The Land before YEG – The most interesting part of City of Edmonton construction you didn’t know about

Edmontosaurus (/ɛdˌmɒntəˈsɔːrəs/ ed-MON-tə-SAWR-əs) (meaning “lizard from Edmonton”) is a genus of hadrosaurid (duck-billed) dinosaur. It contains two known species: Edmontosaurus regalis and Edmontosaurus annectens.

Drumheller isn’t the only fossil hot spot in Alberta. There are in fact more than 50 sites with one or more fossil finds that have been recorded in Edmonton. And of those, 10 sites have had significant fossil finds recorded. Finds include dinosaur bone beds (Danek Bonebed), partial dinosaur skeletons or scattered bones, extinct Ice Age mammal remains and well-preserved fossil leaf and shell beds. 

Bison skull discovered during the Walterdale Bridge Project

The geological history of Edmonton is long and diverse, especially in our beloved river valley. Because of this, many construction projects in Edmonton have a paleontological or archaeological component to the work. Before we build, we go back in time. Palaeontological resources (fossils) are protected by the Alberta Historical Resources Act and regulated by Alberta Culture, Multiculturalism and Status of Women. 

Consulting paleontologists like Michael Riley at AEON Paleontological Consulting are hired onto City of Edmonton projects to conduct assessments of construction sites and other projects, to aid in the identification, assessment, mitigation, monitoring and reporting of paleontological resources throughout the province. The most recent assessment was conducted as part of the Blackmud Creek Pedestrian Bridge Replacement project

Michael Riley sorting, imaging and identifying fossils

Michael’s role on a project helps protect and preserve Alberta’s palaeontological history while we continue building into the future.

“Officially, we undertake a paleontological Historic Resources Impact Assessment (pHRIA) for on-site work,” said Riley. “We are required to apply and have an approved paleontological permit in place before any field work is conducted or excavations take place.”

This pHRIA can involve a pre-construction (pre-impact) assessment to determine if there are any significant fossil resources present.  If fossils are present then mitigation work (e.g recovering the fossil prior to construction) or a monitoring program during construction may be required, or both. If it is determined there is a high potential for construction/excavation activities to disturb fossil-bearing bedrock or sediments that do or are likely to contain fossil resources, then a monitoring program would be required.

Test pit monitoring

For the Blackmud Creek project, both a pre-construction pHRIA and a pHRIA monitoring program were required due to the paleontological sensitivity of the area, known fossil sites in the surrounding areas and exposed bedrock of the Horseshoe Canyon Formation outcropping within and around the project area. When asked about his work, Riley jumped at the opportunity to bring attention to the rich paleontological and geological history beneath the City of Edmonton. 

How did you get involved with the Blackmud Creek project? 

As a local, Edmonton-area consulting firm specializing in paleontology, we have been involved with many City of Edmonton projects as part of successful bid teams. We have been working on the ground for 20 years and have a detailed knowledge of the paleontological sites and geology of Edmonton and the surrounding regions.

Blackmud Creek Pedestrian Bridge riprap apron excavation into bedrock.

How many pre-construction digs have you been involved with? 

I have undertaken over 500 paleontological projects and over 250 pre-construction assessments and monitoring programs over my 20 year career.  Within Edmonton, I have assessed, undertaken and helped monitor over 20 paleontological projects.  A few of these projects include assessments and/or monitoring programs for the Quesnell Bridge Expansion, new Walterdale Bridge, SE LRT Expansion, Goldbar Waste Water Treatment Plant, Kihciy Askiy Sacred Earth Sweat Lodge, new subdivisions and the 41 SE Avenue and Capital Region Ring Road projects. 

Tools and safety clothing.

Why are paleontological assessments so important? 

Paleo HRIAs are so important because they allow us to survey the project footprint and recover and document any significant fossil resources before they are disturbed during excavation. This way we can recover the specimens or take samples of ancient environmental layers before they are destroyed during construction activities to preserve these rare and scientifically valuable finds. Many times we need to physically be on-site to closely monitor the excavations so we can spot and recover any bones, shells or plant remains that are being excavated. Without a trained paleontological monitor on-site to work closely with the construction crews, many of the significant fossil discoveries recorded around the City would likely go unnoticed. We would lose the opportunity to add to our understanding of the ancient environments and the types of plants and animals that inhabited these lands in our ancient and not-so-distant past.

What’s the most interesting thing you’ve found on a dig?

During the Quesnell Bridge Widening Project, as the crew was preparing to ‘armour’ (rip rap) the bridge abutment, they excavated what remained of an old sandstone channel underneath the existing bridge. They unearthed a weathered hadrosaur (duck-billed dinosaur) vertebra that I was able to recover. I never expected to see such a large bone in what remained of this scrap of highly-weathered and eroded sandstone left underneath the old bridge abutment. A pleasant surprise!

Check out this news story:

Quesnell hadrosaur vertebra, bar = 10cm

What’s your favourite dinosaur?

I am fond of extant dogs and birds and enjoy animals that are social and work or hunt in groups.  Therefore, I am a little partial to the small to medium-sized feathered, carnivorous dinosaurs (Dromaeosauridae), like Velociraptor that lived in the latter part of the Cretaceous Period (74-66 million years ago).

Infrastructure construction is a vital part of our growing city, so it’s important we check all the boxes along the way.  When eroded away and exposed, the ancient lands beneath our feet have yielded significant dinosaur, reptile and plant remains. Thousands of ice-age mammal and post-glacial mammal bones have also been recovered from the ancient river gravels along the North Saskatchewan River. 

Cofferdam monitoring at Walterdale Bridge

Incorporating paleontological assessments into our work is just one of the many ways the City of Edmonton ensures our projects meet all regulatory requirements and are completed to the highest standards. 

Editor’s note: the City of Edmonton thanks the the Royal Tyrrell Museum for help digging this story up.