A debris cone consists of debris deposited in a conical shape with a surface slope greater than 10 degrees (perpendicular to contours), usually transported by small streams or snow avalanches.
[2] A debris cone is commonly made when rock from a high-up narrow slit or gorge falls into a flat-floored valley.
Here the soil and loose materials are deposited, leaving a mound of conical shape.
While an alluvial fan is formed when flowing water rushes rock and soil down a slope, debris cones come from one of several dry processes known as mass wasting.
Similar deposits can also be found lying on boulders moved by a landslide, or on a glacier, where a cone-shaped mound of ice or snow may be covered with a veneer of debris thick enough to prevent the underlying ice from melting.