That sinking sensation: Leda clay in and near Ottawa

By Ellen Bond

In the 1970s, there were two shows I looked forward to every weekend: The Wonderful World of Disney on Sunday (feel-good stories) and The Bugs Bunny/Road Runner Hour (cartoons) on Saturday. It wasn’t the ACME dynamite or the crazy coyote that scared me on Saturday—it was the quicksand! Being stuck in cement-like mud sounded horrendous to me. So imagine my feelings when I learned that most of Ottawa is built over a massive amount of Leda clay, which can liquefy from ground tremors, forming a type of quicksand. Quicksand? Here in Ottawa? Not only in the desert of Wile E. Coyote? Yikes!

A colour map showing the area of land covered by the Champlain Sea

A map showing the former location of the Champlain Sea after the last period of glaciation (Wikipedia) Credit: Orbitale

The Champlain Sea and the formation of Leda clay

After the last ice age, the climate warmed and the snow and ice melted. Massive spillways, which carried melting glacial waters and looked like enormous rivers, moved the water away from the remaining glaciers and sometimes formed lakes. In the area now known as the Ottawa Valley, a vast inland shallow sea formed 15,000 years ago. Geologists named it the Champlain Sea. What is unique about this sea is the Leda clay that was deposited in areas of deeper water.

You may wonder what happened to the Champlain Sea and why these lands are not still underwater. There are two reasons: evaporation and the rebounding of land once freed from the incredible weight of a 1- to 3-kilometre deep glacier. The land previously under the glaciers in North America is still rebounding today, 15,000 years later!

Leda clay (also known as quick clay and Champlain Sea clay) was formed by sediment eroding from the earth and landing at the bottom of the sea. The Champlain Sea was full of both fresh water from the glacial melt and salt water from the ocean. When salt molecules combine with the clay molecules, it makes a stable clay. But if fresh water infiltrates the clay and washes away the salt, the clay becomes very unstable. An unstable clay molecule is prone to liquefying.

Why doesn’t Leda clay liquefy more often?

You may wonder why the Leda clay under Ottawa and the lands around the St. Lawrence River doesn’t liquefy all the time. For the most part, the clay is underneath the surface and away from fresh water, and so is very stable. However, earth tremors, whether natural (earthquakes, erosion) or human created (explosions, blasting, digging), can allow fresh water to seep into the Leda clay, removing the salt molecule. If that clay is on a hill or on the edge of a winding river, this leads to landslides.

Leda clay has been found responsible for over 250 landslides in Canada alone. In the Ottawa area, Leda clay was responsible for the Canadian Museum of Nature building’s tower sinking in 1915 and, more recently, holding up new developments in Ottawa South in 2021. It was also responsible, in part, for the Rideau Street sinkhole that appeared with train construction in downtown Ottawa in 2016.

The landslide disaster at Notre-Dame-de-la-Salette

Notre-Dame-de-la-Salette is in the area formerly covered by the melt waters from the Champlain Sea. The village is northeast of Ottawa, in Quebec, and marked by an orange star in the map of the Champlain Sea above.

Disaster struck in the middle of the night in Notre-Dame-de-la-Salette on April 26, 1908, when a riverbank of the frozen Lièvre River gave way. Fresh water had infiltrated the Leda clay molecules, making them unstable, and the riverbanks collapsed, propelling a wave of mud, ice and ice-filled water across the river and into the town. Thirty-four people lost their lives and at least twelve homes were destroyed.

A river with tree stumps on the left side and homes on the right side.

Looking up Lièvre River from Notre-Dame-de-la-Salette, Quebec (a040044-v6)

Water moves in a straight line until it meets resistance. In this historical photo of the area, the water in the river is flowing towards the riverbank (blue arrow), and it was here that the riverbank gave way. Labelled in green you can see the stumps left behind following the clearcutting of trees along the bank. Without the layer of trees to protect the bank, the entire area was prone to eroding quicker than before the cut. Some of the village of Notre-Dame-de-la-Salette can be seen across the river from where the landslide occurred. At this time, there is no island in the middle of the river, and there are houses close to the river on the town side. Comparing this image to ones after the slide, there is a stark difference. Look for changes to this scene in some of the photos that follow, especially house placement.

