by Matthew Cobb
The internet has a very strange attention span. All of a sudden people get excited about something and it appears in a flurry of excitement all over the place, even if it is old news. These astonishing fossilised footprints from Cal Orko in Bolivia are a case in point. Over the last few months they have popped up on various sites, and today they made an appearance in my Tw*tter feed.
I’ll be honest with you – I had never heard of them, and, having been ticked off by Professor Ceiling Cat on a number of occasions for sending him things that turned out to be not entirely true, I was even suspicious. But it is all absolutely true and has been known for many years. If any readers have visited the site, please chip in in the comments. The first three photos below are from here, but I’m not sure who the original photographer is – let us know in the comments and we’ll give your credit!
This is an example of the 5000 or so footprints that have been identified on what was once a muddy shore. Pretty impressive, and even more so when you realise that this stretch of rock is in fact near-vertical (the sky at the top is a giveaway). This is what the site actually looks like – you can just make out some of the many tracks going up the 300ft high ‘wall’:
Here’s a close-up of what it looks like:
The quarry – for it is still a functioning mine – has been turned into a tourist attraction, with a viewing platform from across the valley (tourists aren’t normally given access to the cliff face). In a 2011 travel article in The Guardian, Ian Belcher described how the site is subject to continual erosion and change:
A landslide has left a savage rip across the rock face, interrupting the trail laid down 65m years ago in Bolivia‘s central highlands. … Cal Orko is a constantly evolving record of life in the Cretaceous era – an epic canvas that due to erosion and local mining will always be a work in progress. “It’s just amazing,” says chief guide Maria Teresa Gamón as we inspect the damage. “We see fresh footprints and fossils all the time. We lose some, we find some. It’s always changing.”
Belcher took this photograph of the viewing platform:
Belcher’s piece concludes:
The Parque Cretácico, opened in 2006, lies further up the hill, with a museum, vast models of dinosaurs and B-movie roars piped through loudspeakers. So far so Spielberg. It’s only when I reach the viewing platform, 150 metres from the rock face, that it starts to become marvellously real – a widescreen view of prehistory. My eyes need to adjust. Cal Orko is a vast optical puzzle requiring time to decipher. Those dots, dashes and holes like super-sized horse hoofprints aren’t random designs – they’re rock-solid semaphore explaining Cretaceous life.
Visitors aren’t normally allowed up to the wall, but with mining temporarily suspended, I’m granted rare access. The immense vertiginous rock face is slightly overwhelming, in the dust and searing heat. Maria, the palaeontologist’s assistant, uses a mirror to transform the sun’s rays into a spotlight, picking out specific tracks.
Her enthusiasm is infectious. “Look! Six footprints going up. Ankylosaurus. And over there! Those are about 80cm in diameter. It’s a titanosaur coming down the wall for about 25m. See where they stop? That soft outer rock will soon crumble and you’ll follow them right to the ground.” (…)
The spoors reveal mundane details of daily Cretaceous life. It’s CSI: Sucre. “That ankylosaur was running. It sank its four toes into the ground, rather than its heel.” (…) For two-legged dinosaurs you multiply the length of the footprint four times to discover leg-to-hip length. Once you’ve got the legs, you know if it was Joe Average or Godzilla.
(…) it was unique climate fluctuations that made the region a palaeontological honey pot. The creatures’ feet sank into the soft shoreline in warm damp weather, leaving marks that were solidified by later periods of drought. Wet weather then returned, sealing the prints below mud and sediment. The wet-dry pattern was repeated seven times, preserving multiple layers of prints. The cherry on the cake was added when tectonic activity pushed the flat ground up to a brilliant viewing angle – as if nature was aware of its tourism potential. (…)
Far from preserving the site, man is adding to the ravages of time. As I leave, a low explosion thumps across the quarry’s fragile earth and reverberates through my chest. More tracks will disappear, more emerge – the endless dance of conservation and industrial progress.