DUANE
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Duane's take
Here's my telling of what the official marker at Los Caballos has to say, and friend, the earth's got a story here that dwarfs just about anything else on this continent. Now, look around you. Both sides of this highway.
You see those whitish bands running through the rock? The Spanish word for horses is caballos, and somebody looked at those winding, rippling bands of pale stone and saw exactly that: the motion of horses, frozen in the face of a mountain. That's what this place is named for.
Those bands are part of what geologists call the Ouachita Fold Belt, a northeasterly trending range of highly deformed rock, uplifted somewhere between two hundred seventy-five and two hundred ninety million years ago. Let that sit for a moment. Two hundred ninety million years.
The intricate folding in these rocks, those caballos etched into the stone, they were old before the dinosaurs ever drew a breath. The Ouachita Fold is comparable in age to the uplift that formed the Appalachians away over in the eastern United States. So next time somebody tells you the Appalachians are ancient, you tell them Texas says hold my hat.
Now swing your eyes to the southwest. That skyline, that long, dramatic ridgeline, that's the Del Norte-Santiago range. It's the southernmost extension of the Rocky Mountains, and the rocks of that range have a whole separate origin story.
They were deposited in a sea. A sea that came in after erosion had already ground down the old Ouachita highlands, after a later submergence lowered the whole area. So these two ranges aren't just different in age; they were born in entirely different worlds.
And that high, flat-topped mountain to the southwest, that's Santiago Peak. Named for a local man who was killed by Indians and buried beneath the peak. There's weight in that name every time you say it.
What you're lookin' at when you look at Santiago Peak is a mass of what was once molten magma that cooled and hardened underneath the earth's surface, and was only uncovered later by erosion. The mountain didn't rise up; the world around it wore away. Now here's where the story gets genuinely remarkable.
The Del Norte-Santiago range was uplifted and folded forty to sixty million years ago. That sounds old. That is old.
But it is not half the age of the Ouachita Fold behind you. You are standing between two mountain systems separated by more than two hundred million years of earth history. One ancient beyond reckoning, one merely old.
And the marker says it plainly: this fusion of old and young mountains is unmatched at any other site in North America. North America. Not Brewster County.
Not Texas. The whole continent. Those whitish bands of stone rippling like horses across the rock face, they've been runnin' that race for the better part of three hundred million years, and they haven't stopped yet.
What the marker says
Highly deformed rocks in the Ouachita Fold Belt, a northeasterly trending range, uplifted about 275 to 290 million years ago. The intricate folding is shown by whitish rock bands--called caballos (the Spanish word for horses)--exposed on both sides of this highway. The Ouachita Fold is comparable in age to the uplift that formed the Appalachians in the eastern part of the United States. The northwesterly trending Del Norte-Santiago range (southmost extension of the Rocky Mountains) forms the southwestern skyline. The rocks of the range were deposited in a sea that coverd the Ouachita Fold Belt after erosion had reduced the highlands and a later submergence lowered the area. Santiago Peak (named for a local man who was killed by Indians and buried beneath the peak) is the high, flat-topped mountain to the southwest. It was once a mass of molten magma that cooled and hardened underneath the earth's surface and was uncovered by later erosion. The Del Norte-Santiago range, uplifted and folded 40 to 60 million years ago, is not half the age of the Ouachita Fold. This is a remarkable fusion of "old" and "young" mountains--and is unmatched at any other site in North America.