A woman and two men using a couple of 2x4s to load a large boulder onto a bot

How fossil #144 came to the Cortes Island Museum

On Saturday, September 3, 2022, Christian Gronau installed a 130 million year fossil on the Cortes Island Museum porch. This is the third rock from his collection on display, and fossil #144 of a series.

“I believe this quest for fossils, the erratics that he’s been searching for has been a 20 year project,” said Melanie Boyle, Managing Director of the Cortes Island Museum and Archives.

Fossil #144 on the beach, North Marina Island – courtesy Christian Gronau

Gronau added, “It’s a very fine specimen, different from the other two specimens that are already there. So it makes a very nice combination.” 

He wrote, “Every one of the fossiliferous rocks (containing Buchia spp. bivalves) found around Cortes and neighbouring islands, is an ‘erratic.’ They have been transported by glaciers of the last Ice Age all the way south from the Potato Range in the Chilcotin  –  a journey of roughly 200 kilometres. The main travel route was down the Homathko River and Bute Inlet.  Once the glaciers escaped the confines of their respective valleys (fjords), they spread out and deposited their rock loads as far as West Thurlow Island and as far south as Smelt Bay, Cortes Island.”

He described finding fossil #144 ‘as a collaborative effort in the widest sense of the word.’

It came to his attention as a result of a conversation during which his neighbour told a visitor from Vancouver that there are fossils on some of the local beaches. 

The girl responded, “Oh, I’ve seen one on Marina Island. It’s much bigger than what you are talking about.” 

She had a photograph of the general location, but said the boulder was too large to move. 

Fossils (l t r) # 144,  # 2,  # 7  on display on the Museum Porch.   Map panel installed above – courtesy Christian Gronau

So with his partner, Aileen Douglas, and regular collaborators, Carrie and Barry Saxifrage, Gronau set out in his boat to locate the boulder.

“We did find it fairly high up the beach on the really bad side of Marina Island, where the boulders reach out about a quarter mile in very erratic patterns and it’s tricky boating.  We realized that we would have to time the tides correctly,” explained Gronau.

 “One beautiful summer day which was very hot, so it was good to work half underwater, we approached the location with our boat. One old trick that every old timer who ever cleared a patch of beach knows, it  is a lot easier to move rocks when they’re underwater because their buoyancy cuts their weight roughly in half. So we were able to move this boulder underwater onto a wooden ramp that led onto the back transom of our boat and walk the rock, which we estimate was about 300 pounds, up onto our boat. We took it to a boat ramp, onto a dolly to our car and onto the porch of the museum, where it has since been properly installed on a base and cemented securely so that it won’t tip over. It’s a very different specimen from the other two that are already there. So it makes a very nice combination.” 

Boyle added, “Christian’s done this beautiful hand painted sign that will track the progress of these erratics and I’m hoping that more and more people will stop by and explore.  There’s a wonderful binder chronicling the whole quest with his team, his friends who’ve been on the journey with him and lots of the young people who were inspired by this research, who’ve probably gone on to careers in geology or palaeontology, many other things.” 

Map panel from the Cortes Island Museum – Photo courtesy Christian Gronau

She added, “Christian has had a long relation with the museum and he has so generously offered his knowledge through this project, but also just generally.” 

This is part one of a series about the erratic fossils found in this area, in part two Christian Gronau describes his research in greater depth.

Top image credit: Loading fossil # 144 loaded onto the boat.  (l to r) Aileen Douglas, Christian Gronau, Barry Saxifrage – Carrie Saxifrage photo.  

Sign-up for Cortes Currents email-out:

To receive an emailed catalogue of articles on Cortes Currents, send a (blank) email to subscribe to your desired frequency: