Boasting the oldest supracrustal rocks in the country, this outcrop located on the Eastern Beartooths is a must see. Occupying an area of about seven square miles, Quad Creek is filled to the brim with amazing geologic specimens (F.D. Eckelmann, A. Poldervaart 1957). While it can't be seen with the naked eye, zircon is the ancient, microscopic mineral which has helped to make this outcrop so famous. Certain specimens of zircon from this area have been radiometrically dated to be as old as 4 billion years. This means these minerals were among some of the first to materialize and crystallize from Earth's original molten form. As in many cases with zircon, it is found with quartz. In this location, the zircons were extracted from quartzite, which is essentially metamorphosed sand. This rock is light cream to light gray colored and has a sandy texture. This quartzite is evidence and remnants of ancient oceans and beaches. Further evidence of this are the other metamorphosed rocks that can be easily found here. The rusty, red-brown colored rocks found at Quad Creek are likely meta-iron formation. These rocks are from an ancient ocean when stromatolites, the first microbes to photosynthesize, began polluting the Earth's atmosphere with oxygen, causing iron-rich rocks to oxidate and turn that characteristic rusty red color.
Quad Creek
Photo courtesy of Darrell Henry
Beartooth Highway with Quad Creek
Map courtesy of Darrell Henry
So, now that you know what you can find at Quad Creek, you're probably wondering exactly how it all got there. How is it that some of the Earth's oldest minerals ended up exposed and elevated? As was the case at Granite Peak, the Laramide Orogeny is responsible for this uplift as well. Much of the folding and foliation at Quad Creek is due to the basement rock pushing and overturning the overlying sedimentary layers. And while granites and gneisses such as those at Granite Peak can be found here, other types of rocks reveal a different history. The Earth has experienced vast changes in temperature and water level. After ancient seas dominated the land, they left behind fossils, sediments, and remnants of their presence. These sediments were then metamorphosed as the Earth continued to evolve and undergo oppressive temperatures, giving us the meta-sedimentary rocks found at Quad Creek.