From Hotsuma Tsutae: A Look at the Mississippi Day and Night

I thought there was no way there wouldn't be ancient ruins on the North American continent, and sure enough, there were. There is no way that North America alone would lack such things within the Circum-Pacific cultural sphere.

Materials on Cahokia by Gemini:

Cahokia was the largest ancient urban site in pre-Columbian North America (north of Mexico), and it is the symbolic center of the "Mississippian culture" that flourished primarily in the Mississippi River basin from around 800 AD to 1600 AD.

Located in the suburbs of present-day St. Louis, Illinois, it was registered as a UNESCO World Heritage site in 1982.

Three Major Characteristics of Cahokia and the Mississippian Culture

1. North America's Largest Earthwork Technology: "Mounds"

The people of the Mississippian culture, who possessed neither metal tools nor wheels, transported vast amounts of earth by hand to build flat-topped, pyramid-shaped mounds.

• Monks Mound: The largest earth mound at the center of Cahokia, it stands about 30 meters high and has a base area of about 5 hectares. In terms of base area alone, it is larger than the Great Pyramid of Giza, and the summit was home to the ruler's residence and a temple.

2. An Urban Population Exceeding That of London at the Time

During its peak between 1050 and 1200 AD, it is estimated thatover 10,000 to 20,000 people lived there, making it the "first city in North America," with a scale comparable to or exceeding that of London or Paris at the same time.

• Maize Agriculture: Large-scale maize cultivation utilizing the fertile floodplains of the Mississippi River supported this high-density population.

• Vast Trade Network: It was also a massive trade hub where copper from around the Great Lakes, shells from the Gulf of Mexico, and minerals from the Appalachian Mountains were gathered.

3. Advanced Astronomy and Social Structure

• Woodhenge: A facility with huge wooden posts arranged in a circle has been discovered, which functioned as an astronomical observation device that perfectly calculated the sunrise directions for the summer and winter solstices, as well as the spring and autumn equinoxes.

• Hierarchical Society and Rituals: From a site called "Mound 72," burial remains were discovered featuring a high-status individual covered in shell beads (commonly known as the Bead Blanket Burial) accompanied by numerous human sacrifices, indicating the existence of a strong social hierarchy and religious power.

Why did it disappear?

After the late 1200s, Cahokia's population declined rapidly. While it was once said to be a "sudden collapse due to war or environmental destruction," recent research suggests it was a gradual reorganization caused by a combination of the following factors:

• The arrival of the Little Ice Age and climate change (poor maize harvests)

• Major flooding of the Mississippi River resulting in the destruction of farmland

• Large-scale deforestation leading to environmental stress and soil erosion

• Population dispersion to surrounding areas due to a decline in political centripetal force

By around 1400, Cahokia as a city was largely abandoned, and its inhabitants, while maintaining the traditions of the Mississippian culture, dispersed as the ancestors of diverse indigenous tribes such as the later Sioux and Cherokee.

Since it is impossible for massive structures to be built suddenly, there must have been knowledge and technology accumulated over thousands of years prior to that.

Explanation of Woodhenge by Gemini:

Cahokia's "Woodhenge" is a magnificent astronomical observation device (solar calendar) of the Mississippian culture, named for its circular arrangement of giant wooden posts, in contrast to England's Stonehenge (stone).

Discovered in the 1960s by archaeologists such as Warren Wittry, it has been determined that it was rebuilt and expanded at least five times between 900 and 1100 AD.

1. Basic Structure of Woodhenge

Excavations have revealed that the most large-scale "Phase 3" (around 1000 AD) Woodhenge had the following structure.

• Layout: A perfect circle with a diameter of approximately 125 meters.

• Number of posts: On the circumference of the circle, 48 giant red cedar logs were placed at equal intervals.

• Center Post (Observation Point): A center post for the observer to stand at was installed at a position slightly shifted to the east from the center of the circle.

2. Mechanism for Measuring the Calendar (Summer Solstice, Winter Solstice, Equinoxes)

The measurement method of Woodhenge is extremely simple and precise. The calendar was determined by the angle of the line of sight (line of collimation) where "an observer standing at the center post watches from which wooden post on the circumference the sun rises directly above."

1. Measurement of the Summer Solstice

• Movement of the sun: The sun rises from the northernmost point of the east in the year.

• Observation method: The day the sun rose directly above the post located at "28 degrees northeast" from the center post was identified as the "Summer Solstice."

• Background landmark: Beyond this northeast line of sight, Cahokia's largest giant earth mound, "Monks Mound," was located, and a fantastic and religious effect was created where "the sun rises from the top of the mound."

2. Measurement of the Winter Solstice

• Movement of the sun: The sun rises from the southernmost point of the east in the year.

• Observation method: The day the sun rose directly above the post located at "28 degrees southeast" from the center post was identified as the "Winter Solstice."

3. Measurement of Equinoxes

• Solar movement: The sun rises due east.

• Observation method: The day the sun rises directly above the post located due east from the central post was identified as the 'equinox' (the day when the length of day and night are equal).

        【北】
          │
          │     [夏至の日の出] (北東28°)  ───> (遠くにモンクス・マウンド)
          │    /
   ─── 観測中心柱 ─── [春分・秋分の日の出] (真東)
          │    \
          │     [冬至の日の出] (南東28°)
          │
        【南】

3. Why were as many as '48' posts necessary?

If the goal were simply to know the 'summer solstice, winter solstice, and equinoxes,' planting a few posts on the east side would be sufficient. However, the following theories are considered compelling reasons for why 48 posts were arranged around the entire circumference.

1. Understanding the agricultural calendar (corn cultivation cycle)

   • To manage and predict the timing of sowing and harvesting in detail along with the changing of the moon and seasons.

2. Lunisolar calendar (aligning lunar and solar cycles)

   • The possibility that it functioned as a ceremonial calendar combining not only the movement of the sun (365 days) but also the cycle of the moon's phases (approximately 29.5 days).

3. Display of royal authority and sanctity

   • It was also a political and religious theater for the ruler (the high priest considered an incarnation of the sun) to demonstrate to the people that they could 'accurately predict the day the sun rises and control the celestial bodies.'

Thus, Woodhenge is not merely a landmark, but can be called a crystallization of the wisdom of the ancient Mississippi culture, where mathematics, astronomy, civil engineering, and religious concepts were brilliantly fused. as well.

Woodhenge is often dismissed by Western archaeologists (though not exclusively) with terms like ritual, ceremony, and religion, but it is actually a practical calendar for agricultural work.
Just as the Hiyomi (Sun-Night Observer) in Hotsuma Tsutae observed the sun to determine the schedule for agricultural work.
Actually, there might have been such Hiyomi structures in Japan as well. There is something similar at the Sannai-Maruyama site, and there is a Stonehenge in Akita.
For now, I feel relieved to know that there is a culture of Hiyomi, or calendars, in the North American continent, which was a missing link for me.
However, it seems this North American city was also reset.

From Hotsuma Tsutae: Save Data Before the Reset | Akitsugu Ueda
From Hotsuma Tsutae: Comparative Study with Ancient Oral Cultures of the Pacific Rim | Akitsugu Ueda
From Hotsuma Tsutae: Solar Calendar | Akitsugu Ueda
From Hotsuma Tsutae: Introduction (Revised and Edited) | Akitsugu Ueda