A slope with stone walls just north of the Boulder CO "Flatirons"

Consider this slope, which I believe has several deliberate stone lines, forcing game to climb the slope along specific routes. 

Here are some possible rows of lined-up rocks I can see in the picture. Some of them might be natural outcrops but "four in a row" (when they are adjacent rocks) makes it statistically unlikely that they are random. You have to look very closely.

The stone rows are loosely defined. It is easy to imagine a hooved animal preferring to step on grass rather than rock. So a stone row would cause an animal to make a choice between sides of the row to walk along. So the slope is covered with binary "gates" running upward and converting the continuum of choices into finite possibilities. 

This would allow for a very flexible trap control system- depending on the wind conditions. Imagine a few runners chasing game uphill towards predictable places above, where hunters with spears waited! Today, you can see places on the hillside where the grass is growing longer, and other places where the grass is short and flattened down. The animals are still using the paths and the hunters are long gone. 

I bet there are arrowheads up there. For reference, this is the slope right across from Chatauqua Park, between the Flagstaff and Crown Rock trails.