From MarineSpecies Introduced Traits Wiki
The extensive, gently sloping or nearly level region of the ocean floor from about 2,000m to 6,000m depth.
The upper abyssal plain (2,000–4,000m) consists chiefly of graded terrigenous sediments known as turbidites.  It is sometimes also referred to as the continental rise.
- Pinet P.R. 1998.Invitation to Oceanography. Jones and Barlett Publishers. p. 508