At the opposite end of the beach at Cushendun, Northern Ireland, we found some outcrops of schist – I’ll be featuring some of them as Friday folds later this week. But cutting across the schist was a pink porphyry, with big well-formed potassium feldspars. I splashed some water from the Irish Sea onto it to increase the contrast:
Here’s a handheld GigaPan image, so you can explore it for yourself. Find a euhedral feldspar! Find a zoned feldspar! Find a beach fly!
[gigapan id=”188379″] Link GigaPan by Callan Bentley
Here is a shot showing the contact between the rhyolite (bottom) and the schist (top):
You can probably tell that schist has a strong potential for featuring Friday folds. Indeed it does. Stay tuned!
Question: In the GigaPan, why are so many of the small porphyritic grains hollow in the middle? What happened here?
Hey Margot!
It’s differential weathering – the cores of these presumably zoned feldspars have/had compositions which were/are less stable chemically than their rims. So they weathered out more rapidly.
C
Grrr… Some local redneck with a tractor was out here last week stealing shingle and turned a lot of the big boulders over.