Finding Rocks

All Day:

Finally, now that the maple tree had been removed, the moraine could be leveled. Once Dan and Martin began digging into the dirt, many different kinds of dirt were found. The structure fascinated me to the point of where I have done a little web research. I have been calling the two irregular shaped hummocks on which the house is being built a glacial moraine.

Here is a rendering, created in Bryce, of the building site terrain based on an approximate 2-foot contour map we had created by Northwestern Territories, Inc, the geo-tech company that did our original site survey:

Same image annotated

As I began researching I found that there are two terms for debris left by a glacier: kame and moraine. Kames seem to be more related to melt-water deposits and moraines to the bulldozer effect of the glacier itself. It was a bit confusing, but I finally found a working definition that makes sense for this discussion:

A kame is a steep and sharp hill ridge, caused by the deposit of moraine - the gravel and boulders deposited at the end of a glacier. Moraine is sometimes deposited forming a dam rather than a hilly ridge.… The difference is that moraine describes the deposited material and a kame may result from this deposit.

However the soil got there and whatever it's called, the cutting of the moraine debris revealed several kinds of soil:

• Powdery crushed rock fluff full of organic matter we'll call duff
• Large deposits of several different grades of gravel
• Large pockets of coarse and fine sand
• Minor pockets of silt/clay
• Rocks ranging from basketball sized to over 6 tons, including erratics - boulders made from material different than the local bedrock

We found many rocks in the beautiful soil, mostly basalt - the volcanic bedrock of this area, but also a few erratics of Canadian granite, Cascade Jade, and compressed-ocean bottom shale:

The following video shows the removal of duff, the beginning efforts to cut down of the moraine to form a level building site, and the discovery of many rocks, including an approximately 7-ton whopper that had to be shoved and rolled off the building site. All these rocks and boulders are valuable as landscaping elements and will be put to good use before we are finished.

For those of you with additional interest in the geography of glaciers, here is a great site describing the Cairngorms region of Scotland.