Bonnechere Museum | Eganville Ontario

Natural History of The Bonnechere Valley

Source: Clyde Kennedy, The Upper Ottawa Valley

Glaciation and climate change shaped the Bonnechere Valley. The weight of mile-thick ice compressed the land, pushing it towards the earth’s crust and below the existing sea level. When the Wisconsin glacier receded, the land gradually rose, but not before the Atlantic Ocean swept in from the east, flooding the Ottawa Valley and the lower Bonnechere Valley, creating a branch of the ocean known as the Champlain Sea which lasted from about 11,000 to 9,500 years ago.

The rising land ended the drainage of the Great Lakes into the Ottawa Valley and caused the Champlain Sea to recede. The in-flooding deposited the flat clay sea bed which today’s Highway 60 follows. These same gray clays, which turn reddish-orange when baked, are used in the manufacture of brick and drainage tiles at Arnprior, Renfrew, Pembroke and various other communities.

As you approach Eganville from the east, the land valley becomes more hummocky and hilly. Here, Highway 60 courses along glacial tills and moraines (piles of rock left behind by melting glaciers) which, although nearby, were not likely flooded by the Champlain Sea. This stretch of road travels to the edge of, and briefly into, the adjacent Snake River watershed and along the fault lines which confine the north side of the watershed to a narrow band.

Near Golden Lake, Highway 60 drops down into a huge glacial spillway where an enormous river once flowed through the graben, (an elongate crustal block that is relatively depressed (downdropped) between two fault systems)  depositing sands and gravels across the flat land.

According to Clyde Kennedy in The Upper Ottawa Valley, “Most of the surface rocks in Renfrew and Pontiac counties are Precambrian in age; the region lies within the area termed the Canadian Shield. These very ancient rocks included the dolomite from which magnesium is extracted near Haley’s; the crystalline limestone quarries that supplied some lime kilns, such as the Biederman quarry near Lake Dore; the crystalline limestone host rock at the Black Donald graphite mine; and the great outcrops of crystalline limestone at Calumet Falls and Portage du Fort.

A large part of the Upper Ottawa Valley, which lies within the Grenville Province of the Canadian Shield, is underlaid by gneisses, with large bodies of granite, syenite and other igneous rocks. The age of some of the Precambrian rocks is about one billion years; some rocks of the Shield north of the Ottawa River basin have been dated at about two and a half billion years.

Faults, breaks in the earth’s crust, caused some limestone covered areas to be dropped down and thus protected from erosion. Outliers of limestones may be seen in the Pembroke area; at the northwesterly end of Muskrat Lake near Meath (this outlier also covers much of Stafford Township); along the southerly shore of Lake Dore and extending in a four-mile-wide band past Mink Lake to a point five miles northeast of Douglas, along the Bonnechere River from five miles downstream from Douglas through the Fourth Chute (where the Bonnechere Caves were formed by erosion of the limestone) and beyond Eganville to Golden Lake village; on the northwest side of Lake Clear;  in a large part of Westmeath Township – the ‘peninsula’ portion, enclosed by the great bend of the Ottawa River; and in the Braeside, Sand Point, Lochwinnoch areas.

In the Ordovician limestones are a variety of fossils, including sponges, corals, brachiopods, pelecypods (clam type), gastropods (snail type) cephalopods (the squid is a modern cephalopod), and crinoids (animals that were thought to be plants – crinoids live in the Mediterranean Sea today). Fossils may be seen in the limestones in several places in the Valley, including the Eganville area and the Bonnechere Caves at the Fourth Chute on the Bonnechere River.”

Today, while the larger Ottawa and Madawaska are noted for their white water, the Bonnechere is known for its smooth water, allowing scenic canoe and boat rides, although springtime freshets allow white water activities too.

Stretching 145km (90mi), from near McAskill Lake in Algonquin Park to the Ottawa River at Castleford, the Bonnechere River  drains 2400 square kilometres (935 square miles) — an area larger than Prince Edward Island.

Over the centuries, the Bonnechere (often pronounced locally as the bone-chur) has been a conduit for transportation, as an access route to the pineries, for its square timber drives and later log drives. It spawned sawmills and grist mills, carding mills, and was a powerhouse of energy for mill wheels as well as hydro generators. (Currently, Eganville is served by a generator located right down town.) It became a route along which settlements grew, and farmlands extended from its banks and tributary streams, a source of both food and recreation for residents and travellers. The productive soils and enticing landscape of the Bonnechere Valley watershed (the area of land which feeds the river) were among the first logged, settled and farmed in Renfrew County.

Life along the Bonnechere sprang up at several locations simultaneously, although usually related to logging or its supporting trades and supply lines - including dam building, farming, general store items, blacksmithing, as well as housing, health and family care, education and worship.

The owners of the logging companies were called timber-makers and several acquired the name of “King”; for example, Alexander McDonell was known as the King of the four rivers because of his association with the Madawaska, the Bonnechere, the Indian and the Mississippi; John Egan was called the King of the Ottawa Valley because of his extensive holdings and political influence, and James Bonfield was known as King of the Bonnechere because of his sustained logging in its reaches.