A Steady Chalk Line

I trotted down the sidewalk past the market to explore the public library's wide courtyard! On the third stone step, a child had abandoned a thick piece of yellow sidewalk chalk, perfectly cylindrical and teetering on a slight slope. Every rumble of a passing bus sent it rolling dangerously close to the deep drain grate! I planted my paws firmly, watching the arc of its roll. Stepping up, I leaned in with my snout and nudged an upright discarded bookmark flat into the dust, then pressed the chalk against the raised stone riser. It locked right into the stone groove, completely still and safe from the grate!