Life in the Desert Starts with Life in the Sea

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380 Million years ago the Pahranagut Valley in Southern Nevada was home to sponges.  Lots and lots and lots of sponges. Big sponges, little sponges, green sponges, and blue sponges.  (Actually, no one knows what color they were. I made that part up).  They were busy going about their spongey business, which mostly consists of filtering water for presumably quite a long time.

However, on one particular day, the peaceful sponges met with disaster.

It’s a little known fact that it was actually this mass genocide of stromatoporoid sponges that elicited the famous quote from Obi-Wan Kenobi:

“I felt a great disturbance in the Force, as if millions of voices suddenly cried out in terror and were suddenly silenced. I fear something terrible has happened.”

Obi-Wan Kenobi on the Alamo Impact

The surviving post-inhabitants of Alderaan, being as species-centric as they were, re-wrote the history books, and the Alamo sponges were left out of Star Wars lore entirely. I digress.

When the biolide, or fancy term for “we don’t really know what it was made of”, hit the Earth and killed the Nevada sponges, it left behind a very interesting kind of rock called breccia. The Alamo breccia is full of limestone and, as you may have guessed, dead sponges.

omgsponge

The Alamo impact is particularly cool because it was a marine impact that, through geologic processes, is now available for study on land. So, if you are a thalassophobic geologist that happens to be interested in what happens to marine ecosystems and general sponge high society after they have been pulverized by a biolide, this is the perfect project for you! The Alamo Impact, even though the crater is estimated to be around 44km wide, wasn’t discovered until the early 1990’s.  “What? But the crater is huge!” you might say. Various geologic events have distorted the impact over time, so it took a crack team of geology/CSI fans to solve the mystery as there is no obvious crater to see.  The whole thing started with some geologists finding the breccia during a survey and scratching their heads, “This doesn’t look quite right… How did this get here?”  So kiddos, don’t ever assume there isn’t anything big left to discover, it might be right under your feet.  Once discovered, the geologists did a few analyses, had a few discussions, and I predict (p<.05) a few beers.  They finally concluded that “yes”, there was some kind of catastrophic impact in the Nevada desert.

To me, this whole thing is brain candy. First, there’s a huge crater in Nevada that no one knew was there until after I was born (go science!). Second, It’s pretty damn cool to think Nevada went from this:

To this:

How many non-human dramas and lives have played out here over the millions of years since the impact?  It’s mind boggling. If you have any empathy or capacity for imagination as a human, that thought should leave you in the same awe one gets from staring at the Milky Way too long or hearing the Hallelujah Chorus live for the first time. It is that spectacular.

Take this grasshopper as an example.

_DSC6520_lznThis grasshopper has probably evolved over the past few thousand years, and his camouflaged exoskeleton matches the breccia he’s sitting on perfectly.  The modern grasshopper, which has literally millions of individual ancestors and transitional forms, matches the color of the fossilized sponges that died 380 million years before it. The answer to the question, “Why is this grasshopper gray?” suddenly gets a lot more interesting. His color ties him to the Devonian sea in a very concrete but poetic way, far more elegant than genetic inheritance from his ancient arthropod ancestors alone.  He is gray because he returned to the fossilized sea, millions of years after his first ancestors appeared on the earth, and he must match them to avoid being eaten by still more ancestors of ancient beasts with even more ancestors and transitional forms.

Our kind have not been present long enough on this pale blue dot to truly fathom the ever continuing Opera that is life, or the fact that we don’t even make up an entire note in the music.  The Alamo Impact reminds me of that.

Read more about the Alamo Impact here: http://geology.isu.edu/Alamo/rocks/breccia.php

In current biological events, here are some photos taken near the Alamo Impact.

 

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