The Churchill Quartzite

Along the cove beside the airport, the quartzite seems to go on forever.

This land has bones that are deep and old, bones that give it shape and substance. To the north is the blue water of Hudson Bay, to the south an endless low expanse of muskeg and black spruce, but here at Churchill the sculptured quartzite makes a landscape that might have been imagined by Henry Moore. This hard, resistant stone forms ridges that parallel the bay shore for kilometres east of town, abut the river mouth, and shape the west side of the river for some distance upstream. The dark, sensual Churchill quartzite is omnipresent here, but is not seen anywhere else in northern Manitoba.

Variable patterns of weathering along a quartzite scarp

 Many early visitors to the Churchill River remarked on the stone, and it was first described and named by the pioneering geologist Robert Bell in 1880. Although it has been known for such a long time, it has apparently never received the detailed scientific description that would permit formal formation status. We can talk about the “Churchill quartzite” and every geologist who has visited the region will know what we mean, but we can’t use “Churchill Quartzite” as a proper name.

Quartzite spine of the shore just east of Churchill

Scientifically speaking, the term “Churchill quartzite” is also somewhat of a misnomer, since the rock is apparently closer to being a metagreywacke. A quartzite is a sandstone composed of quartz grains, while a greywacke can be considered a dirty sandstone, its quartz content diluted by rock fragments and minerals such as mica. The “meta-” part of the name simply means that it has been modified by heat and pressure deep within the Earth. Regardless of accuracy, “Churchill quartzite” is what it is generally called, and “Churchill metagreywacke” is not the sort of term that slips comfortably from my mouth during casual conversation.

Many quartzite surfaces exhibit a fine natural polish. Note the angled cross beds in the foreground.

 Churchill quartzite was initially formed as a sedimentary rock during the Proterozoic Eon, some 1.8 billion years ago, back when this area was covered by large rivers that flowed from mountains. The cross beds that can be seen in the quartzite in some places are evidence of sediment deposition by flowing water. The sediment became hard rock, which in time was buried deep beneath overlying strata. There, it was subjected to the heat and pressure that welded the grains together, endowing it with an almost superlithic toughness. And again time passed, such an immense amount of time that the nearby mountains were eroded flat by water, wind, and glacial ice. Those mountains now lie beneath muskeg, while the more resistant quartzite remains as the only bedrock relief for kilometres around.

In a few places, pale brown Ordovician carbonate sits directly against the quartzite

Although the quartzite is so obvious here, it is not the only bedrock in the Churchill area. Around the edges of the quartzite ridges, one can see patches of fossil-rich Ordovician and Silurian rock. These sedimentary rocks, at about 435-445 million years old, could be considered relatively recent additions to the landscape of this area. In a few places they sit immediately adjacent to the quartzite, resting gently against surfaces that had already been exposed to erosion for thousands of millennia.

Water collects in low places across the impermeable bedrock, forming small ponds that are home to a variety of plants and animals.

Walking over the quartzite is like passing across the surface of an ever-changing sculpture. The stone may be smooth and regular, but there can be unexpected turns. Here, a vein of white quartz blazes across a vertical rock face in the sunlight. There, you discover a hidden crevice too deep and wide to cross, and must retrace your steps. Deep in the bottom of that crevice is the last surviving bit of shade-protected snow, even though it is late June. Beside the snow lies a patch of bones and feathers, the remnants of someone’s meal (but whose?). The old quartzite surfaces are covered with a Rorschach test of lichens: grey, green, black, yellow, and most wonderfully, orange. On this dry day they may crunch under your feet if you are not careful, but beware if it should start to rain or mist. You will no longer be able to  gaze across the landscape, but must place each foot with the utmost caution or the greased lichen will pull that foot from under you, and you will find yourself landing on your pack (if you are lucky) on the hardest rock you have ever had the misfortune to encounter.

Samuel Hearne's 18th century signature is one of the pieces of historic graffiti decorating the quartzite at Sloop Cove, across the river from Churchill.

(to make this piece reasonably accurate, I was glad that I could refer to L.A. Dredge’s (1992) Field Guide to the Churchill Region, Manitoba : Glaciations, Sea Level Changes, Permafrost Landforms, and Archaeology of the Churchill and Gillam Areas)