n. Bulk depth of a fuel layer.
Fuelbed depth usually refers to the depth of the surface fuel layer. Albini (1976) suggests fuelbed depth be measured perpendicular to the slope. Such a measurement is valid if the corresponding fuel load is measured along the slope (as assumed for the Rothermelís  surface fire spread model). For fuel loads corrected to a horizontal plane, fuelbed depth should be measured as a vertical distance so that bulk density remains constant.