A Lesson in Geology I

Dunefield against Sangre de Christo Mountains



In 2000 Bill Clinton made The Great Sand Dunes of Colorado a National Park. It wasn't until last year that the proper land acquisitions made it official. I was in the area so I checked it out. The Great Sand Dunes are somewhat of an anomaly and some of the secrets have only recently come to light. The Dunes are over cover 39 square miles, get up to 750 feet high, and are at least 12,000 years old. That's what the last coring of the dunes reviled but the actual age is still a mystery. The picture above shows the dunes against the Sangre de Christo (Blood of Christ) Mountains. The formation of the dunes is quite an amazing process. The Rio Grande and it's tributaries flow from the mountains, around the dunes, and into the San Juan Valley which lies to the west of the dunes.

Streams Surrounding the Dunes



These streams deposit sand from the mountains in the valley. Easterly winds carry the sands onto the dunefield. The streams also pick up residual sand from the dunes and recycle them back onto the field. Pretty neat huh?

Closeup of Dunes