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Sometimes rocks are holey because they are softish.
As they wear through the years,
harder stones and fossils fall out.
Sometimes it's the other way round.
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| This rock holds different kinds of memories. Some are shells but there are also long things which might be . . . might be the muddy casts of burrows and root holes? |
Some changes have gradations so slight, the difference between one and the next is imperceptible. There are others where things change from one state of being to another in single or multiple lurches. Some can be explained by chemistry or physics. Others not. What about accent? From left to right on a map, Devon, Dorset and Hampshire are in a row. They have no big-deal borders like rivers and mountain ranges - just road signs. But they have their own, distinct, accents and elements of dialect. How can that be?
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| With some rocks, it's not so much that they contain stones but that they are themselves made up of several kinds which means different parts wear away in different ways. Here, some are cracking and flaking. Others are eroding more evenly. |
And dinosaur footprints - I have no trouble understanding that mud, given time, can turn to rock (and vice versa). But how can a footprint in it stay undisturbed long enough for it to be set in stone for ever? Imagine being a dinosaur wandering across some mud and yours being the last feet to walk there for millennia! Imagine how odd it would be to have such significance and not to know it! But how can it be that no-one ever goes there again? Or that winds, rains and tides don't blur or rub them away? It's eye-wide-opening, awe-inspiring stuff!
Dinosaur footprints have been found on Portland and on the Isle of White. I'm always hoping I might find one (or a few - can you imagine
that!) where I walk. No such luck! The kind of pre-history I clamber over is
made from shells and different kinds of rock which have folded and squashed and
muddled together and which are constantly cracking and eroding to reveal new
layers.
That a shell sinks into mud and stays there for ever; that, I can understand. But footprints?
That a shell sinks into mud and stays there for ever; that, I can understand. But footprints?
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| If, in the future, people find human footprints, maybe they will be as interested in our various kinds of footwear as I am in the different kinds of rocks. |
Remember in the last post, I mentioned that a great groove had been dug in the path down to the sea and that it seemed to lead to a burrow? Well, the first dig seems to have set a trend. The route is getting more and more churned. Whether dogs are scrabbling for rats or what . . . I don't know . . . but there are little holes and pits all over the place and the step created by the rut has collapsed into an even steeper step. Rain and feet are taking their toll too. It looks as if someone's foot has gone right through the ground into a burrow below. Mud is oozing into the crack, filling and distorting it.
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| Our footprints will say something about the routes we took. Did we go up and down the same track or did we go home a different way? |
Someone, or some people, informally maintain the path. Somebody must bring secateurs when the brambles stick out too far. Sometimes it looks as if someone has scattered cindery stuff to keep the grip underfoot. I don't imagine the path will be abandoned . . . but, what if it is? What if it gets too slippy and too much of it collapses into burrows? Other paths nearby, paths which run parallel with the sea rather than down to it, have cracked and fallen away taking great chunks of mud and footprints with them.
The nice thing about being bewildered by time is that you can imagine almost anything happening. If a dinosaur pottered along and no-one went that way again - what if our path is abandoned and human footprints are preserved the same way? The earth is soft and flakey. I expect rain will slur everything to mush . . . but . . . what if it doesn't?
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| If our footprints are preserved, they may tell stories of how evenly we balanced our weight, how different kinds of footwear gave different grips. They may indicate emotion "Oh, help, I'm slipping!" |
In England, there are probably few of us who have problems with the idea of evolution but I realise this blog is read by people across the world so it may be worth adding a post-script. When I say how extraordinary I find it that footprints can be left undisturbed for so long that they have time to get set in stone - I say this in the same way as I might look at a seed and wonder how on earth it could possibly turn into a tree. I say it in awe and with excitement, not in disbelief. If ever you get a chance to see the bendings-over, the scrolls and folds of rocks in the cliffs at Charmouth and Lulworth, you will easily see how old fossils and rocks can land up on top of newer ones - something that must be very puzzling to people digging from top down instead of seeing the earth in cross-section.
What's more, there must be a wonderful unwritten history of what people made of fossil deposits in the hundreds and hundreds of years before Darwin. Mary Anning sold fossils. She didn't discover them. What did people make of the skulls and teeth of the unknown creatures that have been falling out of these cliffs for as long as the sea has been beating against them? They didn't suddenly appear in the nineteenth century. By then (and by definition) they had been there an awful long time!
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Human footprints from pre-history on Formby Beach. Thanks to Tim at Notes of Nature for the link.
Extra link - February 11th 2013 - Landslide at Lyme Regis (Dorset) - 300 metres of cliff have fallen. If you look at the picture, you'll see some of the geological layers.
Extra link - February 11th 2013 - Landslide at Lyme Regis (Dorset) - 300 metres of cliff have fallen. If you look at the picture, you'll see some of the geological layers.
