Ancient Life Stuck In Sticky Clay – Will Mars Mimic Earth?

Puffy clouds drift near the full moon last night. Details: 16mm lens at f/4.5, ISO 800 and four-second time exposure. Photo: Bob King

Fog filled a grassy field under the full moon last night. After enjoying the scene, I thought I’d try to capture the look and feel of the light with my camera. I quickly walked home, grabbed the equipment and drove instead of walked back. To no avail. In that 12 minutes of time, the fog had dissipated. As a consolation prize,  picturesque clouds soon appeared in the west and briefly brushed across the moon’s face.

Hunting for marine fossils on the Cretaceous ore pile at Hill Annex Mine Friday. Credit: Glenn Langhorst

On Friday my friend Glenn and I drove north to the Hill Annex Mine State Park in Calumet, Minn.  to hunt for marine fossils on a hill of muddy Cretaceous-era clay and rock. For $10, a park guide buses you to the site, where you can search for an hour and a half. We were told to keep our eye out for clams, oysters, vertebrae, shark teeth, worm casings and the like. To help us know what to look for, the guide pulled out a little plastic bag filled with examples.

Some of the 85-million-year old fossils I found while hunting at the mine. The bottom piece looked similar to a copralite or dinosaur doo-doo. Photo: Bob King

It had rained the night before, exposing (we hoped) fresh fossils from the slowly eroding hillside. I poked around and eventually found a few snails, a very nice clam and even an alligator tooth. A young, blond-headed boy near me was the undisputed champ of shark teeth, a fossil high on everyone’s “must find” list. He spotted his first as soon as he walked up the hill. A half-hour later, he found a second.

I discovered that the best way to find fossils was to kneel right down into the sticky clay. Clean pants be damned.  Careful examination of the mud at close range proved a good strategy – even if I never found a shark’s tooth.

The area was covered in a shallow sea some 85 million years ago. Here I was millions of year later, covered in clay stains, a creature evolved during the long night these clams and sharks lay buried and hidden in a layer of rock and clay. There’s was a new, old world to me.

A portion of the west rim of Endeavour crater sweeps southward in this color view taken Aug. 6 from the Mars rover Opportunity. This 14-mile-diameter crater is more than 25 times wider than any that Opportunity has previously approached during the rover's 90 months on Mars. Credit: NASA/JPL-Caltech/Cornell/ASU

Mars also has clays, a sure sign that water flowed on the surface sometime in the past. The Mars rover Opportunity reached a major milestone earlier this week when it arrived at the rim of the 14-mile-diameter Endeavour crater. The impact that created the crater excavated blocks of ancient crust laid down long ago. The bigger the object hitting a body, the deeper the hole, giving scientists the chance to sample much older rocks than ever before.  That’s not all. The Mars Reconnaissance Orbiter detected clay minerals exposed at the crater.

“We’re soon going to get the opportunity to sample a rock type the rovers haven’t seen yet,” said Matthew Golombek, Mars Exploration Rover science team member. “Clay minerals form in wet conditions so we may learn about a potentially habitable environment that appears to have been very different from those responsible for the rocks comprising the plains.”

Can’t you imagine the rover pulling up to a clay hillock like the one that stained my pants red with maybe, just maybe, an enticing fossil poking out from between the pebbles? The chance is more than remote and yet not impossible.

2 Responses

  1. Patricia Enger

    As I was traveling home tonight from Marshall, MN to Canby, MN, I observed a white descending streak of light. It suddenly turned an emerald green and got much wider and then BANG! The lights went sideways like this thing had hit something. What in the world WAS that!?! About 9:30 tonight (August 23) was when it happened. Hard to guage distances, but it was in the South Dakota direction from where I was driving.

    1. astrobob

      Patricia — Sounds like you saw a splendid meteor! It probably fragmented at the point you saw it shoot off to the other side. Thanks for sharing your observation.

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