May 17, 2011

Field photo Set #3

A recent stopover in Princeton, BC gave me an opportunity to sidetrack to a couple interesting outcrops that expose sedimentary strata of different formations. It was a perfect day - clear skies, temps in the high teens, dry but not too dry - summer come early. Without even trying, on occasion I was within meters of adventurous local wildlife - a beaver, several deer, and a young black bear.

One particular exposure along the TCT, nicknamed the "Red Ochre Bluffs" because they were used by natives to create red pigment, is particularly interesting for its very reddish color, due to a high % content of the mineral haematite (iron oxide) within the bedded chert. Technically it is an outcrop of the Vermillion Bluffs shale member, part of the Allenby formation of the Eocene epoch (45-50 Ma). This is a fossiliferous member, where fossils of maple, alder, fir, pine, dawn redwood and ginko have been found, along with one of the world's oldest fossilized bees. There is a noticeable dip to the beds of about 10°, striking NNE-SSW.

At another part of Princeton, behind a small restaurant, is the only exposure in Princeton of the Summer Creek sandstone member of the Allenby formation:
A keen eye will notice the concretions, the cross laminations, and an apparent conglomerate boulder 'xenolith' that became part of the package, though it might be a beaten up granite-family rock. The sandstone layers have an approximate dip of 25°, and a strike of E-W. The member is mantled by a foot of glacial till (Princeton has a few kettle lakes of interest that showcase glacial geomorphology). This sandstone is some of the toughest I've felt; the layers are highly compacted and the presence of plenty of cementing material makes it a strong variant.

The Vermillion Bluffs exposure can be found @  49° 26.695'N 120° 32.665'W, after a 2km walk along the TCT. Part of the walk goes through a long tunnel where you can practice your bet megalomaniacal laugh.
The Summer Creek sandstone rockface can be found @ 49° 27.313'N 120° 30.646'W, behind Billy's Family restaurant, where you can park and take a look at how First Nations hollowed out a cave within the sandstone to store plunder.

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