Tuesday, May 16, 2017

Hiking the Carbon Canyon/Lava Chuar Route in Grand Canyon

Been on many trips and writing from Waikiki where my sister will be married on Wednesday. However, here is a second installment from my first river trip in Grand Canyon in April of this year.

One of the most well-known geology side hikes on a Colorado River trip in Grand Canyon is the Carbon Canyon/Lava Chuar Route, beginning at River Mile 63. This loop hike ascends the Carbon Creek drainage about one and a quarter miles to the intersection of the Butte Fault, then follows the fault for another one and half miles before descending back to the river in Lava Chuar Canyon for the final one and a quarter miles. There is a fantastic scenery (which is to say - geology) along every part of this loop.

Interesting boulder of Tapeats Sandstone with tafoni texture in the Carbon  Creek drainage. There are a dozen or more of these here.

Iron concretions within the Dox Sandstone are always a curiosity begging an explanation. See this science article for a treatment of concretion formation.

Gigantic rock failure in Carbon Creek Canyon that necessitates a short but steep climb around it.

Jim and Billy resting after the climb on natural but well-positioned rock slab chairs.

Close-up of the Tapeats Sandstone showing its arkosic texture. The feldspar grains (pink) were derived from the Zoroaster Granite. But in this area of the canyon, the Tapeats rests entirely upon younger sedimentary rock units, so the feldspars were brought here from rocks not yet exposed in this part of the canyon.

Once on top of the giant rockfall, the creek is confined in a slot canyon within the Tapeats.

Narrow slot canyon along Carbon Creek.

And then, the canyon opens up at the site of, and along the trace of the Butte Fault. For an aerial view of the Butte Fault see this link.

More flowers, this one is the Indigo bush.

Full blooming brittle bush.

A small drainage built this delta fan along the trail. This is a small scale example of how the rapids form on the Colorado River, when side canyons deliver debris that partially constricts the river channel.

View of the Chuar Group rocks in eastern Grand Canyon. This is the only locale where these rocks are found in the Grand Canyon and at 790 to 740 Ma, they are some of the few rocks from this age anywhere on planet Earth.

Finally, after entering Lava Chuar Canyon on the way back to the Colorado River, the route passes by some great exposures of the Dox Sandstone, part of the Unkar group and about 1,100 Ma.

These well-preserved ripple marks were seen and are part of the Dox Sandstone.

I will be headed back down the river this Friday for my third trip of the year and will post more by the end of the month.

Monday, May 01, 2017

Spring Wildflowers and Rocks in Grand Canyon

I recently completed an 11-day Hiking and Geology Special Rafting Trip in Grand Canyon with Colorado River and Trails Expeditions. The wildflowers this season are excellent. We did some great hikes in perfect conditions - 80 degree days and 50 degree nights.

Our first hike was up inside North Canyon, famous to geologists for it exfoliated sandstone surfaces.

At the reflecting pool in the back of North Canyon.

Note how the exfoliation planes mimic the shape of the open space in the canyon. As the canyon becomes progressively opened through this massive sandstone (massive meaning that it lacks significant bedding features or fractures and so behaves as a coherent substance), the sandstone in the walls "pops out" parallel to the shape of the open space. On the walls, the exfoliated planes are vertical but they turn to horizontal on the canyon floor. It makes for striking forms.

Enjoying the solitude and stillness in a Grand Canyon tributary.

Dan enjoys looking at a conglomerate-filled channel that was cut into the underlying sandstone. Such channels are not uncommon in the Supai Group rocks. This happened in the Pennsylvanian Period, some 300 Ma.

Huge, cross-bedded sets of sandstone in there Supai Group in North Canyon. The cross-beds are very planar and might suggest a dune blowing across the floodplain.

We saw two Chuckwallas on the way back to the boats. I love the Latin name for this species, (Sauromalus obesus), the "Big bad fat lizard."

The second one was this little juvenile with its distinctive banded tail. Chuckwallas are strictly herbivorous.

The Marble Canyon section of Grand Canyon has wonderful springs that issue from the Redwall Limestone. Here trip participants observe a travertine encrusted spring on the wall of the canyon. Maidenhair ferns (Adiantum capillus-veneris) and Golden columbines (Aquilegia chrysantha) are often growing at these sites.

Inside Redbud Alcove at River Mile 39.

Slopes covered in yellow brittlebush (Encelia farinosa) downstream from the Eminence Break at River Mile 44.

The Sedesrt globe mallow (Sphaeralcea ambigua) was just beginning to bloom.

Desert fleabane (Erigeron divergens) was found up in Saddle Canyon at River Mile 46.

A typical day on the boats below Nankoweap Canyon. Both oar-powered trips and motor-powered trips have pluses and minuses. I used to strictly use oar-powered craft but have now switched to motor-powered. There are numerous reasons why and you'll just have to come on one of my trips to find out why.

