Dead Dinosaurs and Underwater Abysses

Not Geography Geography Lesson 13

Dead Dinosaurs and Underwater Abysses 

Apologies that it has been many, many weeks since I have posted but I had to revise for exams for my actual degree so that I can afford to buy several dogs when I'm a real adult. But now I'm back, with a blog - inspired by Chris Packham of all people - about the Chicxulub meteor impact and the formation of the Yucatan's 'Ring of Cenotes'. 

Chicxulub Is A Weird Word

Chicxulub is actually Maya for 'tail of the devil', taken from the native language of the Yucatan where the meteor struck approximately 65 million years ago,  marking the end of the Cretaceous period of history. It is estimated to be the biggest meteor to ever have impacted our planet, measuring a rather mind-boggling 100km in diameter, and creating a crater nearly double that size. The impact was the equivalent of 100 megatons of TNT and not surprisingly then, it also marked the end of the dinosaurs. The ones which were not directly killed by the impact, the enormous tsunami it generated, or the fact that everything within hundreds of miles was on fire, were killed by the change in climate caused by the ash and particulate matter thrown into the atmosphere blocking the sun. If you have seen Walking With Dinosaurs then you will know that it was the season finale of nightmares.  

Researchers only discovered the crater in 1991, which seems strange because I think even I, who is the worst 'dad-looker' in the world and regularly can't find the milk in the fridge, would notice a 200km impact crater. But over time it has been buried under over a kilometer of sediment, and was originally thought to be an ancient volcano. Only when examining material for boreholes at the site and scanning it with RADAR did researchers realise something very big and very bad had happened.

Cenotes Is Also A Weird Word

A cenote is a large freshwater sinkhole up to 100m deep, formed by the erosion of limestone rock by acidic groundwater. The word is taken from Maya for 'well' (not as exciting as 'tail of the devil'...). There are over 6000 cenotes of various sizes in the Yucatan Peninsula of SE Mexico, and have been utilised as a vital water source for thousands of years by the areas populations. They are also super beautiful features, in a 'very lovely to look at but all kinds of horrible beasts are probably lurking in there and I will stay on the ground thanks' kind of way. 

Only in the past century have scientists begun exploring and documenting the cenotes, and who can really blame them for avoid swimming into the abyss.... But they have found that the water in the cenotes is not actually still, and is flowing very very slowly into other cenotes, meaning that they are all connected by an enormous network of underground caves. They could be one of the largest and most intricate karstic (systems created by acidic erosion of limestone rock) systems in the world. Scientists have also found sacrificial items including gold, jewelry, figurines and human skeletons in the cenotes, which supports evidence that the Mayan civilisation associated them with powerful gods, and had strong cultural connections to the wells. 

How Is Chicxulub Connected To The Cenotes?

There are 900 cenotes of particular interest to scientists, which are all located along the Southern rim of Chicxulub crater. They believe that the rim and side of the crater created a barrier which trapped groundwater and forced it back into the rock, encouraging erosion and the formation of the cenotes. Hence being named the Ring of Cenotes.  

Hence, without the meteor there would be no crater and no cenotes in that area, and the native populations would have been unable to survive. So on one hand the meteor wiped out the dinosaurs and nearly every living thing on Earth, but also facilitated the creation of these amazing and terrifying freshwater wells; give and take then. 

So far only a handful of the ring have been fully mapped and explored, but they already are appearing to be highly important for the survival of surrounding ecosystems and boast an enormous variety of biodiversity (another reason to admire from the surface in my book). I hope you enjoyed this rather delayed post, and see you next week!