[Amabel Dolostone cliffs dominate the heights of the Beaver Valley at Old Baldy, Metcalf Rock and Eagle’s Summit (shown here). Photo by Beth Gilhespy.]

The Beaver Valley is, at heart, a story written in stone.

Its cliffs, waterfalls, rolling fields and forested slopes are the visible expression of a sequence of sedimentary rocks laid down between about 450 and 428 million years ago in a warm, shallow tropical sea that once covered southern Ontario. Those layers, deposited in the Michigan Basin, now form part of the great arc of the Niagara Escarpment.

OVERVIEW

[Cross section of the Beaver Valley looking south from the Kimberley area, showing Niagara Escarpment bedrock layers.]

2. MANITOULIN DOLOSTONE

[At an unnamed creek below Pinnacle Rock, water flows over the thin layers of Manitoulin Dolostone to reach a steep drop over a plunge pool formed in the Queenston Shale. Photo by Lilla Fodor.]

Resting directly above the shale is the Manitoulin Dolostone, a thinly bedded, grey reef rock formed as tropical seas cleared and coral communities flourished in the early Silurian. This layer marks the boundary between the Ordovician and Silurian periods, a time of mass extinction and gradual biological recovery.

In the Beaver Valley, the Manitoulin Dolostone forms flat terraces, secondary ledges, and the lips of many waterfalls, including Webwood and Hogg’s Falls. Fossils of brachiopods, crinoids and rugose corals are preserved within it, reminders of the ancient sea that once shimmered overhead.

4. FOSSIL HILL DOLOSTONE and

5. AMABEL DOLOSTONE

[The view from the Amabel Dolostone eights at Old Baldy, high above the village of Kimberley. Photo by Bo Penny.]

Capping these layers is the Fossil Hill Dolostone and, above it, the magnificent Amabel Dolostone caprock. The Fossil Hill layer contains corals and stromatoporoids (extinct sea sponges), whose silica contributed to the formation of chert used by Indigenous peoples for toolmaking after the glaciers retreated.

The overlying Amabel Dolostone, thickly bedded and resistant, forms the bold cliffs of Old Baldy, Metcalfe Rock and Eagle’s Nest. Built from reef mounds that grew upward toward sunlight as the basin slowly subsided, this layer is the escarpment’s defining crown.

[Syringopora (organ pipe coral), dating from about 430 million years ago, is one of the many fossil corals found in Beaver Valley rock. Photo by Beth Gilhespy.]

GLACIERS CARVED THIS BEDROCK

[Photo by Beth Gilhespy.]

Yet the Beaver Valley landscape we see today is far younger than its bedrock. About 12,000 years ago, retreating glaciers released torrents of meltwater that carved the V-shaped valley at right angles to the escarpment face. The modern Beaver and Boyne Rivers are modest heirs to that cataclysmic flow.

Glacial debris, including igneous and metamorphic erratics carried to the area from the Canadian Shield, as well as the sweeping Banks and Gibraltar moraines, records the ice’s final pauses across the region, before the glacier retreated about 12,000 years ago.

Thousands of years later, European settlers to the area moved these boulders to the field edges as they cleared the land for farming.

To walk the Beaver Valley is to walk through time: from tropical reef to glacial torrent to living landscape. Its geology is not static stone, but a dynamic interplay of deposition, uplift, erosion and renewal. It is an ancient foundation beneath a continually changing, vibrant world.

Throughout the Beaver Valley, explorers can find numerous deep crevices in the Niagara Escarpment bedrock, including at Old Baldy, Duncan Escarpment and Metcalf Rock.

The Beaver Valley is home to several sparkling waterfalls that spill over the rock layers as the water makes its way down the slopes into the valley, carving gorges and creating intriguing geological features. Waterfalls develop when water flows over a harder, more resistant rock (e.g. dolostone) overlying softer, more easily eroded rock (e.g. shale). Water erodes the softer rock which creates an overhang. This unsupported rock will eventually collapse, causing the waterfall to retreat upstream. A steep-sided river valley is created as the waterfall retreats.