Rio Grande // Medano Pass Sand Peel
The Headwaters / Eastern Divide
Collected September 15, 2020; lat 37.856011 long -105.432377; elevation 3041 meters
Medano Pass is the northeast edge of the Rio Grande basin. The western/left side of the pass drains to Medano Creek and the Rio Grande while the eastern/right side drains to the Mississippi River.
The pass is where Zebulon M. Pike Jr.’s expedition to explore the Louisiana Purchase entered the Spanish Empire in search of the headwaters of the Arkansas River in 1807. Soon after, the party was captured by Spanish soldiers from Santa Fe. Pike may also have been a spy for the United States tasked with learning about the Spanish military force and settlements in the Spanish-held territory in North America.
Location
Medano Pass in the Sangre de Cristo mountain range, southern Colorado
Interpretation
Poorly sorted, slightly transported weathered arkose of the Sangre de Cristo formation. This immature formation was shed ~300 million years ago off the Ancestral Rocky Mountains. These mountains were reactivated ~ 20 million years ago to form the modern Sangre de Cristo Mountains.
