Northwest New Mexico is one of the driest places in the country – the region gets less than 12 inches of rain a year, most of it during the late summer monsoon season. But despite the aridity, this desert is shaped by water. During the Mesozoic Era, starting around 160 million years ago, what is now New Mexico was flooded by the Jurassic Ocean, a shallow inland sea that covered most of the Southwest United States. The Jurassic Ocean was very salty and rich in minerals that left behind extensive deposits of limestone and gypsum.
These layers of gypsum, a white crumbly rock, have eroded away to sculpt a formation known as the “Dragon’s Back”, a 2.5 mile-long ridge with a bulbous head and a tapering tail that, from the air, has the appearance of a great white serpent, standing out starkly against the red and orange landscape. Look closely and you may see tiny mountain bike riders or hikers making their way along the spine of the Dragon’s Back. The trail is not for the faint of heart: gypsum is a water-soluble mineral and eons of rare rains have melted a few sinkholes into the top of the ridge, some big enough to swallow a bike whole.
The top of the Dragon’s Back is wide enough to bike or hike across without much danger of falling off, but narrow enough in some sections to trigger vertigo. The east side of the ridge drops steeply down into a enormous bowl, carved out by erosion over the past 150 million years. This bowl is known in geologic terms as an anticline: a fold in the Earth’s crust that creates a convex dome. This anticline, however, is different. It’s no longer a dome – the middle layers have been scooped out by erosion – leaving behind a bowl with upswept sides. This feature is so unique that geology classes from the University of New Mexico in Albuquerque journey here each year on field trips to see it in person.
The name the Dragon’s Back is fitting, and not just for the formation’s distinctively reptilian shape. During the Mesozoic, when the layers that form the Dragon’s Back were laid down, dinosaurs dominated the land and the sea. New Mexico is home to some of the most productive dinosaur bone yards in the country, including in the Ojito Wilderness, just 10 miles south of the Dragon’s Back, where one of the longest dinosaurs found to date – the 110-foot long Seismosaurus – was uncovered in 1985. The long-necked, long-tailed Seismosaurus was a species of Sauropod, related to the more famous Apatosaurus and Brontosaurus. Other fossils are common in the area, including whole petrified trees.
Flight pattern: You may catch a glimpse of the Dragon’s Back flying into or out of Albuquerque, located 50 miles southeast of San Ysidro. From the air, the Dragon’s Back appears as a curving white ridge against a red background, just west of highway 550.
Read more about the Dragon’s Back and 99 other North American geologic wonders in Aerial Geology, out now! Order your signed author’s copy direct from me for $27 plus $5 shipping per book through