Last summer my family and I went to Oregon and we decided to visit Mount Ashland to hike. According to the brochure that we got, it said that Mount Ashland is the highest peak in the Siskiyou Mountains of southern Oregon. I found out from the brochure that Mount Ashland is mostly composed of granite with other igneous intrusive rocks like diorite and granodiorite. From geology class I got to learned that igneous rocks are classified into two groups, granite and rhyolite. Mount Ashland is classified in the first group. From class I learned that granite is made up of 10-20% quartz and 50% feldspar. If you look closely at these rocks on Mount Ashland you can see that it has specks of black on them, which is an indicator of small amounts dark silicates and that will tell you that it is a granite type. Mount Ashland is a large pluton of igneous rocks that was formed from slow cooling of granitic magma that intruded the Khalmath Terranes at depths of several miles below the earth’s surface. From these rocks I can tell that they are dikes because some of the rocks were forming from preexisting rock body. You can’t tell from the picture, but there were a lot of granodiorite, and you can tell it was them because they have more feldspar than granite and because of their specks of dark silicate. The brochure also said that the pluton of Mount Ashland deposits minerals like gold, silver, and other minerals! That would’ve been cool if we found some. Oh well, better luck next time. Until then….
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