Colorado
Showing posts with label geology. Show all posts
Showing posts with label geology. Show all posts
Tuesday, July 14, 2015
Tuesday, June 23, 2015
Red Mountain Number 1
Red Mountain Number 1, Ouray and San Juan Counties Colorado.
Check out @goflight001's Tweet: https://twitter.com/goflight001/status/613513362538803201?s=09
Monday, May 18, 2015
Pratt County Kansas Volcanic Ash Pit
Five deposits of volcanic ash have been located and sampled in Pratt County.
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Have you ever rolled around in the dirt just because it’s there? Ever wonder where that dirt came from? Me too!
Greetings. I'm Russ Dale. I’m not new to Pratt Kansas as I am “from” Pratt in a cosmic sense, as my great-great grandfather Whitney Bailey arrived in the county in 1887 at the age of 15. He was a wheat farmer in McPherson and Saratoga Townships.
I enjoy learning about the past. I am a history buff who is heavily interested in genealogy and geology. And I roll around in dirt.
I was at the Pratt County Historical Museum one day pouring over historic maps of the county. Wallowing in a pile of old maps is how I roll. Pratt County landmarks like Skunk Johnson’s Cave, Pilot Knob and Arrowhead Hill made my imagination whirl. Fascinating.
Then something called “Volcanic Ash Pit” caught my curiosity. The tiny drawing on this aged 100-year-old map was akin to a modern orbital satellite photo of the fictional Sarlacc pit, the Great Pit of Carkoon, in “Star Wars Episode VI: Return of the Jedi!” A nerdy rock hound from Colorado, a geologic paradise in its own right, I am in love with rocks and the stories they tell. And, being a dirt flounderer, I immediately knew I needed to find out more about this pit. Who doesn’t like to visit pits? Pits are exciting. Pits are amazing. If I had a nickel for ever pit I’ve visited I would have a gaggle of nickels.
I scoured over satellite imagery of Pratt County in search of the pit. I searched the internets. I spoke with local old-timers. I became obsessed with this mysterious oddity.
A friend of a cousin’s cousin made me privy to an enigmatic area called the “silica pit,” a place in the county where generations of children played in the dirt. Corroborating this first-hand knowledge with information gleaned from a 1973 Kansas Geological Survey Bulletin #205 and a thesis about the “chemical fingerprinting” of volcanic tephra found in Kansas by Brian T. David of Kansas State University, I was pointed to what I believed was the “Volcanic Ash Pit.”
I went there. All of my pit dreams came true.
My eyes did behold the majesty of the “Volcanic Ash Pit!” It was an old pit with layers of volcanic ash 14 feet thick along the walls! The ash, essentially fine shards of white to grey glass spewed from a volcano, was once excavated from the site and used in concrete for roads. Others uses for “silica” included soaking up blood at meat packing plants and in bathroom cleansers. Long abandoned, this pit was now just a hole in the ground inhabited by animals and plants.
Where did this “dirt” come from? The ash, from an erupting volcano, was carried by winds over Kansas many years ago and settled to the ground. Streams washed the ash into shallow depressions.
Could this Pearlette ash bed be Lava Creek B Tuff of the Yellowstone Caldera, the last major eruption from the Yellowstone volcanic center 640,000 years ago? Was it derived from the explosion of Valle Grande Caldera supervolcano in north-central New Mexico roughly 1.2 million years ago? That was a time when humans were an endangered species! I am filled with questions.
The debate is still out on the origin of the ash and where it fits on the geologic time scale. Regardless of its origin, it is a superb geologic site. Especially for Kansas. It is doubly superb it exists in Pratt County Kansas.
My mission complete and personal dirt quota satisfied, I prepared for another learning adventure into the surrounding area in which my ancestors, and myself, call home.
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Xxx
Tuesday, January 6, 2015
Vogel Canyon, Colorado
Vogel Canyon Gallery
American Indians lived in the canyon 300-800 years ago and left rock art which is visible on the canyon walls. Geologically scenic Vogel Canyon is a tributary of the Purgatoire River drainage.
The sedimentary layers of rock at Vogel Canyon indicate that this was a lake basin in the past. Alternating layers of tough, light grey limestone and soft, dark grey shale. The limestones are erosion resistant while the shales are easily weathered and crumbled, allowing the river to undercut the limestone beds and causing limestone slabs to collapse into the river.
The shales represent accumulations of mud in the ancient lake itself whereas the limestones represent accumulations of coarser, sand-textured sediments along the lake shore when water levels were low. The shales contain fossilized remains of algae, snails and tiny crustaceans known as "seed shrimp" and "clam shrimp." All of these species are common in quiet, shallow lakes. In contrast, the limestones contain impressions of large plant stems, dinosaur bones, trampled clams, scattered fish bones and lots of tracks. The limestones are also marked by ripple marks (caused by wave action) and by ooids (tiny, limey spheres) caused by wave action in shallow water.
This evidence supports the conclusion that the lake level fluctuated on a seasonal basis and also on longer term cycles covering decades and even centuries. The lake itself was probably 20 to 30 miles in diameter, shallow but with potable water most (if not all) of the time, and inhabited by a large variety of healthy flora and fauna of snails, algae, crustaceans and fish. The margins of the lake were partly or totally vegetated, the mud inhabited by clams and the whole area frequented by several types of dinosaurs. All in all, there's clear evidence of at least six times when dinosaurs visited this part of the shore of that ancient lake.
American Indians lived in the canyon 300-800 years ago and left rock art which is visible on the canyon walls. Geologically scenic Vogel Canyon is a tributary of the Purgatoire River drainage.
The sedimentary layers of rock at Vogel Canyon indicate that this was a lake basin in the past. Alternating layers of tough, light grey limestone and soft, dark grey shale. The limestones are erosion resistant while the shales are easily weathered and crumbled, allowing the river to undercut the limestone beds and causing limestone slabs to collapse into the river.
The shales represent accumulations of mud in the ancient lake itself whereas the limestones represent accumulations of coarser, sand-textured sediments along the lake shore when water levels were low. The shales contain fossilized remains of algae, snails and tiny crustaceans known as "seed shrimp" and "clam shrimp." All of these species are common in quiet, shallow lakes. In contrast, the limestones contain impressions of large plant stems, dinosaur bones, trampled clams, scattered fish bones and lots of tracks. The limestones are also marked by ripple marks (caused by wave action) and by ooids (tiny, limey spheres) caused by wave action in shallow water.
This evidence supports the conclusion that the lake level fluctuated on a seasonal basis and also on longer term cycles covering decades and even centuries. The lake itself was probably 20 to 30 miles in diameter, shallow but with potable water most (if not all) of the time, and inhabited by a large variety of healthy flora and fauna of snails, algae, crustaceans and fish. The margins of the lake were partly or totally vegetated, the mud inhabited by clams and the whole area frequented by several types of dinosaurs. All in all, there's clear evidence of at least six times when dinosaurs visited this part of the shore of that ancient lake.
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