People are often confused by the use of the word soil for what the Priorat vines live in. Technically, “soil” is the surface of the Earth that is composed of organic matter, air, water and sediment, which together support plant growth. Most agricultural crops do get their nourishment from that top layer. But in the Priorat, the surface is mostly rock without a lot of organic matter. Fortunately, the minerals that make up the rocks of the Priorat possess the sustenance vines need. When it rains, tiny molecules of nutrients are collected by the water as it flows deep into the crevices of the rocks.

Llicorella [yik ō rāl ya] is the local word for metamorphosed rock which, combined with air and water, defines the Priorat soils and its wines. There are many different ideas about the meaning of the word, but etymologically it likely comes from the Celtic word likka, which means “stone.” Celtic people occupied the area in 1500 BCE, so this is plausible.

Geologically the rocks considered llicorella are metamorphic. Most are slates from the Carboniferous Period, but some llicorella was formed in the Devonian Period, anywhere from one million to 100 million years prior.

Slate is a fine-grained metamorphic rock altered by low-grade tectonic pressure to form compressed layers that break easily. There must be sufficient heat and pressure to do this to a rock. In the Priorat, this pressure likely occurred when tectonic plates were shifting to form continents 400 million years ago. The Iberian Peninsula is its own small tectonic plate and was probably jostled by Africa when it hit Catalonia’s coast during the formation of the supercontinent Pangea.

The name of the older Devonian llicorella, pissarres llimoses, translates to “calcareous slate,” but the rock’s foliation suggests it is schist. It still breaks into layers the way slate does, but it has more visible texture. Other metamorphic rocks regarded as llicorella include hornfel, quartzite and black slate.

Priorat rocks that are not llicorella are either sedimentary or igneous. Sedimentary rocks were formed near the Earth’s surface, where temperatures were cooler, making them easily broken down into clay. The igneous rocks are porphyry and granite, which emerged from below the Earth’s surface.

The Paleozoic and Mesozoic Eras produced rocks that naturally broke into many shapes and sizes depending on composition, heat and compression when they were formed. Oxidation added colorful patinas, creating a geologic wonderland.

This story is a excerpt from Ethos Priorat by Elizabeth Hecker.

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