J.Haynes - Week Two - Igneous Rocks

This week, my wife and I decided to visit the volcanic plug of Morro Rock. This igneous rock is almost all dacite and is located in Morro Bay, California. My wife was curious about why its' called a volcanic plug, in which I informed her that it is when magma within a volcanic vent solidifies, forming the feature of the rock in which is visible today. Morro rock is also considered extrusive due to some of the lava within the vent reaching the Earth before solidifying, hence the dacite that this rock is mostly composed of. Upon examination of the rock, I could easily parse its' dacite properties due to its' texture being between aphanitic and porphyritic. Considering its' location, it was often used as a landmark for sailors and explorers throughout history. It it truly fascinating to see a formation that took millions of years to accomplish!