Engelman hedgehog cactus (Echinocereous engelmanni) at the confluence of the Little and Big Colorado rivers.

Imagine 10,000 people a day coming down from the point on the skyline in a tramway. No way!

Part 2 to follow later in the week.

Sunday, April 16, 2017

Landslide in Alaska's Taan Fjord

Ground view of the landslide scar in Taan Fjord.
In October, 2015, the land gave way in a remote Alaskan fjord letting loose 200 million tons of rock. When the rock entered the sea, it sent a wave 600 feet high up onto the other side. No one saw it, except those monitoring a seismograph at Columbia University in New York. You can read an article about the event here.

Note the landslide scar at the head or the fjord to the left of the glacier.

Thursday, April 13, 2017

Giant Paleoburrows in South America Thought to be Dug by Ground Sloths

Discover Magazine is reporting on giant paleoburrows that have been identified in the Amazon Basin in South America. The burrows are thought to have been excavated by Ice Age megafauna.

The morphology of the caves as well as the youthful nature of the material they are found in, suggests that they were dug perhaps by giant ground sloths or giant armadillos. The full article in Discover Magazine can be read here. (The images I have included in this post are from the article).

Researchers note that these paleoburrows have been also identified from the southern Brazilian states of Santa Catarina and Rio Grande do Sul, but not across the border in Uruguay. They also have not been identified north of the Amazon. Now some are beginning to wonder if they simply have not been recognized, although a lack of suitable rock type or the distribution of species could also explain their absence elsewhere.

Monday, April 03, 2017

Rocky Mountain Association of Geologists Honors "Carving Grand Canyon" with the 2016 Geosciences in the Media Award

I was honored this past November to receive the Geosciences in the Media Award from the Rocky Mountain Association of Geologists for my book, "Carving Grand Canyon." I am honored to have this book recognized. First published in 2005 by the Grand Canyon Association, it was re-released in a 2nd edition in 2012. The book highlights the history of thought on how and when the Grand Canyon may have formed and details all of the current theories. You can read reviews on Amazon of the book here.

All of the past awardees for this honor can be found at this link. In 2014 another one of my books co-authored with Dr. Ron Blakey won the same award - "Ancient Landscapes of the Colorado Plateau."  Reviews on Amazon.com can be seen here.

Thanks to everyone who reads and shares my books. Geology rocks!

Wednesday, March 29, 2017

Trackway Paradise in Australia's Kimberley Region

A new trackway in the Kimberley region of northwest Australia was recently announced. Here are two photos and the story is here.

And thanks to reader and friend Joan L., here is another story about the find. To see more fantastic rock photos of the Kimberley, see here. And finally, a map and description sent to me from Joan L.


Geology and Geomorphology of the Kimberley 

The rocks of the Kimberley region contain a geological record that spans the last 1900 million years of the Earth's history. The oldest rocks in the Kimberley form the Lennard Hills in the west Kimberley and the Bow River Hills and the Halls Creek ridges in the east Kimberley. These comprise metamorphosed sediments,volcanics and granites.

Geological Map of the Kimberley Region 

The main part of the Kimberley, known as the Kimberley Plateau comprises of generally flat lying sedimentary rocks. These sandstones and quartzites were deposited about 1800 million years ago by major river systems that flowed from north to south across the whole region. These rocks also contain considerable volumes of concordant basalt lava flows that are a characteristic of the Mitchell Plateau. Subsequent to around 1790 million years ago the region has seen several periods of geological activity that has resulted in deposition of further sedimentary sequences, largely around the margins of the Kimberley Plateau, and there is evidence for periods of major glaciations.

The current landscape of the Kimberley has been evolving over a period of at least 250 million years. Periods of uplift resulted in peneplanation of the land surface and deeply incised rivers. A lengthy period of tropical conditions 70-50 million years ago resulted in the development of a lateritic cap, particularly over the volcanic rocks which are more susceptible to weathering. This is a characteristic feature of the Mitchell Plateau.

As sea levels rose from approximately 120m below current levels following the end of the last glacial maxima 18 000 years ago, the Kimberley coast line became drowned with the sea filling what were once river valleys. This phenomena gives the coastline its distinctive irregular outline.

Reference: Geology and Landforms of the Kimberley. I Tyler. Department of Conservation and Land Management. 2000

Sunday, March 12, 2017

Funky Valparaíso Chile

There's no other way to describe Valparaíso. Starting as an important port in the southern Spanish Empire, it then became the center of the Chilean Navy. In 1990 the National Congress of Chile was moved here from Santiago. However, the main purpose of our visit was to see the Historic Quarter of the city, which is a UNESCO World Heritage Site. The colorful street art is not to be missed. No words can describe it  - so I won't. Enjoy the color and textures of Valparaiso.