Happy Holidays

I had intended to take a short trip to northern Virginia this week, to look at Ordovician and Devonian rocks in the Winchester area. The east coast snowstorm put a damper on those plans; I’ve had to dig fossils out from under snowbanks before, and it’s not an experience I’m eager to repeat. Instead, while technically on vacation, I’m at home trying to finish my book chapter before the end of the year.

The images I’ve included in this post have nothing to do with paleontology, but they do present a bit of a geological mystery appropriate to the season. About two weeks ago we had a hard overnight frost in Martinsville. The image at the top is the view through my truck windshield, of the ice crystals that formed on the glass.

Zooming out a bit, you can see that there were actually two types of ice crystals:

Zooming out even more, the real weirdness is apparent; the regions covered by the two types of crystal are defined by the sweep of the windshield wiper blades, with the large crystals covering the area swept by the blades and the small crystals occurring in the unswept areas:

What’s even stranger is that I had not used the wipers in days. My assumption is that the varying amounts of dirt on the different parts of the windshield caused this variation. Perhaps since there was more dirt on the unswept areas, there were more nucleation points for crystals to form, resulting in less room for each individual crystal. I’m not sure about this (mineralogy was not my strongest subject!), so if anyone has an alternate hypothesis feel free to post it in the comments.

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2 Responses to Happy Holidays

  1. Doug says:

    Wish i could help you, but seeing as I live on California’s Central Coast, i don’t encounter ice very much. As such, i haven’t been hard pressed to learn anything about it.

    On Nat Geo news, i came across this neat article. Apparently an early whale (28 to 25 mya) in Australia was a mud sucker. The article briefly mentions the possibility that the style of feeding may have been a precursor to baleen feeding. Hopeful more detailed reports will make their way into the blogosphere.

    http://news.nationalgeographic.com/news/2009/12/091223-whale-dwarf-australia-sucker-fossil.html

    Oh, and happy holidays!

  2. Alton Dooley says:

    Erich sent me a copy of his paper a few days ago, and I’m still reading through it. However, he told Brian and me about his ideas on Mammalodon feeding when we saw him at the Smithsonian a few months ago; needless to say, we were intrigued given our thoughts on baleen evolution.

    One of the coolest things about this is that the closest-known relative of Mammalodon is Janjucetus (which Erich described a few years ago). Janjucetus was pretty clearly a pursuit predator, eating relatively large prey, while its close relative was apparently a suction feeder. As usual, things are more complicated than they first appear, and it seems that early mysticetes were doing all kinds of things.

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