Chalked tributes to Canadian politician Jack Layton in August 2011. Randy Risling/ Toronto Star.

In July, when I launched my Pavement Appreciation website, many people emailed to tell me about their own work, suggest references, or alert me to websites and pavement occurrences. My thanks to you all. A number of you told me about recent events where acts of defiance or public memorialization had been accompanied by pavement chalking.

For example, in July Occupy L.A. used the popular Downtown L.A. Art Walk as a stage for their own ‘Chalk Walk’ but things got out of hand the moment the first chalker was arrested.

Some weeks later Los Angeles artist Alex Schaefer deliberately chose to chalk protests against the collusion between banks and the state as an act of civil disobedience, and ended up in handcuffs.

Such events reminded Jacob Miller of the time in 2009 when he was arrested for protesting about the commercialization of higher education by chalking on University of Arizona sidewalks where he was a graduate student.

A quite different event occurred in Nathan Phillips Square, Toronto, after the death of Jack Layton, well-respected and much-liked leader of the left-leaning federal National Democratic Party in August 2011. What began with a single chalked tribute on a wall became a spontaneous outpouring of public grief.

And in an act of memorialization, on 25 March each year in New York volunteers fan out across the city to inscribe in chalk the names and ages of the 146 victims of the infamous 1911 Triangle Shirtwaist Factory fire in front of their former homes.