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The Midwest and Southern states are home to numerous Native American earth mounds. When our country was being settled, explorers found thousands of these mounds in the Ohio Valley alone. Iowa, Georgia and Indiana among others, all have similar ancient mounds you can visit. Another well-known mound in Ohio resembles a writhing snake with a egg in its mouth, and is called fittingly, Serpent Mound.

Although they're less spectacular than some prehistoric constructions such as the pyramids of Egypt, these mounds reveal some fascinating insights into the early cultures of North America. Mystery still surrounds these Native-Americans. They disappeared and left little evidence as to where they went and why. Was it famine, warfare, natural disaster or a breakdown in social order?

No discussion of Moundbuilders would be complete without including Cahokia in western Illinois. The site is the largest and most sophisticated prehistoric Indian city north of Mexico. At its zenith, A.D. 1050-1150, population estimates range from 8000 to 40,000 inhabitants, though the most constant figure is 20,000. In its day, Cahokia was a major trading center, whose influence extended throughout much of North America. The city covered roughly six square miles, only part of which can be seen today.

The people of this area were known as Mississippians and they built as many as 120 earthen mounds in this vicinity. The part of the mounds made from dirt were dug with tools of stone, wood or shell, and transported on people's backs in baskets to the mound site...very hard work indeed! The digging left large depressions called borrow pits, which can still be seen. Experts believe most of the mounds were built in several construction stages.

Cahokia was laid out in neat rows with a ceremonial central plaza featuring "stepped" pyramid temples. At the heart of the central plaza was Monks Mound. Monks Mound, named for French Trappist monks who farmed its terraces in the early 1800s, is the largest Indian mound north of Mexico. It's also considered the largest prehistoric earthen construction in the New World. At 100 feet tall, the four-tiered platform was probably built in stages over a period of 300 years. Its base covers more than 14 acres. A large building sat atop Monks Mound, where the scientists speculate the principal ruler may have lived, conducted ceremonies and governed the city below. Modern man can't be absolutely sure of its purpose however, because the Cahokians left no written language and relatively few artifacts have been found. Climbing to the top of Monks Mound is now easier, as new stairways and railings were recently added.

Surrounding Monks Mound were once hundreds of smaller burial, boundary and minor ceremonial mounds. Some were flat-topped, others conical and the some ridge-shaped. Of these, only about 80 remain today. The others were victims of the urban progress and farming.

One of the most interesting features of Cahokia is a reconstructed sunrise horizon calendar, known as "Woodhenge" because its astronomical function was similar to that of Stonehenge in England. The circle consists of 48 large cedar posts arranged in a 410 foot diameter circle around a central observation post. This calendar marked the seasons and important dates for the ancient Cahokians. Evidence suggests there were four other similar "calendars" at this site.

So what did happen to the Cahokians? One theory says their increasing reliance on lumber for fuel, houses and temples may have caused its collapse. Removing too much timber from the area would have left nothing to anchor the soil, so that heavy rainfall would have washed it away, wiping out the crops. As the decades pass, Cahokia is slowly emerging from the shadows, thanks to the work of scientists and archeologists. Perhaps someday we'll know the fate of these people.