Niagara Escarpment --- NY to Wisconsin

It is not a fault line, but instead the outer edge of a circular basin exposed by the glacier

Part I


An escarpment is a long, steep slope, especially at the edge of a plateau or separating acres of land at different heights.

The Niagara Escarpment, marked in red, is a landform called a cuesta and it travels some 650 miles from Niagara Falls, New York in a semi circle westward through eastern Wisconsin. It runs predominantly east/west from New York State, through Ontario, Michigan, ending in Wisconsin**. The escarpment is most famous as the cliff over which the Niagara River plunges at Niagara Falls, for which it is named.

The Niagara Escarpment consists of a gently-sloping layer of rock forming a ridge. One side of the ridge has a gentle slope, a so-called dip slope that is essentially the surface of the rock layer. The other side is a steep bluff.

Fundamentally, the escarpment was formed over millions of years of erosion of rocks of different hardnesses. The “caprock” is dolomitic limestone. It is more resistant and sits atop weaker, more easily eroded shale.

In Wisconsin, the escapement is often referred to as “The Ledge.” It extends about 250 miles within the state. There are several notable areas in the state where you can easily view the escarpment. Ro Stieglitz, writing for “Geoscience” Wisconsin, noted “A number of state, county and town parks are located on or adjacent to the escarpment, from Rock Island State Park  in the north to at least Ledge County Park in Dodge County to the south.”

In looking at this graphic, you can conclude the Niagara Escarpment travels through the Eastern Ridges and Lowlands Geographic Province of Wisconsin. The Eastern Ridges and Lowlands region is primarily a plain with elevations between 700 and 900 feet above sea level, with some elevations that  exceed 1,000 feet above sea level

Door County - Introduction

For all the time I have driven through Door County, not once did I realize that the escarpment ran through its west side bordering the Green Bay.  This is a good lesson to study some things to see and know before traveling!

Robert Schrock, prior to his death a highly respected geologist at MIT,  Wrote “Geology of Washington Island.:” In an excerpt, he provided a nice description of the escarpment relevant to Door County:

“ One of the most spectacular surface features in eastern Wisconsin is the Niagara Escarpment or ‘The Ledge’ as it is called locally. It is a steep, westward-facing cliff that rises out of the glacial drift a few miles south of Waukesha (located just west of Milwaukee) and increases in height northward until it stands over 100 feet above the northern end of Lake Winnebago at High Cliff (southwest of Green Bay).

“It then dies out for a short distance, but soon appears as a low bluff east of Green Bay, and clinging to the eastern shores of the bay, it increases steadily in height until it culminates in the bold, precipitous cliffs at Eagle Point Park near Ephraim and at Ellison Bay near the northern end of the (Door) peninsula. The cliffs at their greatest height rise over 150 feet above the waters on Green Bay.

“Northward from the tip of Door Peninsula, the escarpment base becomes submerged beneath at least 140 feet of water; yet because of increased height, it still rises well over 140 feet above water in Boyer Bluff, at the northwestern tip of Washington Island, and in the precipitous, triple-notched cliff at Pottawatomi Park, Rock Island.”

The Door County Coastal Byway web site tells us this:

“Door County’s Green Bay side has the true escarpment with exposed dolomite rock 200-250 feet high. At the base of these rock faces are remnants of the chunks of stone that fall from the cliffs to form ‘talus.’ Some of the oldest living trees in all of the Midwest, some are almost 1200 years old, are found on the Escarpment. These trees are deformed, barely alive, white cedars found on the rock cliffs. Interestingly, the same tree growing in optimum conditions lives only 1/3 as long as the ‘cliff hangers.’

“In Door County, the landscape slopes downward to the Lake Michigan side in what is known as a ‘cuesta,’ or a ‘dip slope plain’ in geology speak. Generally on the Lake side there are sand beaches and the shallow inland lakes that are the remnants of glacial bays that have filled in over time. “

Rock Island - Door County

In Wisconsin, the escarpment begins on Rock Island.  About four miles to the northeast lies St. Martin Island, Michigan. St. Martin is one of seven islands extending from the Garden Peninsula of Michigan.

All together these islands in Michigan and Wisconsin, and several others in Wisconsin I will mention in a moment, form group of islands collectively referred to as the Potawatomi Islands. They extend across Lake Michigan between the Door Peninsula  and the Garden Peninsula of Michigan to the northeast. 

Rock Island is the northernmost island of the Wisconsin part of that chain.  These islands and others I will mention shortly are part of the Niagara Escarpment.

This is a Google Earth shot of Rock Island. Looking closely, you can see the ledges on the west and northern side.

This photo was taken by Gary Jean during a kayak paddle from  Washington Island to Rock Island. The escarpment here on Rock Island is obvious. I commend a video of the kayak journey.

Washington Island - Door County

Washington Island lies just a mile or so to the southwest of Rock Island. It, along with Hog and Fish Islands lying to the east and Detroit, Plum and Pilot Islands lying to the south are all part of the Potawatami Chain.

returning to Dr Schrock, recall he wrote:

“Northward from the tip of Door Peninsula, the escarpment base becomes submerged beneath at least 140 feet of water; yet because of increased height, it still rises well over 140 feet above water in Boyer Bluff, at the northwestern tip of Washington Island,

This is a photo of Boyer Bluff, photographed by Irene Kuiper.

This is part of the Jackson Harbor on Washington Island. Both this and the previous photo require you be in a boat of some kind. I’ll note here that much of the area of Jackson Harbor is known as the Jackson Harbor Ridges. The Ridges are a Wisconsin Scientific Area marked by a series of sand dunes and swales. A swale is a low or hollow place, especially a marshy depression between ridges.

Ellison Bay - Door County

As you “round the corner” from Door Peninsula’s northern tip and head to the southwest, you come across Ellison Bay.  Shortly after driving through this wonderful town, you come across Ellison Bluff State Natural Area noted by the green arrow.

This is a 174-acre park that offers a fabulous view of the Green Bay. There is a wooden walkway-boardwalk to take you to the edge of the sheer, 100-foot limestone bluffs of the escarpment.

Standing at the overlook I could see Michigan’s Upper Peninsula across the bay.

And then I looked down and saw these two people fishing.

It is likely the boaters saw this from where they were at, or something a lot like it.  Recall I reported earlier that there are a lot of trees on this portion of the escarpment, some of the oldest in the Midwest.

Ephraim - Door County

To the southwest of Ellison Bay is Ephraim. The town sits on a small bay off of the Green Bay.  The green arrow points to Peninsula State Park. Once again you can clearly see the shadow of the escarpment running along the north and then west of the park.

While on Water Street in the heart of town I caught this glimpse across the small bay. To the left is Peninsula State Park. You can see the escarpment. To the far right center you can see an island, known as Horseshoe Island. It is a small island, about 38-acres, but was a home and fishing site for Native Americans over 2,500 years ago. Many people today kayak or boat over there and enjoy the trails, fishing and viewing of wildlife.

I do want to show you a glimpse of on part of the escarpment in the park., again from the water. Hopefully you kayakers have seen by now the tremendous adventure you could have by paddling along the escarpment of Door County.

Go to Escarpment Part II

Lots more to see and learn