“I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.”
– Sir Isaac Newton
Warning: This blog post is about rocks. As I’m sure you can imagine, blog posts about rocks feature an extreme degree of adrenalin-fuelled drama that often proves too excessive for many readers. Those with a nervous predisposition or known heart condition should proceed with caution.
This is the fifth post about my trip to the Isle of Wight. The first can be found here. It’s also my third post about rocks. I’ll save the links to the other rock posts until the end. You need to pace yourself. If you can survive the below then feel free to tackle the others.
As I crunched my way over the pebbly beach one particular pebble amongst the thousands of others caught my attention. I stopped. “Hmm…now that is interesting,” I thought to myself. I bent down. Picked it up. Inspected it. Turned it over in my hand. “Interesting,” I thought again. I slipped it in my pocket and continued on my journey.
Many thousands of years ago our Neolithic ancestors undoubtedly walked along similar such beaches looking for similar such rocks. Admittedly, their vision was far keener than mine and their attention was focused far more on survival.
The next day I pulled into a car park besides a different beach. After grabbing my coat and rucksack I joined the gathering crowd of strangers assembling at the meeting point. There were parents struggling to herd their excited children, young couples hugging each other in protection against the building breeze and well-equipped older enthusiasts patiently waiting in earnest. As the scheduled time of our meeting passed our guide, Oliver, concluded that everyone who intended to join had likely done so; it was time to begin. Over his shoulder was a well-worn satchel. He dug in deep and retrieved a small collection of rocks. He then began passing them around amongst the eager audience. They were like the clothing of a missing person to rescue dogs. They were the examples to train our eyes upon before departing on our quest. The rocks were fossils. And we were on a fossil hunt.
The Isle of Wight constitutes one of the richest fossil hunting sites in Europe. Over twenty-five different species of dinosaur have been identified on the island. The connection to dinosaurs is so strong that it’s become a major tourist draw. This point is illustrated by a fun walking tour created along the south coast. This ‘Dinosaur Island Trail’ has a series of ‘meteorites’ (rocks) which you can locate. There’s an associated phone app. When you reach the meteorite you open the app and point the phone’s camera at the meteorite. It then super-imposes an animated dinosaur, complete with sound effects, on the scene allowing you to take a photo. Each location has a different dinosaur to discover. Here’s a photo I took at one location:
Besides the walking tour there are also opportunities to go on fossil hunts. Having been fascinated by dinosaurs since I was a kid (as mentioned here) I opted to take a tour and learn some more.
My first discovery came less than a minute into the hunt. I was standing on a raised ridge when I heard a panicked lady asking if anyone had seen a young boy in a red coat. From my vantage point I could see a lone child playing on the other side of the ridge. He was wearing a red coat and appeared too young to be safely playing on his own. From my elevated position I was able to direct the appreciative lady to the missing child. He wasn’t quite a dinosaur fossil, but I guess it was a good find nonetheless. His mum seemed rather relieved anyway.
As we made our way along the beach, armed with our new know how of what to look for, we scoured the ground. Oliver was a local professor of palaeontology and, along with a fellow expert, was on-hand to identify the various finds. He was a jovial fellow and seemed more than accommodating to the relentless queue of budding-fossil hunters hoping for confirmation of having found something special. “That’s a good find, but unfortunately it’s just a bit of wood…” “They look a bit like that, but unfortunately that just some flint…” “Umm…that’s some glass…”*
I was determined to find a fossil. I forensically scrutinised the scene at my feet as I slowly made my way along the beach. Every slightly unusual rock or oddly coloured example was plucked from the sand, excitedly examined , before disappointedly discarded.
We’d been searching a lot longer than I realised when Oliver called out to announce we’d reached as far as we were to go. I was initially disheartened to have progressed so far through the hunt without success. That was until Oliver drew out attention to this:
140 million years ago the Isle of Wight was a floodplain with a monsoonal climate of long dry summers punctuated by flash floods. It was also home to a great many Iguanodons. It seems that a whole herd of these 3.5 ton herbivores had made their way across the muddy terrain that eventually became the Isle of Wight’s coast. It seems likely that a flood struck causing a river to burst its bank filling the footprints with sand. Over millions of years the mud turned to mudstone and the sand turned to sandstone. Sandstone is tougher than mudstone so as the relentless waves erode the soft mudstone cliff the perfectly formed sandstone casts fall out onto the beach.
