Threading a Needle in a Haystack

I tried posting photos last night and I "broke the bandwidth" here at the mining camp. While they have internet access, it's not good enough for photos.

Last night, it rained like like Noah was building an ark, but our Weatherhaven hut kept us nice and dry, and the diesel heater was so hot I didn't even need to zip up my LL Bean sleeping bag. This morning, it's clearing and chilly. Lovely weather for what we're doing, flying around in a helicopter and looking at rocks.

I spent a lot of time flying around in a helicopter and looking at rocks yesterday. Mark, who is the head geologist and co-founder of the company (and a very nice guy), is taking us to things he thinks are interesting.

We're looking at diamondiferous kimberlite, i.e., the kind of rock you find diamonds in. The base rock surrounding it (and making up this corner of Canada) is some of the oldest rock in the world – three billion years old. The kimberlite is much younger – 500 million years old or so. The kimberlite formed much deeper in the Earth and erupted in carrot-shaped cones through the surrounding base rock.

So the team here is looking for a very small amount of rock in a much bigger area to start with. But we also have to take into account the glaciers. A little over 10,000 years ago, this part of Canada was covered in a kilometer-thick sheet of ice. It scraped off the top of the kimberlite eruptions and dragged the rock along, dumping it here and there as the ice retreated.

This scattered kimberlite is called “float” and this is the first stuff that the diamond hunters find. They then do surveys with magnetics and till (soil) samples to hunt down the main areas of interest, and then they drill to find out if they’re in the right spot.

As the glaciers melted, huge rivers formed. I told you in an earlier post how the Hay and Slave rivers formed and filled the glacier-carved basin we now call Great Slave Lake. Well, the same action was going on around here. Yesterday I stood on a bluff overlooking an old riverbed that would have rivaled the mouth of the mighty Mississippi in its day. 10,000 years ago, huge rivers merged and thrashed around, dropping huge amounts of clay silt that now lay in giant forms across the landscape. This clay obscures the results of the airborne surveys that the companies do in this area, hiding kimberlite that might be underneath.

Other kimberlite is probably hidden under lakes that have formed in the last 10,000 years. You can drill-sample it in the winter by parking a drill rig right on the ice and drilling down. But no way in heck are you going to drain a lake on a hunch.

As one geologist explained to me last night, it’s not like they’re just looking for a needle in a haystack. They’re trying to thread that needle in the haystack.

Time to get cracking. I'll write more later.

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