Field Trip to Outcrops Near Perth, Ontario

This posting is a field trip guide to outcrops in Potsdam Group sandstone near Perth that contain trace fossils. All of the outcrops can be visited in less than four hours.

Outcrop 1: Dodds & Erwin parking lot, 2870 Rideau Ferry Road, County Road 1, Perth. (Within Town of Perth) -  Photo 1 -  Paired U-burrows
This outcrop is a glacially polished, flat outcrop of Nepean sandstone that falls within the town of Perth’s boundaries and functions as the parking lot for Dodds & Erwin and adjacent businesses. The irregular shaped flat outcrop/parking lot is about the size of four football fields. It is approximately 300 meters south of Scotch Line (County Road 10), on the Northeast side of Rideau Ferry Road (County Road 1). The outcrop is full of abundant vertical worm holes, including paired u-burrows (probable Diplocraterion, but possibly Arenicolites) . The glacially polished surface shows two directions of glacial striae.

Outcrop 2: Waste Management Site, 666 Wild Life Road - at Southern boundary of Perth - Photo 2.
A similar outcrop to the one at the Dodds & Erwin parking lot can be found just inside the entrance to the Town of Perth’s dump, on the north side of Wild Life Road, West of Rideau Ferry Road, approximately one kilometer southwest of the Dodds & Erwin parking lot. The glacially polished, flat outcrop is about 30 meters by 20 meters. It displays abundant vertical worm holes, including paired u-burrows (Diplocraterion?) and, in one location, ripple marks. The dump is open Tuesday, Wednesday, Friday 8 am to 4:30 pm, and Saturday from 8 am to noon.

Outcrop 3: Quarry on Wild Life Road - Photo 3
On the opposite side of Wild Life Road from the town dump is a large (60 meter by 30 meter), water filled, Nepean sandstone quarry. The rock around the top of the quarry (close to the road) is a flat surface showing abundant vertical worm holes (Skolithos?) and bioturbation. Because of the water in the quarry it is almost impossible to access the walls of the quarry (while an extension ladder might work at the shallow end, this is not recommended).
The dump and the quarry can be easily seen on Google Maps and Google satellite view. In the satellite view you can identify the shallow and deep ends of the quarry.

Outcrop 4: 348 Elm Grove Road - Photo 4 - Perth stone
Many buildings in Perth are made with Perth stone, or accented with Perth stone, a purplish and white Potsdam Sandstone that shows incredible bioturbation. It was mined in the late 1800's from the Hughes Quarry, off Hughes Road, about 8 kilometers southeast of Perth. The Hughes Quarry is overgrown. However, the Perth stone outcrops approximately one kilometer to the west of the Hughes Quarry, opposite 348 Elm Grove Road. This outcrop, up to two feet high and 20 meters long, displays vertical worm holes on a glacially polished surface, as does an outcrop on the other side of Elm Grove Road.

Outcrop 5: West side of Elm Grove Road, just south of the second intersection with Glen Drive, and north of Long Lake Road
This location, one of three outcrops on a pegmatite dyke (not Potsdam Group sandstone), is likely the type locality for Perthite, an exsolution texture in feldspar.  (See Ann P. Sabina (1965), Rock and Mineral Collecting in Canada, Vol. II, Ontario and Quebec, GSC Miscellaneous Report 8, Page 118.)Specimens can be easily found. The second outcrop lies about 300 meters to the north, but is the front lawn for a house in a subdivision, and is out of bounds for collecting.   The third outcrop is likely another 500 meters to the north.   Photo 5 - specimen of Perthite collected this year

Outcrop 6: South West Corner of Narrows Lock Road and Powers Road - 18 minutes Southwest of Perth - Photo 6
This is a good exposure of vertical worm holes (Arenicolites??) on a flat outcrop about 10 meters by 10 meters. I suspect that the sandstone is Covey Hill rather than Nepean sandstone, as the same worm holes and rock can be found 30 meters to the north along Powers Road in a barely visible outcrop where the rock under the worm hole bed is a red bed sandstone.

Outcrop 7: Stanley Road, East of Narrows Lock Road - 15 minutes Southwest of Perth - Photo 7 - Diplocraterion cross-section
This past summer a drainage ditch has been dug on the north side of Stanley Road. For about 150 meters the trench cuts through flat lying sandstone, and provides an outcrop from a few inches up to 4 feet high. The rock taken from the ditch has been dumped in five locations along Stanley Road: three areas where it has been used to cover culverts and to make laneways, and two large piles (15 feet long by five feet high by five feet wide) where I expect it will be used to cover culverts and make laneways.   The sandstone is mostly speckled with rust, with some solid grey sandstone and one 6 cm thick siliceous bed that is a dusty rose colour. Quinoa sized (2-4 mm) rounded quartz, very coarse sand/very fine gravel, occurs in a few beds. I found a few samples of ripple marks with varying wavelengths, a few samples of worm tunnels parallel to the bedding surface, two samples with worm tunnels between the ripple marks, a sample with Diplocraterion and two specimens (which, sadly, are no longer with us) that were a chalk like substance showing well defined worm burrows parallel to the bedding that when rubbed disappeared.
　
Outcrop 8: Bowes Side Road just south of Tay River
This is another outcrop of Nepean Sandstone that displays abundant vertical worm holes including paired U-shaped worm holes (probable Diplocraterion), and shows ripple marks. The sandstone outcrops on both sides of the road (close to a private museum) just south of where the road crosses the Tay River. This outcrop is 10 minutes west of Perth.  Photo 8 - note that centres of tubes are preserved in the Diplocraterion.

Let me know if you enjoy the tour.
Regards,

Chris Brett

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