Not Visiting the Famous Gallows
Alas, we had no time to stop by the Towne Center, where people are hanged by the neck until they cheer up. It's an effective incentive, by the way. Everyone seemed pretty happy.
Rocks On My Alleged Mind
I've had three great small-rock experiences* since my youth. The second was receiving a beautiful specimen of cobalto calcite for my birthday! I thought I had "everything" but no!
The most recent was related to my suggestion yesterday that the Grand Canyon has especially dangerous gravity. As you walk along the rim of the Canyon (using caution near the edge), there are rocks. Not just the usual rocks, but rocks on pedestals. For example,
|On the left is a chunk of "Duppa sandstone," 770 million years old. Farther along the "Trail of Time" you find this chunk of "Phantom granite," 1,662 million years old.|
I view that "1,662 million" with some suspicion. Normally, things this old are dated by comparing the decay of radioactive isotopes. Four decimal places seems improbable, but I'm hardly an authority. Even so, it's pretty impressive being in the presence of something that has been around billions of years.
While I'm not an authority on isotope dating, I am a terminally compulsive proofreader**, which brings me to my first adult rock encounter. The American Museum of Natural History in New York City has a marvelous collection of geological specimens. Some years ago we went to the Museum (which they call a Mvsevm) and, several dinosaurs later, spent some time in the hall of rocks or whatever its correct name is. There I discovered the phenomenon of pleochroism, which I had seen but didn't know it had a name. According to the signs, however, it has two names, the other being pleochromism, a probably incorrect variant. Even more bizarrely, sulfur in some rocks is "sulphur." I guess they're old rocks. This is the tragedy of compulsive proofreading: I actually noted this years ago and found it necessary to mention instead of providing more pictures from the fascinating "Trail of Time."
* I've recently been having some big-rock
experiences, too. Some have been famous. (The rocks,
not the experiences.)
** Which doesn't mean anything with respect to this blog. Everybody needs an editor. I don't have one. Obviously.