The largest and grandest of Marietta’s earthworks is the well-preserved Quadranaou. Its vast, rectangular form stands 10 feet tall, and nearly 200 feet long. Elegant, broad ramps climb to the centers of its four sides. Grand gatherings, dances, and games are easily imagined on its level surface. In Civil War times, the Union army used it for mustering recruits. It was also here (or nearby) where one of Marietta’s founders tried a novel method of dating the earthworks. The Reverend Manasseh Cutler recalled:

When I arrived, the ground was in part cleared, but many large trees remained on the walls and mounds. The only possible data for forming any possible conjecture respecting the antiquity of these works, I conceived must be derived from the growth upon them. By the concentric circles, each of which denotes the annual growth, the age of the trees might be ascertained.

Reverend Cutler counted 463 rings on one old stump, but then noticed it was coming out of another, older ancestor – so he doubled the number. It was a good, early effort to use a scientific method – what we now call “dendrochronology.” Little did he know he would have needed to double his number again. His “900 year” figure, though, still appears on some city plaques, instead of reflecting the correct age of 2000 years.