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 )

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New Mexico Lava Beds Along I-40

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The first two photos show the McCarty’s Lava flow beside Rt. 124 (historic Rt. 66) about 4 miles east-southeast of I-40 exit 89 between Grants and McCarty’s, New Mexico. The upper layer is full of gas bubbles. [November photos] – © Dave Spier

New Mexico’s El Malpais Lava Beds at I-40 — © Dave Spier

East of Grants, New Mexico (USA), Interstate 40 passes through the north end of the El Malpais lava fields. (Malpais is Spanish for “badlands” and was used by early map makers to describe volcanic terrain.) The area is related to the Zuni-Bandera volcanic field. Of the numerous basalt flows, two reached the present I-40/Rt. 124 highways. The youngest, the McCarty flow, is a mere thousand years old. Stop at the mile 93 rest areas for a closer look or drive Rt. 124 parallel to the interstate. The older Calderon flow reached to Grants and can be accessed from the exits. The small volcanoes at the source are 20-30 miles southwest in El Malpais National Monument which is reached by Routes 117 and 53.

On Google Earth 6.2, you can zoom in on I-40 between Grants and McCarty’s to the southeast. (Exit 89 GPS co-ords are 35° 05′ 04.82″ N, 107° 46′ 12.77″ W)  The geologically “recent” McCarty’s lava flow is an irregular black line heading north along the west side of Rt. 117 at the base of the Las Ventanas Ridge, then widening and “pooling” east of exit 89 (where Rt. 117 begins at I-40), then streaming east-southeast along Rt. 124 (Historic Rt. 66) most of the way to McCarty’s. The dissected north rim of the McCarty’s Mesa is south of Rt. 124 and formed the southern barrier constraining the lava. The older Calderon lava flow is an irregular brownish-gray blob west of exit 89 on the Google aerial view.

The basalt is similar to the dark lava flows that form the Moon’s “seas.”

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This series of three photos shows the McCarty’s Lava flow on the east side of Rt. 124 (historic Rt. 66) at I-40 exit 89 between Grants and McCarty’s, New Mexico. [November photos] – © Dave Spier

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Closer image of the left side in the photo above…

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Closeup of the basalt in the McCarty’s Lava flow on the east side of Rt. 124 (historic Rt. 66) at I-40 exit 89 between Grants and McCarty’s, New Mexico. – © Dave Spier

Reference:
Roadside Geology of New Mexico, by Halka Chronic (© 1987/reprinted 2005), published by Mountain Press

Corrections, comments and questions are always welcome at northeastnaturalist@yahoo.com or connect through my Facebook photo page or my personal page, Dave Spier (northeast naturalist). Related topics can be found on the parallel blogs http://northeastnaturalist.blogspot.com and http://adirondacknaturalist.blogspot.com/