Summer Science II: Night of the Concave Earth
Rock Hunt
The area around Lakefield has a rich geological history, making it a prime hunting ground for geologists and mineral collectors. The town itself lies on a thick layer of limestone, the sedimentary rock left behind after the seas receded hundreds of millions of years ago. The surface, however, bears the telltale scars of glaciation--drumlins, eskers, spillways, moraines, and more--as great ice sheets melted away 10,000 to 14,000 years ago. And the ancient, mineral-rich igneous rocks of the exposed edge of the Canadian Shield are less than an hour's drive away.
So, it wasn't surprising that field trips played a major role in the half-week that we spent studying geology (week of July 12, 1965). Our jovial leader was Dr. David M. Baird of the University of Ottawa.
Fossil hunting at the abandoned Lakefield quarry, once operated by the Canada Cement Company.
On our Saturday field trip, we initially traveled along hilly, often unpaved roads, experiencing firsthand the drumlins and other glacial features of the terrain. We stopped at a newly opened gravel pit to observe the layers of glacial silt and sand deposits exposed along the pit's sides.
The bus took us to the town of Marmora and the nearby Marmoraton Mine, a huge open-pit mine for extracting iron ore (mainly magnetite). The mine was hundreds of feet deep, partly because the top 100 feet of limestone had to be removed to even begin getting at the ore.
Our bus carried us more than 500 feet down to the lowest level of the Marmoraton Mine, a source of iron ore.
We heard a description of how the mine operates, then were free to scramble up heaps of rock in the middle of the mine to look for mineral samples. We were not allowed to venture near the exposed faces, however, because of the dangers posed by cascading loose rock.
Exploring a rock heap at the Marmoraton Mine.
I came away with several nice rock samples, including one bearing a cluster of garnets and calcite crystals.
After the mine visit, we stopped for a roadside picnic lunch. Inevitably, perhaps inspired by a session on social psychology earlier in the week, many of us started an impromptu experiment of waving at passing vehicles to see if drivers or passengers would wave back.
Blurry photo (sorry) of the picnicking group waving to passing vehicles.
Our next major stop was a nepheline syenite quarry, source of a mineral used in the manufacture of glass and ceramics. Nepheline syenite is a feldspar-like rock that looks a bit like granite, but lacks the quartz typically found in granite.
Visiting a nepheline syenite quarry near Havelock, Ontario.
As we explored the two levels of the quarry, we found a variety of minerals, ranging from nepheline itself to biotite mica, magnetite, pegmatite, and sodalite.
Collecting samples of nepheline and other minerals.
I found the entire sequence of geology lectures and field visits fascinating. In his guest lecture earlier in the week, Dr. Robert Uffen of the University of Western Ontario had introduced us to the startling idea that Earth's magnetic field may have fluctuated in the past, at times reversing or disappearing entirely--with potentially dire consequences.
In his lectures, Dr, Baird often emphasized critical analysis. One of our exercises was to watch the well-regarded National Film Board of Canada movie "Universe" to see if we could detect any inconsistencies or problems. Are the clocks right? Is it actually sunrise or sunset in the morning scene? How were the closeups of comet tails done? How accurate are the closeup images of the planets? And more.
Another session involved taking a close look at sand and what it reveals about an area's geological history. Of course, that meant an afternoon trek down to the beach to examine the sand on the shore and ripple patterns in the shallows.
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