Wednesday, February 1, 2017

Swimming Holes


Once upon a time, Earth looked a lot different than it does today. It was wild and primordial and completely uncivilized. If you were to take a time machine back to let's say 80 million or so years ago, you would not find a single person on the surface of our planet. But you might find between a few and many many species of dinosaurs, creatures far far larger than any living animal today.

It is estimated that the first dinosaurs appeared on Earth between 230 and 245 million years ago and were the dominant lifeform on our world for almost 200 million years. If that seems like a long time, it is. Both actually and relatively speaking. The earliest evidence of man on planet Earth is about six million years old and the first civilizations date back only about 6,000 years. 200 million years is about 28 times longer than man has even existed.

So let's stop here because I know what you are thinking: what do the introductory paragraphs of this post have to do with a goofy picture of me floating in some water against a background of rock and vines? Well, read on, please. And we'll stick with the dinosaurs for a little bit.

I assume the emergence of the dinosaurs was a gradual sort of evolutionary process and not just a group appearance of enormous vertebrate animals. But when it was time for the dinosaurs to go away (about 65 million years ago as it turns out), it appears there was something that caused a mass and sudden extinction of all species.

The event that led to the dinosaurs' death has been a subject of great debate but eventually most scientists agreed on a common cause: the striking of the Earth by some giant meteor that would have caused a global climate change from which the dinosaurs couldn't recover. The meteor theory seems to have been agreed upon by the middle of the twentieth century even though nobody could point to exactly where the thing hit the globe.

Then in 1978, a geologist working for Mexican oil company Pemex named Glen Penfield noticed a large semicircular arc along the north edge of Mexico's Yucatan Peninsula on a magnetic survey map of the area. He had accidentally stumbled across one of the largest craters on the planet, one so large that it is imperceptible when standing on the ground. The only way it could be discovered was with some kind of large scale map of the area that would show more detail than something like a satellite photograph. If the crater wasn't difficult enough to spot already, the fact that more than half of it is in the Gulf of Mexico made it even harder to make out.

The depression in the Earth's surface would ultimately be named Chicxulub (pronounced CHEEK-she-loob) Crater and would be found to date to pretty much the exact same time in history that evidence of dinosaurs stopped appearing. It is now generally accepted that this was the meteor that caused a global blackout of the sun for years, effectively killing off the dinosaurs. For perspective here, the meteor is estimated to be six miles in diameter; that's huge. The impact on the surface of our planet caused an explosion of an estimated 100 million megatons of force, about 2.5 billion times the power of the atomic bombs dropped on the cities of Hiroshima and Nagasaki combined at the end of World War II. The crater itself is about 110 miles across. It's impossible to see in person.

Last month, I traveled south to the Yucatan to visit Chicxulub and see for myself some of the evidence of what caused what is likely the greatest mass extinction on our planet. Now, obviously I couldn't see where the meteor struck our planet; I mean I just finished writing about that and I'm nothing if not prepared when I explore a new part of our world. So to visit the remains of Chicxulub, I went underground. Well, barely.


The sacred cenote at Chichén Itzá. No swimming here.
When the dinosaur-killing meteor crashed into present day Mexico, it hit a part of the world that is pretty much a huge flat limestone surface, and the impact caused a series of underground caves or open basins (sort of like sinkholes) to form which subsequently filled wholly or partially with fresh water filtered through the limestone below the surface of the Earth. These caves or sinkholes are known as cenotes (pronounced se-no-tay) and have played an important part in life in the Yucatan for centuries. The Mayans used these things for religious ceremonial and sacrificial purposes but more importantly in a part of the globe without rivers, the cenotes provided a reliable source of fresh water to simply survive. They quite literally gave life.

Today the cenotes are not used as a water source. After all, there's bottled water on trucks for that sort of thing nowadays, right? But they are a reminder about how the first peoples in the area came to settle there and they provide awfully convenient and somewhat otherworldly cooling off spots on a hot Mexican summer day. Or even a hot Mexican winter day. And since they are the only real way to connect as a tourist with the event that killed the dinosaurs all those millions and millions of years ago, I had to have one or two of these things on my vacation itinerary. 

Our first encounter with cenotes occurred on our first full day in Mexico during a visit to the ancient Mayan city of Chichén Itzá. Head north from El Castillo on that site and you'll find (after a gauntlet of souvenir vendors) the sacred cenote of the old city, a place associated more today with ceremonial sacrifice to the gods than a spot to cool down on a sunny day. From the description in our guidebook, it appears the locals at Chichén Itzá used to regularly throw their enemies in their local sinkhole as sacrifices to the gods. Once you were in the sacred cenote, there was no way out, the sides are pure vertical; no matter your age (and more than 50% of the bones recovered there have been those of children), you would eventually drown. Nice, right? 

