Native America

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Narrator

Is Cahokia also laid out to harness the power of celestial bodies. To find out archeologist Melisa Baltsis and Sarah Baires are taking to the sky. We're really interested in a human made feature that we think is located in this area here. So were hoping to get some data points over in this region just south of where we're standing now. -

Narrator

To uncover Cahokia's urban plan they're using a laser based ariel mapping system called Lidar. There have been a lot of modern building projects, the highway goes through here, so we're hoping that the Lidar will actually show us the archeological features and give us a totally new look at this ancient Native American city of Cahokia. (sound of laser) -

Narrator

Lidar uses quick bursts of lasers fired from a drone to create a precise 3D map. Once processed the Lidar data can be used to peel back trees, modern development, and layers of time. Okay so let's take a look at the data. Oh wow look how clear that is. Okay so we've got Monk's mound to the north. -

Narrator

The Lidar reveals the city is laid out with remarkable precision. Each mound follows along the exact same alignment to form a city grid. The grid is centered along a feature rediscovered only today, a road way. This looks like a causeway running north doesn't it? Maybe it's a little bit off north. -

Narrator

Discovery of this long straight road leading to Cahokia's largest mound is bringing the city's precise alignment into focus. Using the Lidar data, we are able to determine that this is definitely a causeway made by human beings early on during Cahokia's formative years. And it aligns Cahokia to its city grid which is five degrees offset of north.