By Sonjie Johnson
It’s not every day that a Como Park resident finds a 450-million-year-old fossil in his backyard. But that’s what happened to Joel Alter a few years ago.
A retired, non-partisan researcher for the Minnesota Legislature, Joel has lived in Como Park for nearly 40 years. He was digging in a ravine behind his house in 2006 when he unearthed a large piece of limestone. When he picked it up, a section split apart and he saw what appeared to be a fossil.
Ever the researcher, Joel brought the two pieces to the Minnesota Science Museum’s paleontology curator for identification. The fossil turned out to be an Endoceras, a large, straight-shelled cephalopod, a squid-like creature found in Minnesota roughly 450 million years ago. At that time, this part of Minnesota was covered by a large, shallow sea. High mountains, vast seas, glacier ice – all are part of Minnesota’s geological past. More amazing is this fact: what is now Minnesota was then located south of the equator.
Minnesota contains some of the oldest rocks on earth, rocks that formed roughly 3600 million years ago and went through numerous changes from heat and pressure. Joel’s find was in limestone, common in this area. Limestone appeared much later in time (during the Ordovician Period), and formed from marine sediment deposited on sea floors. The calcite in limestone includes seashells, most likely from that long gone sea.
The limestone fossil remains in Joel’s back yard. He summed it up best – “ I had always hoped to find an arrowhead in our yard, but I think finding the remnants of a 450-million-year-old squid is even better! These stones, together with their prehistoric fossils, sit inconspicuously along a path in my back yard.”
Now that’s history!
Additional information on Minnesota geology can be accessed at this site.
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