Dodds & Erwin has been serving the agricultural community of Lanark County for over 100 years. Established in 1918 they supply feed and farm supplies to local farms, sell wild life feeds and pet foods, and in the summer operate a landscape supply depot, all from their outlet one kilometer south of Perth at 2870 Rideau Ferry Road/County Road 1.
What is particularly interesting is that Dodds and Erwin’s parking lot (and the parking lot for adjoining businesses) is a glacially polished, and highly striated, flat outcrop of Nepean (Keeseville) sandstone that displays thousands of examples of the trace fossil Diplocraterion (U shaped burrows with spreite between the two limbs) . The parking lot is about the size of four football fields.
The vast majority (over 98%) of the glacial striae trend roughly perpendicular to Rideau Ferry Road, suggesting the glacier was moving in a southwesterly direction. Most incise the sandstone to a depth of 2 to 3 mm, but some striae are a centimeter deep. Below are two photographs of these glacial striae. The ruler, a meter stick, is oriented parallel to the direction of the glacial striae.
In a few places a second direction of glacial striae is visible. Here is photograph of striae at an angle to those trending in the predominant direction. The ruler in the photograph is oriented parallel to the prominent direction of the glacial striae on the outcrop (namely the striae pictured in the above two photos).
Glacial striae are fairly common in eastern Ontario and have been reported from Eastern Ontario since the Geological Survey of Canada was formed. Johnson (1917) noted that “There are at least two distinct sets of glacial striae in the [Vicinity of Ottawa] . One set, which is the more pronounced, trends nearly south; the other, which is the later, trends nearly southeast. This shows, at least, a marked change in direction of movement of the ice-sheet during the closing stage of glaciation.” Hill and Billings (1985) reported glacial striae and crescent marks on Nepean sandstone outcrops along the Queensway in Kanata, Ontario. They reported and included photographs of two sets of glacial striae: “The main set, indicating ice flow toward the south-southwest across the Ottawa Valley, is transacted by short, deep, west-east striations indicating a late and final ice flow down valley to the east.” They also reported and figured crescent marks. Crescent marks (chatter marks) are also present on the outcrop that is Dodds and Erwin’s parking lot, but I could not find them to photograph when I dropped over this week.
An interesting feature visible in sandstone in the parking lot is a ‘stream’ of angular pieces of rock in the sandstone. Here are two photographs of this feature.
Here are two photographs of the Diplocraterion burrows visible in the parking lot.
The parking lot exhibits thousands, and perhaps even tens of thousands, of Diplocraterion burrows. While Skolithos burrows are visible at other locations in the Nepean (Keeseville) sandstone in Lanark County, it is questionable whether they are present at this outcrop. Further, Diplocraterion is by far the dominant trace fossil that I have observed in the Nepean sandstones of Lanark County. This accords with observations made by others. Bjerstedt and Erickson (1989) reported that the intertidal habitats preserved in the upper Potsdam of New York State and Nepean Formation of Ontario “contain a Skolithos Ichnofacies of low-level suspension feeders dominated by Diplocraterion. ... Skolithos forms only a minor component in the Potsdam Skolithos Ichnofacies.” Bjerstedt and Erickson (1989) also commented that “The principle of competitive exclusion states that single-species dominated trophic groups are more common than not. The mutual exclusion of Skolithos and Diplocraterion in Cambrian tidal facies has been noted by the many authors in Cornish (1986, p.484).”
Frank Cornish (1986) makes the following additional points: “Diplocraterion Terrell 1870 is a U-shaped, spreitten-bearing burrow that is always perpendicular to bedding. A spreite is a biogenic sedimentary structure composed of the remains of the tunnel walls of dwelling structure produced successively as a burrower shifts through the substrate... [T]he spreite represent upward and downward motions of the Diplocraterion-producing organism in response to repeated episodes of deposition and erosion of sediment.... [as the] Diplocraterion-producing organism attempted to maintain a constant burrow depth while sand was being dumped and scoured away from the substrate... Diplocraterion [is] found in the high energy intertidal and upper-most tidal zone. .. Perhaps the greatest significance of trace fossils..., and of Diplocraterion in particular, is we can use them to identify the marine origin of this sandstone without body fossils.”
[At the end of the blog posting is a photograph showing the cross-sections of three closely spaced Diplocraterion burrows, all of differing burrowing depth, obtained from an outcrop of Nepean sandstone off Stanley Road, about eight kilometers southwest of Dodds and Erwin’s Parking Lot. The top of the specimen is to the right.]
Trace Fossils in Sandstone Outcrops Along Wildlife Road
Various outcrops of Nepean Sandstone occur along Wildlife Road, approximately one kilometer due south of Dodds and Erwin’s parking lot. These outcrops display predominantly Skolithos burrows. Here is a photograph of them.
In addition I noticed some bedding parallel burrows (possibly Treptichnus pedum):
Diplocraterion at the Intersection of Powers Road and Narrows Lock Road, South of Perth
Here are two photos of the trace fossil Diplocraterion in the Nepean sandstone outcrops at the intersection of Powers Road and Narrows Lock Road, Lanark County, about ten kilometers due south of Dodds and Erwin’s parking lot.
Christopher Brett
Ottawa
References and Suggested Reading
Bjerstedt, Thomas W. and J. Mark Erickson, 1989
Trace Fossils and Bioturbation in Peritidal Facies of the Potsdam-Theresa Formations
(Cambrian-Ordovician), Northwest Adirondacks. PALAIOS, 1989, V. 4, p. 203-224
Brett, Christopher P., 2013
Glacial Erratics and Eskers in the Township of Lanark Highlands, Lanark County, Ontario
Blog Posting dated Thursday, 18 April 2013
Brett, Christopher P., 2014
Lake Iroquois and the Glaciofluvial Deltaic Deposit at Joes Lake, Lanark Highlands, Ontario.
Blog posting dated Wednesday, 17 September 2014.
Brett, Christopher P., 2015
Hunting for Whales in Eastern Ontario. Blog posting dated Friday, 24 April 2015
Brett, Christopher P., 2016
Fluvio-glacial Sculpted Forms in Outcrops Near Newboro, Eastern Ontario. Blog posting dated
Tuesday, 26 January 2016
Brett, Christopher P., 2018
A Glacial Sand and Clay Deposit in the Basement of St. Paul's United Church on Gore Street in Perth, Ontario. Blog posting dated Tuesday, 20 March 2018
Cornish, Frank G., 1986
The trace-fossil Diplocraterion; evidence of animal sediment interactions in Cambrian tidal deposits: PALAIOS, v. 1, p. 478-491.
https://doi.org/10.2307/3514630
https://www.jstor.org/stable/3514630?seq=1
Hill, Patrick Arthur and Dennis Billings, 1985
Glacial Striae and Crescent Marks in Nepean Sandstone near Ottawa. Geoscience Canada, Volume 12, Number 3, 105-109
https://journals.lib.unb.ca/index.php/GC/article/view/3420
Johnson, W. A. 1917
Pleistocene and Recent Deposits in the Vicinity of Ottawa, with a Description of the Soils
Geological Survey of Canada, Memoir 101
Martin, Anthony J., M. Blair, B. F. Dattilo, S. Howald & J. O. Farlow (2016)
The ups and downs of Diplocraterion in the Glen Rose Formation (Lower Cretaceous), Dinosaur Valley State Park, Texas (USA), Geodinamica Acta, 28:1-2, 101-119,
DOI: 10.1080/09853111.2015.1037151
https://www.tandfonline.com/doi/pdf/10.1080/09853111.2015.1037151
