Category Archives: Under the microscope

Sliced thin; an unfolding story of sandstone

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What do you think of this analogy; sandstone, and a pile of garbage? I jest, of course. Garbage is no laughing matter – it has become a defining environmental issue of global import. Sandstones too are not to be sneered at.

Your pile of refuse will consist of the flotsam and jetsam of a lifestyle – things you no longer need or want, things acquired over time, from any number of localities, some of which may be very far away. Garbage anthropology is a thing. Enlightened folk examine piles of old rubbish because they provide data that allows them to decipher lifestyles and cultural norms.

Sandstone is a sedimentary rock made up of a collection of grains; these too accumulated over time and could have been derived from sources close by or very far afield. Grains of sand Continue reading

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Sliced thin; time and process recorded in igneous rocks

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This is the second in a series on the geological world under a microscopeGeologists, it seems, are never satisfied with just looking at rocks from a distance; there is some innate need to wield their pointy geological hammer. Break that rock; give it a good bash! To the uninitiated, this may seem a bit pugilistic, a kind of primal wonton destruction. But a good geo won’t hit rocks just for the hell-of it; a good Geo will be selective. Most of my field assistants and post-graduate candidates needed to be reminded of this. Find something of interest? Before you do anything else, sketch and photograph it; no one will be interested in looking at photos of rubble.

Looking ‘inside’ rocks serves a unique purpose; it allows you to travel back in time, to picture the ancient world, ancient events, outcomes of processes that involve the benign and the brutal, terrifyingly beautiful. Rocks contain memories of all these. And that is why we sometimes break them apart. The optical, or polarizing microscope allows us to unlock these rock memories in a uniquely visual way.  Continue reading

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Sliced thin; kaleidoscopes with a geological purpose

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This is the first post in a series on the geological world under a microscope

As a kid visiting my Scottish grandparents, I would make a bee-line for two delights in their house (after the hugs); the kitchen (following my nose) to the inevitable trays of homemade donuts and shortbread, and the living room credenza wherein was kept an old kaleidoscope. It was a triangular prism (most modern forms are tubes), filled with glitter, two mirrors at one end, and a peep-hole at the other. This simple toy introduced me to the world of symmetrical, kaleidoscopic, never-repeated patterns.  Years later, as a geology student, I was introduced to optical mineralogy, the science and art of identifying minerals under a polarizing microscope – flashbacks to my childhood. Continue reading

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Burnt soles: black sand beaches in New Zealand

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February in New Zealand is mid-summer and this means beaches, swimming, BBQs, and generally chilling (often literally).  One beach we frequent, a 50-minute drive, is Ngarunui.  It is a popular surf beach near the coastal town of Raglan on New Zealand’s west coast.  Here, the Tasman Sea rolls in, as it has done for millennia; the ancestral Tasman began to form about 80 million years ago, when the NZ subcontinent split from what then was a combined Australian – Antarctic continental block.  The ‘Ditch’, as the Tasman is often called, is about 2000km wide so there is lots of space to develop a decent wave set. Continue reading

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Throwing the Celestial Dice

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lunar crater nasa

The expression global extinction frequently conjures images of all life being snuffed out by an act of celestial hubris.  Asteroids, bolides or comets can be lobbed our way at whim.  Earth, in its first billion years or so was probably hammered by extra-terrestrial bits of rock and ice.  The cratered surface of our moon attests to this.  Some argue that it was these early collisions that provided at least some of our water and possibly even the organic compounds that eventually gave rise to life itself. Continue reading

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Measures of Temperature in the Bowels of the Earth

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Te Puia

We don’t need to look far to see evidence that the interior of the earth is hot; geysers and geothermal power stations tap similar sources of heat and erupting volcanoes represent the end point for magmas journeying from the earth’s mantle.  The same heat sources are responsible for many geological processes. Convection in the mantle is the primary driving force for plate tectonics. Piles of sedimentary strata, commonly 1000s of metres thick are transformed to rock as the fluids within heat up, promoting rock-forming chemical reactions.  Internal heat also transforms organic matter; peat becomes coal and organic-rich shales produce hydrocarbons Continue reading

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The Oil Kitchen Rules

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organic shale - kananaskis folds

How Geologists Interpret Ancient Environments; Oil is a Part of the Rock

As a kid growing up in NZ, my only contact with ‘O&G’ was watching my Dad filling the family car with (at that time leaded) gasoline, and Jed Clampett watching black gold oozing from his backyard.  Jed and his family had to forgo the possums, grits and cat’s paws for the rarefied atmosphere, with a twist of lemon, of Beverly Hills.  They had made their fortune on Texas Tea like countless others have done since. Continue reading

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