Showing posts with label geology. Show all posts
Showing posts with label geology. Show all posts

June 02, 2019

An Earth-Shattering Kaboom at Trinidad Lake State Park

Right here is when (most of) the dinosaurs died.


Things you learn. Not being a paleontologist or a geologist, I did not know that that the K-Pg boundary — Cretaceous-Paleogene boundary — is visible at a southern Colorado state park. (It used to be the K-T boundary [Creataceous-Tertiary], but the kool kidz have changed the name, and if you don't keep up, you're just so 1990s.)

In a  recent New Yorker article, "The Day the Dinosaurs Died," Doug Preston writes,
Today, the layer of debris, ash, and soot deposited by the asteroid strike is preserved in the Earth’s sediment as a stripe of black about the thickness of a notebook. This is called the KT boundary, because it marks the dividing line between the Cretaceous period and the Tertiary period. (The Tertiary has been redefined as the Paleogene, but the term “KT” persists.) Mysteries abound above and below the KT layer. In the late Cretaceous, widespread volcanoes spewed vast quantities of gas and dust into the atmosphere, and the air contained far higher levels of carbon dioxide than the air that we breathe now. The climate was tropical, and the planet was perhaps entirely free of ice. 
You stand there, and you look at it, and you think, "Right there. Death and chaos like we cannot imagine."
His X-Acto knife unearthed the edge of a fossilized fin. Another paddlefish came to light; it later proved to be nearly six feet long. DePalma probed the sediment around it, to gauge its position and how best to extract it. As more of it was exposed, we could clearly see that the fish’s two-foot-long snout had broken when it was forced—probably by the flood’s surge—against the branches of a submerged araucaria tree. He noted that every fish he’d found in the site had died with its mouth open, which may indicate that the fish had been gasping as they suffocated in the sediment-laden water.

Here is another view of the layer from sciencebuzz.org.
This site is on the Long's Canyon Trail at Trinidad Lake State Park. It is just a quarter mile or so from the trailhead. 

April 09, 2017

Colorado Sand Dunes from Space and How to Say the Creek's Name

Great Sand Dunes National Park and Preserve
photographed from the International Space Station (NASA photo).
I came across this quick explanation for why southern Colorado has sand dunes on the Great Sand Dunes National Park and Preserve's Facebook page.
Many visitors wonder: Why is there so much sand only here, but not at other locations along the mountains?

In this view from space, part of the answer becomes clear. The Sangre de Cristo Mountains are curved here, and at the same location are low passes to funnel wind and sand from the valley floor into this pocket.

Then why doesn't sand accumulate, for instance, at the base of La Veta Pass to the south? The mountains also curve there below a low pass.. The answer is that this northeast part of the San Luis Valley is a closed basin. Streams carrying sand into this basin don't exit, so all the sand they carry is deposited here. In the past, these streams fed into huge lakes; when these lakes disappeared through natural climate change, vast quantities of sand blew and accumulated here below Mosca, Medano, and Music Passes. In other parts of the valley, and in most places in the Rocky Mountains, sands are continually washed away and carried downstream into larger and larger rivers.
That is the San Luis Valley on the lower left and the Wet Mountain Valley to the upper right, so the top of the photo is roughly northeast.

A lot of visitors also pronounce the name of the creek that flows by the dunes as "Meh-DAH-no," thinking that that is the correct Spanish pronunciation, whereas in the Wet Mountain Valley, you hear something more like "MAD-uh-now" or "MAD-uh-no," usually in reference to Medano Pass, which connects the two valleys.

The latter is actually closer to the Spanish Médano — note the accent mark — which means "sand dune" and comes from an old Castillian word for mountain.

October 03, 2016

The Earth Is Trying to Kill You, Cabela's Is Sold, Trees Talk

¶ "Landslides in the United States cause approximately $3.5 billion (year 2001 dollars) in damage, and kill between 25 and 50 people annually." I think we need a cartoon character: Rocky Bear. "Only You Can Prevent Landslides." Sort of.

¶ Outdoor retailing empires merge: Bass Pro Shops is buying Cabela's.
The deal marks a dramatic expansion of the outdoor retailing empire controlled by Bass Pro Shops CEO Johnny Morris, who founded the company in 1972. The billionaire will lead the newly combined entity as CEO and will retain majority ownership.
Foresters ponder how trees talk to each other:
The main reason humans cannot perceive how clever and complex they are is because we exist in such short time scales by comparison. There's a tree in Sweden for instance, a spruce, that is more than 9,500 years old. That's 115 times longer than the average human lifespan.

