Sunday, October 6, 2019

What I Did While I Was Out: On the Way to the Grand Canyon

As I mentioned a few months ago, I've been spending a lot of time on the fossils and rocks of Grand Canyon National Park this year. Part of why I've been doing this culminated on Saturday, September 28: our special National Fossil Day event, held at the park as part of their centennial festivities. (You can see the whole group that worked the event here.) We've been working for months on a Grand Canyon NP paleontological inventory, and to further that work as well as help at the public event, I spent the end of September in Arizona, visiting various places.

I did have time to make some other stops. Driving from Phoenix to Flagstaff, I took a short side trip to Tuzigoot National Monument, where ruins left by the Sinagua people are found overlooking the Verde River floodplain.

Part of the stabilized and partially reconstructed ruins.

North and east of the ruins is Tavasci Marsh, in a filled part of an oxbow of the Verde River.

I spent a couple of days working in the collections of the Museum of Northern Arizona. Oftentimes I don't get to play the tourist, but I had some time on a Sunday afternoon to visit the public part of the museum, where I was greeted by Nothronychus graffami.

Well, kind of; the sloth theropod wasn't in the mood to turn around and shake hands.

The geological and paleontological exhibits at the MNA focus on northern Arizona (which, after all, is right in the name), including many examples of fossils from the Grand Canyon area in the Paleozoic section. One of the most outstanding is a tooth of Megactenopetalus kaibabanus, from the Permian-aged Kaibab Formation. The display identifies it as a shark tooth, but this is a bit of a simplification: M. kaibabanus was actually in the chimera line of cartilaginous fishes. Although the tooth is enormous, this did not mean the animal was huge; instead, it had a pair of large multi-cusped teeth, one above and one below, something like the beak of a bird.

Forgive the reflections; it's in a case.

I also spent part of a day at Wupatki National Monument, making a brief field visit in advance of upcoming work. Aside from its archeological resources, Wupatki has good exposures of the Kaibab Formation and Early–Middle-Triassic-aged Moenkopi Formation. The Moenkopi Formation is primarily terrestrial and hosts abundant well-preserved sedimentary structures, such as ripples and mudcracks. The outcrops were gorgeous from a sed-strat perspective:

Several types of bedding are apparent here, including an interval that resembles loaves of bread.

A bit lower than a bread-bed interval, we can see a number of filled mudcracks exposed in cross-section (the light-colored vertical features).

Yet another bed in the Moenkopi package shows small ripples in situ.

The day was overcast and rainy, thanks to moisture from disintegrated Hurricane Lorena. The camera didn't really capture the clouds, giving an odd, washed-out appearance to landscape photos.

The effect vaguely reminds me of photos from unmanned landers sent to other planets and moons, except of course for the plants. (And the moisture.)

I also got to see my first packrat midden in the wild. It's partially indurated, as you can see from the dark blocks within the pile of loose plant fragments and rat poop.

The rat was not in at the time.

Next time in the series: Grand Canyon itself...

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