A canyon on the ocean floor at which crust bends downward is called a subduction zone.

Here's why:

* Subduction Zones: These are areas where one tectonic plate (the denser one) slides beneath another. This process creates a deep trench where the descending plate bends downward.

* Oceanic Trenches: These trenches are the deepest parts of the ocean and are a defining characteristic of subduction zones.

* Canyon Formation: While subduction zones are not technically canyons in the same sense as those found on land, the downward bending of the crust creates a steep, often canyon-like feature along the edge of the descending plate.

Let me know if you'd like to know more about subduction zones or other ocean floor features!