Tuesday, February 11, 2020

New Grand Canyon Geology Video - In Rap!

It isn't often that geology and rap music are intertwined (well, maybe I'm wrong being trained in the subject in the 20th Century). But my wife just passed along a YouTube video that helps teach about the layers of the Grand Canyon. There is even a mention of how it all happened - uplift and erosion. I think this will be a big hit - right now it is just showing 77 views. But I'm thinking this is a great way to bring along another cohort of future geologists! See the video here.

Saturday, February 01, 2020

A Classic Post From 2010 - A "Ground Zero" Hike Into Meteor Crater, Arizona

The Barringer Meteor Crater in Arizona is Earth's best preserved extraterrestrial impact site and is located  35 miles east of Flagstaff. The understanding that this feature is extraterrestrial in origin is complicated by the fact that it lies adjacent to the San Francisco volcanic field, where over 600 volcanoes are strewn across the landscape. After seeing it for the first time in 1891, none other than the eminent 19th century geologist G.K. Gilbert concluded that the feature was formed by a volcanic steam blast through rock and groundwater. However, a self-taught geologist from Philadelphia,  Daniel Barringer, was convinced that it was an impact site and set about to prove this through careful field study, borehole drilling, and persistence. Although he never lived to see his ideas widely accepted, the evidence is overwhelming now for an impact origin.

On Wednesday, December 15, 2010 I had the pleasure of hiking down to the floor of the crater with Barringer's grandson, Drew Barringer. I serve with Drew on the Board of Trustees of the Museum of Northern Arizona and when he offered to take myself and other geologists and friends on a hike to the floor of the crater, I jumped at the chance. It was certainly one of the top "bucket list" destinations for a geologist. (Note that liability and safety concerns render hiking to the floor of the crater off limits to the general public. For this hike, Drew wanted the chance to visit his childhood "playground" with a few friends who are also trained geologists. Do not attempt to hike to the bottom of Meteor Crater without prior permission).

Travelers heading east on Interstate 40 from Flagstaff can see the upturned edges and ejecta blankets of rock that outline the crater (background). Prior to its interpretation as the site of an impact, the low hills were locally known as Coon Mountain or the Franklin Hills. Most travelers have no idea these low hills are Meteor Crater or that a 550-foot deep hole exists within them. 

Here is Drew Barringer besides the largest meteorite ever found from this impact. It is on display within the museum present on site. Incredibly, this stone weighs over 1,400 lbs. and was discovered about 5 miles from the impact! Look at how the flash from my camera is superimposed on the aerial image of the crater behind Drew. It makes it looks like the bolide is on its way into the ground.

Drew leads us west along the Rim Trail, walking on a blanket of ejecta material.

A view to the west along the Rim Trail showing the overturned ejecta blanket that rests on top of Meteor Crater. The light colored material on top is the Kaibab Limestone which is overturned in this position. It rest on reddish Moenkopi formation of which about half is overturned as well. Bedded Kaibab Limestone, which is locally brecciated from the impact, makes up the tilted strata below. 

A view of the south (shadowed) and west (sunlit) crater walls and floor from the rim. The crater is about 550 feet deep and is deeper than the surrounding plain outside the crater. Studies indicate that between 100 and 150 feet of post-impact material has washed into the enclosed crater.See the following image to know something of the size of the bolide that created the crater.

Same photo as above with a red dot indicating the interpreted size of the bolide, about 150 feet in diameter. This image shows how small of an object it takes to create such a large landform. The bolide hit the earth at between 26,000 and 32,000 miles per hour. The kinetic energy was enormous. The crater is about 4,000 feet in diameter and 2.5 miles in circumference.

Image taken from the publication, "Guidebook to the Geology of the Barringer Meterorite Crater, Arizona" by David Kring, 2007. This image has the postulated Ice Age vegetative zones superimposed over the modern landscape (note the Spruce Forest Zone on the left which no longer exists in this part of Arizona). The red circle denotes the 12-mile diameter scorch zone where everything was burned upon impact. The yellow ring denotes the 20-mile wide zone where all large animals were killed or wounded. And the blue ring denotes the 40-mile wide zone of hurricane force winds away from the blast.

Starting down the trail into the crater. The ruins of the original visitor center building can be seen in the background.

View of the ejecta blanket from inside the lip of the crater. Remember that the white Kaibab Limestone lies stratigraphically below the red Moenkopi Formation. But here, blocks of white Kaibab lie over the Moenkopi as ejecta was forcefully thrown from the impact site.

As we approached the floor of the crater, I was taken by these eroded blocks of Kaibab Limestone that have dislodged from the walls of the crater and come tumbling down the slopes.

Our group approaching the borehole site on the floor of the crater. 

The borehole site is fenced for safety and on it is a cut-out of an astronaut and a real American flag.

A piece of the ruined equipment near the borehole.

Giant levers on the wench serve as artful beacons on the floor of Meteor Crater.

Author Rose Houk and geologist Michael Collier pose in front of the old boiler on the floor of the crater. We did not find any coal debris around the boiler and we were stumped as to how the boiler could have been fired.

As we made our way uphill along the steep trail, the clouds of an oncoming winter storm framed the crater walls. Thankfully, the storm held off until our return to the visitor center.

Not everything we saw related to the impact which is thought to have occurred about 50,000 years ago. Here in beds of the Moenkopi Formation are the burrowing remains of some Triassic critter (right of the lends cap) and in the block above this are impression of rip-up clasts within sandstone. To learn more about rip-up clasts, see my blog from a Henry Mountains field trip here.

