Isthmus: a narrow piece of land linking two larger areas of land
Volume: amount included within limits
Complex: made up of many related parts
Abandon: to leave, often because of danger
To successfully complete a task; to gain something by working for it
The Great Serpent Mound, made up the Mound Builders, still exists in southern Ohio. This mound may have been used in religious ceremonies.
The Mound Builders were mostly hunters and gatherers, but they began to practice farming.
In the west, rugged mountain chains run nearly the entire length of the Americans