Outside the Manitoba Legislative Building, a gentle snow was falling. On the west porch, feather-light Hollywood snow gathered on the statues of Lord Dufferin and General James Wolfe, blanketing them deeply in its fluffy whiteness. In the absence of wind, Dufferin grew a stunning mohawk, a coiffure midway between those of Mr. T and a tamarin monkey. Meanwhile, Wolfe acquired an ermine stole and a layer of striking white lipstick, furnishing him with the mien of a mature Boy George.
This scene was completely mundane and yet wonderfully strange. And it helped to show why these statues have weathered the way they have.
They were carved from Indiana’s Bedford Limestone because it is such a compliant material for stonemasons, but it does not hold up to the fierce Manitoba climate. The Legislative Building was opened in 1920, and since that time the limestone has weathered to the extent that Lord Dufferin has not only received a nose transplant, but he has gained a set of facial tribal tattoos that beautifully match his mohawk (these tattoos represent layering of the limestone’s sediment). The adjacent Tyndall Stone has weathered modestly, so that its dolomitic mottles stand out in bas relief from the softer limestone between.
For both the Bedford and Tyndall stones, visible weathering is concentrated markedly in places where the snow gathers and the rain strikes. In both cases, the weak acidity of rain and snow attacks the limestone’s calcium carbonate, slowly breaking its bonds and washing it away. As our friends Dufferin and Wolfe approach their century, they are not only style icons: they are precisely timed examples of the weathering of natural materials.
For a geological explanation of the Bedford Limestone, see the quotes from Brisbin et al. (2005) below. For the geology of the Legislative Building, the entire reference in pdf form can be found here.
“Bedford limestone was used for most of the statuary of the Legislative Building. … Decades of weathering have developed some inter-granular relief on the surfaces of the exterior carved works. … The Bedford Limestone now is formally known as Salem Limestone, but also simply as Indiana limestone. It was quarried in south-central Indiana, between Bloomington and Bedford. It has been used as a dimsnsion stone for over 100 years because of its uniform texture and ease of working. It is fairly soft and can be shaped easily with carving tools.
The limestone is described as a cross bedded calcarenite that is medium to coarse-grained, tan, grey tan, and light grey, porous, and fairly well sorted. it occurs in exceptionally thick beds. Individual grains are mostly microfossils (including the foraminiferid Globoendothyra baileyi), macrofossil fragments, and whole diminutive forms of macrofossils. Coated grains and oolitic textures are also common …
The stone was deposited in an epi-continental, warm-water, marine environment during Mississippian time. The fine-grained oolitic texture suggests that wave action and marine currents winnowed the fossil fragments to a uniform size …” (Brisbin et al., 2005, p. 189)
Brisbin, W.C., G. Young, and J. Young. 2005. Geology of the Manitoba Legislative Building. Geoscience Canada, 32(4), p. 177-193.
© Graham Young, 2012