on saturday morning I googled the geology of St Andrews, thinking about how different what is underfoot here is from Norfolk’s younger rocks – chalk and greensand overlaid by glacial deposits, and the flints that go with that. so we went on a walk to have a look at some of the more interesting features, from East Sands beach along the coastal path.

it takes you past a cabin campsite/trailer park, and then up steep and narrow paths, up and down.  at low tide you can see the folds and tilts in the Carboniferous (about 300 million years ago) sedimentary rocks, squeezed into wiggling lines and loops by the incredible forces of tectonic plate movement.

at some points they merely slope down underground

you need to look at low tide to see it clearly. it’s all mudstones and limestones, laid down under seas and lakes, when the earth was warmer than now and the carbon dioxide was trapped by lush swampy forests that turned into coal and oil.

at that time this part of Scotland was somewhere south of the equator.

after a mile or so you climb down steps to a cove guarded by spectacular rock formations, formed by a volcano inserted into the older sedimentary layers.

they have been named the Rock and Spindle, or more scientifically the Kinkell Ness vent.

an article in Wiki states that the initial volcanic outburst would have consisted mainly of gas discharge which produced the vent or pipe.


then repeated pyroclastic (broken, or exploded, fragments of rock) activity,

the formation of the bedded tuff (consolidated ash from the eruption) in the volcanic cone,

and subsequent collapse of the bedded tuff into the vent,


basalt dykes


(vertical intrusions of volcanic rock) which may extend outside the vent.

this rock looks completely baked

but what puzzles me are lines of something that looks like quartz cutting through the ash beds – a later intrusion?

they run at right angles to the way the ash was laid down. I’d have to ask a geologist ….

it’s hard to imagine that this was once a place of fire, explosions, molten rock, pyroclastic bombs and air thick with ash – maybe a bit like Hawaii.

now re-excavated by the sea

into a cove guarded by dead dragons.