Abstract
Did you know the Grand Canyon can help us figure out what happened on Earth long ago? As in, 1.7 billion years ago? As we go down into the Grand Canyon, we find older and older rocks. Some of the oldest rocks are in a section of the canyon called the Upper Granite Gorge. These blocks of metamorphic rock formed when older rocks experienced extreme heat and pressure. We wanted to figure out the pressure experienced by four of the blocks. We collected five samples and analyzed them. We used the minerals in the rocks to determine the pressure each block experienced. We learned that the blocks formed under different pressures. We also found out that the blocks that formed at higher temperatures experienced higher pressure than blocks that formed at lower temperatures. The difference in pressure made us realize the blocks formed at different depths. Then they moved when tectonic plates pushed together to form mountains.
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