Before revision: In this classification, ridges are in the following subgroups : Coastal Marine and Estuarine, Lacustrine, Glacial, Volcanic and Hydrothermal, Tectonic and Structural, Slope, and Erosional .
After revision: In this classification, ridges are found in subgroups that include Aeolian,subgroups Coastal Marine and Estuarine, Lacustrine, Glacial, Volcanic and Hydrothermal, Tectonic and Structural, Slope, and Erosional .