Week 2 - Igneous Rocks

This weekend, my daughter and I decided to escape our quarantine here in Washington, and head south to Joshua Tree National Park in California. After the 18+ hour drive with the two of us trapped in a car together, tensions were running high. I wanted to escape the confines of the vehicle, she, wanted a baa baa and her lamb-y-kins. We finally arrived and began exploring the beautiful park together. Her legs being very short, not much distance was covered. We did however, manage to stumble upon the granite formation above, commonly known as the "Old Women" rock formation.

She asked with her inquisitive tone, "Rock?" I responded, "Indeed tiny human. Let me tell you where it came from." I explained that this rock was granite, but not always called by that name. Long ago, deep underground, this hard granite surface was molten magma. Over millions of years, the magma cooled, and it began to crystallize. Because the process took a long time, the mineral grains had plenty of time to grow, just like you grow as a person. This created granite formed with large, visible crystals, or a phaneritic texture. The classification for this type of rock is intrusive igneous rocks. The granite itself is not called granite, but a Felsic Igneous Rock.

At this point she looked up at me, thoroughly confused. "How Rock?" she asked. "Patience my sweet, I am explaining". This Felsic Igneous Rock, granite, is composed of a little bit of quartz, and mostly feldspar. I told her that I suspected the feldspar was darker pink in color, hence the light reddish color of the rock. She looked up at me, with complete and total understanding in her eye. "Rock alone?" She wondered. "No sweetie, the rock is part of a family." I explained that long ago, the rock was probably a granite batholith. One giant amalgamation of cooled magma, technically called a granite composition. Because of the intense pressure of being underground, the batholith cracked into many pieces. Water seeped into these cracks, and over time, with ground erosion, each piece became its own independent piece of granite, or stock.

As we walked back to the car for her journey home I asked my daughter, was it worth the long drive just to see the "Old Women"?  She replied, "Old women. Nice rock." I couldn't agree more.