Who’s been chalking our sidewalks?

When I walked into work this morning, I noticed something odd: all the sidewalk tiles were outlined with ragged, chalky lines. It sure was a lot of work to go to to get such a minimal, if striking effect.

The explanation was obvious (look at the top right tiles), and was clearer a little later when I came home. Melting snow and ice filled the cracks first, and then there’s a race between slow diffusion of meltwater and evaporation due to the sun, leaving precipitated salts at the leading edge of the front.

It looked cool, anyway.


  1. davidc1 says

    Pah ,god did dun doed it .What an inquiring logical mind you have Doc ,if only more American and British people were like you we would not be ruled by the snatch snatcher and bojo
    Talking of bojo England is under water at the moment,and the cry has gone up” Where is the Prime Minister ?”.

  2. chigau (違う) says

    We get that here, too. Mostly due to the massive quantities of ice-melter scattered on the sidewalks.

  3. jrkrideau says

    @ 5 chigau
    We get that here, too.
    Must be nice. Here the city seems to despise pedestrians. Their motto is “Slip-sliding away”.

  4. DanDare says

    And once again science proves that watching paint dry CAN be interesting. I say again because there was a science paper in the 80s about precipitation rings from coffee spills and paint splodges.

  5. says

    That reminds me of the time I watched flies fuck. It’s a lot more interesting than people give it credit for.

  6. peterellis says

    Saw something similar – but more biological – in Cambridge (UK) a few years back. There was a major episode of flooding, and when it receded, all the paths across the green spaces with edged with small drifts of drowned earthworms.

  7. says

    @5 chigau. That makes sense.
    @8 jrkrideau Buy some YakTrax and wear some non skid boots. you get used to it or you get a bruised tailbone.

  8. A. Noyd says

    I recognized it for what it was immediately because I see the same phenomenon at the end of every day that I wear a dark-colored undershirt in summer.

  9. chigau (違う) says

    jrkrideau #8
    I would prefer to do my old lady shuffle/hobble over putting that icemeltershit into the river.

  10. says

    @14 chigau
    Precisely the reason we don’t salt our roads here in Oregon. Salt is bad for the rivers, bad for the land and bad for the water table.

  11. jrkrideau says

    @ Ray Ceeya
    Not sure of the brand name but I have had the equivalent of YakTrax for years.

    Now try getting an electric wheelchair over a four foot pile of snow the city has left at the corner of the street. It took four fairly large men ( I think I was the smallest at 5 foot 8) to wrestle the blasted thing onto a relatively clear bit of sidewalk.

  12. jrkrideau says

    @ 14 chigau
    Sand would be nice. Even timely snow removal.

    I have friends who do not do well with glare ice and three or four foot snow banks to clamber over at every intersection.