"The brownstone quarries in Portland, Connecticut, owe their existence to millions of years of prehistoric sediments accumulating in the Connecticut River. Quarried as far back as the 17th century, the brownstone around Portland proved soft enough to allow for carving and polishing, making it one of the most desirable materials for gravestone markers and building construction for nearly three centuries. Portland’s location along the Connecticut River allowed for easy transport throughout the state and, later, the world.
During the height of America’s fascination with brownstone in the late 19th century, quarrying around Portland employed roughly 1,500 people and required a fleet of no less than 25 ships for transporting the material to market. In Portland, brownstone constituted the foundation of schools, churches, and public buildings (such as the Town Hall built in 1894). Some local residences even featured mantels and other brownstone fixtures embedded with the footprints of dinosaurs."