The edge of a carbonate platform may be marked by an abrupt change in slope or there may be a lower angle transition to deeper water facies.
The front of a reef can form a vertical ‘wall’ and along with other slopes too steep for sediment accumulation are by-pass margins.
Sediment accumulates at the base of the slope, brought in by processes ranging from large blocks fallen from the reef front to submarine talus slopes, slumps, debris flows and turbidites.