I believe Calcareous is not a hydrogenous sediment. Hydrogenous sediments are example of marine sediments that are formed directly from chemical processes in sea water. They include, manganese nodules, phophorites, metal sulfides, evaporites and carrbonates. In shallower areas, such as on continental shelves and near islands, rock salt, calcium salts and sulfates may settle on the ocean floor.
Physical change. Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. ... Physical changes occur when objects or substances undergo a change that does not change their chemical composition.
