Recently, one of our facebook page members (Heidi Burns) posted a photo on our site. See it right here. She wondered what it was. Yep, it is one of those geological oddities that turns up from time to time. We would like to tell you that it is the fossil of a petrified toothy smile, but we don’t think that you are that easy to fool. No, it must be something else, but exactly what? Let’s work on that. What’s the story here?
This is not going to be a simple story. That smiley face started out as a fracture in a brown sandstone. But there is more; this fracture is filled with crystals. Those are probably crystals of quartz. Something made the fracture open up but how did that happen? Also, how did it fill with quartz? And, if we are really going back into time, then where did that brown sandstone come from? Those might sound like questions that are hard to answer, but they really aren’t. As we understand it, we have been taken back in time to when there was an ocean lying adjacent to a rising mountain range. Those mountains were rained upon, and the rainwater began a chemical transformation of the bedrock. We geologists say it was chemically weathered and converted from solid rock into soft, even squishy sediment. That sediment was washed down a steep mountain stream and into the ocean where it became a sandy sediment. There, and over a very long period of time, it hardened into rock. In this case that was the brown sandstone.
The mountain building continued, mountain building events typically span tens of millions of years. Eventually our brown sandstone was caught up in all this. All its surrounding bedrock was lifted and then folded. One of those folds, a very small one, became our smiley face. That smile didn’t just fold, it actually came to yawn! A smile shaped gap was left in the rock. Now all we have to do is fill it with quartz. How did that happen?
One way was for injections of very hot water to have risen out of the even hotter crust deep below. They filled that smiley-face gap and then cooled down. Hot water can dissolve a lot of silica but when it cools that produces crystals of quartz. We geologists have a name for these; they are called hydrothermal injections. How long does this take? The two of us have pondered this question. There is no possible solid answer. After all, we can’t go down into the earth with a stopwatch and time these things as they happen, can we? But our suspicions are that it takes quite a while. A mountain building crust is very hot and takes a long time to cool.
We have used the word pareidolia from time to time and want to bring it up once again. It’s important here. Pareidolia is the recognition of human faces in an otherwise random image. Seeing a human face on the surface of Mars is a great example. Take at look at our second illustration. Is that a Martian or just an oddly shaped small hill? You decide. Well, our earthbound smiley face is a good example of pareidolia.
Contact the authors at “randjtitus@prodigy.net.” Join their facebook page “The Catskill Geologist.” Read their blogs at “thecatskillgeologist.com.”
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