Sand & geology
Playa de Gulpiyuri
lithic-rich (volcanic/collisional terrane)
What's in the sand
Gulpiyuri sits 100 metres inland, in a sinkhole fed by seawater through a karst tunnel. Its sand is pure shell carbonate, washed in with each tide through the limestone aquifer — a rare inland beach that breathes with the Cantabrian Sea.
References: source 1
Predicted regional composition
Q-F-L (quartz, feldspar, lithic) fractions sampled from the GloPrSM global sand model at this beach's location.
Q 19%
L 79%
GloPrSM v1.0.0 (IJ_QFL). GloPrSM is calibrated on modern river sand; beach sand in the same watershed is a reasonable proxy but not identical.
Got a close-up photo of the sand here?
Take a picture with a coin for scale and send it over. We're building a global grain-photo library and this beach isn't in it yet.
Playa de Gulpiyuri43.4476, -4.8860