Flashback to November 1, 2015 - Ayers Rock and The Olga's Australia

After a few days in Alice Springs, it was time to head southwest to the main attraction of this region, Ayer's Rock, also known by its Aboriginal name Uluru.

The distances are long in the outback and I took this picture at the highway junction in Erldunda. Distances shown are in kilometers and this is half way to the rock from Alice.

Connor Butte as seen from a scenic overlook along the way. It is composed of Paleozoic sedimentary rocks.

Lake Amadeus is one of the many dry lakes located in central Australia

Our first view of Ayers Rock from the Yulara Resort. This would be the sunniest view of it during our stay, as wet and thundery weather moved in.

Dramatic skies frame the eastern side of the rock

The grass is called spinifix and it is very tough and drought resistant species

The rock is composed of a coarse sandstone called the Mutitjulu Arkose (arkose is a term used for sandstones that have a lot of feldspar mineral included - a feature that distinguishes arkose as having been deposited relatively close to the source area).

Eucalyptus trees frame the rock. Note the desert tapestry streaming down from the top, formed where water allows bacteria and lichens to grow.

On to the waterhole

Rock art in one of the overhangs near the waterhole. Aboriginal culture extends back more than 40,000 years in Australia and recent DNA testing shows that the line is most closely related to people now living in Sri Lanka.

Graceful canyon cut into the Mutitjulu Arkose

The rock is part of an upturned package of sandstone deposited about 550 Ma. That means it was laid down within about 9 million years of the Precambrian/Cambrian boundary. No land plants or animals existed when this sandstone was laid down.

This is the northwest side of the rock and we walked to the amphitheater seen where the long desert tapestry come down the cleft.

A closer view with gum trees in the foreground

This is a special spot

Looking up through the trees at the edge of the monolith

Rock and trees

Around the base of the rock are numerous cavities called tafoni. They are formed when water in the soil seeps into the rock, helping to dissolve the cement around the sand grains. This weakens the sandstone here and a cavity is formed, The dissolved cement is then transported by the same water to nearby where it precipitates causing the nearby sandstone to become extra hardened, That is how the roof pendants are formed.

Champagne and h'ors douves at the Ayers Rock

Group photo at sunset

At 6:01 the sun set but it was nowhere to be seen

Sunrise at Ayers Rock. Many people turned out even though it was raining at 5 AM.

This was about as good a shot as I could get. It was very dark and cloudy.

After breakfast we went west to see the Olga Mountains (or Kata Tjuta in the local Aborigine language). These rocks are the same age as those in Ayers Rock but as you will see are composed of something different.

Walking up into  a gorge cut between one of the 18 domes of rock

Yep. This is a very coarse-grained conglomerate with clasts of crystalline gneiss and granite. Look at the size of those clasts! The interpretation is that this and the arkose at Ayers Rock were derived from the Petermann Mountains just a few miles west of here in latest Proterozoic time. At the Olga's, the streams delivered bouldery sediment whilst at Ayers Rock it was coarse sand. Two co-eval alluvial deposits from an ancient mountain range.

Tafoni and desert tapestries in the walls of the gorge

Three of the domes at the Olga's

The wind blown sand here is extremely red - more red than that seen in Arizona, which is more orange. In spite of the cloudy weather, this was a great visit and I was more impressed with "the rock" than I thought I would be. Still it is a small feature compared to all that we have in the American Southwest but Australia's Red Center is a unique and intriguing place.

A first view of Sydney, Australia. Watch for my next posting from Sydney soon.

Another Flashback Post - February, 2013 Angkor Wat, Cambodia

This flashback posting shows images and impressions from my first trip to Angkor Wot ruins.

After leaving Angkor Wat, my guide and I headed north to another temple complex, this one even larger. Called Angkor Thom it contains the ruin of Bayon

Like Angkor Wat this complex is surrounded by a huge rectangular moat measuring eight miles in circumference. As we approached the gate, I had the driver stop and let me take a photo.

The bridge over the moat contains 54 statues with the ones on the right representing good and those on the left evil

Detail of some of these statues

The moat towards the setting sun

And looking to the east

Close-up of the entrance gate

The central complex is not as restored as Angkor Wat and in many ways makes it more interesting

The approach

More fantastic sandstone carvings

Detail of an elephant carving

The wheel was known to these people

Can you see the buddha faces carved in the temple heights?

Perhaps you can now

Close-up

I wish there was time to write more about this great place but you'll have to read it here

Profile of one of the numerous Buddha faces that appear on each of the great towers

Close-up of a Buddha face

Stone faces and jungle

Smiling face captured in stone

It was very hot and humid. My shirt was drenched in sweat.

The road back to Siem Reap town

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.

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.