Mar 26, 2017

From ‘Ring of Fire’ to ‘Ring of Water’

I travel light.
But not at the same speed.

Jarod Kintz

Surreal world of Rio Secreto, a 12,730-meter cave (7.9 miles) with crystal clear water. 
All pictures from Rio Secreto photographers as no one is allowed to take pictures
About 200 million years ago, the Yucatán Peninsula was located near where northern Africa is today.  For many years, it was covered by the sea, emerging from it some 13 million years ago.  It is a shelf composed of a flat stone layer known to the Mayas as chaltun that many nickname a ‘Stone Sponge’.

One of the entrances to the cave - first portion is dry now (end of dry season). 
No electricity in the cave, only candles, headlamps, or flashlights.
Absolutely stunning formations
Barely hidden under thin layers of sediments and mud are buried very large accumulations of sascab (unconsolidated limestone), a thick lime-sand deposit that acts as a sponge with enormous capacity to store rainwater.  Without this lime-sand, the region’s vegetation would resemble that of African grasslands, where conditions differ enormously between rainy and dry seasons. 


Natural underground pools called cenotes form because limestone is very sensitive to erosion.  Tropical storms over millions of years have helped create caves, underground rivers, and cenotes, a process known as karstic, a chemical weathering that helps dissolve soluble rocks by the action of water.  Due to the presence of so many holes, water runs mostly underground in this region.


Cenotes dot the jungle by the thousands, and explorers can still dive down to find intact artifacts and remains.  There is a peculiar pattern to some of these cenotes, they form a very dense ring around the capital city of Merida.  This discovery becomes a very important evidence in the evolution of life as we know it today but more on that later.


Mirror like clear water

Mayab, the Land of the Mayas or the Yucatán peninsula, covers 300,000 km2 or 186,000 square miles.  Below the surface run the three longest underground water systems in the world:  Ox Bel Ha = 180 km (112 miles); Sac Aktun = 172 km (107 miles); Dos Ojos = 82 km (51 miles).  These molded the distribution of settlements for the last 10,000 years... Every major Maya ruin is located near one.

A
‘cenote’ is a natural sinkhole created where a fragile cave ceiling (such as limestone) has collapsed, exposing groundwater. Cenotes were the only source of water in the jungle for the Mayan civilization and are considered sacred by the Mayan people. The Mayas considered cenotes to be an entrance to their underworld or ‘Xibalba’ where their Gods live and their spirits reside after death.  Although found in 6 or 7 other countries, the Yucatán peninsula has the most cenotes with anywhere between 6,000 and 7,000, of which only 2,400 have been registered.  Similar features exist in other parts of the world, but not in the abundance or the natural beauty found here.

Bottom is white, helping create such light-colored water

The word cenote is derived from the Mayan word ‘D'zonot’ and refers to any subterranean chamber that contains permanent water or sacred wells. While some cenotes are vertical, water-filled shafts, others are caves containing pools and underwater passageways. The water that gathers in these subterranean cenotes is usually a crystal clear turquoise color with a very pleasant temperature of about 25.5C or 78F.  They can be mere centimeters to hundreds of meters deep.  Visiting them, you may be able to enjoy the dazzling effects of refracted light beams moving through the water when they are open to the sky.


Besides being a distinguishing characteristic of the Yucatán landscape, cenotes are an integral part of the history, customs and traditions of the Mayas, wrapped up in myths and legends.

During the last ice age, the ocean level dropped (water levels were approximately 90 meters or 300 feet lower than their present-day levels), exposing the reef to the surface. The coral died, jungle grew over the 2,300-meter-thick limestone bed created by the coral reef and became the largest limestone platform in the world. Fossils found far inland are proof of this and are commonly seen during cenote dives.  We personally saw a sand dollar, a clam and another type of shell very similar to a conch.

