The Land Beneath our Feet

Three of the Inuit homelands: Nunavut, Nunavik, and Nunatsiavut, are all located upon the oldest rocks on the planet: the Canadian Shield. The Canadian Shield is the original core of the North American continent. The formation of the Shield involved the collision and build-up of a large number of rock plates, beginning more than three billion years ago.¹ Originally consisting of mountain chains up to 12,000 m high, over geologic time, the mountains eroded away. The main component of the Shield is granite. Granite was formed deep in the Earth as a red-hot molten mixture (magma). As it cooled, minerals of different chemical composition crystallized out (Fig. 1). In the granite sample shown, black, grey, pink, and colourless crystals can be seen. Such large crystals indicate that the magma must have cooled slowly, deep within the mountain core, giving time for the crystals to grow.

FIGURE 1 
Crystals of the different chemical components in a sample of granite, Nueltin Lake; Nunavut. Credit: NRCan Photo Collection

There is a particular interest in the rocks found on the north-eastern shore of Hudson Bay, 40 km south of Inukjuak, Nunavik. Using the two dating methods described below, the rocks of the Nuvvuagittuq greenstone belt (Fig. 2), are at least 3.8 billion years old!² This makes them amoung the oldest rocks on the planet.

FIGURE 2
A view across the at least 3.8 billion-year-old rocks near Inukjuak, Nunavik. Source: https://www.nsf.gov/news/news_images.jsp?cntn_id=112299&org=NSF; Credit: Jonathan O’Neil

Dating the age of rocks

How do we know how old the rocks are? To accomplish this, radioactive dating is used. Each radioactive isotope has a specific half-life – the time it takes for half of that isotope to change into another isotope – often of a different element. One useful decay for determining the age of rocks is that of radioactive samarium-147, which changes to neodymium-143 at a rate of one-half every 106 billion years. Therefore, a rock can be dated by measuring how much of its original samarium-147 content has changed into neodymium-143.

However, scientists are cautious. We should always try and find more than one way of determining the age of rocks. A second route is the transformations of the radioactive uranium-238 to lead-206. This is not a single decay step but a series of steps with an overall half-life of 4.5 billion years (Fig. 3). Thus we can compare the results from these two methods (and those of others) to ensure the age is valid.

FIGURE 3
The common decay sequence of uranium-238 to lead-206. Credit: https://www.epa.gov/radiation/radioactive-decay

When measuring the proportion of lead, how can we be sure the lead has all come from uranium and not some fraction which was already in the rocks? If the rock contains zircon crystals, then we can determine the date at which the zircon started to solidify very accurately. Zircon is the mineralogical name for zirconium(IV) oxide, an extremely hard colourless solid. A beautiful crystal of zircon is shown in Fig. 4 (the colour is the result of traces of other cations trapped within the crystal).

FIGURE 4
Zircon (zirconium(IV) oxide) crystal, ZrO₂, embedded in a lump of calcium carbonate (CaCO₃). Credit: https://en.wikipedia.org/wiki/Zircon#/media/ File:Zircon-dtn1a.jpg

The crystal lattice contains alternating zirconium ions (Zr⁴⁺) and oxide ions (O^2-) (Fig. 5). With such high charges, the ionic attractions are very strong. In fact, as molten rock cools, zirconium(IV) oxide is the first compound to crystallize out. This happens when the temperature of the molten rock drops below 2,715 °C, causing the constituent ions to be ‘frozen’ into the crystal forever.

