Markings on the ground tell a story.
An imprint in the pavement is a registration or an index but it's there all the time, unlike a shadow, that is ephemeral.
Some markings are made by people writing and drawing on still-wet concrete.
Markings register different eras of settlement and construction. Some are traces: different kinds of weathering produced by flows of water, vehicles, and pedestrians, the erosive force of storm water runoff that makes something happen between the pavement of the sidewalk and the curb, which are usually, but not always, separate pieces. Patterns of wear at crosswalks register and make visible forces that belong to different ecological and social systems.