by Neil Carleton
How many people does it take to deliver two and a half tons of sandstone to Canada’s first municipal geoheritage park? The crane operator made it look easy when he set down two large specimens last week at Metcalfe Geoheritage Park in Almonte. Before their arrival on Friday, November 2nd, it was a team effort to identify significant sections of a median outcrop on Highway 417 in Kanata, move them away from the construction zone, then load, transport, and deliver the specimens to Almonte.
This was a remarkable georescue operation spearheaded by Dr. Al Donaldson, Professor Emeritus, Carleton University, and founder of Friends of Canadian Geoheritage. The other key players who contributed to the success of this unique project were Ewa Bednarczuk, Ontario Ministry of the Environment; Marten Doornekamp, Cavanagh Construction; Jason Duff, Duff Boom Truck Service; Chad Kean, McIntosh Perry Consulting; Phil Kor, Ontario Parks; and Stan Skeggs, McIntosh Perry Consulting.
ANSI Site Georescue
In Almonte, a large quantity of white-to-tan sandstone was excavated for the construction of the new sewage treatment plant at the west end of town. Outcrops of this bedrock, known geologically as the Nepean Formation, are exposed along both sides, and within the median, of the Queensway in Kanata where construction continues for the widening of the highway. The unique characteristics of the outcrop immediately east of Terry Fox Drive led to a provincial designation in 1970 as an Area of Natural and Scientific Interest (ANSI).
The subsequent research of Professor Donaldson et al confirmed the significance of site. It was the first-reported occurrences in Canada of quartz arenite containing stromatolites and biofims. Don’t worry, there won’t be a test after. Think of the landscape in our area as a shallow marine environment with microbial organisms thriving on a sand bottom. This would some 488 million years ago, at the end of the Cambrian period and beginning of the Ordovician. Stromatolites, from the Greek words ‘stroma’ (mattress, bed) and ‘lithos’ (rock) are layered structures formed by the trapping, binding and cementation of sedimentary grains by biofilms or microorganisms, especially blue-green algae. A classic location for modern stromatolites is Shark Bay in western Australia.
When work started on the Queensway in the summer of 2008, it was identified that the outcrops within the median at the Terry Fox ANSI site would be destroyed when the two new highway lanes were added. A georescue operation was deemed feasible, subject to an expression of interest from universities, museums, or other organizations in securing blocks for display. Carleton University, Ottawa University, the Perth Museum, the Eganville Museum, and the Town of Mississippi Mills each requested one or two large specimens. Approval was granted to remove up to ten large blocks by jackhammer and pry bars, rather than blasting the rock.
Metcalfe Geoheritage Park
The creation of a geological display at Metcalfe Park in Almonte was first proposed to the Council of Mississippi Mills in 2003, as an initiative of the Almonte Geoheritage Project. Metcalfe Park, at the bottom of Bay Hill, was named in honour of Dr. Archibald Metcalfe (1869-1962), local physician for 63 years, town councilor and Mayor (at least 7 terms), and the driving force to establish the Almonte hydro electric generating station.
Through the efforts of Professor Donaldson and community volunteers in Almonte, plans for a geological display evolved during subsequent meetings with Council. Other organizations soon offered their support. The progress of the Almonte Geoheritage Project was well covered during this period in our weekly newspaper, The Almonte Gazette. With the enthusiastic endorsement of Councilors, the Mississippi Valley Field Naturalists, the Mississippi Mills Chamber of Commerce, and relatives of Dr. Metcalfe, the Council of Mississippi Mills unanimously approved the proposal in June 2008. Council further approved the renaming of the park as Metcalfe Geoheritage Park.
Specimens were moved to the site, and a display of large blocks and boulders was started to represent the local geodiversity. Sedimentary rocks of Cambro-Ordovician age included sandstone with ripple marks and limestone rich in fossils. The target list for metamorphic rocks of Precambrian age, about 1 billion years old, included marble and gneiss. The official opening ceremony at Metcalfe Geoheritage Park was held on October 16, 2010.
Rescue Rocks Received
As the truck made its way through Almonte, drivers and pedestrians likely thought the load was landscape rocks destined for a nearby construction site. In the morning, two large blocks had been delivered to the Perth Museum. This was the second delivery of the day, with two specimens for Metcalfe Geoheritage Park. The other two large samples onboard were scheduled for delivery to the Eganville Museum on the following day.
During the past year, the park property by the new Brian J. Gallagher Generating Station has been under construction with sewer work. The construction site includes the display site of the geological specimens. The large rocks were temporarily moved aside, and plans are underway for their relocation farther west from within the semi-circle roadway. This initiative will be part of the development plan for the overall park property by the Mississippi River Power Corp. It’s hoped the new design for Metcalfe Geoheritage Park will be completed in the upcoming year.
Featured in the rearranged layout will be familiar and new samples that tell the remarkable story of our area’s geoheritage. Visiting Metcalfe Geoheritage Park to read the rocks will take you on a journey far back in time to towering mountains, colliding and splitting continents, ocean depths, and a landscape locked in ice.