Monday, April 28, 2008

Tuff Canyon

The grey cliffs of the Sierra Ponce are just visible, marking the southern side of the valley of the Rio Grande. A notch in those distant cliffs marks where the Rio Grande flows out and makes its turn east.

Invisible from the pavement where we parked just several feet away, the white walls of Tuff Canyon plunge down to to a creek bed floor. This is the stuff of pyroclastic flows, eruptions of fluidized gas and rock. Scorching gases. Flowing ash. Sharp fragments of rock. You wouldn't want to be around to see it happen.

We follow a path into the canyon and walk up the dry rocky floor of Blue Creek. The creek starts in the Chisos Mountains and tumbles down igneous peaks into the desert, carving its way thru sediment and this ashy tuff. Most of the time it's dry, but look up at the white tuff walls. Look at what the creek has once in a while wrought. You wouldn't want to be around to see it happen.

So here we are.

Trudy is poking at the canyon walls with her fingers. I am staring, jaw agape, at great grey boulders embedded in the white tuff — boulders bigger than I could lift, boulders picked up and thrown by hot flowing gases, boulders now waiting for one more flood of water to wash away the tuff and liberate them. Just one more gully washer should do it for that one over there that seems to be so close to falling out of its hole that you wouldn't want to stand under it, lest its time (and yours) come early.

The canyon comes to an end. The white tuff walls give way to igneous rhyolite just around the corner. Ben is somewhere over there. We find him scrambling up great rhyolite boulders that hold small pools of murky water.

We could hike for a long time up this canyon, following the creek bed up to its source. That would be some hike. But if we did that, our car would be here and we would be there and it would be many hours hence and we would be hungry and tired and ... well we wouldn't do that, would we?

It's an interesting thought I find myself thinking out here: where you might go if you had the time, what you might do if you had the gumption. But we have no more of either, so we scramble up the last few remaining feet of the canyon walls, having climbed well out of the canyon that we started our hike in. We scramble over the edge and back into the desert and back to our car.

Dinner awaits us back in our humble hotel room.

Tuff Canyon
Big Bend National Park

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No Alarm Bell Sounded

To get to the canyon, we first crossed Terlingua Creek — a shallow trickle of water spread across the sand and pebbles. We barely got our shoes wet.

Here, the limestone face of the Sierra Ponce stands at the water's edge. Eastward as you follow the cliffs with your eyes, the water is swift and wide and deep. Westward as you follow them the other way, the water is just this trickle. And straight ahead, the Rio Grande issues forth from Santa Elena Canyon, joins the creek and makes an abrupt right turn.

We scrambled up a sand bank and followed a path thru tall grasses and riverbank vegetation. We climbed some steep switchbacks that started my heart pounding again and came to a promontory that looked north into the desert from which we had just come and looked back at the last stretch of the river's course winding thru the canyon which is what we had come to see.

From there the path began to descend, winding between large boulders that had fallen from the cliffs some time long ago. Ben had gone ahead, leaving us to inspect the tiny flowers growing in crevices and the seashells embedded in the cliff walls here hundreds of feet above the desert floor and hundreds of miles from the sea.

As the path began to take us back to the water's edge, we saw canoes coming around the bend. The water was shallow, and they had to periodically get out of their boats and push. Tomorrow, people said, the Mexicans were planning to release water from the dam on the Rio Concho and the water level would rise. But today it was shallow.

In fact, as I sat on the American side in the shade of American limestone, Trudy took off her shoes and socks and rolled up her pants and waded out into the flowing stream. Some Japanese people had gone before her, and she caught up to them, pointing out bird prints in a sandbar. They asked her if she was a scientist. Little did they know.

Trudy held up her feet for me to see the black mud that she was wading thru. I zoomed in on the scene thru the lens of the camera. I preferred her smile to her feet. As I watched, she walked over to the far shore and looked first one way and then the other. And then she did something reckless.

There on the far side of the Rio Grande river and the far southern reach of the 48 continental United States, Trudy reached out her hand and touched the Mexican side. Fortunately no alarm bell sounded.

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