CONVERSATIONS For the Love of Rocks

Every three or four months, Bill Ayrton, P.Geol. offers his “Building Rocks of Calgary Geological Walking Tour.” Born in Ireland, schooled in England, and with degrees from the U.S. and McGill University, Ayrton landed in Calgary in 1963 and worked for the oil and gas industry. About 12 years ago he started Ayrton Exploration Consulting and advises clients on exploration and buying and selling oil and gas properties.

But Ayrton also does a lot of teaching — in particular for non-geologists who need some knowledge of the subject for their work in the oil and gas business.

Of all the courses Ayrton runs, the most unusual are the “field trips” he leads in downtown Calgary. Taking along about 20 or 25 people, and armed with a hand magnifying glass, Ayrton goes on a hunt for rock samples and finds them in abundance in the city’s soaring office towers and other buildings.

Q. How did the downtown geology field trips start?

I got a call from the Western Inter-University Geosciences Conference to lead a field trip for them when they came to Calgary. At first I thought of taking them up to Banff, but when they told me they were coming in January, I realized that wouldn’t work. So the idea came that I should put a field trip together around downtown Calgary and look at rocks.

I love rocks and like looking at them. On building walls, either on the exterior or in the lobbies, the rocks are cut and often polished, so you can see everything. In fact you can see them better on buildings than you can where we normally look at them, as in outcrops in the mountains, for example.

Q. What do you see on the tour?

First I ask the participants to identify what type of rock it is. Is it a limestone, or a shale, or a granite? Then we try and get our noses right up to have a look. Occasionally I pour some acid on the stone as well.

Q. Are you allowed to do that?

Outside nobody bothers, but inside the lobbies the securiguys don’t like it. I use 10% hydrochloric acid solution. It doesn’t do damage, but when you put it on a limestone it fizzes aggressively.

One of the best examples is Tyndall limestone. It is quarried in Manitoba and is probably the most popular building stone in Western Canada. Builders call it Manitoba Tapestry because it’s full of little worm burrows that have a brownish tinge and the rest is a cream colour.

To most people the fossils are the most interesting. You see them on both the outside walls of buildings and particularly inside where the stone is polished. There are football sized corals, and there are 18-inch long squids. What are preserved in the rocks are the shells. They’re long and conical. Some are 400 million years old.

That’s one of the amazing things to people. How on earth can we have such beautiful preservation of the structure of these fossils lasting 400 million years? But they are right there in front of you.

We probably go to 30 locations. They’re not all buildings. We look at some statues built out of rocks. We look at what’s in the flower beds, on the sidewalks, and even what roads are made of. Rocks are all around us.cce