FIGURE 5
Crystal packing of zirconium/uranium cations and oxide anions in zircon. Adapted
from: https://ars.els-cdn.com/content/image/
1-s2.0-S0039602813000654-gr1_lrg.jpg

Any uranium ions in the molten rock are present as uranium(VI) ions (U⁶⁺). The U⁶⁺ion is almost the same size as the Zr⁴⁺ion, and some of these uranium ions will become trapped inside the crystal, occupying the space of a zirconium ion. However, any Pb⁴⁺ion in the molten rock is too large to fit into the crystal lattice cavity. Thus any lead found in a zircon crystal can only be the result of radioactive decay. The ratio of zirconium-decayed to lead-formed will therefore give a very precise date of the crystal solidifying.³

Inuksuk

FIGURE 6
Rosalina Naqitarvik sitting on an inuksuk overlooking Ikpiarjuk (Arctic Bay). Credit: Rosalina Naqitarvik

The hard rocks of the Canadian Shield serve one specific role in Inuit life: the construction of inuksuk (plural: inuksuit). Inuksuk is a generic term for carefully stacked blocks of granite, or other indestructible rocks, each with a specific meaning for the peoples living in that locality. A common bond among Arctic peoples from Greenland, across Canada, to Alaska, they have been constructed in varying shapes and forms.⁴ There are over 100 inuksuit located within a few hectares of each other at Inuksualait, Southwest Baffin Island, approximately 90 km from Kinngait (Cape Dorset), Nunavut.⁵ This area is now a National Historic Site.

Inuksuit are reliable message centres.⁶To the travelling hunter, inuksuit were a welcome sight; some described the course to follow, others pointed to good hunting and fishing areas, and some marked where food was cached. They provided purposeful information and assistance to those who knew how to read their forms. Fig. 6 shows an inuksuk on the King George V Mountain, overlooking Ikpiarjuk (Arctic Bay).

An inuksuk can be any shape; a small proportion are in the shape of a human person and these are called an inunnguaq (ᐃᓄᙳᐊᖅ, ‘imitation of a person’, plural inunnguat).⁴ Fig. 7 shows an inunnguaq near Iqaluktuuttiaq (Cambridge Bay).

FIGURE 7
Inunnguag on a promontory overlooking the sea as a navigation aid for Inuit hunters in winter. Credit: Getty Images

To Inuit, inuksuit are embedded in the roots of Inuit society within songs, myths, legends and stories. Archaeological research suggests that some inuksuit were built by the Inuit predecessors, around 4,000 years ago.⁵ The flags of Nunavut and of Nunatsiavut both consist of inuksuk images (Figs. 8a and 8b), indicating its importance in Inuit culture.

Soapstone

Most of the Arctic consists of the very hard ancient rocks which, with few exceptions, such as Ramah Bay chert,⁷ are difficult to transform into any useful function. However, there is one very useful soft rock found in small deposits across the Arctic: soapstone.⁸ Soapstone is a structurally-composite material.⁹ The major component of soapstone is the mineral talc (Fig. 9), which is comprised of layers of silicate ions, SiO₄^4- (yellow tetrahedrons), alternating with layers of magnesium hydroxide, Mg(OH)₂ (blue-green octahedrons). It is the weakness of the chemical bonding between these separate layers that gives soapstone its softness.

FIGURE 9
Crystal structure of the mineral talc.
Adapted from: A.L. Camara, Master’s Dissertation, 2003

The colour of the soapstone depends upon the concentration and identity of impurities in the structure. The colour-centres occur when some of the sites normally occupied by magnesium ions, Mg²⁺, are occupied by other cations, such as chromium(III), Cr³⁺, or iron(II), Fe²⁺. The differences in colours become particularly noticeable when viewing soapstone carvings of different Inuit sculptors. Gertzbein, in their book on the minerals of Nunavut, comments:¹⁰

“The beautiful, bright apple green material from Markham Bay, near Cape Dorset (Kinngait), is in dramatic contrast to the black-and-dark-grey soapstone from around Baker Lake (Qamani’tuaq). Anyone who sees many carvings from around Nunavut can soon learn to identify the unique community from which the rock and the art originate.”

Qulliq

Soapstone has been essential to Inuit life as it can be carved and made into bowls, known as qulliq,¹¹ qulliq were, and are, made in a variety of sizes and shapes (Fig. 10).

