San Juan Raya is a village in a dry valley in the state of Puebla, and it is famous for two reasons that sit oddly together: a ruined sixteenth-century chapel and the sea. The sea part is ancient. The hills around the village are made of rock laid down in a shallow marine basin more than a hundred million years ago, and they are full of fossil snails and other shells, so many that you can find them on the ground. A small local museum, run by the community, shows the best of them. The valley is part of the Tehuacan-Cuicatlan Biosphere Reserve, listed by UNESCO in 2018, partly because this is one of the places where maize and other crops were first domesticated, thousands of years ago.
The landscape here is startling to people who think of Mexico as simply hot and dusty. The valley is famous for its columnar cacti, forests of tall, branching candelabra species and barrel cactus, mixed with agave, thorn scrub and yucca. In the rainy season, from June to September, the hills turn green and the cacti flower, and in the dry months the colour is grey and dust. Birds are plentiful and lizards bask on every warm rock. Early morning and late afternoon bring the best light and the coolest temperatures.
The old chapel stands on a rise above the village, its walls partly fallen and open to the sky. It dates from the colonial period and was never finished, and the stone has a handsome, weathered look. The people of San Juan Raya are proud of their heritage and manage visits themselves, so ask at the museum before heading to the chapel and hire a guide if you want to walk among the fossils.
The ride from Tehuacan is largely on paved road with a few stretches of gravel near the village. Fuel is best taken in Tehuacan, the nearest large city, since the villages along the way have no stations. Zapotitlan Salinas, nearby, has salt pans worked since pre-Hispanic times and a good botanical garden. Bring water, a hat and sun protection. The best time is autumn or spring, when the temperature is moderate.