For the past two days, I’ve been in a post-bolide glow. My thinking has looped something like this: what were the odds? — to be sitting on a frozen shoreline just then?— my gaze already lifted to darkness, open to the world, my pupils properly enlarged — at the moment a green fireball flared through the sky?
It was like walking through darkness to a cabin door. The thick wooden door of the universe was flung open for a few seconds, revealing — lamplight! birch logs crackling in the great fireplace of Creation!! — before the door swung shut again.
The odds against a glimpse were… astronomical.
Brief and unsettling as it was, however, I don’t conclude that the fireball was a rock sent to tear through my fragile web of understanding. Quite the contrary: it was a green beam illuminating a gap in my understanding. Ultimately, the bolide was a cosmic net-mender, dragging a skein of glowing green thread, soldering the gap shut with its fiery departure. Or am I sounding too much like Chris, from Northern Exposure?
The nature of that gap has something to do with origins and endings — as a writer, my burning desire is to learn how did it come to be this way? And then: why did it end? Not just failed relationships, or the plots of great novels, but mass extinctions, Epochs, rocks. For example, I’ve spent a lot of time trying to understand the origins of minerals. Maybe I was writing poems during science class, back in high school, and this is the psychic payback: endless questions. I wonder if everyone else is filled with similar wonderings, or if I’m the only one who didn’t study hard enough.
By diligent reading, I’ve pieced together some of the local mineral story. The copper deposits of the Copper Range have an igneous and metamorphic origin, born as mineral-rich liquid magma upwelled in volcanic faults of the Keweenaw. The nickel deposits of Sudbury, Ontario, located 300 miles due east of here, are not so much “deposits” as scar-tissues, formed after a meteorite struck the earth, cracking the crust, leaving a great impact-crater known as Sudbury Basin. Last year, at a dinner party, I met an amateur geologist who explained to me that “ejecta” debris from Sudbury crater flew all the way to Marquette Michigan, creating smaller impact craters. Fascinating stuff!
Most of my curiosity has focused on the Iron Ranges of Upper Michigan (and northern Minnesota). Around Ishpeming and Negaunee, for example, one finds terrific examples of the “Banded Iron Formation,” which geologists call BIF for short. BIF is typified by layers of gorgeous ferrous rock, striped red-black or red-silver (banded hematite-jaspelite, sometimes with quartz and specularite):
BIF: Banded Iron Formation., Originally uploaded by D E Russell
Chunks of BIF serve as heavy bookends on my bookshelves, and adorn my friends’ desks and gardens, token gifts from my Iron Range travels. BIF deposits formed as ferrous sediments on the floor of a shallow ancient sea. Some theories suggest the iron precipitated “out of” the seawater through chemical interactions, or photochemical means. Other theories suggest that iron precipitation had a biogenic source — it might not have happened without ancient bacterias at work in the ancient seas.
Fossil evidence for the biogenic theory is preserved in the Negaunee Iron formation: Grypania spiralis, considered one of the world’s oldest megascopic fossils (“visible to the naked eye”) was found in the iron ore of the Empire pit mine. Fascinated by the idea that Upper Michigan might claim the world’s oldest fossil organism, I set up a meeting with scientist Tsu-Ming Han (Grypania’s discoverer), who was employed by Cleveland Cliffs’ Research Laboratory. Tsu-Ming arranged permission for us to go down in the Empire mine! As he explained: my opportunity to see the fossil in situ was short-lived. The ore containing Grypania was a bare, narrow “rock bridge” — a ridge separating two vast deep, surreal pits. Covered with pines and fog, the rocky ridge would have resembled a Chinese mountain, impossibly sheer, with a haul-road cutting down-slope at what felt like a 45% grade.
Isolation (mountain painting) originally uploaded by “heart-felt-robot”
In this case, the image was painted within the mountain, rather than OF the mountain. The fossil-bearing ridge was slated to be “mined out.” I remember that day as if it were a fever dream. We donned hard hats and drove halfway down the haul road, dwarfed by trucks big as brontosauri, grunting loads of crushed rock uphill. We picked our way along a precarious talus slope of loose ore, careful as mountain goats, collecting sheets and shards of BIF. The layered rock, oxidizing, could be cracked open, separated like the stuck pages of an old book, to reveal fossils shaped like C’s, O’s and J’s, preserved for 2 billion years, lucky clovers pressed in a book of poems. I keep a large specimen on my bookshelf — evidence — to remind me of our ancient origins. Grypania spiralis. That was ten years ago — the rock ridge is gone, and my guide has since passed away. The rare fossil evidence has been crushed into tailing sludge and taconite pellets, coming soon to some steel girder near you.
Ancient origins, endings — follow the string. That’s the mental nudge I received, as a bolide blazed over Lake Superior. There must be other examples of bolides flaring over Lake Superior, I thought. Witnesses? Previously recorded incidents? That’s what led me to this incredible sentence, from an abstract for a paper presented at the Geology Society of America Conference last month:
“In the Lake Superior region deposition of most banded iron formation (BIF) ended at 1.85 Ga, coincident with the oceanic impact of the giant Sudbury extraterrestrial bolide.”
Suddenly I understood! My Grypania fossils witnessed their own bolide, a meteoric event greater than anything our species have experienced. That bolide did not hit “Sudbury” as we know it, but land under shallow ocean water: the result was broken crust, vapor storms, tsunamis, global oceans stirred. There would be no more deposition of iron. When the great bolide shattered into Sudbury, it closed the chapter of BIF.
One more hole in my mental sock has been mended!
As John Muir put it: “Tug on anything at all and you’ll find it connected to everything else in the universe.”