Where Has Time Gone?

Think of an explosion that would create dust and debris that, when settled, would fill a cube measuring a mile high, wide and deep. Now multiply that by 1,200. That is enough to cover the entire state of California 40-feet deep or to fill Lake Michigan. Twenty-eight million years ago, give or take a million, a portion of Colorado blew up creating such ash and debris. The blast, the largest we have any evidence of in earth’s history, was 4,800 times the force of
the Mount St. Helens eruption. Ash from this explosion, known as the La Garita volcano, is thought by some to have reached the Atlantic Ocean.

This entire area of the San Juan Mountains saw extensive volcanic activity 25–28 million years ago. So much so, that a lot of the obvious remnants of the La Garita blast have been erased. However, during this same period two other volcanoes in particular succeeded La Garita, also under the area where we now sit. First the Bachelor volcano, then the Creede volcano blew like smaller concentric circles within the La Garita caldera.

Our drive between Creede and the ranch is within the outer edge of the Creede caldera. 

We wake in the morning seeing the snow-capped rim of this more recent volcano and look out another window at the dome that has risen in the center. It is not hard to imagine the lake that once filled this caldera until the dome rose up from its depths and the silt choked it, forming a dry, flat valley encircled by the ten- to twelve-thousand-foot peaks of the volcanic rim. The ranch that sits on this valley floor is at about nine thousand feet.

Kelly has had a hard time getting me to watch for elk or to scout for good rapids to raft because, as we drive, I have been mesmerized by my geologic surroundings. I just cannot get my mind around the time it has taken for this valley to go from lake, to silt, to dry land and then to rock, now covered with even more recent debris and top-soil. There is a mile or so of such sedimentary rock beneath us, which when you think about it, only emphasizes the depth of this volcanic hole, at its birth. There must have been more than eight-thousand feet from its newly formed depths to the peaks around it and yet this Creede caldera is just a baby sitting within the much, much larger La Garita rim.

We can leave the house on foot and start climbing the dome within 15 minutes but the several-hundred foot climb is more than what Kelly and I want to tackle even if we ignore the cliff faces and focus only on the slopes. How much time did it take for that dome to push up from the flat lake bottom buried a mile below us?  Which of these uplifted rocks is part of the original terrain that fell back down after the blast? Which are petrified ash? Where could I look and find fossils in that sediment rock?  

The Rio Grande River cuts through this valley floor. In addition to its beautiful meanderings, it provides many opportunities to see the various layers underneath us but I know so little about geology that I can’t understand how to identify the rocks I see or how to know their relative ages. Once again, as in our other travels, I am wishing we had a geologist as a tour guide. Every question I have tried to answer has only led me to more questions. From early questions such as, “How did this mountain get here?” I had new questions. “What are these rocks made of?” which in turn became, “How do I identify minerals?” to “What chemicals comprise the minerals?”

To date, I have found a finger-nail-sized marking in some sandstone that I think is a seed fossil.

Such a tiny accomplishment but such huge wonderment in this overwhelmingly vast and aged place. Did I mention that twenty-five million years is only 7-tenths of one percent of the age of the earth? It makes one stand in awe.