Chaco Canyon Road Network

Hundreds of miles of straight roads centering around Chaco Canyon. 
Trade Routes?  Defense purposes?  Spiritual reasons?  We may never know. 
There were more than 400 miles of roads connecting Chaco Canyon to some 75 communities. The longest road (the North Road) runs 42 miles north toward the site called Salmon Ruin. On the north-south roads, settlements lay at travel intervals of approximately one day. These roads were not simply trails worn by centuries of foot travel. They were the result of sophisticated engineering and required a great deal of energy and thought to plan, construct and maintain. They were laid out in long straight lines with little regard for terrain. The roads averaged 30 feet in width. On sloping ground the roadbed was leveled and a rock berm built to retain the fill.  Where the road passed over bare rock, they were often bordered by masonry walls or a line of boulders. Most roads appear to date from the 11th and 12th centuries.  Construction appears to have stopped around 1150 A.D.  Several roads converged at Pueblo Alto from the north. From there, well-defined stairways led to the canyon bottom. Aside from its obvious purpose of easing travel within the Chacoan world, this network could have improved communications and the transport of goods and materials between towns, making the Chacoans into a cohesive society.. 

Sometimes though, obvious reasons are not enough.  There may have been spiritual reasons involved too. 
If a culture believed that a spirit could only travel in a straight line, then these roads could have been built straight for other reasons.  This would also explain roadside shrines and herraduras with offerings of ceramic pots that were ritually broken.  Not for the living, but for the spirits in the next world.  
Chaco road shrines are usually small stone enclosures with diameters of 3 to 5 meters that are associated with ritual cermaic offerings.  Herraduras (which is horseshoe in Spanish) are horseshoe shaped low masonry enclosures.  Located on elevated breaks, they were larger than shrines with lengths of 6 to 10 meters.  They are often associated with low density scatters of ceramics.  The shards of the broken pots can still be seen today.  To go out in the middle of nowhere and break a perfectly good pot is something my materialistic culture would have difficulty understanding. 
Ceramic Pot Shards in Chaco Canyon
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