FIGURE 10
Qulliq are made in whatever size and shape is required. Credit:https://en.wikipedia.org/wiki/
Qulliq#/media/File:Descriptive_booklet_
on_the_Alaska_historical_museum_
(1922)_(14758775556).jpg)

Filled with seal oil, the flame from wicks in a qulliq was the sole source of heat and light, and it was the only means of cooking food. The wick of the qulliq is made of pualunnguat, Arctic cottongrass (Fig. 11),¹² which is dried and rolled with seal fat.

Lighting and tending the qulliq is another way that Inuit women are passing down the traditions of their ancestors. In contemporary Inuit culture, it is a custom to light the qulliq before ceremonial events. Fig. 12 shows Esteemed Elder Mary Pudlat, an extraordinary Inuit artist,¹³ lighting a qulliq on April 1, 1999, the day of birth of the Territory of Nunavut.

Rosalina reminisces: “My household currently doesn’t have a qulliq handed down from generation to generation. But my grandma gifted me one when I was 16 years old, and I still have it and cherish it. I plan to pass it down to my future daughters.

I remember my first time lighting one was in high school, being surrounded and taught by respected Elders whom were my Inuktitut teachers. I was nervous at the time, but proud to learn. The flames of the qulliq were nice, bright and orange. I loved focusing on the flames and thinking that that was the only source of light and heat back then.

The next time I lit one was on the high school gymnasium stage when the gym was packed. I was again surrounded by inspiring wise Elders. The feeling I felt was great and they were my role models during that moment.

The memory that I love regarding qulliit was when the oldest Elder of Arctic Bay, Qaapik Attagutsiak, lit some at ceremonies. She is over 100 years old right now. When I used to witness her lighting some, it was so respectful and soothing. The whole building felt at peace as we sit quietly watching her light a qulliq.”

Commentary

In previous articles, we showed that ice and snow were key attributes of the lands of the Inuit. Here, we have shown that the rocks themselves, dating back to the formation of the first continents, are also an integral part of Inuit culture.

References

1. Card, K.D. A review of the Superior Province of the Canadian Shield, a product of Archean accretion. Precambrian Research 1990, 48, 99-156.
2. Wikipedia. Nuvvuagittuq Greenstone Belt. https://en.wikipedia. org/wiki/Nuvvuagittuq_Greenstone_Belt.
3. Darling, J.R., et al. Eoarchean to Neoarchean evolution of the Nuvvuagittuq Supracrustal belt: New insights from U-Pb zircon geochronology. American Journal of Science 2013, 313, 844-876.
4. Wikipedia. Inuksuk. https://en.wikipedia.org/wiki/Inuksuk.
5. Hallendy, N. Tukiliit: An introduction to inuksuit and other stone figures of the North; Douglas & McIntyre and University of Alaska Press, 2009.
6. Heyes, S. Protecting the authenticity and integrity of inuksuit within the arctic milieu. Études/Inuit/Studies 2002, 26, 133–156.
7. Andersen, C.; Rayner-Canham, G. Ramah Bay – 7,000 Years of Aboriginal culture – and chemistry. Chem 13 News, September 2018.
8. Wikipedia. Soapstone. https://en.wikipedia.org/wiki/Soapstone.
9. Naqitarvik, R.; Rayner-Canham, G. Composites in Inuit life: What was old is new again. Chem 13 News Special Edition: Chemistry and Inuit Life and Culture, September 2022.
10. Gertzbein, J. Common Rocks and Minerals of Nunavut; Inhabit Media, 2013, pp. 120-121.
11. Wikipedia. Qulliq. https://en.wikipedia.org/wiki/Qulliq.
12. Wikipedia. Eriophorum_callitrix. https://en.wikipedia.org/wiki/ Eriophorum_callitrix.
13. Paskievich, J. Mary Pudlat, Inuit Art Quarterly. https://www. inuitartfoundation.org/profiles/artist/Mary-Pudlat.