July 17, 2014

The Cycles of Sand

I wlll look at the sandstone boulders behind the house in a new way after reading this:
Most of us are used to the idea that sand is created from rock by weathering, but less familiar is the idea that it can be turned back into rock again. "Sand grains originally born from granite long ago", Welland explains, “may accumulate, be buried, and become naturally glued together, lithified (from the Greek for stone or rock) into . . . a sandstone. When this, in its turn, is exposed at the surface, it is attacked by weathering and the sand grains are liberated again. The whole process is cyclic, over and over again." He estimates that half of all quartz sand grains have completed that circuitbeen turned to stone and then rebornsix times.
From a fascinating review article, "The Magic of Sand."

July 21, 2013

Colorado's Redwoods

The Big Stump, a fossilized redwood, was once the pride of a commercial resort at the site. The tree would have been a "little" larger than the ponderosa pines now growing around it.
Taller and faster-growing, Colorado's redwoods were in all respects better than those in California — except for having flourished 34 million years ago, before a series of volcanic eruptions suffocated them.

Flash forward to the 1870s, when residents of Colorado Springs could take an excursion train west into the mountains and wander through the petrified logs exposed on the ground, chipping away bits to take home and place on the mantelpiece or in their flower beds.

Visitors chipped away so industriously that the logs are gone, except for those still buried. A generation later, two adjacent commercial establishments controlled the fossil beds, each one part dude ranch, part museum, and part fresh-air resort.

Only in 1969 did the area become the Florissant Fossil Beds National Monument, which also showcases fossils of quite a few plants, vertebrates, and invertebrates, preserved in volcanic ash.

M. and I stopped by in June 2013 for the first time in (non-geological) ages. We found the new park visitor center and more trails and signage than we remembered.
Too many visitors don't get far from the vistor center. That is actually a stump in the pit, surrounded by a supporting band of steel.

I poop on your signage.
The easy half-mile Ponderosa Loop Trail includes photos of the previous commercial establishments at the fossil bed, as well as a time line of geology and life at the site. Here a modern dinosaur appears to have left some comments on one of the signs.

The monument covers 6,000 acres, and there are 14–15 miles of hiking trails, depending which brochure you read.

We walked another three-mile loop, which crossed the Homestake Pipeline, part of Colorado Springs' water system. The pipeline carries water from a collection system near Aspen, with its flow shared by Aurora and Colorado Springs.

(It's amazing how many Springs residents think their water comes from snow on Pike's Peak, and Aurorans probably don't think at all about it.)

Despite its significance in our hydraulic civilization, the pipeline rates no signage on the hiking trail. Apparently it does not fit the narrative of the fossil beds.

The cleared strip marks the route of the Homestake Pipline through the hills west of Colorado Springs. It was built just before the national monument was created.

January 30, 2012

A Geologist's Hammer under the Pilgrim's Robe

The trouble with the Telegraph's (UK) obituary of explorer and geologist Augusto Gansser is that there is no one good paragraph to excerpt. They are mostly like this:
Due to the war, the Ganssers were unable to return to Switzerland until 1946, when they took passage on a recently decommissioned British aircraft carrier. Augusto took with him two emeralds which he had found jutting out of a Colombian rock but, at the port, learned that it was forbidden to export uncut precious stones. On the spot, he hid them in the nappy of his infant son.
So you will just have to read it all.

December 22, 2011

Blog Stew for Carnivorous Squirrels

A geologist explains the formation of the "teepee buttes" of Pueblo and El Paso counties (Colorado).

• I cannot think of any job more frustrating (assuming that one took it seriously) than to be director general of  Afghanistan’s National Environmental Protection Agency. On the other hand, the news about Persian leopards is surprising.

• Myths about carrying concealed weapons. There is one that I tend to be guilty of too.

• From National Geographic, the economic and conservation effects of hunting:
 When you buy a camouflage camisole ($24.99) from the Ducks Unlimited catalog, a portion of the proceeds goes to conservation projects. If you visit Bozeman, Montana, and buy a pair of Schnee’s Pac boots, you will find a tag dangling from the laces, along with a promise that the Rocky Mountain Elk Foundation will receive some of your money for elk conservation projects.

“It’s the hunters who keep most of these species going,” said Jim Clay, a middle school English teacher, hunter, and maker of turkey calls in Winchester, Virginia. “They put in the money, and they put in the hours. Hunters really care about what happens.”
• You probably did not know that sometimes squirrels are carnivorous.