Grand Canyon-Parashant National MonumentSeite 9 von 18
Fossil Hunting in Parashant: 38 Sites, a Million Acres and No Paved Roads
Fossil hunting at Grand Canyon-Parashant National Monument (PARA) in Arizona means long drives on unpaved roads where sharp volcanic rock punctures tires. Two Geoscientists-in-the-Parks participants, Holley Flora and Rose Weeks, hired for a survey in 2020, had not heard of the monument before applying. The monument turned 20 on January 11, 2021, and this article by the pair describes what their inventory found.
A huge, remote survey
PARA covers a million acres. Because it is large, young and lightly staffed, little paleontological research had been done before the survey, although the monument's founding proclamation names fossil invertebrates as one of its significant resources. Flora and Weeks, recent master's graduates of the University of Oregon and Loma Linda University, saw it as valuable field experience. The work paves the way for future research and for managing a non-renewable resource. It is part of an NPS effort led by senior paleontologist Vincent Santucci to inventory the fossils of every national park. Neighboring Grand Canyon and Great Basin National Parks are done, but PARA's inventory has a larger field component than any other completed so far.
The job had to be done in three months, which is both long for fieldwork and short for such an area. There are no paved roads at all, and the monument border is an hour's drive from the nearest one. The pair became certified to drive utility terrain vehicles first, since some roads are rough with steep drop-offs. A four-hour drive to and from a fossil site in a day is not unusual, so for some weeks the team camped near the outcrops instead of commuting from research cabins and administrative sites.
A trailer tire that "met the Parashant" (NPS, 2020 field inventory).
What they found
With two volunteer scientists and the monument's physical scientist helping for several weeks, the team assessed fossils at 38 localities in 15 geological formations. Highlights were nearly complete Quaternary skeletons of a cat and a fox, and a potentially new species of Permian gastropod. They also found places where current geologic maps leave out rock units in remote areas.
The maxilla of a Pleistocene fox (NPS, 2020 field inventory).
| Formation | Age and setting | What it holds |
|---|---|---|
| Kaibab and Toroweap | Permian, shallow marine | Brachiopods, corals, bryozoans, bivalves; in the Kaibab, a mineral replacement that makes fossils stand out in bright red, malachite rinds around others and fossil sponges, which are rare because they are soft-bodied |
| Redwall Limestone | Mississippian | Thick beds of horn (rugose) corals, though much of it is dolomitized, which destroys fossil detail |
| Chinle and Moenkopi | Triassic, terrestrial | Petrified wood, and rarer trackways, burrows and swim traces; the loose sediment erodes into talus that hides them |
Many of PARA's formations match those of the Grand Canyon, but here they are spread over a wider area and reachable without extreme changes in elevation. Rocks run from Cambrian to Recent, with Paleozoic sedimentary rock the most abundant, which is where the team spent most of its time. Marine invertebrates are hard to identify to species, since fossils are often fragments, and the well-hardened limestone has cut and planed them at odd angles.
A high-spired gastropod from the Harrisburg Member of the Kaibab Formation, where fossils are agatized (NPS, 2020 field inventory).
A fossilized Permian sponge from the same member. Brain-like patterns in spherical chert nodules are the sponge remains (NPS, 2020 field inventory).
To find a trackway in the Chinle or Moenkopi, look in a wash or along a road or water cut for the harder layers, and return after rainstorms, which uncover fresh surfaces.
Packrat urine and sinkhole dens
Among the few fossil vertebrates were those from sinkhole shelters that held Pleistocene carnivore dens. Samples for radiometric dating were taken with extra care to avoid contamination, and the researchers were waiting for the results. Some samples were small bones. Others were amberat, which sounds like a gem but is fossilized packrat urine: after generations in one nest, the buildup becomes a hard, black, glassy substance. The oldest date from these samples will show roughly how long the shelters have been inhabited.
Amberat (NPS, 2020 field inventory).
What it is for
The data will go into a forthcoming inventory report and help staff with interpretation and resource management. It will also help park law enforcement plan how to protect sensitive resources. Specimens and photographs matter too: many nearby communities have not heard of PARA, and many four-wheel-drive vehicles cannot go far without all-terrain tires, so showing the monument may be the only way for people to see it.
Sources
- National Park Service, Park Paleontology News, Vol. 13, No. 1, Spring 2021, "Paleontology in Parashant: No Bones About It" (https://www.nps.gov/articles/000/paleontology-in-parashant.htm); rewritten in hubnx's own words. The page's photograph of the two researchers is left out.