As part of the 2008 Stone Symposium in Barre Vermont we took a large group of our dry stone walling workshop students on a dry stone hunting expedition in Vermont looking for old historic dry stone bridges.
We were crazy enough to think we would find some, and we did.
This one at first glance looked like it was made of old wooden railway ties. But no, it was just very long 'sticks' of a kind of slate-like stone that ran along the vault as well as the length of the bridge and over the arch to form the parapets.
We were collectively amazed at how strong and sturdy it looked for being well over 150 years old.