Tuesday, August 4, 2020
Great News for Public Lands
Sunday, August 2, 2020
Exploring Paleozoic Sediments in Southern Utah
Just before the pandemic locked everything down, I went on a geology hike near Comb Ridge in southern Utah with Professor Gary Gianniny, Chairman of the Department of Geosciences at Fort Lewis College in Durango, Colorado. I’m working on a book about the canyon country of the Southwest and this was a great opportunity to learn from an expert in its geology. While the hike primarily focused on geology, you can’t tour this region without seeing fossils. All our fossil collecting was catch-and-release. I took photos but did not bring back any physical specimens. Here’s a quick overview of our hike.
We started from a point on the southeast side of a feature called the
Monument Upwarp, about 16 miles west of the town of Bluff, Utah. Here
is an annotated Google Maps satellite view of the area:
Our starting point overlooked an abandoned meander of the San Juan River. The river long ago took a shortcut by punching through a narrow wall of the meander (out of site behind the near slope), leaving it now abandoned.
From there, we turned east and went down the side of cliffs bordering Comb Wash. During the first part of the hike on the top of the Monument Upwarp we were in the Honaker Trail Formation, a marine limestone of the Pennsylvanian Period. Gary has done quite a bit of research on these limestones. He pointed out numerous examples of fossils in this formation. The first was a brachiopod (I didn’t get the species). Notice the spring-like squiggly lines along the hinge line at the top. This is called a spiralia. Gary said it is indicative of it being a brachiopod:
Here is an example of crinoid pieces. Gary said this limestone is made up of about 90% crinoid fragments:
As we descended, the layers got younger because of the way they were
tilted. When we
got to the red layers, Gary explained we were now crossing into the
Halgaito Formation, terrestrial sandstones of the Permian Period. He
pointed out fossils of plant roots encrusted in calcium carbonate (the
light gray areas). These are called rhizoliths. He said you can still
see rhizoliths forming today on the roots of modern plants.
Like most geologists who frequently get out onto the landscape, Gary was in good physical condition. I however, was another story. The 600-foot return climb across gullies, boulder fields, and loose scree was about the limit of my sorry physical condition. But it was a great experience and one I wouldn’t hesitate to do again.
Friday, January 31, 2020
Digging for Fossil Fish in Wyoming
It was a productive day, and we both bagged some nice finds. The floor of the quarry was covered with a
fine powder of shale, and by mid-afternoon the wind had picked up and was
blowing the powder around so much we decided to call it quits. Nick loaded our fossils onto a cart and took
me over to a line of diamond saws I could use to cut off the excess matrix and
trim the specimens down to a reasonable size.
As we had to fit all our finds into our car, this was very helpful. After a quick tutorial I was happily working
on my own trimming down all my specimens. Wednesday, February 8, 2017
Berlin-Ichthyosaur State Park, Nevada




Saturday, June 1, 2013
Triangulating Your Position
- How accurately do you need to measure the bearings to each object?
- Will your measurements be more accurate if the objects you measure are far away or nearby?
- Will your measurements be more accurate if the objects are close to each other or far away from each other?
- Under what conditions would your triangulated position be in error by more than a mile, even if you have accurately measured and plotted your bearings?
- Try to measure bearings as accurately as possible. With care, you should be able to measure a bearing to an accuracy of about 2 degrees.
- The accuracy to which you can find your position will be better if the objects are nearby. If the object is a mile away and you measure its bearing to an accuracy of 2 degrees, the uncertainty in your location is less than 200 feet. If the object is 10 miles away, your uncertainty grows to nearly 2000 feet.
- Try to measure objects that are at right angles to you. Avoid objects that are in line or 180 degrees apart.
- The error in your position can be more than a mile if the objects you are measuring are far away (more than 10 miles), the accuracy of your measurement is no better than 5 degrees, and the objects are not at right angles to you.
Sunday, June 3, 2012
How to Tell if You're a Famous Author
Saturday, June 25, 2011
How Long Will Your Digital Photos Survive?
Looking back at color prints from the 1960s and 1970s, our fears were well-founded. Old Ektacolor prints have long since faded and shifted color toward the yellow. Cibachrome prints and Kodachrome slides are much better, but not immune. Whole collections of what were once professional-quality photos are now just interesting anachronisms.
The new generation of photographers, accustomed to shooting only digital, may laugh at such worries today. If a photo print fades, just fire up your computer and print another. Why worry? Digital ones and zeroes don't fade with time.
But there's a whole body of research that suggests such complacency is unfounded. Digital photos may fade away even faster than photographic prints; it's just that the failure mechanisms are different. Here's a link to an interesting article from an unlikely source that describes the problems with digital photography in some detail:
Long-term archiving: digital photography's Achilles' heel







