Canyon Gorge update

My stat counter tells me some of you may have seen the news that Canyon Lake Gorge will now be open to the public. If you are in the area and can get into one of these tours, trust me, it will blow your mind.

A rare opportunity to see the results of a natural “big bang,” a geologic feature that was created in the space of three days.

New canyongorgeorg (say it fast three times) website.

Canyon Lake Gorge, Part 4

fossil
Yet another type of limestone, and more fossils.

fault
One of the most exciting things revealed within the gorge is a major fault within the Balcones Fault zone, the Hidden Valley Fault, shown above. In the picture, note where the group of people are standing. Behind them, on the left of the picture, the stone is layered horizontally. The stone the group is standing on is layered vertically—see how the fault line between the strata rolls downward just behind their feet.

In the left of the picture above, note the huge pile of debris across the stream from the group. This “sandbar” of massive chunks was deposited as the floodwater took a turn along the fault line.

sandbar
A closer look at the same pile of debris.

acqufer

Water spilling from the creases in the limestone, the aquifer at work.

While the Guadalupe Blanco River Authority has plans to develop the gorge in the future for low-impact day use tourism, it will probably be some years before that happens. Currently, only researchers and educational groups are allowed access. It was an incredible treat to explore this area and I hope I can return again.

Hope you enjoyed the pictures.

Canyon Lake Gorge, Part 3

waterfall

The gorge is part of the Trinity Aquifer recharge zone and the dynamics of groundwater are evident everywhere. Here, runoff falls from one level to the next. At the top of this photo, note the shallowness of the topsoil—this is fairly constant for most of the Edwards Plateau region. Limestone is rarely far from the surface.

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pool

Some of the water we saw was simply runoff from recent hard rains but this pool is constant. The mineral content gives the water a bright light blue color. Again, note the evidence of the original floodwaters that tore the limestone out at this bend.

rudists

The limestone here teems with strange patterns left by rudist bivalves. These animals constructed reefs, similar to coral reefs, in the inland sea that covered this area during the Cretaceous.

lime

Another drop down to a lower level. There are no handy steps or stairs, it’s just gravity, rocks and teamwork as we make our way down the gorge.

Continued in Canyon Gorge Trip, Part 4.

Canyon Lake Gorge, part 2

ck

It was cold and incredibly windy as the class gathered up at the dam overlook yesterday morning. Before we descended into the gorge, we got a refresher on Texas geological history from Dr. Carter Keairns. The limestone in this area was formed during depositional cycles when much of Texas lay under a warm, shallow inland sea. trail

Through the wildflowers down to the trail.

spillway

Overlooking the spillway, we hear about the action of the floodwaters and get an overview of the various features of the gorge, including dinosaur tracks on the floor of the spillway.

dinosaur

The dinosaur tracks are pretty indistinct. However, after delineating the left/right pattern of the animal’s steps, it’s clear that it’s a set of tracks made by a three-toed dinosaur. Around some of the tracks, a faint pushed-up ridge evidences the mud displaced by the dinosaurs’s weight as it stepped into the mud. The tracks disappear abruptly under a higher, undisturbed layer of limestone.

level 1

We clamber down onto the next level under the spillway, which is littered with gigantic blocks of limestone, many them larger than cars, pockmarked all over by fossilized remants of marine animals and their movement through the sediment at the bottom of the ancient sea. This calcareous limestone was formed by depositional action upon the skeletons and shells of millions of marine micro-organisms. Around us, there are a few green plants but not many, and tiny patches of yellow damianita dot the rocks, blowing in the wind. It rained hard the night before and it seems scrubbed fresh and clean in the cold air. It is a fascinating and austere landscape.

tree

The power and direction of the floodwaters that created the gorge is evident everywhere.

Continued in Canyon Lake Gorge, Part 3

Canyon Lake Gorge, part 1

gorge1

As promised yesterday, posting on my field trip to the Canyon Lake Gorge. The trip was part of a class I’m taking, and it was quite a privilege to get a look at this place— a pristine “portal” if you will, directly into the Lower Cretaceous.

First, some backstory about the place. Recent backstory, that is.

The photo above, taken yesterday, April 14, 2007, could not have been taken on the same day five years ago. If the two figures above were standing in the same place then, they would have been encased in limestone. Above them would be the same thin layer of fertile top soil and vegetation that you can see on either side of the photo. So, what happened?

Rain. Lots of rain. During the last week of June, 2002, a low pressure system stalled over the Hill Country, dropping more then the annual average rainfall (34-37 inches) in the space of one week.

The dam itself, at the top right of the photo below, is 224 feet above the stream bed surface and the maximum capacity of the lake is 943 feet, mean sea level. The spillway, at the front of the photo, is 31 feet below the level of the dam. After days of rain, on July 5, 2002, a wall of water more than seven feet high crested the 1,250-foot-wide spillway at a velocity of more than 70,000 cubic feet per second, displacing thousands of cubic yards of bedrock and limestone.

as

(Photo: Larry Kolvoord AMERICAN-STATESMAN)

The tremendous force of the floodwater carved out a mile-long gorge several hundred yards wide, with a maximum depth of approximately fifty feet, all the way back to the Guadalupe River, laying bare limestone from the early Cretaceous Glen Rose Formation, rock that had not been exposed for more than 65 million years.

google

(Photo: Google Earth)

Continued in Canyon Lake Gorge, Part 2

Gorge Blogging!

I got to spend today exploring the Canyon Lake spillway gorge – what an experience. Right now, I am too worn out to write much other than “Wow” and “Whoah,” so I’ll just share a couple of pictures. More coming tomorrow.

.canyoneg2gorge 1