Sunday 23 February 2014

Time Travel Without a TARDIS

A little curiosity is a good thing, despite what they say it does to cats. Similarly a little knowledge is probably not as dangerous as they say, so long as we recognise that we have to add to it.

[An outcrop of Permian mudstone, South Hobart] 

For the past 28 years I have lived with the Permian era, or at least on top of land that is underlain by – and derived from – Permian rocks. It has taken me that long to become fully curious about what that really means. Yes, I have always known that our Permian mudstone is very inclined to turn back into mud; that it does not yield rich soils; that the vegetation it supports is seldom lush.

I was also aware of an abundance of fossils in those Permian rocks: some of them literally just out our back door. But it took a visit from our three grandchildren to motivate a little more fieldwork and some more solid background research. They, like many of their peers, have their imaginations fired by dinosaurs and fossils and everything to do with the annals of the former world, as John McPhee called geology. For them it is time travel without a TARDIS.

So, one hot summer's day, we find ourselves on an intergenerational fossil hunt. Attention spans are scarcely troubled. Two minutes up our bush track we are literally tripping over fossils. Spoiled for choice, we are picking up dozens of rocks, discarding most, breaking open a few.

One lump cleaves neatly and the perfect, darkened imprint of a marine bryozoan - its neat lines like a child's drawing of rain - comes to light for the first time in around 270 million years. It is a sunlight brighter than this Fenestella or any living thing would have seen in the Permian. It was an era that was largely cold, often glacial in this part of the world.

[One of my granddaughters holding a Bryozoan fossil] 

It was also an era that saw one of the worst mass extinction events of all time. 90% of all marine species didn’t make it from the Permian into the Triassic. Tectonic plates collided, Pangaea – the all-in-one land mass that preceded supercontinents and continents – was formed. And oceans, seas, and the currents that moved around and between them, were so greatly disrupted that huge pressure was placed on most species. That included shallow-water marine creatures such as the bryozoans and brachiopods we’re finding.

[Fossiliferous mudstone on site in our bush] 

On a quiet Sunday afternoon, wandering through a sunny woodland, it’s hard to imagine such world-changing events. Yet those very environmental changes may be the reason for the abundance of fossils here. Fossils are, after all, the remains of what once lived, and an abundance of them makes you at least wonder about causes.

[Impoverished beauty: woodland on Permian mudstone] 
In the case of the bivalve brachiopods, the process of fossilisation is very plain to see. As I crack open one rock, two sides of a bivalve remain together, like hands still joined in prayer. The shell itself is long gone, but the mud that infiltrated the shell in place of the creature, has preserved the shape of the shell’s interior perfectly.

[A Brachiopod fossil] 
Soon the children depart, along with their little bag of rocks. I turn to identifying the fossilized creatures and some more of the geological backstory. And there, in February 1836, I find Charles Darwin, wandering about our local hills, mountains and shores, collecting the self same fossils. Whether it’s 178 years, or 270 million years, it seems you don’t need a TARDIS to wander through time and space.

No comments: