THE AMAZING MEXICAN-PERSIAN QANAT

For years La Venta Cave has headed our "Queer Caves of Jalisco" list. After all, how often do you find around 75 nice round holes in the ceiling, most of them in a straight line and carefully spaced 12 meters apart? Now, local people told us the thing was man-made, but it is so BIG that we searched desperately for natural explanations. Caver friends, knowledgeable in geology, bent over backwards expounding theories about faults, shock waves and holes created through drop-by-drop erosion.

Well, that satisfied us and years passed by without many visits to a cave which inspired a comment like "Merde!" from Henry de St. Pierre. (Locals use it as a combination garbage dump, well and toilet)... and which once scared the daylights out of Ray Hardcastle and friends when a large snake that had fallen through one of the holes, trapped another caver and me inside the thing (See Subterráneo #1, page 4).

Years later, we took archeologists Phil Weigand and Chris Beekman to visit the so-called cave...

"Oh Wonder of Wonders!" they joyfully chortled. "Ahhh, Look at those lovely hatchet marks all over the wall! Ooooh, Behold the footholds leading right up to the surface! Mmmm, Gaze upon these superb capstones made to cover the holes!

Well, it wasn't long before even us lesser mortals began to see the Hand of Man upon the wall. But little did we suspect just how special our ex-cave really is...

"This appears to be a fine example of a qanat, an underground irrigation system originating in Persia," exclaimed Weigand. He then told us that the qanat concept made its way to Spain via the Arabs and was later brought to the New World by the conquistadores. Historians know of very few qanats in the Americas and Weigand figured "ours" might increase that knowledge by 25 percent!

As far as we could gather, the basic idea of a qanat is to carry known, underground water from Point A where it's found, to Point B where it's needed. The diggers have to determine where the water table lies at Point A and create an underground channel whose floor downslopes just enough to move the water slowly (avoiding erosion) to Point B.

Why so many holes in the ceiling? We heard theories of air vents and maintenance, but personally, I like caver-geomorphologist Ramón Espinasa's explanation: "If you wanted to make a 3.3 kilometer (two mile) long tunnel and live to see it completed, wouldn't you want to get a lot of men in there digging all at once?" On top of that, it seems to me that properly aligned holes would help the excavators go in straight lines.

Why is the tunnel 12 meters high when less than one meter would have done fine? Well, imagine that the conquistador chief engineer is something of a dork or not too familiar with that strange stuff called jal in Mexico (hard-packed pumice dust, from which Jalisco gets its name). He successfully digs a meter-high tunnel at around 9 meters down, but... it doesn't fill up with water! "¡Caramba!" exclaims the Spaniard. "We'll have to go down a few more meters, but, what the heck, these Indian slave-laborers are a centavo a dozen." After digging out enough dirt to fill Guadalajara's sumptuous Cathedral, water flow is finally produced at the bottom of what has grown to be a twelve-meter high passage.

How many people were involved in such a project? Were the holes dug upward or downward and using which techniques? In what year did all this take place? Well, folks, here's where Speleology bows out and other disciplines move in. For the very latest on qanats, don't miss the Beekman-Weigand-Pint report (soon to hit the newsstands).

Meanwhile, take another look at those "caves that aren't caves" ── you "qanat" tell WHAT they might be! (Sorry, I just qanat resist such opportunities, but rest assured it's all in good pun!)

John Pint