Question 2. What types of rocks are now in the Catoctin Mountain area?
Metamorphic rocks formed when they were altered (not melted) by heat and pressure. This metamorphism happened in the Catoctin area when the continents of South America and Africa collided with North America. Rocks in Catoctin were metamorphosed turning shale into phyllite, quartz sandstone into quartzite, graywacke into metagraywacke, conglomerate into metaconglomerate, basalt into metabasalt (or greenstone), rhyolite into metarhyolite.
Metamorphic rocks are harder than the surrounding sedimentary rocks of the valley, so that's one of the main reasons Catoctin Mountain is higher in elevation.
Last updated: April 10, 2015