A river cutting through a hilly landscape with houses along the river.

Southeast view of the Lièvre River Valley and Notre-Dame-de-la-Salette (a044070-v8)

Another old photo from the LAC collection shows the river flowing away from the viewer. Look closely, and you can see where the earth gave way and the island formed in the middle of the river after the landslide.

A river with hills in the background. There is a small island in the river and a bridge farther upstream.

Former town site of Notre-Dame-de-la-Salette, Lièvre River, Quebec. Photo looks upstream. (a020267)

In the photo above, the river is flowing towards the viewer, and you can see the bridge crossing the river, north of town. A red arrow points to where the riverbank gave way during the landslide. A new island formed in the middle of the river from the sediment and material moved in the slide. The other change is that there is now a clearing where the town site had been—people rebuilt the town further away from the river.

A white cross on the edge of a ridge. The land below the ridge is considerably lower than the ridge.

A white cross stands on the edge of where the land gave way in 1908, leaving a scar on the land still visible today. Photo credit: Ellen Bond

The colour photo above was taken recently, and you can see the area affected (where the land gave way along the ridge), the island formed from the slide and a memorial white cross on the hill.

A river bend with water flowing towards the shoreline of the bend.

A recent photograph of the area affected by the landslide. Photo credit: Ellen Bond

The above photo looks downstream at the slide location. The slide area is shown in yellow, and you can see the ridge above. On the left, you can see the edge of the island that formed after the slide.

A large rock with a metal plaque describing the event and the names of the victims. The rock is across from the slide location. There is a bench nearby overlooking the memorial and the landslide site.

A memorial across the river from the slide location. Photo credit: Ellen Bond

Inscription on plaque reads: Memorial On April 26th 1908 around 3:30 am, the village was brutally awakened by a loud grumbling noise. A 1200 foot long by 500 feet deep piece of land on the west side of the river suddenly slipped in the river, sweeping in a mass of water, ice and clay, houses, buildings and 34 victims. Ten (10) of the thirty four (34) victims were never found.

A memorial plaque located near the landslide area. It describes the event and lists the names of the victims. Photo credit: Ellen Bond

Although this landslide occurred over 110 years ago, the effects can be still seen and felt today. In the middle of the night, due to no fault of their own, 34 people lost their lives tragically and unexpectedly. Their names, in each family group, were

  • Alexina, Amanda, Adélard and William Charron-Lamoureux,
  • Cléophas Deslauriers, Célina, Damien, Wilfrid, Albert, Lucien, Béatrice and Alice Deslauriers-Paquin
  • Émélie, Florimond and Alias Desjardins-Gravelle
  • Émélie, Daniel, Eddy, Arthur, Angus and Henri Lapointe Labelle,
  • Rose-Anna, Camille, David, Emma, Rose and Albert Larivière-Charron,
  • Alexina, Arsidas, Wilfrid, Florida and Anna Murray-Légaré
  • Georges Morrissette
  • Adélard Murray

The power of the earth is incredibly strong, and those that inhabit the planet are sometimes the unfortunate recipients of its fury. It happens in regions affected by hurricanes. It happens where two of the Earth’s plates meet and are moving in different directions. It happens where Leda clay has formed. As humans, we cannot control this power. In Notre-Dame-de-la-Salette, the people have adapted to the Leda clay by moving their houses away from the river. Unfortunately, lives were lost learning this lesson. RIP to all of the victims and their families.

A recent photo of the slide area.

Looking across the river to the slide location. The ridge is visible as is the island. Photo credit: Ellen Bond

Additional Resources


Ellen Bond is a project assistant with  the Online Content team at Library and Archives Canada.

 

 

Improving your online experience: What to expect at LAC’s new online home

Image of fingers on a keyboard

By Andrea Eidinger

Here at Library and Archives Canada (LAC), we take user feedback very seriously. Over the years, one point has come through loud and clear: our existing website is not meeting the needs of the public. This is why we are proud to announce that we will be launching a completely new website later this summer—library-archives.canada.ca. In this blog post, I will go over what LAC’s new web presence will involve and how these changes will impact your experience.

