Little, an Easthampton resident, is a Professor Emeritus at Greenfield Community College.


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