Erratic Behaviour 

Regular readers will be well-versed in the action-packed, adrenalin-fuelled, rip-roaring, white-knuckle, rollercoaster rides that comprise my posts. Today, dear reader, is no exception. Today’s post is about this large rock: 


It’s unusual in that it’s positioned upon a strange platform. It’s also unusual in that it doesn’t belong in the surrounding landscape. It’s a completely different type of rock. So how did it get there? Well, for a long time people believed its anomalous predicament was evidence of an infamous Biblical tale. 

There are many such rocks scattered throughout the world. They are called erratics – rocks larger than a pebble which differ from the surrounding rocks. Some religious people have argued that erratics were deposited after a great flood, serving as evidence for the Noah myth.  

During the 19th century scientists began to realise that erratics did indeed owe their existence a great geological phenomenon, but it wasn’t liquid water that did the work. The rocks were deposited by glaciers. As ice sheets expand across the land they envelop the rocks they encounter encasing them within the ice. The rocks are then transported away inside the moving ice sheets. When the ice later melts the rocks are deposited many miles from their place of origin. 

This action can have odd results, such as with a group of erratics in the Yorkshire Dales called the Norber erratics. They’re made of sandstone and were deposited upon softer limestone. Over time wind and rain and eroded the limestone, not the tougher sandstone. The result is that the erratics have been left perched, seemingly precariously, upon little limestone platforms, such as in one photographed above.  

Some erratics are much larger than the one in my photo. The largest one in the UK is thought to be the Merton Stone, located in a field in Norfolk. It weighs an estimated twenty to thirty tonnes. Big as that may be, it’s a mere midge compared to some found across the globe. Most of the biggest examples can be found in North America, along with what’s thought to be the world’s largest. It’s known officially as the Okotoks Erratic but is colloquially, and aptly, known as the ‘Big Rock’. It is situated just west of Okotoks, Alebrta, Canada. It’s thought to weigh 15,000 metric tons, which is certainly a little on the portly side.  

Every school child learns the famous story of Noah and the great flood. What they’re rarely taught is that such flood myths were common amongst ancient civilisations. Interestingly, many of the myths share striking similarities. 

An ancient Greek myth describes Zeus sending a great flood to destroy all humanity. A man, named Deucalion, survived the flood by building an ark. In one version of the story he and his wife survived when their ark came to rest on Mount Parnassus. Sound familiar? 

A Hindu story describes a man named Manu who was warned of an impending great flood by a giant fish. The fish instructed him to build a boat, which he did. The fish then guided him to another mountaintop. A Native American legend describes a flood that killed everyone except an old man who sailed around rescuing animals in his canoe.  

The Sumerian Epic of Gilgamesh exhibits even more elements from the Noah story. Incidentally, it dates back almost 5,000 years and is considered by some to be the world’s oldest written story. In it a sage named Utnapishtim builds a huge boat to protect his family and animals from a storm caused by the gods. After the rains have passed he releases a bird in search of dry land, just like Noah. 

Around 10,000 years ago the world was beginning to recover from the ice age which had dominated for millennia. But leaving rocks in odd places wasn’t the only consequence. As the great glaciers began to melt they created huge lakes of melt-water. These lakes became dammed by giant walls of ice. As the melt continued the pressure on the walls grew making the dramatic events that followed inevitable.  

As the walls of ice collapsed they released walls of water that carved their way across landscapes devastating everything in their path. It’s unknown how many such catastrophic floods surged across North America and Eurasia. It is known, however, that it was one such flood that rendered Britain an island, but some floods were much, much bigger. 

One famous example occurred when glaciers damming an ancient lake in western Montana collapsed. The lake was 2,000 foot deep and the collapsing dam released 600 cubic miles of water. The result was a wall of water hundreds of feet high that flooded across eastern Washington.  

It’s tantalising to think that perhaps the Mesolithic humans who witnessed these great floods passed their tales onto their children and grandchildren, who later passed the stories on to their descendants. And perhaps it was these stories, orally passed down through the generations over millennia, that entered folklore and became the basis of the many flood myths told by ancient civilisations, such as the one concerning Noah. So, in a way, perhaps the strange erratic rocks are indeed linked to giant ancient floods after all.  


About lanceleuven

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