Flaxcombe Erratic EarthCache

Just west of the town of Flaxcombe along the southside of Highway 7 atop the valley is a roadside turnout. Stop and have a stretch. While you’re there have a look at the giant rock embedded in the earth.

These large rocks are commonly known as glacial erratics to the geologically inclined and sometimes also known as buffalo rubbing stones to the more historical and/or archaeologically minded person. The rocks are remnants of a glacial past that dot the landscape throughout Western Canada. Glacial erratics are parting gifts left by receding glaciers.

Erratics can vary in size from small cobbles to house-sized boulders and are often found in locations where no obvious means of transportation are evident. What makes an erratic unique is that its composition and size is different from the surrounding landscape, essentially making it foreign to the region in which it was deposited. These features are an obvious clue that glaciers once covered the immediate landscape in the area (Christopherson 2003). The most famous of erratics is probably Big Rock near Okotoks, Alberta (see GCP7ZG), a remnant of the Foothills Erratics Train deposited by the Cordilleran ice sheet approximately 12 to 18 thousand years ago. The Flaxcombe erratic likely dates to this last deglaciation around 12 thousand years ago and was likely carried by the Laurentide ice sheet (Dyke et al. 2003). These two ice sheets covered much of Canada, the Laurentide from the east and the Cordilleran from the west, and met at the Continental Divide.

Historically, many large erratics featured prominently in relation to First Nations history. In some cases, erratics can be the seen as landmark features or even have spiritual connotations. Many erratics are known to be covered in petroglyphs (rock engravings) and pictographs (rock paintings). The Flaxcombe erratic was used for another purpose. Over the years, wild bison herds would use the rock to scratch themselves in order to dislodge hair and insects (Anderson 1998). Centuries of bison have worn a deep grove in the earth encircling the rock. In some places, parts of the erratic have been worn smooth from constant rubbing.

In order to log this cache, email us (through our profile) the answers (do NOT post in your log) to the following:

1. Estimate the size of the erratic in metres.

2. Based on the information from the cairn, what has happened to many erratics on the prairies?

3. What did settlers find on the stone?

4. Post a picture with your log of yourself and your GPS at the cairn with the erratic in the background.

References Cited:

Anderson, F.W.

1998 81 Interesting Places in Saskatchewan. Gopher Book No. 3. Gopher Books: Humboldt.

Christopherson, R.W.

2003 Geosystems: An Introduction to Physical Geography. Fifth Edition. Pearson Education, Inc.: New Jersey.