There was a time when people would collect the footprints. This was fine until some budding entrepreneurs began selling them. This kick-started a lucrative business creating great demand for the footprints. Unsurprisingly, demand soon out-stripped supply. The unsustainable situation came to a head when a footprint was destroyed by someone trying to cut it from the rocks. In desperation the National Trust, who owns the stretch of coastline, sought legal advice. It was recommended that a by-law should be introduced making removal of footprints illegal. The law was introduced in 1984. Since then, any unusual or scientifically important footprints have been removed and taken to the local museum. All others are left on the beach for the public to enjoy. Here, enjoy some yourself:
And here’s another of the Dinosaur Trail photos:
It’s a Pelorosaurus. It’s one of the rarest types of sauropods and grew up to 20 metres in length.
The highest concentration of the footprints can be found around Hanover Point. It’s a geologically interesting location. The underlying rock is being pushed north. This has caused it to rise and at Hanover Point it has cracked and given way. As such, it features the oldest layers of the beach. This can be explained by imagining several layers of paper stacked upon one another. If you push the stack from each end then the middle will rise, creating a peak (Hanover Point). Wind, rain and glaciers has since eroded the top few layers leaving the older layers (the lowest layers of paper) exposed. It’s Africa’s gradual movement northwards which, alongside creating the Alps, has caused this phenomenon.**
While walking back Oliver stopped to point out an apparently incongruous anomaly in the rock strata. Near the top of the cliff was a 128 million-year-old layer. Sat directly on top of it was a layer only 6,800 years old. He asked us if we could explain the odd feature. Can you? (Answer at the end of the post)
Naturally, I assumed I’d discover a completely new species of dinosaur that would totally revolutionise our whole understanding of them. Surprisingly, this didn’t occur. I found a few interesting things, but sadly no dinosaur fossils. As we neared the car park and the end of the hunt I excitedly approached Oliver with my latest find. I was convinced that it must be something. It looked nothing like else I’d seen. The fossils are very, very dark black. And, despite having been subjected to unimaginable heats and pressures for millions of years, their surface still looks remarkably like bone. This was the darkest, blackest thing I’d seen. It also had a slight bone-like surface. Sadly, it was nothing of interest. It was just an odd, dark rock. I think Oliver must have taken pity on me though. He offered me a small fossil that he’d found. He thought it was likely a turtle bone or something. He said I could keep it, which was very good of him. Maybe I didn’t find my new species of dinosaur (The Lanceasaurus), but at least I got my own fossil. I found a few other interesting things as well:
On the left is a 115 million-year-old lobster burrow. The top-right is a piece of fossilised wood (you can see the grain), and the sample at the bottom-right has white shells and fish bones.
I also got the chance to ask Oliver if the stone I’d found the previous day was anything of interest. I was pleased to be informed that it was a 90 million-year-old fossilised sponge that he considered a good find:
The fossil is made from flint. Flint is made from silica. It turns out that the majority of silica comprising flint comes from the remains of ancient creatures (such as sea sponges or various microorganisms). That’s something to bear in mind next time you see some flint. You’re looking at fossils. It’s also interesting to note that our ancestors found flint to be a great source of cutting blades. As they combed beaches in search of cutting tool material they were undoubtedly unaware that they were in fact searching for the remains of ancient creatures. Ancient creatures that had lived and died lived long before our ancient ancestors could possibly have imagined.
Incongruous Rock Strata
The reason for the disparate layers being so close is that the ancient layers were pushed up and eroded. This resulted in the 128 million-year-old layer being near the surface. During the Ice Age glaciers carved away the remaining layers. When the glaciers melted, 6,800 years ago, the ancient layer was left exposed. Subsequent layers then began to be laid down.
*To be honest, I was the one who excitedly showed him the piece of glass. It had been smoothed by the sea and severely scuffed up, so it looked peculiar and unlike anything else around.
**As an interesting side note, a documentary I watched a few years ago explained that Africa’s northward migration will eventually result in Morocco and Spain meeting, making the Mediterranean the world’s largest inland sea. With the water not being replenished it will eventually evaporate creating the world’s largest salt bed (something to consider next time someone offers you an investment in a beachside property on the Med).
If you managed to make it all the way through this rip-roaring rock post without requiring hospitalisation, feel free to see if you can survive the excitement of my other rock-based posts here and here.