On beach walks and reading the stories of the land

Waitemata sandstone; the sedimentary rock that forms the cliffs around much of Auckland's shoreline. Photo: Su Leslie, 2015

Waitemata sandstone; the sedimentary rock that forms the cliffs around much of Auckland’s shoreline. CastorΒ  Bay, Auckland. Photo: Su Leslie, 2015

There was a moment, thirty odd years ago, when I considered switching from a social sciences degree to one in earth science — specifically geology. I like puzzles, and it’s always seemed to me that rocks contain all the clues necessary for a really good puzzle — if only one can read them.

Auckland, where I live, is built on around 53 volcanoes, and New Zealand generally is one of the most geologically active places in the world. Our rock formations then, are tapestries which tell of tectonic events on a monumental and destructive scale.

The cliffs of East Coast Bays, where these photos were taken, are comprised of sandstone; volcanic sediments deposited when Auckland was submerged under ancient seas.

Waitemata sandstone, with layers of iron and other minerals. Photo: Su Leslie, 2015

Waitemata sandstone, with layers of iron and other minerals. Castor Bay, Auckland. Photo: Su Leslie, 2015

One of the most fascinating things about a walk along the beaches under these cliffs, is how quickly one formation gives way to another. Not only do the depth and colours in the layers change — so does the direction. Within the space of a few metres, horizontal layers become almost vertical, deformed by the movement of faults in the base rock.

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Tectonic activity has deformed the cliffs, forcing some areas up so that the layers of sediment run vertically, rather than horizontally as they were formed. Sandstone cliff at Castor Bay, Auckland. Photo: Su Leslie, 2015.

Zoomed out — another puzzle. What forces made these cool patterns in the sandstone?

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How quickly the colours and patterns change. Cliffs at Castor Bay, Auckland, with the city’s newest volcano, Rangitoto Island, in the background. Photo: Su Leslie, 2015

This post was written for Sally’s Mobile Photography Challenge at Lens and Pens by Sally.

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Source: Geology of Auckland, University of Auckland.

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27 thoughts on “On beach walks and reading the stories of the land

  1. This is fascinating, Su. I’ve always wanted to understand geology better. We did a short course as part of my prehistory degree, but it was delivered with such dry and dusty terminology that it put me off. I often wondered why a subject potentially so exciting and filled with such dramatic activity could be made so dull.

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    • It’s so sad when teaching makes learning unenjoyable. I learned the little of what I know about geology from a physical anthropology paper, and one in physical geography. The teaching styles were so different they almost cancelled each other out! It’s easy to see why so many Victorians were fascinated with geology and paleontology!

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  2. Pingback: Sally D’s Mobile Photography Challenge: Macro (Edible Nasturiums) | Lens and Pens by Sally

  3. A wonderful post, Su ! – of course, your poor country is beset by tectonic movement, but that makes it all the more beautiful in terms of its … ahh … bottom. πŸ™‚

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  4. Those rocks are fascinating in close up. I did an Open University module in geology years (ok decades) ago and loved it. I enjoy looking at cliffs and how they are formed – we’ve just been to Orkney and Shetland which have wonderful examples.

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    • How did that happen???? I started off intending to be a town planner, ended up with a sociology degree, worked in marketing and then retrained as an archivist. So I guess we’re both dealing with layers of paper..

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