Integrative Natural History of Fayette Historic State Park, Part 18: For All Fans of Alluvial Fans | Garden Peninsula, on Michigan's Upper Peninsula, USA
At the base of the bluff and below the Visitor Center. Facing west-northwestward.
This photo complements the Part 17 image, which shows the same geologically significant spot from the opposite direction.
That's quite a North Woods arroyo! A rainstorm that occurred not long before my visit incised an impressively well-defined channel out of the carefully graded gravel path.
Note how, farther down, the rushing rivulet hit some sort of rise or more compacted substrate that made it pond up and burst the grassy bank to its right in several places.
The water was moving so fast down the incline and over the bank that it was carrying not just lighter sand grains but also larger bits of gravel. When this mini-flood encountered the more densely matted grass of the lawn proper it finally slowed down enough to drop its cargo of sediments. The result was an intricate, multi-lobed alluvial fan.
Nevertheless, rainwater coursing down after the fan had been deposited still had enough velocity and erosive power to carve miniature canyons in the fan lobes.
In the previous essay I mentioned how impressive this all would have appeared to a local ant or chipmunk. If I were one of those critters, I'd quickly declare this patch of ground a National Park or at least a National Natural Landmark before the human maintenance crew could rake the gravel back onto the path.
But I have long since noticed that such things happen only in my imagination. I'm sure the alluvial fan, its geologic significance completely unheeded, was soon removed. After all, this is America, and our Sacred Turf must be protected from all enemies foreign and domestic.
Integrative Natural History of Fayette Historic State Park, Part 18: For All Fans of Alluvial Fans | Garden Peninsula, on Michigan's Upper Peninsula, USA
At the base of the bluff and below the Visitor Center. Facing west-northwestward.
This photo complements the Part 17 image, which shows the same geologically significant spot from the opposite direction.
That's quite a North Woods arroyo! A rainstorm that occurred not long before my visit incised an impressively well-defined channel out of the carefully graded gravel path.
Note how, farther down, the rushing rivulet hit some sort of rise or more compacted substrate that made it pond up and burst the grassy bank to its right in several places.
The water was moving so fast down the incline and over the bank that it was carrying not just lighter sand grains but also larger bits of gravel. When this mini-flood encountered the more densely matted grass of the lawn proper it finally slowed down enough to drop its cargo of sediments. The result was an intricate, multi-lobed alluvial fan.
Nevertheless, rainwater coursing down after the fan had been deposited still had enough velocity and erosive power to carve miniature canyons in the fan lobes.
In the previous essay I mentioned how impressive this all would have appeared to a local ant or chipmunk. If I were one of those critters, I'd quickly declare this patch of ground a National Park or at least a National Natural Landmark before the human maintenance crew could rake the gravel back onto the path.
But I have long since noticed that such things happen only in my imagination. I'm sure the alluvial fan, its geologic significance completely unheeded, was soon removed. After all, this is America, and our Sacred Turf must be protected from all enemies foreign and domestic.