Dana over at En Tequila Es Verdad (you know the place were they discover the truth by drinking Tequila) Put out this call to find out what really is weird in geology.
01 May, 2011
Accretionary Wedge #34: Call for Posts
And this time, it's gonna get weird.Not just because I'm hosting, although that's weird enough. But we're talking about Weird Geology.
Let's face facts, people. Geology can be strange. Outrageous. Bizarre. I'm sure you've all run into formations and landscapes and concepts that have left you scratching your head. Maybe they got less weird later. Maybe they stayed strange. But however transient or permanent that weirdness was, it got weird.
So tell us about it. Hit us with the strangest stuff you've got.
And then throw me a link in comments here, or at the main Accretionary Wedge site. Let's say, oh, by May 27th, so that I can have us all weirded out by the 29th.
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This was such a hard one to decide upon. I could come up with a number of different ones. But which one should I write about? That is the question? Then it came to me which one it should be, because it is one of the main reasons I got interested in geology.
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I grew up in NE Ohio and when I was a child I used to like to help my mom with her flower garden. The boys in my family were responsible for the vegetable garden, and I was told I wasn't to play in that, but it was okay for me to be in the flower garden. I was a tomboy at heart and I loved digging in the dirt with the flower garden being a perfect place to do that. I spent many an hour digging in that garden. I did it to because I found watching flowers grow to be so fascinating. But I also did it because my mom loved her flower garden and I liked helping her with it since it gave her so much pleasure.
One spring, I was helping get the soil ready so we could plant some seeds in it. I must have been about 8 or 9 years old at the time. I was old enough to have worked in the garden some but not so old to not want to do the work. I was also old enough where I had done this enough to know what to do without supervision. I just remember digging in the clayey soil and having fun when all of a sudden my trawl hit something hard. At first I thought it might be one of my sibling toys or something like that left there from last summer. I wanted to dig it up and get my siblings into trouble for not putting away their things. But it was in the ground too deep for it to have been a toy left out over the winter. So I kept digging trying figure out what it could be and to get it out. While I was digging my imagination started to kick in and I thought maybe it was a buried treasure. That gave me all the more incentive to get it out. What was really weird to me was the fact that I had dug in this area many times before and had never found this object. I began to wonder how I could have missed something this big? Surely someone brought it there, but who and when could they have done it? I moved some more dirt around and as I got the soil off of it I was finally able to see what it was. I got really excited when I started to see some sparkly things, giving me all the more will power to keep on digging it out. Finally, after what seemed like an eternity, I was able to free it from the ground. It was a small boulder (or very large cobble) about the size of a football. In fact it was rounded and shaped like a ball, except for this one spot where there was a crack in it and I could see the sparkly stuff. I thought I was rich because I found a huge rock with diamonds in it. I was so excited about it.
I could hardly lift it but I took it to the sidewalk close to the water spout and started to wash it off. Those sparkly things fascinated me. I could see them coming from inside the rock. I got a stick and was able to scrub all the soil off it. I began to be in a quandary over what to do with it. I didn't want to leave it outside because I knew it was worth a lot of money, yet I knew I would get in trouble for bringing a rock inside. While I was trying to figure out what to do my best friend and neighbor came over to play.
He was just as amazed by the rock as I was. He asked where did it come from and I said the garden. He didn't believe me and called me a liar because he had dug in that garden with me before in that area and it hadn't been there before. He thought I brought it from some other place but when I tried to get him to carry it, he agreed it was too heavy to carry far. He insisted someone must have brought it and left it. But who? because it was so big and not easy to carry. To pacify him I told him maybe the fairies brought it and buried it and it really was a magical rock to protect the house. We couldn't agree on how the rock got there and had an active discussion about how it came to that location, to settle thing we asked my mom. My mom thought that the previous owner must have put it there, but thought that was a weird place to put a rock like that in that location and why would they let it get buried like that since it was so pretty.
My mom did let us bring it into the house because I told her that it had magical properties and it would protect the house. She liked it too and placed in a spot of honor in front of the fireplace. My dad joked about the only way it would protect the house was if he would to throw it at someone trying to break into the house, but who would want to break into our house when all they could get is kids. He didn't object to it being there either and so it stayed there for the longest time until the house was sold. (I can't believe I actually found a picture from 1972 with it in it and was able to scan it into the computer and here it is:
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| Glacial erratic from our garden |
To bad I didn't get the angle where you could see the crystals in it.)
That rock fascinated me and I wanted to learn as much about it as I could. So on my own I started to get books from the library about rocks and crystals. I figured out that the rock was not made up of diamonds but very clear quartz crystals that gave it its sparkle due to their rhombohedral terminations. I wanted to break the rock open to see what was inside but knew if I did it would be destroyed so it was left as it was found. I finally decided it had to be a geode of some sort. For the longest time I couldn't figure out where it could have come from since it did not look like any of the shales that out cropped in our area. (I thought geods were weird at first but then when I realized they were a vug being filled in by minerals in solution I didn't think they were too weird to write about.)
When I started to study geology, I realize that it must have been a glacial erratic that was probably brought in from the Canadian shield granites. Because of its size I figured it had to be the ice that brought it and not water. I could tell the ice action smoothed the corners, and there is no telling how big the initial rock started off as or how far it has traveled.
Glacial erratics are weird stuff in their own right - it took a while for people to figure how the erratics got to be where they were. But that wasn't what was the weirdest part to me.
The weird geology part of it of it to me. - How can a large rock be moved upward through the soil? You would think it should stay were it is or get deeper in the soil with time and not come to the surface. This is an actually example of pedoturbation(1) or cryoturbation (2) or frost heave/weathering (3) or creep (4) at work (I'm not too sure what the exact terminology to use with this). Namely that rock was buried in the ground but due to the freezing and thawing nature of the soil where I lived the rock was able to migrate upwards and finally made it to the surface after being buried for a long long time in glacial debris. (NB the gutter system on the back of our house drained into the garden, giving it a source of water for the freezing action. Also there was a lilac tree in the garden and an elm tree to the side - so it could be the result of some bioturbation too.) Once I became aware of this rock I saw a lot of other examples of rocks most of which were pebbles or small cobbles in size exposed at the surface where there used to not have been anything at all. I know with cutting grass in the early spring this can be a problem because the mower can throw these pebbles quite a distance and they do break things or hurt if you get hit by one..
I always mused on what else would turn up in that garden. Also even though I now know how the rock turned up in the garden, I still like to reflect upon the fact that the rock did have and still does have magical powers to me. This rock and my trip out west when I was ten where some of the many reasons I got into geology - trying to figure out how these rocks came to be the way they are. They have created a fascination in me about geologic processes that has stayed with me my entire life- pretty powerful stuff.
References:
(1) "Soil Genesis and Classification" by S.W. Buol, F.D. Hole & R.J. McCraken (1973), fig 6.1 pg 89.
(2) "Geomorphology From Earth" by Karl W. Butzer (1976) pg 340.
(3) "Principles of Geology 3rd ed" by J. Gilluly, A.C. Waters & A.O. Woodford (1968) pg 188-89.
(4) "Essentials of Geology, 3rd ed" by S. Marshak (2009), pg 363,
see also Wikipedia for these terms.
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