My raleigh scorpion currently has the original tyres, which are starting to wear out. The current tyres are fairly knobbly, but with a smoother central strip. One of the routes I sometimes take to university follows the canal towpath, which is just a bare dirt trail that's been worn into a path by use, with a few tree roots sticking up here and there. It gets very muddy in the wet, so usually I only take this route when the ground is dry. Other than that, my commute is all on-road. I'm looking for a set of replacement road tyres that can handle a bit of use on dirt or light snow.

I was looking at Schwalbe city jet tyres, since they're relatively cheap and available in 26x1.9 which matches the current tyres, but wasn't sure how effective they'd be on the towpath.
Anyone have any good suggestions?

Cheers

Pete