Absolutely right. How are the circles formed.

1: Take one hungry horse.
2: Tie a big bag of fast growing grass seed to its rump.
2: Tether it to a post with, say 15 feet of rope.
3: Point the nag so that it will wander clockwise.
4: It will eat its way around the post winding itself closer and closer to the middle all the while depositing the grass seed as it goes.
5: After a couple of weeks, go up to the horse.
6: Turn it around.
7: Refill grass seed bag and give it a shove.
7: It will unwind the rope as it eats its way back to the start.
8: After a couple of weeks, return to the horse.......... I think you've got it.