A fire edge that crosses a control line or natural barrier intended to contain the fire.
Slop over is a term used by firefighters to describe a situation when a fire crosses an intended control line or natural barrier. There are several common ways a fire can breach the line or barrier to form a slop over: direct flame contact across the barrier, a short-range spot fire from lofted firebrands, rollout of burning debris, a falling burning tree, or fire spread across the barrier via a small piece of burnable material such as a root, stick, or area of duff. A slop over is differentiated from a spot fire in that a slop over is connected to the main fire while a spot fire is not connected by burned area to the main fire. The designation of a slop over compared to a spot fire would typically be done at the time of discovery of the breach of the fireline. And so a short-range spot fire could go undiscovered and eventually grow to connect to the main...