The BEST definition of the outer edge of the continental shelf is that point where the seabed slope abruptly steepens, marking the transition from the relatively shallow shelf to the much deeper continental slope.

Here's why:

* Shelf Break: This steepening is known as the shelf break. It's a significant geological feature, often accompanied by a change in sediment type and marine life.

* Depth: While the depth at the shelf break can vary, it's generally around 140 meters (460 feet). However, this depth can be shallower or deeper depending on the specific location and geological history of the region.

* Continental Slope: The shelf break is the boundary between the relatively flat continental shelf and the much steeper continental slope that leads down to the abyssal plain.

Let me know if you have any more questions!