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| Autumn scene from the base of the west observation tower, Blue Mound State Park. Photo courtesy of Wisconsin DNR. |
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| Flint Rock Nature Trail map. Click for larger version. |
The 1.5-mile Flint Rock Nature Trail loops up and down Blue Mound’s side as well as around and over large rocks. It ends near an observation tower that hikers can go to the top of.
Blue Mound peaks in a flat meadow at 1719 feet, making it the highest point in southern Wisconsin. Limestone once covered the surrounding landscape at that height, but over millions of years it eroded away, leaving this remnant.
Interrupted fern
To reach the trailhead, from County Road ID in Blue Mounds head north on Mounds Park Road (maps sometimes refer to it as Mounds Road). Follow the road to the beginning of where it circles back on itself. Park in the small roadside lot on the circle’s northwest side. From there, walk west along the roadside for a little more than 100 feet to the trailhead, which goes north into the woods.
From September through October, hikers will be delighted by the array of autumn colors here – the yellow, orange and red hues of sugar maple as temperatures cool, the amber of basswood, the deep crimson of red oak, the russet of white oak, and the gold of shagbark hickory.
The trail narrows as passing around half-buried boulders amid the trees. At 0.2 miles, the path intersects Indian Marker Tree Trail; continue straight/north.
From there, the path heads down a slope through a growth of interrupted fern. Reaching up to 40 inches high, colonies of the interrupted fern grow in clumps. They like both shade and open, moist woods. When the fern emerges each spring, a light wool covers it then falls off.
Maples and basswood
On the loop’s north side, the Willow Spring Trail briefly joins the trail; continue left/west and then straight/west when the Willow Spring parts ways. You’ll know you’re going the right way if you cross a plank bridge over a small stream at 0.3 miles from the trailhead.
Among the trees you’ll spot on the loop is the sugar maple. Wisconsin’s state tree, the sugar maple is popular first for its seasonal leaf color – which changes from summer’s deep green to fall’s yellow, orange, red and then a dark burgundy – and of course, for its sweet maple syrup that tastes perfect on pancakes, waffles and French toast. The tree reaches heights of 80-115 feet and is easily identifiable by its distinctive leaf, seen on the Canadian flag. Sugar maples can live up to 400 years.
The next half-mile is downhill. At 0.5 miles is another plank bridge and a bench to catch your breath, followed by three more small bridges.
Often found mixed with sugar maples is the basswood. Usually basswood rises between 60 to 120 feet high with a trunk diameter of 3 to 5 feet. It grows faster than most North American hardwoods. The leaves can be between 3-6 inches long. They alternate on the twig with the one nearest the branch the largest. The tree can live around 200 years.
Oaks and hickory
The path goes uphill then down to a flat wetlands at 0.9 miles. At a mile in are more boulders to walk around and a couple of more bridges to cross.
Red oaks, which prefer to grow in glacial drift and well-drained soils along streams, also can be found in Blue Mound’s woods. The red oak grows straight and up to 92 feet high; its trunk diameter can be up to 39 inches. The tree is easy to differentiate from other oaks; its stout branches grow at right angles to its stem branch, resulting in a narrow, round head. Younger red oaks also can be quite tall, as they grow rapidly; a 10-year-old tree can be up to 20 feet high. Red oaks live up to 400 years.
White oak also can be found in Blue Mound. The tree’s name comes from the color of its wood; its bark actually is a light gray. It usually grows up to 100 feet high with a massive canopy supported by large branches. Mature oaks drop massive amounts of acorns, so don’t be surprised to see squirrels and chipmunks scampering beneath them. White oaks can live 200 to 300 years, though some are known to be around 600 years old.
Shagbark hickory likes to grow among the oaks. In Wisconsin, hickory is found in only the southern part of the state. The leaves are long, between 12-24 inches, usually with five leaflets. Hickory grows well over 100 feet high and often lives around 350 years.
West observation tower
After the boulders and bridges, the trail ascends again. Steps laid into the ground help make the climb easier. The trail reaches the west observation tower at 1.7 miles. Hikers can head to the tower’s top and enjoy a view of the surrounding forest, which stretches for several miles. It’s a particular spectacular view when the autumn leaves are in their full color.
Just east of the tower, the trail leaves the woods and enters the open meadow atop the mound. At the park entry road, turn left/north and follow it back to your parking lot.
Be sure to wear good hiking boots for this trail. The path and rocks along it can be slippery after a rainfall.