In front of columns, when a stalactite meets a stalagmite 
Caving helmets came in very handy.
 At times, there was barely a foot of clearance over our heads as we floated around.
Massive cave systems were formed by gradual dissolving of the highly porous coral limestone. These caves are called ‘solution’ caves because they were formed by the slightly acidic rainfall dissolving the alkaline limestone. Inside these caves stalactites and stalagmites would often join to create columns and are a spectacular sight to see. These formations number in the millions and range in sizes from a small pencil to a big tree.  They are made up of crystallized calcium carbonate.  These deposits can evolve into many other shapes as well such as waterfalls, flowers, ripples, pearls, lettuce, rafts, lace, helictites, etc.  Because stalactites are hollow, they create bell-like sounds when banged lightly.

‘Wave action’ in the white bottom
Akin to a huge pipe organ but upside down.  Millions of stalactites. 
How do you know it is a stalactite when broken off? 
It has a small hole in the middle, like a straw.
Among the interesting archaeological discoveries in recent years are ancient fossilized remains of camels, giant jaguars, mammoths, sloths, and horses. To date, four human skeletons have been found. Tests on charcoal found beside one female skeleton (Naia, about 15 years old) would place it at 13,000 years ago, which makes it one of the oldest human skeleton found in the Americas.

The Ring of Cenotes of Chicxulub Crater, Yucatán, seems to be exclusive, not comparable with other sites in the world. Its origin is evidence of an extraordinarily large impact event that has been related with the extinction of dinosaurs.

About 65 million years ago, a meteor or asteroid, about 10 km in size, struck Earth near Chicxulub, on the western Yucatán coast.  It created a huge crater now buried beneath massive amounts of deposits.  With new technology that can read through thick layers, scientists calculated that its diameter is near 200 km (124 miles) making it the largest confirmed impact on Earth.

Stalactites from below.  Color variations come from different minerals
The energy of that impact would equal six million times the volcanic eruption of Mount St. Helen, Washington, USA, in 1980.  The shock of the impact would produce a magnitude 10 earthquake. 

The only visible proof of this immense crater are the cenotes.  They form a ring that lines up with the rim of the crater lying below the surface. 

Despite still being disputed, many believe this is the impact that helped kill the dinosaurs, creating a nuclear winter that lasted over a year, disrupting photosynthesis, starting a 2-km high tsunami and enough heat to set vast swaths of forests on fire over extremely large areas, eliminating over 50% of the species alive at the time. 
Now that this Ring of Cenotes, filled with their beautiful waters have been revealed to the world, they are heavily visited and it is becoming increasingly difficult to keep them as clean and natural as they were before tourism’s influence.  With so many people diving in with shampoo, sunblock, perfume, sweat, conditioner, cigarettes, deodorant, etc., the water is becoming increasingly murky.  There is a movement to request people clean up before entering these waters and several divers make vast efforts getting the trash out of them. 

Dripping for millions of years, slowly growing
Jungle meeting white limestone meeting aquamarine waters – breathtaking but can we keep it that way?  I feel we were very lucky to see Rio Secreto.  It has been open since 2007 yet only 80,000 people have seen it.  They restrict the number of visitors so that the impact on this natural wonder is lessened, something other places should follow.  This is a site we will never forget.

From a Ring of Fire when the meteorite/asteroid hit to a Ring of Water with cenotes… thousands of years later.  From destruction and cataclysmic changes to great historical sites.  Don’t miss visiting them is you can.

The pyramid of Chichen Itza sits on a large cenote (water cave). 
Only a few meters are left holding up the pyramid. It keeps eroding. 
Although it probably won't fall during our lifetime, it will eventually happen.
So much beauty.  Hard to know where to look next.
Small window view to the outside world
Sources: www.divecenotesmexico.com and www.yucatantoday.com and Gran Museo de Mundo Maya in Merida, www.riosecreto.com










1 comment:

  1. What a fantastical adventure...beneath the surface! Thank you for sharing this wonder of the world and for the history and evolution notes too! Very informative and breathtaking post! Dianna

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