Prairie on the Rocks

August 2, 2020

Author: Phyllis Root
Photographer: Kelly Povo

Morton Outcrops Scientific and Natural Area is a gift from the glaciers.  When glacial River Warren emptied out glacial Lake Agassiz 10,000 years ago, the vast torrent exposed some of the oldest known bedrock in Minnesota–3.6 billion years old. On a perfect August day we drove out to Morton to see these ancient knobs of rock rising up.  

The rocks are Morton gneiss, a kind of granite, swirled with bands of pink and grey and white in wildly gorgeous patterns. Rainwater collects in slight depressions in the rock and in potholes formed by the force of the glacial river, and in these ephemeral pools plants grow. We identify four of them as Englemann’s spikerush, false pennyroyal, thyme-leaved spurge, rock spikemoss, and small-flowered fameflower, but there are many more new-to-us plants we’ve yet to learn. We don’t find any of the rare plants that grow here, but we do find two frogs soaking in a pool on top of the highest outcrop, the water around their throats rippling. How did frogs get up on these high rocks in the middle of a dry prairie?

We know how we got here:  on a path through the surrounding prairie, past leadplant, hoary vervain, grey-headed coneflower, stiff goldenrod, bee balm, prairie onion, and orange butterfly-weed with the biggest butterfly weed seed pods we’ve ever seen (plus something we didn’t identify with sticky seedpods that clung to our boots and socks and pants).  The prairie rose up, and we climbed the sloping rock surfaces to gaze at the view in all directions. The rock outcrops themselves are mini-habitats.  Tiny long-leaf bluets grow along cracks in the rock, and brittle prickly pear are tucked away in crevices. Wherever a bit of soil can collect or a pool of water fill up, something will grow. We saw so many plants we we still need to identify, which we will do very soon, and everything we saw was pretty amazing!

We’d hoped to see prairie bush clover which is both federally threatened and also state threatened, but we couldn’t venture far from the rock surfaces into the surrounding grasses and forbs without encountering poison ivy higher than our hiking boots.  Normally we’d wear our rubber boots for protection, but rubber boots don’t work so well for scrambling up on ancient rock.

The rocks themselves held plenty to look at, the wind blew, the sky stretched over us, and we felt as though we were on top of the world.  

And the frogs? Who knows what you’ll find in an ephemeral pool on top of a rock outcrop in a dry prairie?  The world is full of surprising questions.

And maybe surprising answers to questions we didn’t even know to ask.

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