Where Geologists Go to Heaven!

By: La Geologa Reyna (Emily;-)

What does the number five-hundred million mean to you? Probably something you can’t even imagine right? 500 million M&Ms would fill about 35 average-sized bedrooms. 500 million dollars would buy you 500 thousand 2012 Porsche 911s. And the rocks you observe in the Peruvian Andes are more than 500 million years old.

Mountain building, rock ages, and the geologic history of the Earth are hard concepts to wrap our minds around. When I think of human history and ancient cultures like the Egyptians, Polynesians, or Incas, it is hard for me to imagine what life was like so long ago. It is hard for me to even fathom these peoples’ existence, and they lived a mere 5,000-600 years ago. So how is it possible that I can understand, like a video playing in my mind, the entire geologic history of the Andes mountains that have been building for 500,000,000 years?! I don’t know.

All I can say is that I am obsessed with rocks! Since we arrived in Ecuador, I have been completely taken by the igneous intrusions, structural geology, stratigraphy, and volcanoes of the Andes. So to let you all in on some little facts about what I am seeing, here goes:

1) Background: 500-240 million years ago the supercontinent of Gondwana began to break apart, and the Nazca and Antarctic Plates (crust of the Earth that float, essentially, in separate pieces called plates, on the surface of the planet) began subducting under the South American Plate.

a. Supercontinent:

b. Subduction:

2) The rocks we see in the Andes today were once sand at the bottom of an ocean. I know this because I see rocks here that look like they were once sand or mud.

a. In this picture below you see fine-grained, dark-colored rock layers that would come from deep-ocean. You also see layers of lighter rocks that are larger-grained, which would have come from shallower oceans. This means you see layers from an ocean that receded and regressed over and over again:

3) The mountains came about when the plates (described above) ran into one another and began to squish and fold the sand and mudstones you see in the picture above. The Andes were formed in three different orogenic (mountain building) events.

a. 360 million years ago: Eo-Hercynian Orogeny- rifting and river conglomerates. Also random igneous intrusions like this:

b. 300 million years ago: Jurua Orogeny- folds and faulting like this:

c. 200 million years ago: Nevadan Orogeny- high planes uplifted to 14,500ft like this-

4) And through all of this some of the worlds largest, most impressive, and most visited volcanoes were formed.

a. How? When one plate subducts under another, it melts and magma rises to the surface. Then, exploding like a zit, lava and ash flow over the surface of the Earth:

b. Now we see peaks like these:

c) c. And beautiful layers of white ash that cover the uplifted valleys that surround the volcanoes:

5) The final result of these extraordinary geologic events is the incredible landscape we have been biking through for the last four and a half months. However, we were all particularly taken by the scenery we rode through from Juliaca to Arequipa—the beautiful mountains, high altitude deserts, massive volcanic peaks, and strange sand formations.

I knew there was something particularly special about our surroundings when I saw my friends, friends who constantly laugh at my enthusiasm for a boulder, finally appreciate the geology lessons I often voluntarily provide. This must be where I will go to heaven!

The Neighborhood Bike Gang

Like most young women, my biking career began on a bright pink and purple tricycle in the cul-de-sac above my house. When I was quite young, around three, I decided to ride down the steep winding Fish Creek Falls road on my tricycle. A lady in a minivan picked me up and drove me home explaining how dangerous it was to ride down that road. Once she arrived to my house, she scolded my mother for being so lackadaisical while I adventured out by myself. She explained in sharp words that I could have easily lost control and got hit by a car. My mother smiled and nodded as the woman scolded her, but knew in her heart that I was born to be an adventurer. She understood the risks of having a daughter like me, but came to the conclusion that I was going to ride down that hill by myself with or without her permission. And thus, the biking career began.

As I grew older, I was eventually introduced to the neighborhood bike gang. My brother and his friends were the bullies of the gang, and rode around the cul-de-sac like Hells Angels. My childhood friend, Brian, and I found refuge in the drainages on the sides of the roads. At first, we were just trying to escape my brother and his evil cronies, but then we realized the joy of riding through the water that flowed past our ankles. The children of my neighborhood would ride until they were beckoned by their families for dinner. Riding around the neighborhood became an afternoon tradition.

This morning, we biked 45 kilometers to a small Peruvian community, Checacupe, where we encountered the neighborhood bike gang. About 10 kids were riding around the main plaza of the town, quite similar to my cul-de-sac given the smallness of the town. They were playing the same bike games we played and had the same sibling bullies.

The bikes were a bit different. There were mountain bikes, old fixed gear bikes, cruisers, and bikes I would classify as only two wheels and a chain. The bikes were in bad condition but it did not matter to the kids. As long as the bikes moved forward as the kids pedaled, the laughter and fun continued.

The most wonderful image I saw was the smallest kid riding the largest bike. The little boy could not even reach the pedals if he sat on the seat properly, in fact he had to rotate his hips side to side in order to get enough length in the leg to reach the pedals.

Although we are far from home, and many things are different here in Peru, that bike gang brought me back to my childhood. I realized that kids all over the world get the same pleasure out of the simple things in life. Maybe one day, these kids will grow up to cycle around the world or maybe just continue to bike around their small village. Hopefully, their love of biking will continue to grow and will be an influence on their adult lives.


By: Rayna (Queen)