STRATIFICATION
Storyboard Text
- My story began nearly 60 million years ago as hot magma erupting from a volcano. Upon exposure to to the cool temperatures of Earth's surface, I immediately solidified into what they call an "extrusive igneous rock".
- Since I cooled so quickly from lava to a rock, there was no time for crystals or grains to form, and I was smooth- some may even say I was glassy.
- Being a young volcanic rock was tough. It wasn't easy to withstand the frequent weathering; ice, wind, and rain scratched my surface daily. Eventually, I noticed fragments of myself chipping off. It reached a point where I couldn't even recognize myself anymore.
- I realized then that I was undergoing erosion. I saw my fragments float away with the rain to a faraway stream. Over the course of the next 15 million years, I too joined my fragments in the stream. It was difficult to say goodbye to my life as an obsidian rock and accept that change was coming. I could no longer see the ocean either; it was a vast landscape of continental plates everywhere.
- The next 10 million years went by rather slowly while I waited. Other sediments floated past, some staying and some going. I rested on the stream floor, patiently waiting as these sediments layered over me thickly. The pressure became so great that I started to undergo compaction with them. My fragments combined with the sediments began to weakly resemble rocks!
- Dissolved minerals started crystallizing in the open pores of the rocks, which is what scientists call cementation. The minerals filled the available gaps, creating a more stable and cohesive form of my new self. I remember that I was a clastic sedimentary rock because my composition consisted of sand, gravel, and other assorted rock fragments.
- I was also termed a conglomerate because of my large grains and visible pebbles. The abundance of clasts- another word for rock fragments- is why I was clastic! The entire process of deposition and lithification took a toll on me. I rested for another 10 million years on the stream floor, until I began to pick up on something strange..
- ALL ROCKS CAN CHANGE
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