A Watermelon in the Desert

I knew I should have taken that left turn at Albuquerque“, Bugs Bunny said after getting lost once again. If he passed by Albuquerque though, in the high desert of the US state of New Mexico, he actually should have stayed there for a while. Rising more than 5000ft (1500m) above the city is an impressive, almost vertical wall of granite known as Sandia Peak. This natural feature formed during an uplift along the Rio Grande rift, and a hike from its foothills to the top is the botanical equivalent of a road trip from Albuquerque into Canada.

The word sandia is Spanish for watermelon. This name was inspired by the beautiful desert sunsets that cover the Sandia mountains in a deep red hue. These mountains were created by an uplift along one of two parallel fault lines. Running north-south, from southern Colorado into Texas and Mexico, these fault lines cut the state of New Mexico in half, geologically speaking. The area in between the fault lines, about 30 miles (50km) wide near Albuquerque, started sinking down around 30 million years ago, forming the Rio Grande rift. This rift gradually filled up again later on, with sediments brought down by the Rio Grande river and with lava and ash from volcanoes that had formed along its western fault line.

An overview of the Rio Grande rift, cutting the state of New Mexico in half. Inset: The location of New Mexico within the USA. Image source: USGS and Wikipedia.

Along the eastern fault line a series of uplifts took place, one of which created the Sandia range. A large part of these mountains is made up of Precambrian granite, topped with several hundred feet of sedimentary rock, mostly limestone. To give an idea of the vertical movements that have taken place over time along this eastern fault line, sedimentary rock corresponding to that on top of Sandia Peak has been found 20,000ft (6000m) beneath the rift. Add to that the height of the mountain above the rift, and you get an elevation difference of almost 5 miles (8km)!

Because of the abrupt change in elevation, traveling from the foothills to the top of the Sandias takes you through several different life zones. Starting at the bottom in the upper Sonoran (semi-desert) zone with an abundance of cholla cactus, the vegetation then goes through different transition zones and into the Canadian and Hudsonian (sub-Alpine) zones with douglas fir and aspen trees at the top. Botanically speaking, this transition is the equivalent of a road trip from Albuquerque all the way north into Canada.

The Sandia mountain range along the eastern side of the Rio Grande rift, as seen from the Rail Runner train. Click the pic for a larger view.

The top of Sandia Peak can be reached in three different ways. On the eastern (shallow) side of the mountain, a paved road goes all the way to the very top. On the western (steep) side, the Sandia Peak tramway whizzes you up in 15 minutes to a large viewing deck and restaurant. A narrow hiking trail along the crest connects the upper tram terminal with the actual peak, about 1.5 miles to the north.

As a third alternative, you can hike all the way up on the western side, a 9-mile (14.5km) long and 4000ft (1200m) vertical ascent to the top. The trail starts at the lower tram terminal, going up along the Tramway trail and then the La Luz trail, and ends at the upper tram terminal. This hike provides the best way of experiencing the changing vegetation and life zones as you work your way up.

From the top you can see all the other mountain ranges along the rift: the volcanic Jemez mountains to the west, the Sangre de Cristo mountains (the southernmost tip of the Rockies) to the north, and the Manzano mountains to the south. This gives an excellent impression of the scale of this geological formation.

A view down into White Rock Canyon, with the Rio Grande river flowing through, along the western side of the rift.

A good way to get a more close-up impression of the rift valley is by taking the New Mexico Rail Runner Express between Albuquerque and Santa Fe (New Mexico’s state capital). This very scenic 1.5hr train ride offers perfect views of both the Jemez mountains and the Sandia mountains. It also passes through various native indian reservations and large stands of cottonwood trees along the Rio Grande river, where time seems to have stood still.

So, next time before taking that left turn at Albuquerque, be sure to make a little detour up Sandia Peak, that beautiful watermelon in the desert. For a brief moment, forget about your day-to-day worries while pondering New Mexico’s impressive geological and botanical diversity, shaped by the forces of nature over millions of years…

A view across tent rocks, an area where the layers of ash, deposited by volcanoes along the western fault line, have been eroded by wind and water into shapes resembling teepee tents.

For more detailed information, read Roadside Geology of New Mexico by Halka Chronic (Mountain Press Publishing Company, 1987).

All photographs © Wim Hordijk

This article is part of the Beauty and Science of Nature series.