Not all of the round rocks at Roundrock are round rocks.* It's funny (though not alarming) to me that I can be so very forgetful at the office or even in my day-to-day life about things that ought to be important to me, yet for months and months I can remember the specific location and condition of round rocks in my forest. I unearthed the roundish rock above just above the spillway on our dam more than two months ago. I thought at the time that it would be a good one to grab and add to our slowly growing collection of keepers. At the time, however, we must have been outward bound or busy with some other project for I left it where I had found it. Then, in ensuing visits, I suppose we simply hadn't crossed the dam to that part of Roundrock so had no occasion to grab the pill-shaped rock. But on our last visit, as we were making our more-or-less aimless hike down the Central Valley, I surreptitiously aimed our feet in the general direction where I knew this rock was waiting for me so patiently. By the time we reached it, we were on the truckward bound leg of our walk in the woods, so I picked it up and carried the rest of the way. (It may have gone in my daypack because the truck was still more than half a mile away, as the crow flies, and they tend to fly straight, but our treks through the woods tend to meander, so that would be a long way to carry a large rock in my hand.) When I first began posting pix of my beloved round rocks, some commentors wondered how they could have formed as they did (a concretion of a sort forming in a mineral soup) without being deformed by gravity. I noted that they were suspended in a solution (though I'm really far beyond the frontiers of my understanding the science of it), and thus they were more or less free of gravitational forces (though as I understand it, nothing is free of gravitational forces). But I babble. Today's image is an example of a not-so-round round rock. (You've seen this fellow before, by the way.) How do I account for this? Well, I don't. I can speculate that the nucleus bit of blue shale within was an elongated shard at the time the minerals began to accumulate around it. That's not a very satisfying explanation since many of the split round rocks we find show that their nucleus was elongated though the rock that formed around them was nicely round. Or it might be that two separate round rocks somehow merged as they were forming. That's a tempting idea, though I think there would be a "waist" to this one if it were the case. Slicing it open might be revealing, in an oh-so-literal sense. Or it may be that gravity had some influence on this. We have all sorts of roundish shapes to our rocks. While the vast majority of them are spherical, there are enuf oddballs (ouch!) to leave the doors of speculation open wide. See! This is why I go to the forest! *Yes, I realize I've used this line before. Exactly one year ago today, by amazing coincidence.

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Today is the last day of deer season in Missouri for those using serious firepower. (Special, localized hunts, black powder, and such will still go on through the new year.) It will be safe for Pablo to go back in the forest, and I intend to do so at the first opportunity. It has been a custom of recent years for our family to go to Roundrock on the day after Thanksgiving to have a weenie roast and to make s'mores. (I don't like s'mores, but if it means the gang will come . . .) Alas, as most of you know, one of mine is now far away in Oregon (a nice place -- I've been there!) and another is even farther away in Kenya (and I'll be going there). The remaining two spend much of their time in some place called Azeroth, but I may be able to pry their crabbed little fingers from the keyboards to join us. And if not, it will just be Libby and me (and maybe it's time to begin taking Max back in the woods -- we've had some good freezes lately, and the bugs should be less of a problem for him). Missouri calendar:

• Mammals seek winter shelters.

This entry was posted on Tuesday, November 21st, 2006 at 1:01 am and is filed under Geology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.