Question

this feature is formed by the erosion of rivers or glaciers before the continental shelf was submerged under water. this feature is a flat - topped submarine volcano is common in the pacific ocean. this feature is a submarine volcano in the abyssal plain. seamount

Explanation:

1. A feature formed by river or glacier erosion before continental - shelf submersion is a canyon. Submarine canyons are carved by these erosive forces and then submerged as sea - levels rise.
2. A flat - topped submarine volcano common in the Pacific Ocean is a guyot. Guyots are volcanic mountains that have been eroded flat at the top and are now underwater.
3. A submarine volcano in the abyssal plain is a seamount. Seamounts are isolated volcanic peaks rising from the ocean floor.

Answer:

1. Canyon
2. Guyot
3. Seamount