Chippewa Falls, Ontario

ChippewaFalls,ON_©DaveSpier_D019393blog

approaching the lower Chippewa Falls

Chippewa Falls (introduction) — © Dave Spier

At the east end of Lake Superior, Highway 17, the Trans-Canada Highway, crosses the Harmony River on the east side of Batchawana Bay near Harmony Beach. (This is the second bay on Lake Superior north of Sault Ste. Marie.) Just upstream from the bridge, a wayside park provides access to Chippewa Falls, which is actually two cascades 150 feet apart. The original bedrock is 2.7 billion-year-old pink granite, but, at the lower falls, it is still covered with a remnant of a 1.1 billion-year-old lava flow called the Keweenawan basalt that was extruded during the Grenville orogeny. The contact between the two rocks types represents 1.6 billion years of erosion that brought the granite to the surface by the time of the volcanic activity. A lateral fault cuts through both layers on the north side of the present-day lower falls (out of sight in the two opening photos).

A remnant of the gray, 1.1 billion-year-old lava flow called the Keweenawan basalt, extruded during the Grenville Orogeny (mountain-building episode), covers the 2.7 billion-year-old pink granite next to the lower Chippewa Falls (hidden right rear).

A remnant of the gray, 1.1 billion-year-old lava flow called the Keweenawan basalt, extruded during the Grenville Orogeny (mountain-building episode), covers the 2.7 billion-year-old pink granite next to the lower Chippewa Falls (hidden right rear).

Potholes in the Keweenawan basalt are geologically-recent erosion features resulting from swirling eddies carrying abrasive sand, gravel and cobbles in a circular motion that grinds them down into the base rock.

Potholes in the Keweenawan basalt are geologically-recent erosion features resulting from swirling eddies carrying abrasive sand, gravel and cobbles in a circular motion that grinds them down into the base rock.

A small remnant of the gray Keweenawan basalt covers the pink granite as we climb toward the lower Chippewa Falls.

A small remnant of the gray Keweenawan basalt covers the pink granite as we climb toward the lower Chippewa Falls.

erosion along several of the many joints in the pink granite provides a partial view of the lower Chippewa Falls

erosion along several of the many joints in the pink granite provides a partial view of the lower Chippewa Falls

the lower Chippewa Falls

the lower Chippewa Falls

several visitors provide scale next to the crest of the lower Chippewa Falls

several visitors provide scale next to the crest of the lower Chippewa Falls

view across the pink granite bedrock toward the upper Chippawa Falls at upper right

view further upstream looking across the pink granite bedrock toward the upper Chippawa Falls at upper right

The upper falls was created by a vertical diabase dike cutting across the granite. Here the fault displaces the dike by 30 feet upstream on the northwest side of the river. The upper falls can be reached by an 800 foot trail from the parking area although we didn’t have time to try it. Apparently the trail continues another 500 feet upstream to a bed of large boulders. If you were able to travel six miles further upstream, you’d reach the confluence with the Chippewa River.

The upper Chippewa Falls was created by a vertical, gray, diabase dike cutting across the pink granite. Here the fault displaces the 65-foot thick dike by 30 feet upstream on the northwest (left) side of the river.

The upper Chippewa Falls was created by a vertical, gray, diabase dike cutting across the pink granite. Here the fault displaces the 65-foot thick dike by 30 feet upstream on the northwest (left) side of the river.

Corrections, questions and suggestions are always welcome at northeastnaturalist@yahoo.com or connect through my Facebook page and photo page. There is a separate community-type page for The Northeast Naturalist. Other nature topics can be found on the parallel blog Northeast Naturalist.

calcite fills veins in the basalt at the contact with the original granite bedrock as we return to the lower level

calcite fills veins in the basalt at the contact with the original granite bedrock as we return to the lower level

Logs become trapped in erosional features that often result from joints and other fractures. Note the dark basalt at the top overlying the granite underneath.

Logs become trapped in erosional features that often result from joints and other fractures. Note the dark basalt at the top overlying the granite underneath.

reference: Roadside Geology of Ontario — North Shore of Lake Superior by E. G. Pye, 1997, pgs. 130-131

“A plaque erected by the Ontario Motor League highlights Batchawana Bay (at Chippewa Falls) as the mid-point in the longest national highway in the world — the Trans-Canada Highway.” (from the Batchawana Bay PP page )

Advertisements

2 thoughts on “Chippewa Falls, Ontario

  1. alanyshapiro says:

    Great geology adventure. Thanks!

  2. Charles Sapcoe says:

    looks like an awesome area! I loved my college field trips, and I have taken my wife on some geology trips around northeastern US…always rewarding!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s