Castle Rock

One place my family and I like to go and hike is right here in our backyard at Rock Park Trail. We live here in Castle Rock and have taken this hike a number of times but I have never considered what type of rock formation this land mark that welcomes visitors in to our little city is. 

 This formation consists of rhyolite, an igneous rock which is strongly resistant to erosion. Thanks to trail head signs I learned that, about 37 million years ago, a volcanic eruption covered this area with approximately 20 feet of rhyolite. After a few million years, mass flooding and erosion of the volcanic rock gave way to the castle rock shaped butte that's visible today.