More than 5,000 placard-waving activists gathered Saturday in Burnaby, B.C., to voice their opposition to the federally approved expansion of Kinder Morgan's Trans Mountain pipeline.

The protest comes on the heels of an Alberta-imposed ban on B.C. wine, which was later rescinded, after B.C. said it would restrict the flow of bitumen though the pipeline until more research was completed into pipeline safety and spill response.

In downtown Vancouver, a couple hundred others held their own pro-pipeline rally.

But what fuels a mass gathering like Saturday's — and what gets people so riled up about bitumen transport, anyway?

UBC sociology professor David Tindall, an expert on social movements, met CBC's On the Coast host Gloria Macarenko to try to answer these questions.

UBC professor David Tindall studies social movements. (Supplied by David Tindall)

How did the weekend's events stand out?

I think this was one of the biggest recent protests, at least on the anti-pipeline side.

In the social movements literature there's a scholar named Charles Tilley who has talked about a concept called "WUNC" — which is kind of a funny name, but it refers to worthiness, unity, numbers and commitment.

To some extent what happened on Saturday is a reflection of that.

Worthiness, such as who was involved in the protest, like Aboriginal leaders. Unity, [as in] the types of songs and signs. Numbers, [meaning] the 5,000 people who showed up, and commitment — this is something that's been going on for some time, in all kinds of weather.

So where does WUNC fit in with the pro-pipeline protest?

I think the folks who have mobilized against the pipeline are much more committed and feel much more strongly than perhaps some rural folks in B.C. who would like to see a pipeline, but are not willing to drive down to Vancouver and get involved in this kind of thing.

Some Canadians rallied in support of the pipeline expansion on Saturday. (Darryl Dyck/Canadian Press)

A few people did come from Alberta for the pro-pipeline protest. How far-reaching do you think this debate is?

The debate goes across the country. There are regional patterns.

I've done survey research on this — certain provinces like B.C. and Quebec are much more concerned about this issue, and much more opposed to the pipelines.

Alberta is often in support of it, as well as the other prairie provinces.

Some anecdotal evidence: if you look at what happened in social media in recent weeks, there was a lot of activity about the wine ban in Alberta with environmentalists and activists in other provinces such as Ontario and Quebec chiming in.

I think it's something that people are paying attention to, although it's more likely you're only going to see people on the streets in B.C.

Accusations about foreign funding have been lobbed at these anti-pipeline protesters, saying these groups aren't exactly 'grassroots.'

I would start off by saying this is mostly a red herring. In environmental disputes you often hear this sort of thing, which pits environmental groups against companies.

You often hear the claim that environmental groups have unlimited resources. The opposite is true — most groups are running on a shoestring.

Saturday's protest against the Kinder Morgan Trans Mountain pipeline expansion in Burnaby, B.C., drew many thousands. (Darryl Dyck/Canadian Press)

What do we know about who's organizing the pro-pipeline side?

There may be parallels to what happened In the 1990s.

[Pro-industry events] were organized at one level, really, by industry. Then they were made to look as if it were a grassroots type of thing.

What impact could these protests have and should governments be paying attention?

The B.C. government should be paying attention, and I think they are.

On a federal level, the Liberal government, I think, has miscalculated the level of commitment in B.C. I think they're going to lose some seats in the next election.

This interview has been edited for clarity and length.