Casa Grande Ruins
National Park Monument
Coolidge, AZ

February 16th, 2003

One of the wonderful things about traveling without any particular agenda is the ability to follow up on some relatively unknown place or thing which we come across in our travels.  Such was the occasion shortly after leaving Phoenix by way of I-10, heading for Tucson.  This took us through the town of Casa Grande where Laura mentioned that there was a federal monument. Shortly after leaving Casa Grande we came to State Route 87.  Some 16 miles North on this road lays the site of the very first National archeological preserve.  Without any specific expectations, and no knowledge of what we might find, we turned North and made the trip.  This part of Arizona is flat and dry.  Very dry!  But it was not always that way.  Many years ago the raging waters of the nearby Gila river supplied more then enough water to maintain a flourishing community.  Since about 300 A.D. the Hohokam Indians  lived along the Gila and its tributaries.  The Sonoran Desert that make up this land laid in natural terraces just above the river banks. The very survival of these hunter/gatherers in such a barren land is just short of miraculous, but these industrious ancient dwellers surpassed all others of their time by forming a  federation of peoples living along the river and through co-operation, designed and built an intricate canal system, irrigating miles of farm land. For a thousand years they lived and prospered along the canals.  They then vanished, taking with them the knowledge of the life and culture which had been so marvelous.  Little remains.  What does remain is subject to speculation and conjecture.  The center of these thoughts is called the Great House, or Casa Grande, and the subject of our adventure.  Built in the 1300s,  the Casa Grande differed from the other structures built in this area.  Normally the Hohokam used what ever was convenient and ready available, to build one or two room huts.  Not so with the Casa Grande.  This structure was 60 feet long and a respectful 4 stories high.  It is the largest structure known to exist among this tribe during that time period.  There were many other unusual aspects of its construction.  The Casa Grande once contained hundreds of imported beams. Pine, fir and juniper obtained from mountains over fifty miles away.  Floor supports spanned the width of each room; saguaro ribs were laid perpendicular to these; reeds were set on this framework, and coated of caliche which completed the floor. Caliche (cuh-LEE-chee) was one of their surprising creations, is a construction material with properties similar to concrete, comprised of a mixture of sand, clay and calcium carbonate or limestone.  It took 3,000 tons of this material to build the house.  It was poured in successive layers to form walls that are up to 4 feet thick at the base.   When you consider, even the most elementary of axes were not available, it was quite a feat.  However for me, the most marvelous thing about this house was its location, physically I mean. Its walls face precisely to the cardinal points of a compass.  Twice a year, the morning sunlight passes through a pair of holes located in opposite walls of the uppermost room of the Casa Grande.  These events mark the midpoint positions of the sun as it moves along its north-south path.  The vernal Equinox occurs in March, and the Autumnal Equinox arrives in September.  At that time, sunlight will pass through both holes, marking that date.  The holes are part of a system of alignments incorporated into the Casa Grand that helped the ancient Hohokam keep track of time.  Other openings also align with the sun and moon at specific times. From these facts it is believed that the ancient inhabitants had extensive knowledge of celestial movement and used it in planning crop planting and hunting times.  This turned out to be a great afternoon.

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