Researching the disaster that created Clearwater’s townsite

Damming around Spahats was likely the culprit, leading to a jökulhlaup

Have we been living on the site of a mega-disaster for years and years without realizing it?

When your editor first came to Clearwater several decades ago, someone tried to tell me that Dutch Lake was originally a volcanic crater – even though the lake is surrounded by sand and gravel, not by lava or other volcanic debris.

Now many people recognize that it is a kettle lake – formed by a big chunk of ice melting after it was left behind by a glacier.

Kettle lakes are quite common across the northern part of this continent and other places around the world that were previously covered with glaciers.

Thoreau’s Walden Pond is a kettle lake, as are many of the small lakes across the prairies.

Most kettle lakes are found on flat land – the remains of the outwash plains found downstream from retreating glaciers.

An exception is when the kettle lake was formed by a jökulhlaups – the sudden drainage of an ice-formed lake.

Dutch Lake is not in a flat plain. In fact, it is surrounded by sizeable ridges and bumps made of sand, gravel and rounded rocks.

Recently, I was able to ask Dr. Cathie Hickson, a geologist who has done extensive work on the volcanoes of Wells Gray Park, if it was possible that Dutch Lake had been caused by a jökulhlaup.

Here is her reply:

“You are absolutely correct. Damming around Spahats was likely the culprit, leading to a jökulhlaup with deposition of large ice blocks at the confluence. The bay on the east side (of Dutch Lake) is actually a scoured channel.

“Also because of the change in the size of the valley, any outwash slows dramatically when it disgorges from the Clearwater into the (North) Thompson River. That is why there are the very large sand banks along the North Thompson. Also the constriction downstream south of Blackpool on the North Thompson led to a lot of water backing up northward into the Clearwater and North Thompson, likely as far as Birch Island.”

In other words, several thousand years ago a glacier dammed the Clearwater River near Spahats, forming a lake upstream. Such ice dams are inherently unstable and, when it let go, it washed big chunks of ice and a whole load of rocks and gravel downstream, forming what today is Dutch Lake and surrounding areas.

It would have been an amazing sight to see – hopefully from a safe distance, of course.

The history of Dutch Lake is just one of many stories that we are learning about the geological history of this area.

People who know about such things tell us that no other place in the world (including Iceland) has a more unique mix of glacial and volcanic features than does Wells Gray Park and area.

It is to preserve those unique geological features, plus important biological assets such as mountain caribou as well as the area’s First Nations and pioneer cultural heritage that people have proposed creating a Global Geopark here.

Recently, however, that effort seems to have stalled.

Where to locate the boundaries for the Geopark seems to be one sticking point.

The volcanoes of Wells Gray Park are a good core to start from but there are so many other features that could be included, such as natural rock bridges, waterfalls, inland rain forests, petroglyphs and so on, that it is hard to know where to draw the line.

Including more communities brings in more resources to help promote and develop the Geopark idea.

On the other hand, if the proposed area becomes too large it loses any unifying theme and the Geopark concept becomes meaningless.

 

Governments can only do so much. Consultants can only do so much. If the people of the North Thompson Valley want a Global Geopark for this area, then it will happen. If we find we have other priorities, then it won’t. It’s as simple as that.