Near the top of the trail are many old artifacts from days gone by. This looks to be some kind of contraption for use with mules that brought supplies to the crater floor. 

Scott Harger inspects a huge block of ejected Coconino Sandstone on the rim of Meteor Crater. This specimen retains original Permian-age cross-bedding within it but was thrown out of the impact site. It is most likely overturned in this position.

This is a close-up view of the same block, which can be seen to be brecciated but still retaining original cross-bedding.

Looking into the ruins of the old visitor center on the rim of the crater.

Debris is strewn about the ruin site and documents a time long gone in northern Arizona.

Our group returning back to the museum area and walking on top of a slab of Coconino Sandstone ejecta.

Here is a normal view of the Coconino Sandstone ejecta blanket on Meteor Crater's south rim. See the next photo for a clearer view of it.

Enhanced view of the Coconino Sandstone ejecta blanket. The rocks outside the colored area are Kaibab Limestone ejecta which is more golden in color.

A view northwest to the oncoming storm. The photograph was taken on the crest of the ejecta blanket and looks down about 120 feet onto the surrounding landscape. Thanks to Drew Barringer for allowing us geologists to experience this world-class landform from its central heart.

Monday, January 27, 2020

Another Great Post From 2014 - To the Roof of Africa - Climbing Mt. Kilimanjaro

There are shorter routes to the top of Kilimanjaro but I was not interested in a 'burn-run' to the top of a mountain - I was not interested in "bagging a peak." I discerned that most of the people I met on the trail were here just to reach the top. I had no such desire and the top of Kilimanjaro was never really a "goal" for me. My goal, if there was one, was to experience the place, to enjoy a hike day after day on such a grand volcanic edifice. I had some resistance to signing on for this trip because arriving at the top held no allure for me. With these pre-conceived "goals" in mind, I was surprised when I realized that failure to reach the top never really crossed my mind, while we were trekking. We had a great guide who was invested in our success and he made the pace reasonable so that it was not only doable, but actually not that hard. And the group I was with was nothing but positive. The cold and the dirt were hard in some ways, the climb was not in any way. Such is the reward of good leadership and pacing!

Day Six - Karanga Camp to Barafu Camp

Karanga morning camp scene.

Sunrise light on Kilimanjaro from Karanga Camp.

This was not our ascent day but we could clearly see the our route up on the mountains east (right) shoulder.

White-necked ravens waiting to pounce on any unattended food.

Check out this view of the mountain from about 14,000 feet. Only one mile up is the top.

Helen R. feeling no pain at 14,000 feet.

Chris H-N. taking photos on the mountain.

George A. was the best dressed man on the mountain. Here he is communing with the rocks.

The trail from Karanga Camp (background) toward Barafu Camp.

The many moods of Mawenzi are shown here in the next set of pictures. This is the third volcano in the area.


Late afternoon light. I just loved seeing this 16,893 foot peak from Barafu Camp. This is a big mountain!

Late evening shot back to Mt. Meru.

Day Seven - The Pay-Off - Barafu Camp to Stella Point and Uhuru Peak

Sunrise over Mawenzi on our ascent day, August 19.

The initial climb out of Barafu Camp. I was expecting dread at the thought of climbing 4,000 feet in 2.4 miles, between the elevation of 15,000 and 19,000 feet. But climbing Kili is as much of a mental exercise as it is physical. There simply was no time to think of dread, just one foot in front of the other and keep moving, Po-le. po-le (slowly, slowly).

A quick break for water and a snack. Mawenzi in the background.

Climbers making their way upward. We had a beautiful, exquisite day for the climb.

We passed this group heading up the mountain. I didn't think of it at the time but passing another group was kind of a miracle. The average age of our group was 53 years and if you exclude the two 30-somethings our average age was 59.5. In fact, our guides repeatedly called us 'babu's' (grandfather's). We were some of the oldest people on the mountain - most trekkers were in the 20's and 30's. Obviously, age is just a number.

Upwards toward the sky.

Nearing Stella Point, the lip of the crater rim. Look at the smile on Helen's face!

Sign at Stella Point. To a man, we were all surprised that it only took us 4.5 hours to climb the 4,000 feet.

Chris and Wayne at the top.

Helen and Wayne at Stella Point.

It is another 300 vertical feet and about 1/2 miles up to Uhuru Peak. Along the way we pass the warm edge of the Rebmann Galcier.

The glaciers face is about 50 feet high. They obviously are declining with time.

James celebrating getting his whole crew to the top.

Approaching Uhuru Peak on a gentle grade. The air was quite thin but the sun was out and relatively warm.

Wayne and Helen on the Roof of Africa.

This is what is left of the Furtwangler Glacier on top of the mountain. Note the tents pitched in Crater Camp at the base of the cliff for scale.

Remnants of the Ratzal Glacier on the eastern lip of the crater rim. Note the Ash Pit on the left. See an aerial photo from a jet of this feature taken from one of my previous blog postings here.

I noticed numerous fulgurites on the top of the peak where summer lightning had melted the rocks. This one is about 4 inches across.

Unbelievably, the descent down was equally as hard as the ascent! We took a parallel trail in the cinders and it was a lot of work to descend 4,000 feet on the same day. I found that I was out of breath on this down-hike as much as the up-hike. Like I tell my clients in Grand Canyon, "Down is hard, up is slow."

Back at camp the crew sang Swahili songs for us celebrating with us in our accomplishment. It was a magical moment for us.