Thanks to a variety of weathering and erosive processes, rocks can come in all shapes and sizes. The above rock from the McDowell Mountains near Phoenix, AZ has a peculiar shape similar to that of a mushroom! This rock is an example of a tor--an exposed mass of rock that abruptly rises above the surrounding ground… Continue reading How do you form a mushroom rock?
Wolf River Batholith (WI) - 1.45 Ga Ravakipi is a rather unusual, and distinctive, type of granite with rounded orthoclase (K-spar) crystals. These crystals typically have plagioclase rims, and hornblende and biotite are other common minerals present. Image by author