Buffalo Rock State Park and Effigy Tumuli (Blog Hike #1085)

Trails: Effigy and River Bluff Trails
Hike Location: Buffalo Rock State Park
Geographic Location: west of Ottawa, IL (41.32747, -88.91200)
Length: 2.3 miles
Difficulty: 2/10 (Easy)
Date Hiked: October 2025
Overview: A semi loop beside effigy tumuli with blufftop views of the Illinois River.
Park Information: https://dnr.illinois.gov/parks/park.buffalorock.html
Hike Route Map:

On The Go Map

Photo Highlight:

Hike Video: (coming June 12, 2026)

Directions to the trailhead: From downtown Ottawa, take Main Street west 0.6 miles to Clay Street and turn left on Clay St.  Drive Clay St. south 0.2 miles to Ottawa Avenue and turn right on Ottawa Ave.  Ottawa Ave. becomes Dee Bennett Road after you leave Ottawa.  Drive 3.5 miles from Clay St. to the signed park entrance on the left.  Turn left to enter the park, drive the narrow park road uphill to the top of Buffalo Rock, and park in the parking lot beside the picnic shelters and restroom building at the park road's end.

The hike: Formed as an ancient island in the Illinois River, Buffalo Rock was first discovered by European explorers in 1673 during Louis Jolliet's and Father Jacques Marquette's journey up the Illinois River.  The French explorers discovered the Illinois Confederation, a.k.a. the Illiniwek or Illini, living here, but within a few years the Illini were on the brink of defeat to the Iroquois.  In the early 1680's, the French built a military, trading, and missionary post atop the rock that became a headquarters for opponents of the Iroquois.  In 1912, the Crane Company of Chicago purchased the rock for use as a sanitarium and summer vacation home for its employees, and the company deeded the land to the State of Illinois in 1928.

            Located across the Illinois River from famous Starved Rock State Park, Buffalo Rock State Park and Effigy Tumuli protects 298 acres on and around its historic and namesake rock.  The rock's name comes from a legend that ancient peoples used the box canyon formed by the rock to trap and capture buffalos.  The park has no developed campground, but it offers some picnic shelters, a bison pen, 2 hiking trails, some blufftop river views, and the interesting effigy tumuli, which I will describe below.  This hike uses both of the park's trails to tour all major points of interest in the park.

Trail beside restroom building

            There are several places where you could start this hike, but I started at the restroom building at the northwest corner of the main parking lot.  A concrete path heads into the woods, and quickly it curves left to arrive at the dedication area for the effigy tumuli.  Technically a type of earth art, the effigy tumuli are a series of animal-shaped dirt mounds built in 1983 by Michael Heizer.  The tumuli are designed to be a tribute to the Mound Builder peoples who lived in eastern North America from 3500 BC until the 1700's.  The animal shapes of the tumuli are almost impossible to discern from the ground, and you will need to look at the park brochure while you are hiking if you want to know the shape of the mound you are standing beside.

Hiking through the prairie atop Buffalo Rock

            Continue south past the dedication area, and at 0.2 miles you reach the trail intersection that forms the loop portion of this hike.  Turn right to begin a counterclockwise journey around the loop.  The wide dirt/grass trail heads southwest through a prairie area, and this was a warm and sunny hike on the seasonally warm early October afternoon when I hiked here.  The park brochure tells you that you pass the frog and water strider tumuli on the left as well as the catfish tumulus on the right, but they look like formless mounds of dirt to the naked eye.

Catfish tumulus

            At 0.8 miles, you reach the west corner of the loop.  We will eventually turn left to continue the loop, but first angle softly right to add-on an out-and-back that takes you past the rest of the tumuli.  The trail descends slightly as it heads out the western part of Buffalo Rock, and this part of the rock has equal amounts of broadleaf trees and prairie.  The park brochure says that you pass the turtle tumulus on the left, but again it is hard to discern.

Western part of Buffalo Rock

            1.2 miles into the hike, you trace around a very tiny loop, almost a cul de sac, at the west end of the trail.  The mounds you see in this area form the snake tumulus, and they look more like a snake than any of the other tumuli do their animals.  Retrace your steps back east to return to the loop, then angle softly right to continue a counterclockwise journey around the loop.

Developed Illinois River overlook

            Just shy of 1.6 miles, you reach the developed Illinois River overlook.  This overlook is getting a little overgrown, but it still provides a mostly clear view of the river and Starved Rock State Park on the other side.  I am always amazed at how wide the Illinois River is; that width is partly due to the river's prairie setting and partly due to the river's extensive system of locks and dams.  Past the developed overlook, the trail continues east along the top of the river bluffs, which drop to the right.  Some unofficial river overlooks are passed, and I liked the view from some of the unofficial overlooks more than the view from the official overlook.

Unofficial Illinois River overlook

Bison pen

            2 miles into the hike, you reach another trail intersection.  The trail going straight leads down and up through a steep ravine to reach a secondary parking area, so you want to turn left to hike a more level trail back to our parking area.  Just before you finish the hike, you pass the park's bison pen on the right.  I saw several bison in the pen, and these bison form a fitting way to finish your hike at Buffalo Rock State Park.