New website

So, what does this mean in practical terms? We spent a lot of time gathering feedback from members of the public, expert researchers and members of our staff to make our website user-centric. This involved creating several working groups as well as user-testing different possibilities for the new website. We also incorporated the latest research on how people actually use websites.

A major part of this work has been to ensure that all our users can easily find and understand the information on our website. Two very important components of the new website are consistent web navigation and plain language. All our new web content is organized in the same way so that users always know where to go, and the language has been simplified to make it clearer and easy to understand, no matter your skill level.

Finally, our website is dynamic. Our goal was to create a website that lives and breathes. Gone are the days of web pages being posted and then never touched again. Part of renewing our web presence is a commitment to continually update the website with new material and make improvements based on user feedback. We are also taking what is called an “iterative approach.” Essentially, we will start with a scaled-back version of the new website. This will be a launching pad for us. Our work will build on this initial version to develop the new website.

Screenshot of the Rare Book Collection webpage on the LAC website.

An example of the new template for subject guides for the new LAC website.

New structure

One of the biggest changes users will notice is the look and feel of the website. To make the information on the website more easily accessible to the public, we have developed a new structure for the website based on tasks, topics and themes that align with our users’ needs. In other words, we looked closely at how members of the public were using our existing website and what they were looking for (tasks). We then grouped those tasks into broad categories (topics). Finally, we grouped these topics into themes.

These themes are the basis for the website’s new structure and align with the Government of Canada’s design system. This system provides a more practical, consistent and reliable online experience for people who access Government of Canada digital services.

The first theme, Corporate, contains all of the institutional information relating to LAC. This includes information about our mandates, policies, initiatives and partners. This is where you will also find information about transparency at LAC and be able to read reports and plans about our activities.

The second theme, Services, is self-explanatory. It is where users can access our services or complete a task related to one of our programs. Under this theme, users will find information on how to visit us, how to order material, how to apply for ISBN numbers, how to make an ATIP request, and more. Also under this theme is information about the various services that we offer for gallery, library, archives and museum (GLAM) professionals, publishers, public servants, and Indigenous communities and individuals. This section will also contain information about our different funding programs.

Finally, there is the Collection theme. Our goal in rethinking how we present the Collection theme was to build user autonomy and discovery. This section will be home to all kinds of materials that will help Canadians access the documentary heritage under LAC’s care. In this section, you will find our databases, guides on researching various topics, publications, and podcast episodes, as well as a basic introduction to research. This section also includes many of LAC’s more interactive features, such as Co-Lab, our transcription program.

New navigation

One of the biggest challenge that users faced on our website was finding the information they were looking for. This was a problem particularly for material included under the Collection theme. Often, users would travel down rabbit holes and never be able to find their way back again. We have corrected this problem with a completely new navigational system based on tables. The new navigational table will include all pages listed by topic, sub-topic and type. For example, a web page on the First World War personnel files we have available would be appear as follows:

First World War Personnel Files – Military History – First World War (1914-1919) – subject guide

Even more important: this table will be filterable and searchable. This means users can easily see all of the resources that we have on a particular topic and find their way back without difficulty.

New content

The last exciting change to tell you about is the new content on our website. The existing site is enormous: it consists of 7,000 pages. Much of the information it contains is no longer up to current web and historical standards. We also know that many of the pages are hard to read, especially for beginners, and sometimes confusing. In preparation for our new website, we have systematically reviewed every single one of those 7,000 pages. Anything outdated or no longer up to current standards was archived (and will be available to the public), and the rest of the pages were reworked. All of the information on LAC’s new website is presented in plain language and is therefore clear and easy to understand. We hope this approach will attract an entire new wave of users interested in learning about Canada’s documentary heritage.

Since there is so much content, we focused on preparing material for the three most popular and most consulted topics for the launch: genealogy and family history, Indigenous history, and military history. Please note that, in the weeks and months ahead, we will add more material to these and other topics. We will be updating our material regularly in response to user feedback and to reflect the latest available information.

We’re so excited to show you all of the new material we’ve been working on! So, while this does mean that your URLs will change, we’re hoping that these changes will make your online experience at LAC a more positive one. Since this work is only beginning, the best is yet to come!

We look forward to your feedback. Please send us your comments and thoughts when we go live.


Andrea Eidinger is a team lead in the Online Experience Division at Library and Archives Canada.