The Myth of East-West Pointing Mountains

A fascinating piece on the geology of the Santa Monica Mountains by our colleagues at KPCC inadvertently offers the latest example of one of my favorite pieces of geographical myth.

If you're surprised that there are such things as geographical myths, you shouldn't be. We live on the landscape, and we tell stories about that landscape that help us figure out how we fit into it. And sometimes those stories turn out not to be precisely true.

The geographical myth at hand is one that pops up in scattered places around the country despite abundant evidence proving it false. That myth: mountain ranges mostly don't point east-west.

Here's the relevant passage, really just a footnote in the KPCC article, in which reporter Sanden Totten conveys a geological history of the Santa Monica Mountains offered by geologist Arthur Sylvester:

Slowly, the plate dragged the mountains that would become the Santa Monica and San Gabriel ranges north. Sylvester says at some point the mountains got snagged on some feature of North American Plate and were forced to rotate about 110 degrees."So that now, the Santa Monica Mountains, which use to be parallel to the San Diego coast line are now east-west mountains!"He says it's one of only a few east-west ranges in the country.

As reported on Totten's piece, Sylvester nuances the statement admirably. You usually hear this myth repeated in much more absolute tones. I first heard it in the summer of 1982, when I was first heading for California on a Greyhound bus from the distant East Coast. As we slowly made our way across the southwest corner of the state of Wyoming, the driver directed our attention to the view out the leftward windows.

"The Uinta Mountains you see there," said the driver, "are the only east-west trending mountain range in the United States."

I accepted his words at face value. It was six months before I realized he was in need of correction, when I visited Wrightwood over the winter holidays with my new girlfriend from Berkeley. Wrightwood perches at the east end of the San Gabriel Mountains a few minutes' drive from the west end of the San Bernardino Mountains, and looking at the map I realized that I had not one but two counterexamples to that bus driver's confident assertion.

The San Bernardinos and San Gabriels are part of a cordillera called the Transverse Ranges, to which the Santa Monica Mountains also belong. So do the Santa Ynez Mountains near Santa Barbara, the Little San Bernardinos in Joshua Tree National Park, the mighty Tehachapis, and smaller ranges like the Chino and Puente hills. Of the 18 or so mountain and hill ranges that make up the Transverse Ranges, most are oriented along a more or less east-west axis. Admittedly, as with the Shandin Hills in San Bernardino, some of those ranges' axes are a judgement call.

The fact that the cordillera that demarks the South Coast and low desert is called the "Transverse Ranges" hints at the admittedly unusual orientation of the mountains. California's other big groups of mountains tend to point more north-south. The Transverse Ranges cut across the state sort of perpendicular to the neighboring Peninsular and Coast ranges and the Sierra Nevada. That's as a result of a kink in the San Andreas fault system, which makes a left turn at Indio in the Coachella Valley, heads for the coast, and then veers right again near Taft in Kern County. That kink indicates resistance between the two tectonic plates that have created California as they slide past each other, and that resistance raises mountain ranges that happen to point more or less east and west.

That "more or less" is important to note. A quick glance at a map of North America's terrain does indeed show that the continent's major mountain chains do trend more or less north-south. But look closer. Those "north-south" ranges are far from lined up. The north end of the Sierra Nevada, at Lake Almanor, is around 150 miles west of its south end at Tehachapi Pass. The Front Range of the Rocky Mountains in Colorado runs close to north-south, but the chain as a whole slants strongly to the northwest as it runs from New Mexico toward Alaska.

And the "north-south" Appalachian Mountains don't run north-south at all, but northeast to southwest. The southern end of the Appalachians is as far west as Chicago, and its north end -- depending on whose definition of the range you listen to -- is as much as 1,500 miles farther east. We look at the Appalachians on a map and they seem to fit into the overall continental trend of north-south mountain ranges, but we'd probably think they fit in just as well if that overall trend was east-west.

Here's another complication: many of North America's mountain ranges don't seem to point anywhere, necessarily. How are the Northern Plains' famous Black Hills oriented? Or the Klamath Mountains in Northern California? In the Mojave Desert, the Soda Mountains seem to point in at least two directions. A few miles north, it's hard to find a direction the Owlshead Mountains don't point in.

And of course, even outside the Transverse Ranges it's not hard to find California mountain chains that point east-west, or thereabouts. Fort Irwin has a lot of them, as do Joshua Tree National Park and the lands to its southeast.

Really, though, the California desert is full of mountain ranges that point every which way. The desert is a geological blender. Basin-and-range stretching encourages the formation of mountain ranges that point more or less north like they do through much of Nevada. The aforementioned San Andreas and its family of faults create mountain ranges along the faults' axes, then spin them around. Here and there some mountains have been created through volcanic eruption, and they point every which way. Standing in the California desert and figuring out which way most of the mountain ranges point is kind of like standing in a blizzard and charting which way the snowflakes point.

And yet the story persists: such and such mountain range is the only one, or one of very few, or the only one in California, that points east-west. It's like the story about your local river being the only one in the world that flows north, or the multiple and conflicting claims about which is the "largest urban park" in the U.S./North America/The World.

It's folklore, in other words: part repetition of stories told without factchecking, part local pride, part fitting the chaotic natural world into arbitrary categories by rounding off a few percentage points' worth of deviation.

Sometimes, as Sylvester did, we nuance our claims to that they're more likely to stand up to scrutiny. In Utah these days, for instance, people are less likely to claim the Uintas as the "only" east-west range. They'll nuance the claim by saying things like the "only major mountain range", or some such.

The Uintas, of course, are a perfectly lovely mountain range no matter where they point, and Utahns are rightly proud of them. So pointing out that the U.S. has a much larger mountain range that points more or less east to west would just be mean.