A Good Year to Look at the Stromatolites along the Ottawa River

We were blessed with a fairly dry summer in Eastern Ontario.  As a consequence  the Ottawa River is low and it is a very good year to look at the stromatolites that outcrop along the Ottawa River (which are best viewed when the Ottawa River is low).  The most frequently visited outcrop is likely the one that is in Quebec just across the Champlain Bridge from Ottawa.

Below are photographs that I took two weekends ago on my visit to look at the outcrop.

The outcrop is easy to locate.  Take the first left when you cross the Champlain Bridge, and look on your left for the Champlain Parking Lot about 150 meters from the stoplights.   Then walk about 50 meters back towards the bridge along the bike path.  The outcrop is the river bed.

A little over decade ago J. Allan Donaldson and Jeffrey R. Chiarenzelli provided the following description of the “closely packed domal stromatolites” visible at this outcrop, when describing ‘Stop 4. Stromatolites in Pamelia Formation (Ordovician)’:

“Mapping at 1:25 scale has revealed strong local north-south trends of elongation for the stromatolite heads.  In many places two or more are coalesced in parallel, strings oriented in the same (north-south) direction.   ...these trends are readily attributed to the action of tides and onshore-wind-driven waves .  Some small stromatolites are elongate perpendicular to the prominent north-south trend ...[which] is attributed to longshore currents.   ...  [A] hypersaline environment in which biofilm predators  could not survive is inferred.  This is supported by the observation that, whereas the underlying stromatolite-free beds of carbonate are fossiliferous (with gastropods and vermiform trace fossils particularly abundant), the stromatolite unit is free of megafossils.  Only conodonts have been observed, and those extracted from the stromatolite unit are compatible with a hypersaline environment...”
[Citations omitted]

J. Allan Donaldson and Jeffrey R. Chiarenzelli, 2004a,
Stromatolites and Associated Biogenic Structures in Cambrian and Ordovician Strata in and Near Ottawa, Ontario; 76th Annual Meeting, Field Trip Guidebook, New York State Geological Association, 283 pages, at pages 1-20. 

That field trip guidebook can be downloaded in pdf format from:
http://www.nysga-online.net/    Click on the tab “NYSGA Guidebook Archive”, select “2000s NYSGA Guidebooks” and then select 76th NYSGA 2004.pdf

If you download the guidebook be sure to also look at the following field trip:
J. Allan Donaldson and Jeffrey R. Chiarenzelli, 2004b,
Precambrian Basement and Cambrian-Ordovician Strata , as Displayed in Three Provincial Parks of Canada, 76th Annual Meeting, Field Trip Guidebook, New York State Geological Association, 283 pages, at pages 63-78.       Stop 1 is a visit to Fitzroy Provincial Park to look at the stromatolites while  Stop 3 is a visit to Almonte, Lanark County to look at the stromatolites.


If you are planning to visit  the Champlain Bridge stromatolites I’d recommend that you first visit the following web sites:       

1)    http://http-server.carleton.ca/~jadonald/fieldtrips.html
Ottawa-Gatineau Geological Field Trips, by Professor Allan Donaldson for a course at Carleton University.   This guide contains six stops, including the outcrop of Stromatolites on the Quebec side of the Champlain Bridge.  It includes a map showing the location of stromatolites in relation to the Champlain Bridge, together with two detailed maps of the stromatolites, that I assume is the mapping at 1:25 scale  referred to by Donaldson and Chiarenzelli, 2004a.  (Note that the Blvd. Champlain on Dr. Donaldson’s map is now Blvd. de Lucerne.)
           
2)  http://geo-outaouais.blogspot.ca/2009/11/colonie-de-stromatolites-gatineau.html
This blog posting contains some very good photographs of the outcrop.

3)  http://www.ottawagatineaugeoheritage.ca/subsites/4
This web page of the Ottawa Gatineau Geoheritage Project  is devoted to this outcrop.  

Geoheritage Day, Sunday, October 18, 2015

The Champlain Bridge Stromatolites  is one of the eight sites for Carleton University’s annual Geoheritage Day to be held on Sunday, October 18, 2015 from 10:00 a.m. - 3:00 p.m.  Volunteers from Carleton University’s Department of Earth Sciences and the Ottawa Gatineau Geoheritage Project will be on hand at each of the sites  to explain what there is to see and how each site fits into the local geological history.   I first visited this outcrop two years ago for Geoheritage Day and enjoyed Dr. Donaldson’s description and explanation.

Further details on the sites for this year's Geoheritage Day can be obtained at:

http://www.earthsci.carleton.ca/outreach/explore-geoheritage-day

Christopher Brett
Perth, Ontario