It was a good day to be out on the trail, yesterday was. Clear and cold, just as the last day of November should be. Perhaps a little too cold even, plodding along in the shadowy forest of the Cathance River Nature Preserve in Topsham.
Closed in beneath the canopy of hemlocks and pines, with little in the way of direct sunlight reaching in to us to warm our bones, we grew increasingly chilled. No matter, as we added a layer and carried on, stringing together the five loop hikes that navigate through this beautiful place.
First, a circumnavigation of the 30-acre wetland on the Heath Loop, then on to the Ecology Center (closed) and the start of the Barnes Leap Loop, which eventually wound down to the Cathance River. From here we followed the twists and turns, placid pools and frothy ledge drops, through narrow gorges in deep woods, for at least a mile, merging with the Beaver Loop and then the Rapids Loop.
It was along these last two loops that we discovered a phenomenon in the river that completely surprised us, something neither my wife nor I had ever seen before.
I was chugging along behind, fiddling with my camera and scribbling notes when I heard Fran say, “Oh my gosh, will you look at that!”
And sure enough, there bobbing in a big eddy pool were dozens of nicely rounded ice shapes, like pie crusts or pizza pies. Maybe a foot in diameter each, some more and some less.
We both stood in awe, just staring at the icy shapes. And watching as every now and again, as one of the ice pizza pies, with the turned up crust and everything, would break away from the pack and drift downstream, only to be caught by the eddy current and pulled back in toward shore. It would then drift obediently back upstream to rejoin the group.
From where we stood we could also see them in the eddy pool across the river as well, bobbing and spinning happily.
It was a long while before we could tear ourselves away to continue the hike. Further along on the Beaver Loop we found another stash of ice pies. Not as many as above but still, what a cool thing to observe. Another group of ice pie crusts below, then the river roared down the final chute into a huge pool, and here the trail turned away inland.
When we returned home I posted a photo of the ice pies on Facebook. Wow, did that ever spark some comments! And a couple of friends were kind enough to share several links describing this most interesting ice formation we’d seen in the Cathance River.
“Pancake ice” is what one site called them, “formed when temperatures hover right around zero degrees with at least moderate wave activity. Usually, it starts with a thin film of slush on the top of agitated water… that breaks up into circular sections. Collisions as they float about lead to the raised rims, either from the edges getting bashed up from bonking into each other, or from the slush that gets splashed onto the edges and freezes to gradually form a rim.”
Another site calls them “ice discs,” which “form on the outer bends in a river where the accelerating water creates a force called ‘rotational shear’, which breaks off a chunk of ice and twists it around. As the disc rotates, it grinds against surrounding ice — smoothing into a circle.”
That’s it exactly. Ice discs!
“A relatively uncommon phenomenon” apparently. Yeah, I’ll say…
Have you ever seen these ice pancakes or ice discs before? Where and when?
By the way, we decided to check out the new bridge and the trail that leads from the Ravine Loop in the Cathance River Nature Preserve over to the Head of Tide and the new park on Cathance River Road. A project of the Brunswick-Topsham Land Trust, the Cathance River Corridor Heritage Trail when combined with the Ravine Loop will provide a nice hike of about four miles out and back. For us, next time for sure.