On our recent visit to Botswana we aranged to stay with a friend of a
friend in Francistown, the mining center in the northern part of the
country. Charles Byron, our host, met us in town and led us out
to the farm he and his wife owned, about 10 km NW of the city center.
As we were pulling in past the house, we noticed a 2-seat kayak
on the lawn - an old, faded kayak, orange on top and white on the
bottom. Memories started churning , but our attention was
diverted by unpacking and being handed a welcoming glass of wine.
The next day, however, Tom was able to ask our host about
the kayak and where he had gotten it. Turns out that when the
local office of Falconbridge Explorations was closing, Charles put in a
bid and ended up getting all the company's files. While
collecting this windfall, he happened to notice the prow of a kayak
sticking out of a dumpster outside the office (not an everyday
occurrence on the edge of the Kalahari). In response to his
questions, he learned that the kayak had been lying around the office
for years, that it was still in good condition but wasn't worth the
cost of shipping back to the home office, and that he could have it if
he wanted. So it ended up at his place where family and
friends used it to challenge the nearby river when it was in flood.
With a chuckle, Tom informed his host that he had purchased that very same
kayak nearly 30 years before as a diamond exploration tool.
Back in 1976-77, Tom worked as a field geologist for Falconbridge Explorations
(Botswana) Ltd. The company had just flown an aerial magnetic
survey of its prospect area in the north-central part of the country
and detected a number of "paired bullseye" anomalies in the area east
of the Makgadikgadi Pans. In this part of Africa, patterns like
that mean kimberlite pipes - and diamonds.
The next step was to confirm the size, shape, and intensity of the
magnetic anomalies with a higher resolution ground-based survey.
This involved identifying the approximate location of the
bulls-eye anomaly on air photos, and establishing a survey grid on the
ground . For the largest and most attractive of the anomalies,
the grid extended from the shoreline on the northeastern margin of Sua
Pan out across a small [dry] embayment. The grid was
marked out by meter-long stakes cut from the local mopane scrub and
hammered into the ground every 50 meters along a grid line. This
particular grid took a week or more for the crew to survey and put
all the stakes in - then it was time to head into town for payday and
re-supply. It was March, and while we were in town the rains came - lots of rain.
By the time we were able to get back out to camp, the Semowane River
had come down in flood, and the little embayment had over a meter of
water in it. We stood on the shore line and gazed at all the
mopane stakes floating in the breeze. So, here's a problem; the
most significant target of the lot, and no way to collect meaningful
data until the next dry season - months away. That was when Tom
had a flash of inspiration. In the window of Haskins' hardware
store in Francistown was a 2-person kayak, intended for local anglers
to use on the nearby reservoir. He got on the radio phone
to Johannesburg and "floated" his idea by the chief geologist.
Would he be willing to authorize a 200 Rand (about US$270)
purchase on the possibility of getting the desired information in the
next few days? It was actually a no-brainer; the cost of the
kayak was less than the cost of keeping the exploration camp in the
bush for one day.
Thus, bright and early the next day Deb and I strapped a shiny new
kayak to the roof rack of our Land Rover and headed off to the pans.
The plan was for Deb to sit in the front cockpit with the
magnetometer, set on automatic recycle, nestled between her feet.
As each number came up she would record it on a notepad. Tom
would sit in the back and attempt to paddle a straight line at a
constant speed against a stiff cross wind. To give us a visible
target to aim for, we parked a truck on each side of the embayment at
the point where the surveyed grid lines intersected the shore.
And then it was off - heavy aerobics in the rear seat and studied
concentration in the front. Back and forth, ten lines, twelve,
done. Returning to camp, Tom transfered the magnetometer readings
to the base chart of the grid - spreading the data points evenly along
each line. The resulting contours showed an absolutely beautiful
double bulls-eye, in gloroius resolution. Two days later the data
was in the hands of the company's geophysicist, and in a month we had a
drill rig on site.
In the end it wasn't clear what we had found, though the suspicion was
that we had encountered a carbonatite pipe rather than kimberlite
[carbonatites are an unusual igneous form of calcium carbonate found in
association with deep crustal rifts]. However, the concept of
kayak-borne surveys had been proven successful.