Saturday, May 07, 2022

Private Jet Adventure Over the American Southwest

The story and video that was posted here yesterday has moved to my personal blog site, All In A Day's Karma. Google changed some functions on its platform and I am still learning to navigate the changes. Sorry for any confusion. However...

It's been awhile since I posted something here. I've been busy on lot's of trips. One was a Private Jet adventure over parts of the American Southwest. Here are a few photos from the trip.

The Sonoma California coast

Mono Lake California 

Frenchman Mountain Nevada

Where the San Juan river (bottom) meets the Colorado River (top) now under the Powell reservoir, looking west

The Salt Valley Utah

Grand Mesa Colorado

The Black Canyon of the Gunnison River Colorado

Charcoal kilns, Ted Turner's Rancho Vermejo New Mexico

Sangre de Cristo Mountains, Ted Turner's Rancho Vermejo New Mexico

Saturday, March 19, 2022

Rivers as Circulatory Systems on Earth and Other Planets

 Too cool for words to see this in public media. Read the article here.

Evidence of rivers on Mars (left) the Nile (center) and on Titan.

Sunday, February 13, 2022

A Spectacular and Unusual Trilobite Trackway in Grand Canyon

I enjoy sharing my 47 years of experience in the Grand Canyon with interested readers. Although much travel has been suspended during the Covid pandemic, I reach back into the archives of photos I have accumulated to share interesting items of Grand Canyon and World geology - enjoy!

The Grand Canyon is nearly 280 miles (450 km) long! And no less than 26 named rock units are exposed in its walls. John Wesley Powell, in seeking funding for his river trip survey in the 1860s wrote to Congress saying, "the Grand CaƱon of the Colorado will give the best geological section on the continent."

Paleogeographic map of the southwest USA 505 Ma when the Bright Angel Shale was deposited. The red dot denotes the location of the fossil in this posting. Map courtesy of Ron Blakey and DeepTime Maps

In far western Grand Canyon, the Cambrian Bright Angel Shale thickens and becomes more carbonate-rich, documenting the continental transgression of the paleo-Pacific Ocean onto the edge of North America. Recently dated at about 505 Ma (Mega-annum or million of years ago) this progressive onlap of the sea occurred only 37 million years after the Great Cambrian Explosion, when more simple life forms evolved into many of the genera familiar to marine biologists today. Mollusks, corals, arthropods, and other forms made their appearance and were abundant in the area that was to become the Grand Canyon.

One form of arthropod is the trilobite and about 10 years ago, a river guide in Grand Canyon showed me this spectacular trace where a specimen crawled around in the soft, limey mud.

This is the largest slab of rock, which fell from the cliff above to expose a fossil-rich bedding plane.

Note the gentle and discreet symmetrical ripple marks on the right hand side of the slab. When the ripple marks are symmetrical in cross-section, they denotes fluctuating current directions (as opposed to asymmetrical ripple marks formed from singular current directions as in rivers). These here likely formed in oscillating currents in relatively shallow water.

Two individual specimens are represented on the slab as the trackway to the left's a bit smaller in diameter than the more obvious trackway on the right.

This ichnofossil (or trace fossil) is called Cruziana. (Yes, trace fossils have binomial nomenclature like the animals that created them). This one is really well-preserved and shows where the appendages of the animal pushed the sediment backwards, leaving an axial groove in the middle. We can also tell something about the direction of movement of the animal from this view. It appears that the animal came and "landed" in the sediment from the top right quadrant, then traveled down before turning left. It then makes the large loop around to the right on top before looping again within the larger loop. All of this can be ascertained because of the way the "exit track" on the middle far right seems to cross over and disturb the underlying track. This is amazing preservation.

Here is another Cruziana, this one from Deer Creek father upstream in the Grand Canyon. The detail of appendage push-back textures and the axial grooves are wonderfully preserved.

Many folks are more familiar with the many annelid worm burrows that are present in the Bright Angel Shale in Grand Canyon. They are also abundant here.

The fossil slabs in context to the river.

Our boar drifts by the trackway site.

In the lower left quadrant, it appears that the trilobite "took off" once again after making the two loops.

Another view with lens cap for scale.

Please do not disturb in any way fossil track sites. These are extremely precious specimens that must be preserved. And enjoy the Grand Canyon!

Saturday, January 15, 2022

Geology of the Eruption in Tonga

January 15, 2022. Courtesy of the Tonga Geological Survey

It's all over the news and there is good reason. At 16:28 local time in Tonga on January 15, a powerful submarine volcanic eruption rattled the area. Satellite photos are astounding. The noise from the explosion was heard as far away as Aukland New Zealand (1300 miles away) and tsunami warnings are posted for much of the Pacific Rim. 

Check out this link from Forbes and all of the embedded links. They are pretty astounding.

If you follow Twitter here is a video of the tsunami coming ashore in Tonga. (We have a neighbor who has done anthropologic research on the island and the proper pronunciation is Tong- ah).

Thanks to the folks at the Arizona Geological Survey for this first hand description of the geology of the volcano and published first of The Conversation. The maps are very instructive.

Geology Hub is another good resource to check out. Watch the whole video as the last half of it has the geologic story of this caldera. Note that some of the photos to illustrate a tsunami are not from this event and may not be of tsunami waves at all. A tsunami wave typically moves 500 miles per hour when in the open ocean and may only be six inches high. But as the wave approaches land and the water shallows, the wave height increases.

Great videos can be watched here.

We hope all will be all right and all will be safe from this.

UPDATE ***My colleague George Marsik, forwarded this pre-eruption view of Hunga-Tonga volcano using Microsoft Flight Simulator. There are some great views of what this volcano used to look like before January 15.***

2nd UPDATE: Please see Roseanne Chambers geology blog as well for a great description of the eruption and tsunami:

This satellite image taken by Himawari-8, a Japanese weather satellite, and released by the agency, shows a volcanic plume produced by Hunga Tonga-Hunga Ha'apai volcano on Saturday, Jan. 15, 2022.