Rocks rock !

"GEOLOGY FOR DUMMIES" - A M Spooner (2011 USA) 

        I've always liked rocks. They give you a sense of your universal context. But I've never dived into a serious study of Geology, until now. Well, semi-serious. And this (Xmas Pres) is an ideal place to start. And probably end, as I'm not looking to launch a new career. I'd just like to know the facts.

        So many of the lovely beaches of Adelaide have a line of boulders as a last defence against high tide, all about the size of a dishwasher, and taken from the Adelaide Hills. We walk past these early every morning to and from coffee, and can't help but marvel at what they are.

        These rocks are 500 million years old - bits of teenagers when you consider the oldest in the world (they're in Canada) are 4 billion years old - but still something to hold in awe, considering that these rocks that we hacked out of the Hills to protect out beach front real estate were already about 450 million years old when the dinosaurs went extinct. And for my money they, and the waves, will still be here when Homo Sapiens is long gone.    

        There's many of these rocks on our morning walk that catch the eye - one of my favs still has the riverbed ripples in it, clear as the eon they were laid down - but these two are intriguing. The one on the left is a simple Sedimentary, its layers put down one at a time over millions of years, at the bottom of a lake or slow-moving river, with some change in conditions on a regular basis to separate them. This one I can get my head around.

        But the one on the right beats the hell outa me! Its main body - the grey stuff - is clearly sedimentary as well, as you can see the layers, but how did those thin white layers of quartzy stuff get to be at right angles to those layers, and not just to them, but with another one at right angles to that?! And these bands run all the way around the boulder.

        I presume that they are made of the shells of billions of crustacea who each lived for a blink of the universal eye, then settled to the "bottom". But you have to ask - of these three diametrically-opposed layers of material - considering that each had to be "flat-on" at the time - which came first?

        This will be one of the first things I intend to ask Whatever is behind all this, when it's my turn to find out the Answers. And I tell you now, I will be deeply pissed off if I don't get to find out.

        Cheers....

                    T.R.E.

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