Considering the macabre and archaeological significance of the sacred cenote, not to mention the fact that we too would drown if we jumped in, we had neither the desire nor the opportunity to cool off in the Mexican heat in the first one we saw. We'd go farther afield for that.

Cenote Ik Kil near Chichén Itzá from the water's edge.
To today's residents of the Yucatan, the hundreds of cenotes scattered about that peninsula are literally like local swimming pools. Some are publicly owned and some are privately owned, but most are well used as escapes from the temperatures. We debated visiting a number of different cenotes within about an hour's drive of our hotel near Chichén Itzá but ultimately settled on two close to home: Ik Kil, which ended up being within walking distance of where we were staying, and Yokdzonot, about 10 kilometers or so west of town. Let's go swimming!

There are three basic types of cenotes in the Yucatan: those with vertical walls; pitcher shaped cenotes where the water surface is larger than the opening in our planet's surface; and cave cenotes, which may extend a little bit or a lot into the depths of the Earth. Ik Kil turned out to be pitcher shaped and Yokdzonot had purely vertical walls. Both had manmade staircases leading down to the deep water at the bottom and were ringed with vegetation whose long dangling roots extended from the ground almost all the way down to the water below, an estimated (by me) maybe 100 feet in some spots.

If I were to characterize the difference in character between the two, I'd say Ik Kil was marketed towards tourists trying to grab a piece of local flavor after a bus trip to the pyramid and ruins at Chichén Itzá and Yokdzonot was a local hangout providing a place to cool off for the kids and adults living around the town. Yokdzonot looked very natural with unaltered rock walls and a rough stone and steep wooden staircase to get to the water. Ik Kil had clearly had some work done; some of the walls of the depression in the Earth looked like they were injected with concrete to shore up the sides. Yokdzonot admitted more light and the water looked clearer; Ik Kil was probably a little more picturesque with the diffuse light entering through the narrower-than-the-water opening above.


Yokdzonot cenote. Watering hole for the locals. Felt worlds away from touristy centers just to the east.
The most surreal part of swimming in these deep (I think we heard estimates of about 60-70 feet) pools is swimming underneath and around the roots and stalactites that crowd and form around the perimeter of the top openings of the cenotes. At Yokdzonot these form a curtain around the water's edge, with about five or ten feet behind them to the walls of the basin. At Ik Kil because the hole in the Earth is smaller than the pool below, the roots of trees form a ring in the middle of the water that you can swim around and look up to the bright sunshine. I imagined the long roots hanging in space to be connected to the Tree of Life in Mayan mythology while I swam around them.

As a calm place to cool off on a hot day, I think I'd pick Yokdzonot over Ik Kil, which is built for tourists, complete with restaurants, a hotel and lockers and changing rooms. While the lockers to store our stuff were nice, it was obvious on our way out that it would be getting very crowded in the late morning. We got to Ik Kil just after 10 am and found the place comfortably used; there was more than enough space for the dozen plus swimmers in the water and we spent a pleasant hour or so relaxing. But on the way out we walked past busload after busload of arriving tourists at just 11 am. If all those folks were piling into the pool, I could see it being more busy than comfortable.

We fled to Yokdzonot right after Ik Kil and found a calm emptyish pool mostly used by locals and it stayed at that level of use for the entire time we were there. I'm not saying Ik Kil wasn't worth a visit; it totally was if for no other reason than they have a platform about 15 feet above the water for diving or jumping into the water. I've never jumped off anything that high into a swimming pool, lake or anything else and looking down at the water was a little daunting. But hitting the surface and then popping back up quickly was exhilarating.

Thumbs up ready to go. Here goes nothing!
Hitting the water. Hooray!!
The point behind visiting these spots for me was not to feel a connection to the death of the dinosaurs and think about not only how tenuous life on Earth can be but to spend a few moments thinking about what a meteor about a quarter the size of Washington, D.C. could create 65 million years after the fact. What I ended up getting out of them was so much more. 

We read a little bit about Mayan history and culture before we arrived in the Yucatan. But being immersed in that world for a few days really got us an appreciation of how advanced and sophisticated that culture was. We got glimpses into their understanding of mathematics and astronomy and their religion and culture in ways that we couldn't have by reading books. It all started with the cenotes. Without these things there would have been no Mayan settlements on the Yucatan Peninsula. Spending a morning bobbing about in their waters provided just one more way for me to connect with the Mayans. Plus I got a break from the heat.

Water's eye view looking up at the sunlight at Ik Kil.

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